<PAGE>   1
                                                                 EXHIBIT 10.1(g)


                  AMENDMENT NO.6 AND AFFIRMATION OF GUARANTIES
                         TO LOAN AND SECURITY AGREEMENT

         This Amendment No. 6 and Affirmation of Guaranties (this "Amendment")
dated as of July 21, 1998 is by and among LDM Technologies, Inc., a Michigan
corporation ("Borrower") the Guarantors listed on the signature page, the
Lenders (as defined below) and BankAmerica Business Credit, Inc., a Delaware
corporation, as Agent (in its capacities as Agent, the "Agent").

                                R E C I T A L S:

         WHEREAS, Borrower, the financial institutions from time to time party
thereto (the "Lenders") and the Agent are parties to a Loan and Security
Agreement dated as of January 22, 1997, as amended and otherwise modified prior
to the date hereof (as so amended and modified, and as the same may be further
amended, restated, supplemented or otherwise modified, the "Loan Agreement"),
pursuant to which Lenders have made and may hereafter make loans, advances and
other extensions of credit to Borrower;

         WHEREAS, Borrower wishes to obtain, and Lenders are willing to grant,
an amendment to the Loan Agreement as set forth herein, subject to the express
terms and conditions specified in this Amendment; and

         WHEREAS, this Amendment shall constitute a Loan Document, these
Recitals shall be construed as part of this Amendment and capitalized terms used
but not otherwise defined in this Amendment shall have the meanings ascribed to
them in the Loan Agreement.

         NOW, THEREFORE, in consideration of the foregoing and the agreements,
promises and covenants set forth below, and for other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereto agree as follows:

1. Amendment of Loan Agreement. 

         (a)      SECTION 1.1 OF THE LOAN AGREEMENT IS HEREBY AMENDED BY ADDING 
THE FOLLOWING DEFINITION IN ITS PROPER ALPHABETICAL ORDER:

                  "Sunningdale Investment" means the equity investment of the
                  Borrower in Sunningdale Plastic Industries, Pte. Ltd., a
                  Singapore company, whereby the Borrower owns a thirty percent
                  (30%) equity interest in such Person, in the form held by the
                  Borrower on February 6, 1998."

         (b)      SECTION 1.1 OF THE LOAN AGREEMENT IS HEREBY AMENDED BY
DELETING THE DEFINITION OF "RESTRICTED INVESTMENT" AND REPLACING SUCH DEFINITION
WITH THE FOLLOWING:

                  "Restricted Investment" means any acquisition of property by
                  the Borrower or LDM Canada in exchange for cash or other
                  property, whether in the form of an acquisition of stock,
                  debt, or other indebtedness or obligation, or the purchase or
                  acquisition of


<PAGE>   2

                  any other property, or a loan, advance, capital contribution,
                  or subscription: except (A) the Borrower may make intercompany
                  loans to (x) LDM Canada pursuant to Section 9.13(d)(I) and (y)
                  LDM Germany pursuant to Section 9.13(d)(II), (B) the
                  Sunningdale Investment, and (C) acquisitions of the following:

         (a)      Equipment to be used in the business of the Borrower or LDM 
Canada so long as the acquisition costs thereof constitute Capital Expenditures 
permitted hereunder;

         (b)      goods held for sale or lease or to be used by the Borrower or 
LDM Canada in the ordinary course of business;

         (c)      current assets arising from the sale or lease of goods or the 
rendition of services in the ordinary course of business of the Borrower or LDM 
Canada;

         (d)      direct obligations of the United States of America, or any
agency thereof, or obligations guaranteed by the United States of America,
provided that such obligations mature within one year from the date of
acquisition thereof;

         (e)      certificates  of  deposit  maturing  within  one year from the
date of acquisition, bankers' acceptances, Eurodollar bank deposits, or
overnight bank deposits, in each case issued by, created by, or with a bank or
trust company organized under the laws of the United States or any state thereof
having capital and surplus aggregating at least $100,000,000;

         (f)      commercial  paper  given a rating of "AT" or better by  
Standard & Poor's Corporation or "P2" or better by Moody's Investors Service,
Inc. and maturing not more than 90 days from the date of creation thereof;

         (g)      life insurance premiums of up to $2,500,000 per annum for life
insurance on the lives of the Borrower's principal stockholders;

         (h)      loans to employees outstanding as of the Closing Date;

         (i)      loans  and  advances  in  the  ordinary  course  of  business
to officers, directors and employees for business-related  travel  expenses,  
moving expenses and other similar expenses in an aggregate principal amount not 
to exceed $250,000 at any time; and

         (j)      the conversion of all or portion of the Closing Date 
Intercompany Note into equity interests of a Guarantor (other than LDM Holding).
 

         (c)      SECTION 9.13 OF THE LOAN AGREEMENT IS HEREBY AMENDED BY 
DELETING CLAUSE (d) CONTAINED THEREIN IN ITS ENTIRETY AND REPLACING IT WITH THE 
FOLLOWING NEW CLAUSE (d):

                  (d)     Debt consisting of intercompany loans and advances
                          ("Intercompany Loans") made by the Borrower to (I)
                          LDM Canada, provided that (i) LDM Canada


                                       2
<PAGE>   3


                          shall have executed and delivered to the Borrower, on
                          the Closing Date, an Intercompany Note to evidence any
                          such Intercompany Loan, any security interests granted
                          to the Borrower on the assets of LDM Canada to secure
                          the payments under its Intercompany Note shall be
                          assigned to the Agent pursuant to documentation in
                          form and substance acceptable to the Agent, and such
                          Intercompany Note shall be pledged to the Agent
                          pursuant to the Pledge Agreement as additional
                          collateral security for the Obligations, (ii) the
                          Borrower shall record all such Intercompany Loans on
                          its books and records in a manner satisfactory to
                          Agent, (iii) at the time any such Intercompany Loans
                          is made by the Borrower and after giving effect
                          thereto, each of the Borrower and LDM Canada shall be
                          Solvent, (iv) the aggregate outstanding principal
                          amount of Intercompany Loans under this clause (I)
                          shall not at any one time exceed $17,000,000,
                          consisting of the Closing Date Intercompany Loan and
                          additional loans not to exceed $1,000,000, plus an
                          amount equal to the sum of (A) an amount equal to the
                          lesser of (x) $5,000,000 and (y) LDM Canada's
                          Borrowing Base, plus (B) $4,000,000, provided,
                          however, that the Intercompany Loans pursuant to
                          clauses (A) and (B) above shall not exceed in any
                          fiscal quarter the amount of LDM Canada's EBITDA for
                          the immediately preceding fiscal quarter and (II) LDM
                          Germany, provided that (i) LDM Germany shall have
                          executed and delivered to the Borrower an Intercompany
                          Note to evidence any such Intercompany Loan, and such
                          Intercompany Note shall conform to the requirements of
                          a loan to an Unleveraged Wholly Owned Restricted
                          Subsidiary (as defined in the Indenture) pursuant to
                          the terms and conditions contained in the Indenture,
                          (ii) the Borrower shall record all such Intercompany
                          Loans on its books and records in a manner
                          satisfactory to Agent, (iii) at the time any such
                          Intercompany Loan is made by the Borrower and after
                          giving effect thereto, each of the Borrower and LDM
                          Germany shall be Solvent and (iv) the aggregate
                          outstanding principal amount of Intercompany Loans
                          under this clause (II) shall not at any one time
                          exceed $13,400,000.

         (d)      SECTION 9.24 OF THE LOAN AGREEMENT IS HEREBY AMENDED BY
DELETING SAID SECTION IN ITS ENTIRETY AND REPLACING IT WITH THE FOLLOWING NEW
SECTION 9.24:

                  9.24 Operating Lease Obligations. The Borrower shall, and 
         shall cause each of its Subsidiaries to, promptly notify the Agent
         after entering into any lease of real or personal property as lessee or
         sublessee (other than a Capital Lease), if, after giving effect
         thereto, the aggregate amount of Rentals (as hereinafter defined)
         payable by the Borrower and its Subsidiaries on a consolidated basis in
         any Fiscal Year in respect of such lease would exceed $1,500,000,
         individually, or $12,000,000 in the aggregate for all such leases. The
         term "Rentals" means all payments due from the lessee or sublessee
         under a lease, including, without limitation, basic rent, percentage
         rent, property taxes, utility or maintenance costs, and insurance
         premiums.



                                       3
<PAGE>   4



         (e)      SECTION 14.12 OF THE LOAN AGREEMENT IS HEREBY AMENDED BY 
DELETING CLAUSE (A) CONTAINED THEREIN IN ITS ENTIRETY AND REPLACING IT WITH THE
FOLLOWING NEW CLAUSE (a):

                  (a) The Lenders hereby irrevocably authorize the Agent, at its
         option and in its sole discretion, to release any Agent's Lien upon any
         Collateral, Pledged Collateral or Guarantor Collateral (i) upon the
         termination of the Commitments and payment and satisfaction in full by
         Borrower of all Loans and reimbursement obligations in respect of
         Letters of Credit, and the termination of all outstanding Letters of
         Credit (whether or not any of such obligations are due) and all other
         Obligations; (ii) constituting property being sold or disposed of if
         the Borrower certifies to the Agent that the sale or disposition is
         made in compliance with Section 9.9 (and the Agent may rely
         conclusively on any such certificate, without further inquiry); (iii)
         constituting property in which the Borrower or a Guarantor owned no
         interest at the time the Lien was granted or at any time thereafter; or
         (iv) constituting property leased to the Borrower or LDM Canada under a
         lease which has expired or been terminated in a transaction permitted
         under this Agreement. Except as provided above, the Agent will not
         release any of the Agent's Liens without the prior written
         authorization of the Lenders in accordance with Section 13.2; provided
         that the Agent may release the Agent's Liens on Collateral, Pledged
         Collateral or Guarantor Collateral valued in the aggregate of not more
         than $5,000,000 without the prior written authorization of the Lenders.
         Upon request by the Agent or the Borrower at any time, the Lenders will
         confirm in writing the Agent's authority to release any Agent's Liens
         upon particular types or items of Collateral, Pledged Collateral or
         Guarantor Collateral pursuant to this Section 14.12.

         (f)      EXHIBIT C TO THE LOAN AGREEMENT IS HEREBY AMENDED BY DELETING 
IT IN ITS ENTIRETY AND REPLACING IT WITH EXHIBIT C ATTACHED HERETO.

2.       Warranties and Representations. Borrower and each Guarantor hereby 
warrants and represents to Lenders and Agent that:

         (a)      Authorization, etc. Each of Borrower and each Guarantor has 
the power and authority to execute, deliver and perform this Amendment and the
Loan Agreement, as amended hereby, as applicable. Each of Borrower and each
Guarantor has taken all necessary action (including, without limitation,
obtaining approval of its stockholders if necessary) to authorize its execution,
delivery and performance of this Amendment and the Loan Agreement, as amended
hereby, as applicable. No consent, approval or authorization of, or declaration
or filing with, any Governmental Authority, and no consent of any other Person,
is required in connection with Borrower's or any Guarantor's execution, delivery
and performance of this Amendment, except for those already duly obtained. This
Amendment has been duly executed and delivered by Borrower and each Guarantor,
and constitutes the legal, valid and binding obligation of Borrower and such
Guarantor, enforceable against it in accordance with its terms without defense,
setoff or counterclaim. Neither Borrower's nor any Guarantor's execution,
delivery and performance of this Amendment do or will conflict with, or
constitute a violation or breach of, or constitute a default under, or result in
the creation or imposition of any Lien upon the property of Borrower or any of
its Subsidiaries by reason of the terms of (a) any contract, mortgage, Lien,
lease, agreement, indenture or instrument to which Borrower or any of its
Subsidiaries is a party or which is binding upon it, (b) any Requirement of

  

                                       4
<PAGE>   5


Law applicable to Borrower or any of its  Subsidiaries,  or (c) the  certificate
or articles of incorporation or by-laws, partnership agreement or limited
liability company agreement of Borrower or any of its Subsidiaries.

         (b)      Other  Warranties  and  Representations.  After giving effect 
to this Amendment, all of the warranties and representations of Borrower and
each Guarantor contained in the Loan Agreement, the Guarantor Guarantees and the
other Loan Documents (including, without limitations, this Amendment) are true
and correct in all material respects on and as of the date hereof to the same
extent as though made on and as of the date hereof (except those representations
and warranties made expressly as of a different date).

         (c)      No Default or Event of Default. After giving effect to this
Amendment, no Default or Event of Default has occurred and is continuing as of
the date hereof.

3.       No Novation;  No Consent or Waiver.  This Amendment is not, and shall
not be construed as, a novation, consent, waiver, release or modification with
respect to any of the terms, provisions, conditions, representations,
warranties, covenants, rights, powers or remedies set forth in the Loan
Agreement or any of the other Loan Documents, except for the specific instance
and purpose for which it is granted as expressly specified herein. Agent's or
any Lender's failure, at any time or times hereafter, to require strict
performance by Borrower of any provision or term of this Amendment shall not
waive, affect or diminish any right of Agent or any Lender thereafter to demand
strict compliance and performance herewith. None of the undertakings,
agreements, warranties, covenants and representations of Borrower contained in
this Amendment shall be deemed to have been suspended or waived by Agent or any
Lender unless such suspension or waiver is (a) in writing and signed by Agent
and the Lenders in accordance with the terms of the Loan Agreement and (b)
delivered to Borrower, notwithstanding any prior practice or course of dealing,
or any waiver, forbearance or other similar agreement or understanding, whether
any of the foregoing were or are oral or written, by or between the parties
hereto.

4.       Documents Remain in Effect.  (a) This Amendment shall become  effective
as of the date first written above upon the receipt by Agent of an executed copy
of this Amendment from Borrower, each Guarantor and the Majority Lenders.

                  (b)     Except as amended and modified by this  Amendment,  
the Loan Agreement and the other Loan Documents remain in full force and effect,
and Borrower and each Guarantor hereby ratify, adopt and confirm their
representations, warranties, agreements and covenants contained in, and
obligations and liabilities under, the Loan Agreement and the other Loan
Documents.

5.       Reference to Loan Agreement.  On and after the  effectiveness  of this 
Amendment, each reference in the Loan Agreement, as amended hereby, to "this
Agreement", "hereunder", "hereof", "herein" or words of like import, and each
reference to the "Loan Agreement" in any other Loan Document, or in any of the
other agreements, documents or other instruments executed and delivered pursuant
to the Loan Agreement, shall mean and be a reference to the Loan Agreement, as
amended hereby.



                                       5
<PAGE>   6


6.       Incorporation of Loan Agreement.  Article 15 of the Loan Agreement is 
incorporated herein by reference with the same effect as if set forth in full
herein with only those modifications necessary to permit such Article to refer
to this Amendment.

7.       Affirmation of Guaranties.  Each of LDM Holding and LDM Canada (i) 
consents to and approves the execution and delivery of this Amendment by the
parties hereto, (ii) agrees that this Amendment does not and shall not limit or
diminish in any manner the obligations of the Guarantors under their respective
Guarantor Guarantees, or under any of the other documents executed and/or
delivered by any of the Guarantors in connection therewith, and agrees that such
obligations of the Guarantors would not be limited or diminished in any manner
even if the Guarantors had not executed this Amendment, (iii) agrees that this
Amendment shall not be construed as requiring the consent of the Guarantors in
any other circumstance, (iv) reaffirms its obligations under each of the
Guarantor Guarantees and such other related documents, and (v) agrees that the
Guarantor Guarantees and such other related documents remain in full force and
effect and are each hereby ratified and confirmed.

8.       Facsimile Transmission Counterparts. Delivery of an executed
counterpart of a signature page to this Amendment by facsimile transmission
shall be effective as delivery of a manually executed counterpart of this
Amendment.

                            [signature page follows]




                                        6
<PAGE>   7




         IN WITNESS WHEREOF, this Amendment No. 6 and Affirmation of Guaranties
has been duly executed as of the date first written above.

                                          LDM TECHNOLOGIES, INC.

                                          By: /s/  Gary E. Borushko
                                             -----------------------------
                                          Title: CFO
                                                --------------------------

                                          LDM HOLDING CANADA, INC.

                                          By: /s/ Gary E. Borushko
                                             -----------------------------
                                          Title: CFO
                                                --------------------------

                                         


                                          LDM TECHNOLOGIES COMPANY

                                          By: /s/  Gary E. Borushko
                                             -----------------------------
                                          Title: CFO
                                                --------------------------
                                          

                                          BANKAMERICA BUSINESS CREDIT, INC.,
                                          as a Lender and as Agent

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

                                          BANK BOSTON, N.A.

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


                                          COMERICA BANK

                                          
                                          By:
                                             -----------------------------
                                          Title:
                                                --------------------------
<PAGE>   8

         IN WITNESS WHEREOF, this Amendment No. 6 and Affirmation of Guaranties
has been duly executed as of the date first written above.

                                          LDM TECHNOLOGIES, INC.

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

                                          LDM HOLDING CANADA, INC.

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


                                          LDM TECHNOLOGIES COMPANY

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

                                          BANKAMERICA BUSINESS CREDIT, INC.,
                                          as a Lender and as Agent

                                          
                                          By: /s/ Matt J. Downs
                                             -----------------------------
                                          Title: Vice President
                                                --------------------------

                                          BANK BOSTON, N.A.

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


                                          COMERICA BANK


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




<PAGE>   9

        IN WITNESS WHEREOF, this Amendment No. 6 and Affirmation of Guaranties
has been duly executed as of the date first written above.

                                          LDM TECHNOLOGIES, INC.

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

                                          LDM HOLDING CANADA, INC.

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


                                          LDM TECHNOLOGIES COMPANY

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

                                          BANKAMERICA BUSINESS CREDIT, INC.,
                                          as a Lender and as Agent

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

                                          BANK BOSTON, N.A.


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


                                          COMERICA BANK

                                        
                                          By: /s/ William G. Stewart
                                             -----------------------------
                                          Title: Assistant Vice President
                                                --------------------------

<PAGE>   10

 
                                          HELLER FINANCIAL, INC.

                                          By: /s/ Stephen C. Metivier
                                             -----------------------------
                                          Title:         AVP
                                                --------------------------

                                          NATIONSBANK N.A.

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

                                          THE CIT GROUP/BUSINESS CREDIT, INC.

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

<PAGE>   11

                                          HELLER FINANCIAL, INC.

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

                                          NATIONSBANK N.A.

                                          By: /s/ Alison Arbuthnot
                                             -----------------------------
                                          Title:     Vice President
                                                --------------------------

                                          THE CIT GROUP/BUSINESS CREDIT, INC.

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

<PAGE>   12
                                         HELLER FINANCIAL, INC.

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

                                          NATIONSBANK N.A.

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

                                          THE CIT GROUP/BUSINESS CREDIT, INC.

                                          By: /s/  Kevin Caragay
                                             -----------------------------
                                          Title: Assistant Vice President
                                                --------------------------

<PAGE>   13



                                    EXHIBIT C


                               NOTICE OF BORROWING

Date:_____________,_______

 To:     BankAmerica  Business Credit,  Inc., as Agent for the Lenders who are 
         parties to the Loan and Security  Agreement, dated as of January 22,
         1997 (as extended, renewed, amended or restated from time to time, the
         "Loan and Security Agreement"),  among LDM Technologies,  Inc.,
         certain financial  institutions  which are signatories  thereto (the
         "Lenders") and BankAmerica Business Credit, Inc., as Agent

Ladies and Gentlemen:

         The undersigned,  LDM Technologies,  Inc. (the "Borrower"),  refers to
the Loan and Security Agreement,  the terms defined therein being used herein as
therein defined,  and hereby gives you notice  irrevocably of the Borrowing 
specified below:

         1.       The Business Day of the proposed Borrowing is 
                  ______________________, 19______.

         2.       The aggregate amount of the proposed Borrowing is 
                  $ ___________________________.

         3.       The Borrowing is to be comprised of $_______________ of Base 
                  Rate and $___________ of LIBOR Rate Loans.

         4.       The duration of the Interest Period for the LIBOR Rate Loans,
                  if any, included in the Borrowing shall be ______ months.

         The undersigned  hereby certifies that the following  statements are
true on the date hereof,  and will be true on the date of the  proposed
Borrowing,  before and after  giving  effect  thereto  and to the  application
of the  proceeds therefrom:

         (a)      The representations and warranties of the Borrower contained
in the Loan and Security Agreement are true and correct as though made on and as
of such date;

         (b)      No Default or Event of Default has occurred and is continuing,
or would result from such proposed Borrowing; and

         (c)      The proposed Borrowing will not cause the aggregate principal
amount of all outstanding Revolving Loans plus the aggregate amount available
for drawing under all outstanding


                                  EXHIBIT C-1


<PAGE>   14


Letters of Credit and any unpaid reimbursement obligations in respect of 
outstanding Letters of Credit to exceed the Revolver Availability or the
combined Commitments of the Lenders.

                                          LDM TECHNOLOGIES, INC.

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





                                  EXHIBIT C-2
<PAGE>   15

         IN WITNESS WHEREOF, this Amendment No. 6 and Affirmation of Guaranties
has been duly executed as of the date first written above.

                                          LDM TECHNOLOGIES, INC.

                                          By: /s/ Gary E. Borushko
                                             -----------------------------
                                          Title:  CFO
                                                --------------------------

                                          LDM HOLDING CANADA, INC.

                                          By: /s/ Gary E. Borushko
                                             -----------------------------
                                          Title:  CFO
                                                --------------------------
                                          


                                          LDM TECHNOLOGIES COMPANY

                                          By: /s/ Gary E. Borushko
                                             -----------------------------
                                          Title:  CFO
                                                --------------------------
                                          

                                          BANKAMERICA BUSINESS CREDIT, INC.,
                                          as a Lender and as Agent

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

                                          BANK BOSTON, N.A.

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

                                          COMERICA BANK

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