Apparatus for adjusting camber and toe

A shim device adjusts camber and/or toe of a wheel assembly that is attached to an axle assembly by a plurality of spaced apart bolts. The shim device includes a relatively flat tapered plate that has a indicia selectively positioned thereon to indicate the angular position of the plate with respect to the bolts such that the plate may be selectively positioned to adjust camber and/or toe a selected amount.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to shims that are used to correct camber and 
toe of a vehicle wheel, and in particular, it relates to a shim device 
that can be installed without removing the wheel mount from the axle and 
can be angularly indexed to adjust the position of the taper of the shim 
for correction of both camber and toe. 
2. Description of the Prior Art 
There have been various attempts at producing a shim to correct camber of a 
vehicle wheel. Improper camber increases tire wear significantly. 
Shims are well known in the art as evidenced by the following patents: 
The Farnam et al U.S. Pat. No. 4,160,561 describes a shim that is clamped 
between a component of a vehicle bumper assembly and a support member on a 
vehicle to provide desired spacing for bumper alignment. The Perkins U.S. 
Pat. No. 2,431,342 describes a shim device having a slot for use in 
machines wherein the shim is used as a spacer around a cap screw. The 
Castiglia U.S. Pat. No. 2,281,555 shows an annular tapered shim used to 
correct misalignment of knee action wheel mounts in a motor vehicle. The 
Boden U.S. Pat. No. 2,037,961 describes shims that are used to help mount 
the tapered roller bearings in an automobile differential mechanism. The 
shims have an arcuate configuration and are provided with deep notches. 
The notches engage the cap screws when in a slackened position and are 
inserted without removing the cap screws. The Walsh U.S. Pat. No. 776,971 
shows an annular tapered part coupling which permits sections of unaligned 
pipe to be connected. However, none of the immediately above-mentioned 
patents describe shim devices suitable for mounting between an end plate 
of an axle and the wheel mount of a motor vehicle to adjust camber. 
The Trussell U.S. Pat. No. 2,772,596 describes a shim arrangement used for 
adjusting both the camber and caster of an automobile. The shims are 
rectangularly-shaped tapered plates having a slot extending along the 
longitudinal axis of the plate. The shim is inserted so that the slot 
engages the bolt that holds the wheel onto the end plate of the axle. The 
portion of the shim that sticks out can be broken away along transversely 
positioned slots on the shim. Two shims can be used to interact with each 
other to correct both camber and caster. However, the correction of both 
camber and caster using the shim arrangement described in the Trussell 
Patent is very much a trial and error procedure with the shims having to 
be moved around until the desired camber and caster are achieved. 
The Weiss et al U.S. Pat. No. 2,978,253 also has longitudinally slotted 
shims for correcting caster and camber by adjustment of the wheel 
suspension. Correction of camber and caster using the device of the Weiss 
Patent is also a trial and error procedure. 
The Cooper U.S. Pat. No. 774,042 describes annularly shaped tapered shims 
for non-driven axles which may be rotated, coacting with each other 
providing a desired angle in the axle. The shims of the Cooper Patent, 
however, are not suitable for today's modern vehicles. 
The Grove U.S. Pat. No. 4,037,680 describes a tapered annular ring having a 
plurality of bolt holes that is used as a shim for adjusting the camber 
between a spindle and the end plate of an axle. The openings are 
positioned to correspond to the position of the bolts that hold the 
spindle onto the end plate of the axle. The wheel and spindle is removed 
and the shim with tapered end down is positioned so that the bolts extend 
through the holes. 
Similarly, the Specktor et al U.S. Pat. No. 4,195,862, assigned to the same 
assignee as the present application, describes an annularly tapered ring 
that is used as a shim to adjust camber between a wheel and an axle. 
The Johansson U.S. Pat. No. 3,142,352 describes a wheeled vehicle with a 
shim 35 that is placed between two members, which are at right angles to 
the axis of the axle members of the vehicle. 
The Bigelow U.S. Des. Pat. No. 272,392 illustrates a tapered shim having 
four slots. 
SUMMARY OF THE INVENTION 
The present invention includes a shim device for adjusting camber and/or 
toe of a wheel assembly attached to an axle assembly by a plurality of 
spaced-apart bolts. The device includes a relatively flat tapered plate 
including indicia selectively positioned thereon to indicate the angular 
position of the plate with respect to the bolts such that the plate may be 
selectively positioned to adjust camber/and toe a selected amount. 
In a preferred aspect of the present invention, the plate includes bolt 
engaging means for engaging the spaced-apart bolts such that the plate is 
retained in a selected position by virtue of its engagement of the bolts. 
The indicia are selectively positioned with respect to the bolt engaging 
means to aid in indicating the angular position of the plate. 
In a further aspect of the present invention, a chart is provided that 
relates the desired adjustments of camber and/or toe to a selected shim by 
the indicia positioned on the shim so that the angular position of the 
bolt may be preselected.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A shim device of the present invention is generally indicated at 10 in FIG. 
1. The shim device 10 is a plate with a preferred annular configuration 
having a central opening 11. The device 10 is tapered from a lower thick 
end 12 to an upper thin end 14, as illustrated in FIG. 2. The terms 
"lower" and "upper" as used herein to indicate the relative position of 
the shim device 10 in the figures and are not intended to limit the device 
in any way. The device 10 has a plurality of outwardly-extending 
bolt-engaging notches 16 disposed around the periphery. The bolt-engaging 
notches are preferably arcuately configured so that their edges retain the 
shim upon installation as will be discussed subsequently. 
The shim device 10 of the present invention is used to adjust either camber 
or toe and preferably both camber and toe of a wheel mounted to an axle of 
a motor vehicle, and particularly, the rear wheels of a front-wheel drive 
vehicle. The shim is inserted between an end plate 18 of an axle assembly 
20 and a wheel hub backer plate 22 of a wheel mount assembly 24, as 
illustrated in FIG. 3. On other types of wheel mount assemblies (not 
illustrated), the spindle has a flange behind a backing plate that mounts 
on a wheel axle. The wheel mount assembly 24 is attached to the axle 
assembly by bolts 26, 28, 30 and 32, as illustrated in FIGS. 3 and 4. 
For purposes of this application, camber is defined as the vertical incline 
of the tires and is described in angular degrees. Toe, as used in the 
present application, defines side-to-side slant of the tires along their 
forward portion and is described in fraction of inches from a reference 
line positioned along an axis common to the front and rear tires. 
The shim device 10 is formed of any suitable material, plastic or metal, 
having sufficient resilience and strength. A preferred material is 
aluminum. The device 10 is preferably formed by tapered sanding of flat 
stock due to the economics. The device can also be formed by stamping or 
any other machining process or combination of processes. 
The shim device 10 is installed without removing the wheel mount assembly 
24. In the arrangement illustrated in FIG. 4, all four bolts are loosened 
and only two of the bolts, for example, bolts 28 and 32, are removed. The 
shim device 10 is then inserted between the end plate 18 and the wheel hub 
backer plate 22. The shim device 10 is rotatable so that the position of 
the taper can be changed to adjust both camber and toe. The shim device is 
held in place by the bolt-engaging slots 16 abutting against the 
corresponding bolts. The bolts 28 and 32 that were removed are reinserted 
and all four bolts tightened. After tightening, all four bolts engage the 
edges of the bolt-engaging slots, securely holding the shim device in 
place. The bolt-engaging slots 16 retain the shim device in place even 
though one or more of the bolts, or all of the bolts, are loose. 
In a preferred embodiment, the shim device 10 includes at least one set of 
diametrically opposed notches 34 and 36, as illustrated in FIG. 1. 
Preferably, the shim device includes a second set of notches 38 and 40 
disposed 90.degree. from the notches 34 and 36. The notches extend 
sufficiently far into the shim device 10 so that the shim device can be 
easily cut into two pieces using a pair of shears. Although notches are 
specifically shown in FIG. 1, it should be understood that score lines or 
other methods permitting the shim to be cut or broken in two (depending on 
the type of material the shim device is made of) are also includable 
within the scope of the present invention. 
Breaking the shim device into two pieces permits installation of the shim 
device in arrangements where the axle and wheel assembly have a sealed 
rotary bearing (not shown) extending through the plane of the shim device. 
The shim device 10 is broken or cut in half and each half installed 
separately without removing the wheel mount. In a four-bolt arrangement, 
all the bolts that hold the wheel onto the end of the axle are loosened 
and two bolts are removed. The other two bolts retain the wheel mount 
assembly on the axle assembly. The first half of the shim is inserted and 
the two bolts are reinserted to retain the first half of the shim device. 
The other two bolts are then removed and the second half is inserted. The 
other two bolts are reinserted and all the bolts are tightened. 
Both sets of notches 34 and 36, 38 and 40, are preferably included so that 
the shim device can be broken into pieces that are insertable from the 
sides of the wheel mount assembly regardless of the angular position of 
the taper. Installation of the shim from the top or the bottom of the 
wheel assembly is very difficult. 
In an alternative embodiment, generally indicated at 100 in FIGS. 6 and 7 
the shim device 100 includes a plurality of slots disposed 
circumferentially around the plate. Similar to the shim device 10, the 
shim device 100 has diametrically opposed notches 104 and 106 and 
diametrically opposed notches 108 and 110 which are disposed at 90.degree. 
from the notches 104 and 106. 
The slots 102 are provided for engaging the bolts of the wheel mount 
assembly similarly to the notches 16 of FIGS. 1 and 2. 
The present invention includes a shim arrangement in which the camber and 
toe are easily adjusted once a proper reading of the existing camber and 
toe of the vehicle are determined. A series of shim devices are provided 
with each shim device having a different taper. An example of one such 
series of shim devices is set forth in Table 1 below. Each differently 
tapered shim device is identified by a number that is stamped on the shim, 
as illustrated in FIG. 1 by reference character 40. Alternatively, the 
differently tapered shims are identified by different colors. 
TABLE 1 
______________________________________ 
I.D. 
Number Thin Edge Thick Edge 
______________________________________ 
301 .015 .030 
302 .015 .045 
303 .015 .061 
304 .015 .076 
305 .015 .091 
306 .015 .106 
______________________________________ 
In FIG. 5, a chart is illustrated that relates adjustments in camber and 
adjustments in toe to a particular shim in the series in Table 1. The 
chart also indicates the proper angular position of the taper for the 
desired adjustment of both camber and toe with respect to a bolt. The 
taper of each shim in the series was designed to produce the incremental 
adjustments of camber and toe that are shown in the chart in FIG. 5. 
At selected angular positions on the shim corresponding to selected 
bolt-engaging notches 16, indicia are provided to identify the selected 
bolt-engaging notches 16. Similarly, the device 100 includes indicia 112 
so that the relative position of the taper of the device 100 can also be 
determined. The indicia identifying the notches 16 are used to determine 
the angular position of the taper with respect to a reference bolt. For 
example, in the embodiment shown in FIG. 1, the letter "A" is adjacent a 
selected bolt-engaging notch 16a. The notch 16a was selected so that when 
the notch 16a engages the upper right-hand bolt 29 (reference bolt for 
the right rear wheel), the taper of the shim device is positioned to 
substantially vertically. Positioning the shim device 10 so that the notch 
identified by the letter "B" engages the bolt 29 will position the taper 
to point to the right. 
A charge, illustrated in FIG. 5, relates both camber and toe adjustments to 
a shim of a particular taper. Although the specific chart of FIG. 5 is 
herein described. It should be understood that other types of charts are 
contemplated as being within the scope of the present invention. 
In addition, the chart indicates the relative angular position of the shim 
in relation to a reference bolt, as described above. The chart in FIG. 5 
includes incremental adjustments for positive and negative camber along a 
horizontal axis. Along the vertical axis, adjustments in toe described in 
increments of 1/32 of an inch. The term "toe-in" refers to a forward 
portion of the tire pointing inwardly, while the term "toe-out" refers to 
the tires pointing outwardly. 
Between the horizontal and vertical axis, the chart includes a grid 
structure having vertical and horizontal rows of blocks. Each increment of 
camber along the horizontal axis has associated with it a vertical row of 
blocks. Likewise, each increment of toe has associated with it a 
horizontal row of blocks. In selected blocks in the grid are disposed 
means for identifying a shim with a particular taper, such as indicia or 
color. In the chart shown, a three-figure number is used to indicate the 
shim. This three-figure number is identified by reference character 40 on 
the shim in FIG. 1, as previously described. Also included in the 
associated block is the letter which identifies the proper angular 
position of the taper to achieve a preselected camber and/or toe 
adjustment. To use the chart, the desired adjustment and chamber is found 
along the horizontal axis and the desired adjustment and toe is found 
along the vertical axis. A block common to both the preselected camber 
adjustment and the preselected toe adjustment indicates which shim should 
be used to achieve the adjustments in toe and camber. 
In a specific example, it the desired positive camber position is a 
positive chamber of 1/8 and the desired toe position is a toe-in of 1/32" 
on a right rear wheel, and the present camber of the wheel is 1.degree. 
positive camber and the toe-out is 5/32", the camber needs to be adjusted 
7/8.degree. and the toe-out needs to be reduced by 3/16". 7/8.degree. 
positive camber and 3/16" toe-out are located on the chart in FIG. 5 in 
the appropriate boxes along the corresponding axes. As indicated by the 
shading, the vertical row of boxes corresponding to the 7/8.degree. 
positive camber box is followed until a box common to a horizontal row of 
boxes corresponding to the 3/16" toe-out box is found. The common box 
indicates that the shim identified by the number 304 must be used to 
achieve the desired camber and toe-out positions. The chart also indicates 
that the bolt-engaging notch marked "B" on the shim must be engaged with 
the upper right-hand (for right rear wheel) reference bolt 29. 
One preferred method of inserting the shim device 10 that ensures that the 
bolt-engaging notch identified as "B" engages the upper right-hand bolt is 
to hold the shim device with a pair of thin long-nosed pliers, tweezers or 
any other long-handled tool that will grip the shim. The shim is then 
inserted between the end plate of the axle and the wheel hub and the upper 
right-hand bolt for right rear wheel is engaged by the tool that is 
holding the shim device. The shim device is then pulled back so that the 
notch engages the bolt and the bolts that have been removed are inserted 
back into their respective holes. This method is preferred since it is 
difficult to see the indicia that are on the shim when the wheel assembly 
is attached to the axle assembly. 
The procedure to adjust chamber and toe on the left rear wheel assembly is 
the same except that the side of the shim device facing the wheel mount 
assembly and the side of the shim device facing the axle assembly will be 
reversed. The reference bolt will change from the upper right-hand bolt to 
the upper left-hand bolt. 
In the specific example given above, the tire is a 24 inch outside diameter 
tire. Since the reading is in inches, toe is a function of tire size. 
Therefore, for tire sizes of outside diameter of 22 inches, 8% is added to 
the initial toe reading. If the tire diameter is greater than 24 inches, 
such as 26 inches, 8% is deducted from the initial toe reading. It the 
tire diameter is 27 inches, 12% is deducted from the initial toe reading. 
In the chart in FIG. 5, if a particular combination of camber/toe 
adjustment does not have a common block with indicia to designate a shim 
device 10, the nearest indicia-containing block should be consulted. In a 
situation wherein two indicia-containing blocks are within the same 
distance, the indicia-containing block having the closest toe value should 
be used. 
As should be easily understood, the chart illustrated in FIG. 3 is an 
empirical chart that is based on the tapers of the series of shims in 
Table 1 which were designed for use on rear wheels of front-wheel drive 
cars such as a Citation manufactured by General Motors Corporation. 
Front-wheel drive cars of other manufacturers may, for example, require 
shims of different sizes along with a new chart. 
If the use of a single shim device does not adjust the camber and toe the 
desired amount, two shim devices can be used in combination. 
Although the present invention has been described with reference to 
preferred embodiments, workers skilled in the art will recognize that 
changes may be made in form and detail without departing from the spirit 
and scope of the invention.