UH OH, I need some help!!! TA shims
Melting Slicks
Joined: Dec 2000
Posts: 3,364
Likes: 303
From: Lansdale 19446 PA
2024 C3 of the Year Finalist- Unmodified
St. Jude Donor '10-'11, '15, '19
When I did my 76, the guy at the alignment shop suggested the put an equal amount of the left & right of each TA. That will be good enough to get to the shop for proper alignment.
Drifting
Joined: Jun 2007
Posts: 1,404
Likes: 1
From: Ansonia/NYC CT
Without proper tools, this is something you can't just eyeball. You can get the stuff you need at summit for about 200 bucks, or so, or you can pay a shop about 200 bucks or so to do it. It's up to you.
Thread Starter
Instructor
Joined: May 2010
Posts: 118
Likes: 0
From: conway arkansas
Duntov Motor Company
Rear Suspension Alignment School
A lot of us would rather do it ourselves than take our Corvette to an alignment shop that
hasn’t seen a C2-C3 Corvette in 20 years. I have used this method for years, and it will put
your car on the money.
All you need to align the rear end of your 63-82 Corvette is an hour or so, a short level, a pair
of 2’ by 4 x 4 wood blocks, two 3-foot aluminum straight edges, a framing square, some
string, a measuring tape and a helper.
Your car needs to be on the garage floor, with all the trailing arm shims removed from the
front trailing arm bushings.
First the ride height at the rear should be set. Your car’s favorite ride height is where the half
shafts are horizontal. In this position, the U-joints don’t have to work much at all, but that
may be too low for you. Adjust the ride height to your favorite position by tightening or
loosening the spring bolts.
Next is track. We have to have the toe-in equal on both sides so the car will track straight
down the road. Position the rear wheels as close to straight as possible. This is easy even
with weight on the car, as you can use the trailing arm as a big lever to pull or push the front
of each wheel in or out.
Make sure the front wheels are straight. Have your helper hold one end of an 8’ string on the
outside of the left rear tire behind the axle, at the height of the axle. Pull that string taught to
the front of the car and move it in until the string just touches the front of the rear tire in the
same position as your helper has the other end pinned at the rear.
With the taught string in your left hand, use your right hand to measure the distance between
the string and the dust cover of the front spindle. If you have rally wheels, measure to the
center of the cone.
All we are trying to do is get a relative measurement to which we can compare the other side.
Repeat this procedure on the right side, and go back and adjust the tow by hand until both
lines of alignment are equal when measured relative to the front axle reference.
At this point your Corvette is tracking straight, but we have not yet set the toe. We have set
the track.
To set the toe, place the 2’ 4X4 wood blocks on the floor outside, centered and up against
the rear tires. Place the 3-foot aluminum straight edge on top of one of these blocks,
centered on the tire. Have your helper hold the strap tangent to the outside of the tire. In
case you are wondering, the purpose of the block is to elevate the aluminum straight edge
above the bulge in the tire at the floor.
Now you go to the other side and place your block and aluminum strap in the same relative
position and feed the end of your tape measure under the car to your helper on the other
side. Measure the distance between the aluminum straight edges in front of the tire and
behind the tire, again with both aluminum straight edges sitting on the reference blocks and
tangent to the outsides of the tire.
Our target is 1/8-inch total toe. That means the distance between the front of the tires should
be 1/8-inch less than it is at the back of the tires. It won’t be. You will have to torque the
arms in or out to achieve this number, but the trick is to do it half on one side and half on the
other. When you think you are there, go back and do the string trick again to make sure you
are still tracking straight down the road. Adjust accordingly and repeat until it is both tracking
straight and the total tow is 1/8-inch.
When you are there, put the spacers in and tighten up the trailing arm bolts. Check it again
just to make sure, and then insert the cotter pins in the trailing arm bolts and in the shim
packs and you are finished with the toe adjustment.
Last we adjust the camber, which is the angle the rear tire sits to the floor. The target is ¼ to
½ degree negative camber, meaning we want the top of the tire to be tilted in just barely, like
1/8 to 3/16 inch from vertical. You adjust that with the strut rod cam bolts that are located
under the differential. Loosen, twist, tighten, measure, and repeat as necessary until you get
it right. You will have to roll the car between adjustments to allow the tire to move.
When you are all finished, if you are into self-abuse, you can drive the car around the block
and measure the toe again. It will go much faster this time. Remember we need to have the
toe-in right, but we must also have the tracking equal left and right.
Best regards,
Alan
Visit us at http://www.duntovmotors.com
Rear Suspension Alignment School
A lot of us would rather do it ourselves than take our Corvette to an alignment shop that
hasn’t seen a C2-C3 Corvette in 20 years. I have used this method for years, and it will put
your car on the money.
All you need to align the rear end of your 63-82 Corvette is an hour or so, a short level, a pair
of 2’ by 4 x 4 wood blocks, two 3-foot aluminum straight edges, a framing square, some
string, a measuring tape and a helper.
Your car needs to be on the garage floor, with all the trailing arm shims removed from the
front trailing arm bushings.
First the ride height at the rear should be set. Your car’s favorite ride height is where the half
shafts are horizontal. In this position, the U-joints don’t have to work much at all, but that
may be too low for you. Adjust the ride height to your favorite position by tightening or
loosening the spring bolts.
Next is track. We have to have the toe-in equal on both sides so the car will track straight
down the road. Position the rear wheels as close to straight as possible. This is easy even
with weight on the car, as you can use the trailing arm as a big lever to pull or push the front
of each wheel in or out.
Make sure the front wheels are straight. Have your helper hold one end of an 8’ string on the
outside of the left rear tire behind the axle, at the height of the axle. Pull that string taught to
the front of the car and move it in until the string just touches the front of the rear tire in the
same position as your helper has the other end pinned at the rear.
With the taught string in your left hand, use your right hand to measure the distance between
the string and the dust cover of the front spindle. If you have rally wheels, measure to the
center of the cone.
All we are trying to do is get a relative measurement to which we can compare the other side.
Repeat this procedure on the right side, and go back and adjust the tow by hand until both
lines of alignment are equal when measured relative to the front axle reference.
At this point your Corvette is tracking straight, but we have not yet set the toe. We have set
the track.
To set the toe, place the 2’ 4X4 wood blocks on the floor outside, centered and up against
the rear tires. Place the 3-foot aluminum straight edge on top of one of these blocks,
centered on the tire. Have your helper hold the strap tangent to the outside of the tire. In
case you are wondering, the purpose of the block is to elevate the aluminum straight edge
above the bulge in the tire at the floor.
Now you go to the other side and place your block and aluminum strap in the same relative
position and feed the end of your tape measure under the car to your helper on the other
side. Measure the distance between the aluminum straight edges in front of the tire and
behind the tire, again with both aluminum straight edges sitting on the reference blocks and
tangent to the outsides of the tire.
Our target is 1/8-inch total toe. That means the distance between the front of the tires should
be 1/8-inch less than it is at the back of the tires. It won’t be. You will have to torque the
arms in or out to achieve this number, but the trick is to do it half on one side and half on the
other. When you think you are there, go back and do the string trick again to make sure you
are still tracking straight down the road. Adjust accordingly and repeat until it is both tracking
straight and the total tow is 1/8-inch.
When you are there, put the spacers in and tighten up the trailing arm bolts. Check it again
just to make sure, and then insert the cotter pins in the trailing arm bolts and in the shim
packs and you are finished with the toe adjustment.
Last we adjust the camber, which is the angle the rear tire sits to the floor. The target is ¼ to
½ degree negative camber, meaning we want the top of the tire to be tilted in just barely, like
1/8 to 3/16 inch from vertical. You adjust that with the strut rod cam bolts that are located
under the differential. Loosen, twist, tighten, measure, and repeat as necessary until you get
it right. You will have to roll the car between adjustments to allow the tire to move.
When you are all finished, if you are into self-abuse, you can drive the car around the block
and measure the toe again. It will go much faster this time. Remember we need to have the
toe-in right, but we must also have the tracking equal left and right.
Best regards,
Alan
Visit us at http://www.duntovmotors.com
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Simple as that. Take the extras with you.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Agree stringing works, and well enough that it's been a time honored practice at the track for ages, but you could also just use a homemade trammel bar to check and set toe...
That aside, the reason I'm posting is that setting the rear ride height to where the half-shafts are level with the ground will cause rear toe-steer to move towards or into toe-out (highly undesirable) as the suspension travels from static height into bump, possibly requiring additional static toe-in to compensate. IMCO, anyone straying very far from OEM ride height specs (Z and D heights are the best references) should be aware that raising the diff in lowered race prepped chassis, as mentioned in the Chevy Power book, might become necessary to counter this geometry issue.
FWIW, whatever method you might use, I'd add 8 pieces of commercial vinyl tile and some grease to the tool list for making a poor man's set of turntables (sandwich a coat of grease between 4 pair) so you don't have to constantly resettle the chassis after every adjustment.
TSW
That aside, the reason I'm posting is that setting the rear ride height to where the half-shafts are level with the ground will cause rear toe-steer to move towards or into toe-out (highly undesirable) as the suspension travels from static height into bump, possibly requiring additional static toe-in to compensate. IMCO, anyone straying very far from OEM ride height specs (Z and D heights are the best references) should be aware that raising the diff in lowered race prepped chassis, as mentioned in the Chevy Power book, might become necessary to counter this geometry issue.
FWIW, whatever method you might use, I'd add 8 pieces of commercial vinyl tile and some grease to the tool list for making a poor man's set of turntables (sandwich a coat of grease between 4 pair) so you don't have to constantly resettle the chassis after every adjustment.
TSW
