Document:

<PAGE>
                                                                   Exhibit 10.30

================================================================================

================================================================================

                                CREDIT AGREEMENT

                                   dated as of

                                   May 1, 1998

                                      among

                                HAWK CORPORATION,
                                as the Borrower,

                     THE LENDING INSTITUTIONS NAMED THEREIN,
                                   as Lenders,

                                       and

                          KEYBANK NATIONAL ASSOCIATION

                           as the Administrative Agent

                              ---------------------

                                 AMENDMENT NO. 4

                                       to

                                CREDIT AGREEMENT

                                   dated as of

                                 March 25, 2002

                              ---------------------

================================================================================

================================================================================

<PAGE>

                       AMENDMENT NO. 4 TO CREDIT AGREEMENT

     THIS AMENDMENT NO. 4 TO CREDIT AGREEMENT is dated as of March 25, 2002
(this "Amendment") among the following:

                  (i) HAWK CORPORATION, a Delaware corporation (the "Borrower");

                  (ii) the Lenders a party to the Credit Agreement, as
         hereinafter defined; and

                  (iii) KEYBANK NATIONAL ASSOCIATION, a national banking
         association, as the Administrative Agent under the Credit Agreement
         (the "Administrative Agent").

         PRELIMINARY STATEMENTS:

         (1) The Borrower, the Lenders and the Administrative Agent entered into
the Credit Agreement, dated as of May 1, 1998 (as amended and as the same may
from time to time be further amended, restated or otherwise modified, the
"Credit Agreement"; the terms defined therein are used herein as so defined).

         (2) The parties hereto desire to modify certain terms and provisions of
the Credit Agreement, all as more fully set forth below.

         NOW, THEREFORE, the parties hereby agree as follows:

         SECTION 1.        AMENDMENTS.

         1.1. AMENDMENTS TO DEFINITIONS. Section 1.1 of the Credit Agreement is
hereby amended to delete the definitions of "Alternative Currency", "Applicable
Eurodollar Margin", "Applicable Prime Rate Margin", "Borrowing Base", "Maximum
Available Revolving Commitment", "Pricing Grid Table", and "Total General
Revolving Commitment" therefrom and to insert in place thereof, respectively,
the following:

                  "Alternative Currency" means Euros or Dollars.

                  "Applicable Eurodollar Margin" shall mean:

                  (a) for any date prior to March 26, 2002, as such margin shall
         have been determined in accordance with the definition of Applicable
         Eurodollar Margin in effect prior to March 26, 2002;

                  (b) from March 26, 2002 through May 15, 2002, (i) 400 basis
         points for General Revolving Loans, and (ii) 450 basis points for Term
         Loans; and

                  (c) commencing with the fiscal quarter of the Borrower ended
         March 31, 2002, and continuing with each fiscal quarter thereafter, the
         number of basis points determined by the Administrative Agent in
         accordance with the Pricing Grid Table, based upon the

<PAGE>

         Adjusted Leverage Ratio. Changes in the Applicable Eurodollar Margin
         shall become effective on the first day of the month following the
         receipt by the Administrative Agent, pursuant to Section 8.1(a) or (b)
         of the financial statements of the Borrower.

         Notwithstanding the foregoing, unless otherwise agreed by the Required
         Lenders and subject to section 2.8(d), during any period when (A) the
         Borrower shall have failed to timely deliver its financial statements
         referred to in Section 8.1(a) or (b), (B) a Default under Section
         10.1(a) shall have occurred and be continuing, or (C) an Event of
         Default shall have occurred and be continuing, the Applicable
         Eurodollar Margin for all Loans that are Eurodollar Loans shall be the
         highest number of basis points indicated therefor in the Pricing Grid
         Table, regardless of the Adjusted Leverage Ratio at such time. Any
         changes in the Applicable Eurodollar Margin for Loans shall be
         determined by the Administrative Agent in accordance with the above
         provisions and the Administrative Agent shall promptly provide notice
         of such determinations to the Borrower and the Lenders, which
         determination by the Administrative Agent shall be conclusive and
         binding absent manifest error.

                  "Applicable Prime Rate Margin" shall mean:

                  (a) for any date prior to March 26, 2002, as such margin shall
         have been determined in accordance with the definition of Applicable
         Prime Rate Margin in effect prior to March 26, 2002;

                  (b) from March 26, 2002 through May 15, 2002, (i) 275 basis
         points for General Revolving Loans, and (ii) 325 basis points for Term
         Loans; and

                  (c) commencing with the fiscal quarter of the Borrower ended
         March 31, 2002, and continuing with each fiscal quarter thereafter, the
         number of basis points determined by the Administrative Agent in
         accordance with the Pricing Grid Table, based upon the Adjusted
         Leverage Ratio. Changes in the Applicable Prime Rate Margin shall
         become effective on the first day of the month following the receipt by
         the Administrative Agent, pursuant to Section 8.1(a) or (b) of the
         financial statements of the Borrower.

         Notwithstanding the foregoing, unless otherwise agreed by the Required
         Lenders and subject to section 2.8(d), during any period when (A) the
         Borrower shall have failed to timely deliver its financial statements
         referred to in Section 8.1(a) or (b), (B) a Default under Section
         10.1(a) shall have occurred and be continuing, or (C) an Event of
         Default shall have occurred and be continuing, the Applicable Prime
         Rate Margin for all Loans that are Prime Rate Loans shall be the
         highest number of basis points indicated therefor in the Pricing Grid
         Table, regardless of the Adjusted Leverage Ratio at such time. Any
         changes in the Applicable Prime Rate Margin for Loans shall be
         determined by the Administrative Agent in accordance with the above
         provisions and the Administrative Agent shall promptly provide notice
         of such determinations to the Borrower and the Lenders, which
         determination by the Administrative Agent shall be conclusive and
         binding absent manifest error.

                                       2
<PAGE>

                  "Borrowing Base" shall mean an amount not in excess of (a) the
         sum of (i) 85% of the amount due and owing on Eligible Accounts
         Receivable, plus (ii) the lesser of (A) 60% of the aggregate of the
         cost or market value (whichever is lower) of Eligible Inventory, or (B)
         $18,000,000, minus (b) the aggregate principal amount of all Term Loans
         then outstanding, plus (c) $5,000,000.

                  "Maximum Available Revolving Commitment" shall mean at any
         time an amount equal to the lesser of (a) the Total General Revolving
         Commitment and (b) the Borrowing Base.

                  "Pricing Grid Table" shall mean the following pricing grid
         table:

<TABLE>
<CAPTION>
---------------------------- -------------------- -------------- ----------------- ----------------- -----------------
                                                   Applicable
                                 Applicable        Prime Rate
                              Eurodollar Margin    Margin for       Applicable        Applicable
                                     for             General        Eurodollar        Prime Rate        Applicable
                              General Revolving     Revolving       Margin for     Margin for Term     Facility Fee
  Adjusted Leverage Ratio           Loans             Loans         Term Loans          Loans              Rate
---------------------------- -------------------- -------------- ----------------- ----------------- -----------------
<S>                           <C>                   <C>          <C>               <C>               <C>
Greater than 5.50 to 1.00     400 basis points      275 basis    450 basis points  325 basis points  50 basis points
                                                     points

---------------------------- -------------------- -------------- ----------------- ----------------- -----------------
Greater than 4.75 to 1.00     350 basis points      225 basis    400 basis points  275 basis points  50 basis points
but less than or equal to                            points
5.50 to 1.00
---------------------------- -------------------- -------------- ----------------- ----------------- -----------------
Greater than 4.00 to 1.00     300 basis points      175 basis    350 basis points  225 basis points  50 basis points
but less than or equal to                            points
4.75 to 1.00
---------------------------- -------------------- -------------- ----------------- ----------------- -----------------
Greater than 3.50 to 1.00     275 basis points      150 basis    325 basis points  200 basis points  50 basis points
but less than or equal to                            points
4.00 to 1.00
---------------------------- -------------------- -------------- ----------------- ----------------- -----------------
Less than or equal to 3.50    250 basis points      125 basis    300 basis points  175 basis points  50 basis points
to 1.00                                              points
---------------------------- -------------------- -------------- ----------------- ----------------- -----------------
</TABLE>

                  "Total General Revolving Commitment" shall mean $25,000,000,
         or such lesser amount as may be determined pursuant to section 4.2, 4.3
         or 10.2 hereof.

         1.2.     AMENDMENT TO CONSOLIDATED EBIT. The definition of
"Consolidated EBIT" in Section 1.1 of the Credit Agreement is hereby amended
to add the following sentence thereto:

         In calculating Consolidated Net Income for purposes of determining of
         Consolidated EBIT for any period including the fiscal quarter ending
         March 31, 2002, (1) the amendment fee payable in connection with
         Amendment No. 4 to Credit Agreement, dated as of March 26, 2002, among
         the Borrower, the Administrative Agent, and the Lenders (the "Fourth
         Amendment"), (2) the legal fees related to the Fourth Amendment, and
         (3) the fees and expenses related to the Collateral Audit (excluding
         any updates thereto) may be added back to Consolidated Net Income;
         provided that any fees and expenses described in subpart (3) above not
         added back to Consolidated Net Income for the fiscal quarter ending
         March 31,

                                       3
<PAGE>

         2002 may be added back to Consolidated Net Income for the fiscal
         quarter ending June 30, 2002.

         1.3.     AMENDMENT TO ADD BI-MONTHLY BORROWING BASE CERTIFICATES.
Section 8.1(j) of the Credit Agreement is hereby amended and restated as
follows:

                  (j) BORROWING BASE CERTIFICATE. Within 15 days after the
         fifteenth day and the last day of each calendar month, and at such
         other time as the Administrative Agent may request, (i) a Borrowing
         Base Certificate prepared by an Authorized Officer of the Borrower and
         (ii) an Accounts aging report and Inventory report, each in form and
         substance satisfactory to the Administrative Agent and signed by an
         Authorized Officer of the Borrower, provided that the Inventory report
         and the Borrowing Base Certificate with respect to Inventory will be
         updated only for each certificate that is delivered 15 days after the
         last day of each calendar month;

         1.4.     AMENDMENT TO ADD MONTHLY FINANCIAL STATEMENTS AND COLLATERAL
AUDITS. Section 8.1 of the Credit Agreement is hereby amended to add the
following subsections (k) and (l) thereto:

                  (k) MONTHLY FINANCIAL STATEMENTS. As soon as available and in
         any event within 15 days after the last day of each calendar month, the
         unaudited condensed consolidated balance sheets of the Borrower and its
         consolidated Subsidiaries as at the end of such monthly period and the
         related unaudited condensed consolidated statements of income and of
         cash flows for such monthly period, and setting forth, in the case of
         such unaudited consolidated statements of income and of cash flows,
         comparative figures for the related periods in the prior fiscal year,
         and which consolidated financial statements shall be certified on
         behalf of the Borrower by the Chief Financial Officer or other
         Authorized Officer of the Borrower, subject to changes resulting from
         normal year-end audit adjustments.

                  (l) COLLATERAL AUDITS. On or before April 15, 2002 (or such
         later date agreed to in writing by Agent in its sole discretion), an
         audit of the Accounts and Inventory of the Borrower and its
         Subsidiaries, in scope, form, and detail satisfactory to the
         Administrative Agent, performed by a nationally recognized firm (the
         "Audit Firm") acceptable to the Administrative Agent (the "Collateral
         Audit"), the costs and expenses of which shall be paid by the Borrower.
         In addition, on the dates on which the Borrower is required to deliver
         financial statements pursuant to subsection (b) hereof, the Borrower
         shall cause the Audit Firm to complete quarterly updates to the
         Collateral Audit, in each case in form and detail satisfactory to the
         Administrative Agent.

         1.5.     AMENDMENT TO CORRECT PRIORITY DEBT PROVISO. Section 9.4(c) of
the Credit Agreement is hereby amended to delete subparts (A) and (B) therefrom
and to insert in place thereof the following:

         provided that (A) at the time of any incurrence thereof after the date
         hereof, and after giving effect thereto, the Borrower would be in
         compliance with section 9.8, and no Event

                                       4
<PAGE>

         of Default shall have occurred and be continuing or would result
         therefrom; and (B) the aggregate outstanding principal amount (using
         Capitalized Lease Obligations in lieu of principal amount, in the case
         of any Capital Lease) of Priority Debt permitted by this clause (c),
         exclusive of the guarantees by Subsidiaries of the Borrower of the
         Borrower's Senior Notes, shall not exceed an amount equal to the
         greater of (x) $8,500,000, or (y) 10% of the Borrower's Consolidated
         Net Worth as of the end of the most recent fiscal period for which
         financial statements have been delivered to the Lenders hereunder;

         1.6.     AMENDMENT TO LOANS AND ADVANCES TO, AND INVESTMENTS IN,
FOREIGN SUBSIDIARIES. Section 9.5(k) of the Credit Agreement is hereby amended
to delete the reference to "$13,000,000" therefrom and to insert "$17,000,000"
in place thereof.

         1.7.     AMENDMENT TO SHARE REPURCHASES BASKET. Section  9.5(o)(ii)(A)
of the Credit Agreement is hereby amended to delete subpart (1) therefrom and to
insert in place thereof the following:

                  (1) repurchase shares of its outstanding capital stock up to
         an aggregate amount of (x) $0.00 for the period from July 1, 2000
         through March 25, 2002, and (y) $100,000 on March 26, 2002 and
         thereafter.

         1.8.     AMENDMENT TO CASH DIVIDENDS BASKET. Section 9.6 of the Credit
Agreement is hereby amended to delete subpart (iii) therefrom and to insert in
place thereof the following:

                  (iii) the aggregate consideration paid by the Borrower and its
         Subsidiaries for all purchases, redemptions, retirements, or other
         acquisitions of any capital stock of any class of the Borrower is not
         in excess of (A) $0.00 for the period from July 1, 2000 through March
         25, 2002, and (B) $200,000 on March 26, 2002 and thereafter.

         1.9.     AMENDMENT TO LEVERAGE RATIO. Section 9 of the Credit Agreement
is hereby amended to delete section 9.8 therefrom and to insert in place thereof
the following:

                  9.8. LEVERAGE RATIO. The Borrower shall not permit at any time
         the Leverage Ratio to exceed (i) 3.80 to 1.00 on the Closing Date
         through December 30, 1998, (ii) 3.50 to 1.00 on December 31, 1998
         through June 29, 2001, (iii) 4.10 to 1.00 on June 30, 2001 through
         September 29, 2001, (iv) 4.30 to 1.00 on September 30, 2001 through
         December 30, 2001, (v) 5.00 to 1.00 on December 31, 2001 through March
         30, 2002, (vi) 6.90 to 1.00 on March 31, 2002 through June 29, 2002,
         (vii) 6.25 to 1.00 on June 30, 2002 through September 29, 2002, (viii)
         5.65 to 1.00 on September 30, 2002 through December 30, 2002, and (ix)
         4.30 to 1.00 on December 31, 2002 and thereafter.

         1.10.    AMENDMENT TO INTEREST COVERAGE RATIO. Section 9 of the Credit
Agreement is hereby amended to delete section 9.9 therefrom and to insert in
place thereof the following:

                  9.9. INTEREST COVERAGE RATIO. The Borrower shall not permit at
         any time (a) the Interest Coverage Ratio to be less than (i) 2.00 to
         1.00 on the Closing Date through June 29, 2001, and (ii) 1.20 to 1.00
         on June 30, 2001 through September 29, 2001, and (b)

                                       5
<PAGE>

         the Adjusted Interest Coverage Ratio to be less than (i) 2.40 to 1.00
         on September 30, 2001 through December 30, 2001, (ii) 2.10 to 1.00 on
         December 31, 2001 through March 30, 2002, (iii) 1.53 to 1.00 on March
         31, 2002 through June 29, 2002, (iv) 1.71 to 1.00 on June 30, 2002
         through September 29, 2002, (v) 1.80 to 1.00 on September 30, 2002
         through December 30, 2002, and (vi) 2.27 to 1.00 on December 31, 2002
         and thereafter.

         1.11.    AMENDMENT TO FIXED CHARGE COVERAGE RATIO. Section 9 of the
Credit Agreement is hereby amended to delete section 9.14 therefrom and to
insert in place thereof the following:

                  9.14. FIXED CHARGE COVERAGE RATIO. The Borrower shall not
         permit at any time the Fixed Charge Coverage Ratio to be less than (a)
         1.00 to 1.00 on June 30, 2001 through December 30, 2001, (b) 0.83 to
         1.00 on December 31, 2001 through March 30, 2002, (c) 0.72 to 1.00 on
         March 31, 2002 through June 29, 2002, (d) 0.68 to 1.00 on June 30, 2002
         through September 29, 2002, (e) 0.72 to 1.00 on September 30, 2002
         through December 30, 2002, and (f) 0.95 to 1.00 on December 31, 2002
         and thereafter.

         1.12.    AMENDMENT TO REPLACE ANNEX I. The Credit Agreement is hereby
amended to delete ANNEX I therefrom and to insert in place thereof ANNEX I
attached hereto.

         1.13.    AMENDMENT TO FORM OF BORROWING BASE CERTIFICATE. The Credit
Agreement is hereby amended to delete ANNEX VIII therefrom and to insert in
place thereof ANNEX VIII attached hereto.

         SECTION 2.        REPRESENTATIONS AND WARRANTIES.

         The Borrower represents and warrants as follows:

         2.1.     AUTHORIZATION AND VALIDITY OF AMENDMENT. This Amendment has
been duly authorized by all necessary corporate action on the part of the
Borrower, has been duly executed and delivered by a duly authorized officer of
the Borrower, and constitutes the valid and binding agreement of the Borrower,
enforceable against the Borrower in accordance with its terms.

         2.2.     REPRESENTATIONS AND WARRANTIES. The representations and
warranties of the Credit Parties contained in the Credit Agreement or in the
other Credit Documents are true and correct in all material respects on and as
of the date hereof, as though made on and as of the date hereof, except to the
extent that such representations and warranties expressly relate to an earlier
specified date, in which case such representations and warranties are hereby
reaffirmed as true and correct in all material respects as of the date when
made.

         2.3.     NO EVENT OF DEFAULT. No Default or Event of Default exists or
immediately hereafter will begin to exist.

         2.4.     COMPLIANCE. The Borrower is in full compliance with all
covenants and agreements contained in the Credit Agreement, as amended hereby,
and the other Credit Documents to which it is a party.

                                       6
<PAGE>

         2.5.     NO CLAIMS. The Borrower is not aware of any claim or offset
against, or defense or counterclaim to, any of its or any Subsidiary's
obligations or liabilities under the Credit Agreement or any other Credit
Document.

         SECTION 3.        RATIFICATIONS.

         Except as expressly modified and superseded by this Amendment, the
terms and provisions of the Credit Agreement are ratified and confirmed and
shall continue in full force and effect.

         SECTION 4.        CLOSING DELIVERIES.

         Concurrently herewith:

         (a)      the Borrower shall cause each Guarantor of Payment to consent
and agree to and acknowledge the terms of this Amendment;

         (b)      the Borrower shall provide to the Administrative Agent and the
Lenders an officer's certificate certifying the names of the officers of the
Borrower authorized to sign this Amendment and each Guarantor of Payment
authorized to sign the attached Guarantor Acknowledgment, together with the true
signatures of such officers and certified copies of the resolutions of the board
of directors or executive committee of the Borrower and each Guarantor of
Payment, evidencing approval of the execution and delivery of this Amendment and
the Guarantor Acknowledgment;

         (c)      the Borrower shall pay to the Administrative Agent, for the
pro rata benefit of each Lender that signs this Amendment on or before 5:00 p.m.
(Cleveland, Ohio time) on March 25, 2002, an amendment fee equal to 62.50 basis
points times such Lender's Commitment;

         (d)      the Borrower shall pay to the Administrative Agent, the fees
agreed upon by the Borrower and the Administrative Agent and set forth in the
administrative agent fee letter, dated as of the date hereof, executed and
delivered by the Administrative Agent to the Borrower;

         (e)      the Borrower shall pay all legal fees and expenses of the
Administrative Agent in connection with this Amendment and the documents
executed in connection herewith; and

         (f)      the Borrower shall provide such other items and shall satisfy
such other conditions as may be reasonably required by the Administrative Agent
and the Lenders.

           SECTION 5.      MISCELLANEOUS.

         5.1.     SURVIVAL OF REPRESENTATIONS AND WARRANTIES. All
representations and warranties made in this Amendment shall survive the
execution and delivery of this Amendment, and no investigation by the
Administrative Agent or any Lender or any subsequent Loan or other Credit Event
shall affect the representations and warranties or the right of the
Administrative Agent or any Lender to rely upon them.

                                       7
<PAGE>

         5.2.     REFERENCE TO CREDIT AGREEMENT. The Credit Agreement and any
and all other agreements, instruments or documentation now or hereafter executed
and delivered pursuant to the terms of the Credit Agreement as amended hereby,
are hereby amended so that any reference therein to the Credit Agreement shall
mean a reference to the Credit Agreement as amended hereby.

         5.3.     SEVERABILITY. Any term or provision of this Amendment held by
a court of competent jurisdiction to be invalid or unenforceable shall not
impair or invalidate the remainder of this Amendment and the effect thereof
shall be confined to the term or provision so held to be invalid or
unenforceable.

         5.4.     APPLICABLE LAW. This Amendment shall be governed by and
construed in accordance with the laws of the State of Ohio without regard to
conflicts of laws provisions.

         5.5.     HEADINGS. The headings, captions and arrangements used in
this Amendment are for convenience only and shall not affect the interpretation
of this Amendment.

         5.6.     ENTIRE AGREEMENT. This Amendment is specifically limited to
the matters expressly set forth herein. This Amendment and all other
instruments, agreements and documentation executed and delivered in connection
with this Amendment embody the final, entire agreement among the parties hereto
with respect to the subject matter hereof and supersede any and all prior
commitments, agreements, representations and understandings, whether written or
oral, relating to the matters covered by this Amendment, and may not be
contradicted or varied by evidence of prior, contemporaneous or subsequent oral
agreements or discussions of the parties hereto. There are no oral agreements
among the parties hereto relating to the subject matter hereof or any other
subject matter relating to the Credit Agreement. Except as set forth herein, the
Credit Agreement shall remain in full force and effect and be unaffected hereby.

         5.7.     WAIVER OF CLAIMS. The Borrower, by signing below, hereby
waives and releases Administrative Agent and each of the Lenders and their
respective directors, officers, employees, attorneys, affiliates and
subsidiaries from any and all claims, offsets, defenses and counterclaims of
which the Borrower is aware, such waiver and release being with full knowledge
and understanding of the circumstances and effect thereof and after having
consulted legal counsel with respect thereto.

         5.8.     COUNTERPARTS. This Amendment may be executed by the parties
hereto separately in one or more counterparts and by facsimile signature, each
of which when so executed shall be deemed to be an original, but all of which
when taken together shall constitute one and the same agreement.

                  [Remainder of page intentionally left blank.]

                                       8
<PAGE>

         5.9. JURY TRIAL WAIVER. EACH OF THE PARTIES TO THIS AMENDMENT HEREBY
IRREVOCABLY WAIVES ALL RIGHT TO A TRIAL BY JURY IN ANY ACTION, PROCEEDING OR
COUNTERCLAIM ARISING OUT OF OR RELATING TO THIS AMENDMENT, THE OTHER CREDIT
DOCUMENTS OR THE TRANSACTIONS CONTEMPLATED HEREBY OR THEREBY. EACH PARTY HERETO
HEREBY (A) CERTIFIES THAT NO REPRESENTATIVE, AGENT OR ATTORNEY OF ANY OTHER
PARTY HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT SUCH OTHER PARTY WOULD NOT,
IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE FOREGOING WAIVER, AND (B)
ACKNOWLEDGES THAT IT AND THE OTHER PARTIES HERETO HAVE BEEN INDUCED TO ENTER
INTO THIS AMENDMENT BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND
CERTIFICATIONS IN THIS SECTION.

         IN WITNESS WHEREOF, this Amendment has been duly executed and delivered
as of the date first above written.

                                       HAWK CORPORATION

                                       By:  /s/ Thomas A. Gilbride
                                          --------------------------------------
                                       Name: Thomas A. Gilbride
                                             -----------------------------------
                                       Title: Vice President - Finance
                                              ----------------------------------

                                       KEYBANK NATIONAL
                                       ASSOCIATION,
                                         as the Administrative Agent and as a
                                         Lender

                                       By:/s/ Thomas J. Purcell
                                          --------------------------------------
                                       Name:  Thomas J. Purcell
                                             -----------------------------------
                                       Title: Senior Vice President
                                              ----------------------------------

                                       NATIONAL CITY BANK

                                       By: /s/ Eric R. Giesecke
                                          --------------------------------------
                                       Name: Eric R. Giesecke
                                             -----------------------------------
                                       Title: Assistant Vice President
                                              ----------------------------------

                                       LASALLE BANK NATIONAL
                                       ASSOCIATION

                                       By:/s/ Tricia Somoles
                                          --------------------------------------
                                       Name: Tricia Somoles
                                             -----------------------------------
                                       Title:  Commercial Loan Officer
                                              ----------------------------------

                              Signature Page 1 of 2

<PAGE>

                                       COMERICA BANK

                                       By: /s/ Dan M. Roman
                                          --------------------------------------
                                       Name: Dan M. Roman
                                             -----------------------------------
                                       Title: First Vice President
                                              ----------------------------------

                                       BANK ONE, N.A.

                                       By:  /s/James M. Malz
                                          --------------------------------------
                                       Name: James M. Malz
                                             -----------------------------------
                                       Title: First Vice President
                                              ----------------------------------

                                       HARRIS TRUST AND SAVINGS
                                       BANK

                                       By: /s/ Thad D. Raschle
                                          --------------------------------------
                                       Name: Thad D. Raschle
                                             -----------------------------------
                                       Title: Vice President
                                              ----------------------------------

                              Signature Page 2 of 2

<PAGE>

<TABLE>
<CAPTION>

                                                               ANNEX I

                                                      INFORMATION AS TO LENDERS

------------------------ --------------------- --------------------- ----------------- -------------------- --------------------
                         GENERAL REVOLVING     GENERAL REVOLVING     SWING LINE        TERM LOAN            NOTICE ADDRESS FOR
    NAME OF LENDER       FACILITY PERCENTAGE   COMMITMENT            COMMITMENT        COMMITMENT           THE LENDERS
------------------------ --------------------- --------------------- ----------------- -------------------- --------------------
<S>                      <C>                   <C>                   <C>               <C>                  <C>
KeyBank National         26.470588238%         $6,617,647.06         $5,000,000.00     $4,632,352.94165     KeyBank National
Association                                                                                                 Association
                                                                                                            127 Public Square
                                                                                                            Cleveland, Ohio
                                                                                                            44114
                                                                                                            Attn: Large
                                                                                                            Corporate Banking
------------------------ --------------------- --------------------- ----------------- -------------------- --------------------
LaSalle Bank National    20.588235294%         $5,147,058.82         $0.00             $3,602,941.17645     LaSalle Bank
Association                                                                                                 National
                                                                                                            Association
                                                                                                            1300 East Ninth St.
                                                                                                            Suite 1000
                                                                                                            Cleveland, OH
                                                                                                            44114
------------------------ --------------------- --------------------- ----------------- -------------------- --------------------
Bank One, N.A.           14.705882352%         $3,676,470.59         $0.00             $2,573,529.41160     Bank One, N.A.
                                                                                                            600 Superior Ave.
                                                                                                            Cleveland, OH
                                                                                                            44114
------------------------ --------------------- --------------------- ----------------- -------------------- --------------------
Comerica Bank            14.705882352%         $3,676,470.59         $0.00             $2,573,529.41160     Comerica Bank
                                                                                                            500 Woodward Ave.
                                                                                                            Detroit, MI  48226
------------------------ --------------------- --------------------- ----------------- -------------------- --------------------
National City Bank       11.764705882%         $2,941,176.47         $0.00             $2,058,823.52935     National City Bank
                                                                                                            1900 East Ninth St.
                                                                                                            Cleveland, OH
                                                                                                            44114
------------------------ --------------------- --------------------- ----------------- -------------------- --------------------
Harris Trust and         11.764705882%         $2,941,176.47         $0.00             $2,058,823.52935     Harris Trust and
Savings Bank                                                                                                Savings Bank
                                                                                                            111 West Monroe St.
                                                                                                            Tenth Floor West
                                                                                                            Chicago, IL  60603

------------------------ --------------------- --------------------- ----------------- -------------------- --------------------
</TABLE>

                                      A-1
<PAGE>

                                   ANNEX VIII

                                     FORM OF

                           BORROWING BASE CERTIFICATE

Calculated as of: __________________

Calendar Month Ended:__________________

         I, the undersigned and ________________ of Hawk Corporation, a Delaware
corporation (the "Borrower"), do hereby certify pursuant to Credit Agreement,
dated as of May 1, 1998, as amended (the "Credit Agreement"), among Borrower,
the lending institutions listed on ANNEX I thereto (collectively, the
"Lenders"), and KeyBank National Association, as administrative agent for the
Lenders (the "Administrative Agent"), that the following calculations have been
made in accordance with the provisions of the Credit Agreement. All capitalized
terms used herein and not defined herein shall have the meaning given to such
terms in the Credit Agreement.

A.        CALCULATIONS

         1.       ACCOUNTS

                  a.  Domestic Accounts Receivable                $____________

                  b.  Ineligible Accounts                         $____________

                  c.  Eligible Accounts Receivable                $____________
                      (a minus b)

                  d.  85% of Eligible Accounts Receivable         $____________

         2.       INVENTORY

                  a.  Domestic Inventory                          $____________

                  b.  Ineligible Inventory                        $____________

                  c.  Eligible Inventory                          $____________
                      (a minus b)

                  d.  60% of Eligible Inventory                   $____________*
                           *cannot exceed inventory
                            cap of $18,000,000)

         3.       TOTAL ELIGIBLE ACCOUNTS/INVENTORY               $____________
                  (1d plus 2d)

B.       BORROWING BASE

         1.       Total Eligible Account/Inventory                $____________
                  (A3 above)

         2.       Aggregate principal amount of                   $____________
                  outstanding Term Loans

                                       A-2
<PAGE>

         3.       Alternative Currency Advances/
                  Overadvance Amount                              $5,000,000.00

         4.       Net Borrowing Base                              $____________
                  (1 minus 2 plus 3)

C.       AVAILABILITY

         1.       Net Borrowing Base                              $____________
                  (B4 above)

         2.       Revolving Credit Exposure

                  a.  Outstanding General Revolving Loans         $____________

                  b.  Outstanding Swing Line Revolving Loans      $____________

                  c.  Dollar Equivalent of outstanding
                      Alternative Currency Advances               $____________

                  d.  Letter of Credit Outstandings               $____________

                  e.  Revolving Credit Exposure                   $____________
                      (total of a through d above)

         3.       Availability

                  The lesser of (a) $25,000,000, or (b) the Net
                  Borrowing Base minus the Revolving Credit
                  Exposure                                        $____________

         For purposes of inducing the Administrative Agent and the Lenders to
grant Loans and issue Letters of Credit to the Borrower pursuant to the terms of
the Credit Agreement, I hereby certify that this Borrowing Base Certificate and
the information contained herein is true and correct and that no Default or
Event of Default has occurred under the Credit Agreement.

                                                HAWK CORPORATION

                                                By:_________________________
                                                Name: ______________________
                                                Title: _____________________

                                      A-3
<PAGE>

                            GUARANTOR ACKNOWLEDGMENT

         Each of the undersigned consents and agrees to and acknowledges the
terms of the foregoing Amendment No. 4 to Credit Agreement. The undersigned
specifically agrees to the waivers set forth in such agreement, including, but
not limited to, the jury trial waiver. Each of the undersigned further agrees
that the obligations of the undersigned pursuant to the Guaranty of Payment
executed by the undersigned shall remain in full force and effect and be
unaffected hereby.

         Each of the undersigned hereby waives and releases the Administrative
Agent and the Lenders and the directors, officers, employees, attorneys,
affiliates and subsidiaries of the Administrative Agent and the Lenders from any
and all claims, offsets, defenses and counterclaims of which the undersigned is
aware, such waiver and release being with full knowledge and understanding of
the circumstances and effect thereof and after having consulted legal counsel
with respect thereto.

                                                FRICTION PRODUCTS CO.
                                                S.K. WELLMAN CORP.
                                                HELSEL, INC.
                                                LOGAN METAL STAMPINGS, INC.
                                                HAWK MOTORS, INC. (fka
                                                  Hutchinson Products LLC)
                                                SINTERLOY CORPORATION
                                                HAWK BRAKE, INC.
                                                S.K. WELLMAN HOLDINGS, INC.
                                                ALLEGHENY CLEARFIELD, INC. (fka
                                                  Allegheny Powder Metallurgy,
                                                  Inc. and successor by merger
                                                  to Clearfield Powdered Metals,
                                                  Inc.)
                                                QUARTER MASTER INDUSTRIES, INC.
                                                HAWK MIM, INC.
                                                TEX RACING ENTERPRISES, INC.
                                                NET SHAPE TECHNOLOGIES LLC
                                                HAWK PRECISION COMPONENTS
                                                  GROUP, INC.

                                                By: /s/Thomas A. Gilbride
                                                   -----------------------------
                                                Name: Thomas A. Gilbride
                                                      --------------------------
                                                Vice President - Finance of each
                                                  of the foregoing companies<PAGE>
                                                                 Exhibit 4.5.1

                             SUPPLEMENTAL INDENTURE

                  SUPPLEMENTAL INDENTURE (this "Supplemental Indenture"), dated
as of August 3, 2000, among Conspec Marketing and Manufacturing Co., Inc., a
Kansas corporation, and Bristol Investments, Inc., a California corporation,
(each a "Guaranteeing Subsidiary"), each a subsidiary of Dayton Superior
Corporation (or its permitted successor), an Ohio corporation (the "Company"),
the Company, the other Guarantors (as defined in the Indenture referred to
herein) and United States Trust Company of New York, as trustee under the
indenture referred to below (the "Trustee").

                                   WITNESSETH:

                  WHEREAS, the Company has heretofore executed and delivered to
the Trustee an indenture (the "Indenture"), dated as of June 16, 2000 providing
for the issuance of an aggregate principal amount of up to $270.0 million of 13%
Senior Subordinated Notes due 2009 (the "Notes");

                  WHEREAS, the Indenture provides that under certain
circumstances the Guaranteeing Subsidiary shall execute and deliver to the
Trustee a supplemental indenture pursuant to which the Guaranteeing Subsidiary
shall unconditionally guarantee all of the Company's Obligations under the Notes
and the Indenture on the terms and conditions set forth herein (the
"Guarantee"); and

                  WHEREAS, pursuant to Section 9.01 of the Indenture, the
Trustee is authorized to execute and deliver this Supplemental Indenture.

                  NOW THEREFORE, in consideration of the foregoing and for other
good and valuable consideration, the receipt of which is hereby acknowledged,
the Guaranteeing Subsidiary and the Trustee mutually covenant and agree for the
equal and ratable benefit of the Holders of the Notes as follows:

     1. CAPITALIZED TERMS. Capitalized terms used herein without definition
shall have the meanings assigned to them in the Indenture.

     2. AGREEMENT TO GUARANTEE. The Guaranteeing Subsidiary hereby agrees as
follows:

               (a) Along with all Guarantors named in the Indenture, to jointly
          and severally Guarantee to each Holder of a Note authenticated and
          delivered by the Trustee and to the Trustee and its successors and
          assigns, irrespective of the validity and enforceability of the
          Indenture, the Notes or the Obligations of the Company hereunder or
          thereunder, that:

                    (i) the principal of, premium, if any, and interest on the
               Notes will be promptly paid in full when due, whether at
               maturity, by acceleration, redemption or otherwise, and interest
               on the overdue principal of and interest on the Notes, if any, if
               lawful, and all other

                                       1
<PAGE>

               Obligations of the Company to the Holders or the Trustee
               hereunder or thereunder will be promptly paid in full or
               performed, all in accordance with the terms hereof and thereof;
               and

                    (ii) in case of any extension of time of payment or renewal
               of any Notes or any of such other Obligations, that same will be
               promptly paid in full when due or performed in accordance with
               the terms of the extension or renewal, whether at stated
               maturity, by acceleration or otherwise.

               Failing payment when due of any amount so guaranteed or any
               performance so guaranteed for whatever reason, the Guarantors
               shall be jointly and severally obligated to pay the same
               immediately.

          (b) The Obligations hereunder shall be unconditional, irrespective of
     the validity, regularity or enforceability of the Notes or the Indenture,
     the absence of any action to enforce the same, any waiver or consent by any
     Holder of the Notes with respect to any provisions hereof or thereof, the
     recovery of any judgment against the Company, any action to enforce the
     same or any other circumstance which might otherwise constitute a legal or
     equitable discharge or defense of a guarantor.

          (c) The following is hereby waived: diligence, presentment, demand of
     payment, filing of claims with a court in the event of insolvency or
     bankruptcy of the Company, any right to require a proceeding first against
     the Company, protest, notice and all demands whatsoever.

          (d) This Guarantee shall not be discharged except by complete
     performance of the Obligations contained in the Notes and the Indenture or
     pursuant to Section 6 hereof.

          (e) If any Holder or the Trustee is required by any court or otherwise
     to return to the Company, the Guarantors, or any custodian, Trustee,
     liquidator or other similar official acting in relation to either the
     Company or the Guarantors, any amount paid by either to the Trustee or such
     Holder, this Guarantee, to the extent theretofore discharged, shall be
     reinstated in full force and effect.

          (f) The Guaranteeing Subsidiary shall not be entitled to any right of
     subrogation in relation to the Holders in respect of any Obligations
     guaranteed hereby until payment in full of all Obligations guaranteed
     hereby.

          (g) As between the Guarantors, on the one hand, and the Holders and
     the Trustee, on the other hand, (x) the maturity of the Obligations
     guaranteed hereby may be accelerated as provided in Article 6 of the
     Indenture for the purposes of this Guarantee, notwithstanding any stay,
     injunction or other prohibition preventing such acceleration in respect of
     the Obligations guaranteed hereby, and (y) in the event of any declaration
     of acceleration of such Obligations

                                       2

<PAGE>

     as provided in Article 6 of the Indenture, such Obligations (whether or not
     due and payable) shall forthwith become due and payable by the Guarantors
     for the purpose of this Guarantee.

          (h) The Guarantors shall have the right to seek contribution from any
     non-paying Guarantor so long as the exercise of such right does not impair
     the rights of the Holders under the Guarantee.

          (i) Pursuant to Section 11.03 of the Indenture, the Obligations of a
     Guaranteeing Subsidiary shall be limited to such a maximum amount as after
     giving effect to any maximum amount and any other contingent and fixed
     liabilities that are relevant under any applicable Bankruptcy or fraudulent
     conveyance laws (including, without limitation, all Senior Debt of such
     Guarantor), and after giving effect to any collections from, rights to
     receive contribution from or payments made by or on behalf of any other
     Guarantor in respect of the Obligations of such other Guarantor under
     Article 11 of the Indenture, shall result in the Obligations of such
     Guarantor under its Guarantee not constituting a fraudulent transfer or
     conveyance.

     3. SUBORDINATION. The Obligations of the Guaranteeing Subsidiary under its
Guarantee pursuant to this Supplemental Indenture shall be junior and
subordinated to the Senior Debt of the Guaranteeing Subsidiary on the same basis
as the Notes are junior and subordinated to the Senior Debt of the Company. For
the purposes of the foregoing sentence, the Trustee and the Holders shall have
the right to receive and/or retain payments by the Guaranteeing Subsidiary only
at such time as they may receive and/or retain payments in respect of the Notes
pursuant to the Indenture, including Article 10 thereof.

     4. EXECUTION AND DELIVERY. Each Guaranteeing Subsidiary agrees that the
Guarantees shall remain in full force and effect notwithstanding any failure to
endorse on each Note a notation of such Guarantee.

     5. GUARANTEEING SUBSIDIARY MAY CONSOLIDATE, ETC. ON CERTAIN TERMS.

               (a) The Guaranteeing Subsidiary may not consolidate with or merge
          with or into (whether or not such Guarantor is the surviving Person)
          another corporation, Person or entity whether or not affiliated with
          such Guarantor unless:

                    (i) subject to Section 11.05 of the Indenture, the Person
               formed by or surviving any such consolidation or merger (if other
               than a Guarantor or the Company) shall be a corporation organized
               and validly existing under the laws of the United States or any
               state thereof or the District of Columbia, and unconditionally
               assumes all the Obligations of such Guarantor, pursuant to a
               supplemental indenture in form and substance reasonably
               satisfactory to the Trustee, under the Notes, the Indenture and
               the Guarantee on the terms set forth herein or therein;

                    (ii) immediately after giving effect to such transaction, no
               Default or Event of Default exists; and

                                       3
<PAGE>

                    (iii) the Company would be permitted, immediately after
               giving effect to such transaction, to incur at least $1.00 of
               additional Indebtedness (other than Permitted Indebtedness)
               pursuant to Section 4.09 of the Indenture.

          (b) In case of any such consolidation, merger, sale or conveyance and
     upon the assumption by the successor Person, by supplemental indenture,
     executed and delivered to the Trustee and satisfactory in form to the
     Trustee, of the Guarantee endorsed upon the Notes and the due and punctual
     performance of all of the covenants and conditions of the Indenture to be
     performed by the Guarantor, such successor Person shall succeed to and be
     substituted for the Guarantor with the same effect as if it had been named
     herein as a Guarantor. Such successor Person thereupon may cause to be
     signed any or all of the Guarantees to be endorsed upon all of the Notes
     issuable hereunder which theretofore shall not have been signed by the
     Company and delivered to the Trustee. All the Guarantees so issued shall in
     all respects have the same legal rank and benefit under the Indenture as
     the Guarantees theretofore and thereafter issued in accordance with the
     terms of the Indenture as though all of such Guarantees had been issued at
     the date of the execution hereof.

          (c) Except as set forth in Articles 4 and 5 of the Indenture, and
     notwithstanding clause (a)(iii) above, nothing contained in the Indenture
     or in any of the Notes shall prevent any consolidation or merger of a
     Guarantor with or into the Company or another Guarantor, or shall prevent
     any sale or conveyance of the property of a Guarantor as an entirety or
     substantially as an entirety to the Company or another Guarantor.

     6. RELEASES. In the event of a sale or other disposition of all of the
assets of any Guarantor, by way of merger, consolidation or otherwise, or a sale
or other disposition of all to the capital stock of any Guarantor, then such
Guarantor (in the event of a sale or other disposition, by way of merger,
consolidation or otherwise, of all of the capital stock of such Guarantor) or
the corporation acquiring the property (in the event of a sale or other
disposition of all or substantially all of the assets of such Guarantor) will be
released and relieved of any Obligations under its Guarantee; provided that the
Net Cash Proceeds of such sale or other disposition are applied in accordance
with the applicable provisions of the Indenture, including without limitation
Section 4.10 of the Indenture. Upon delivery by the Company to the Trustee of an
Officers' Certificate and an Opinion of Counsel to the effect that such sale or
other disposition was made by the Company in accordance with the applicable
provisions of the Indenture, including without limitation Section 4.10 of the
Indenture, the Trustee shall execute any documents reasonably required in order
to evidence the release of any Guarantor from its Obligations under its
Guarantee.

     Any Guarantor not released from its Obligations under its Guarantee shall
remain liable for the full amount of principal of and interest on the Notes and
for the other Obligations of any Guarantor under the Indenture as provided in
Article 11 of the Indenture.

                                       4
<PAGE>

     7. NO RECOURSE AGAINST OTHERS. No past, present or future director,
officer, employee, incorporator, stockholder or agent of the Guaranteeing
Subsidiary, as such, shall have any liability for any Obligations of the Company
or any Guaranteeing Subsidiary under the Notes, any Guarantees, the Indenture or
this Supplemental Indenture or for any claim based on, in respect of, or by
reason of, such Obligations or their creation. Each Holder of the Notes by
accepting a Note waives and releases all such liability. The waiver and release
are part of the consideration for issuance of the Notes. Such waiver may not be
effective to waive liabilities under the federal securities laws and it is the
view of the Commission that such a waiver is against public policy.

     8. NEW YORK LAW TO GOVERN. THE INTERNAL LAW OF THE STATE OF NEW YORK SHALL
GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL INDENTURE WITHOUT GIVING EFFECT
TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT THE APPLICATION
OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY.

     9. COUNTERPARTS. The parties may sign any number of copies of this
Supplemental Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement.

     10. EFFECT OF HEADINGS. The Section headings herein are for convenience
only and shall not affect the construction hereof.

     11. THE TRUSTEE. The Trustee shall not be responsible in any manner
whatsoever for or in respect of the validity or sufficiency of this Supplemental
Indenture or for or in respect of the recitals contained herein, all of which
recitals are made solely by the Guaranteeing Subsidiary and the Company.

                                       5
<PAGE>

                  IN WITNESS WHEREOF, the parties hereto have caused this
Supplemental Indenture to be duly executed and attested, all as of the date
first above written.

                            Dayton Superior Corporation, as Issuer

                            By:
                               ---------------------------------------------
                               Name:
                               Title:

                            Conspec Marketing and Manufacturing Co., Inc., as
                            Guaranteeing Subsidiary

                            By:
                               ---------------------------------------------
                               Name:
                               Title:

                            Bristol Investments, Inc., as Guaranteeing
                            Subsidiary

                            By:
                               ---------------------------------------------
                               Name:
                               Title:

                            UNITED STATES TRUST COMPANY OF
                             NEW YORK, as Trustee

                            By:
                               ---------------------------------------------
                               Name:  Cynthia Chaney
                               Title: Assistant Vice President

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