I need a suspension guru
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Joined: Dec 2007
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From: Waynesville Ohio
I need a suspension guru
I have a front end shimmy that at times can get severe. I did multiple searches to see if I could find a similar situation but found none.
Car:
- 87 coupe
- GenIII iron block (weight difference?)
- Ball joints ~2yrs old
- tie rod ends - new
- front wheel bearings - new
- front rims are from a C5(rear) with 285/30/18 and 1" spacer
Also I just aligned it, put the toe to within .01 on both sides and the camber was in the green. The caster was not in the green but like 5.3 and 4.7 ish where it wanted 6....I was told that doesn't really matter.
The car has had this shimmy for a long time, but we all know how it goes when your building up a car, you kill one thing at a time. So I just put up with it. Recently I had to drive the car from Ohio to Texas and I dropped the right front rim in mid OK. Snapped all the lugs....of course the local shop blamed it on the wheel spacers. I limped it the rest of the way to Tx and got two new front rims, then bearings etc... to try to figure out what it was. It is better but still has the shimmy around 60. Wheels/tires that are on the front were balanced in ohio. I'm out of parts to change....any ideas?
Car:
- 87 coupe
- GenIII iron block (weight difference?)
- Ball joints ~2yrs old
- tie rod ends - new
- front wheel bearings - new
- front rims are from a C5(rear) with 285/30/18 and 1" spacer
Also I just aligned it, put the toe to within .01 on both sides and the camber was in the green. The caster was not in the green but like 5.3 and 4.7 ish where it wanted 6....I was told that doesn't really matter.
The car has had this shimmy for a long time, but we all know how it goes when your building up a car, you kill one thing at a time. So I just put up with it. Recently I had to drive the car from Ohio to Texas and I dropped the right front rim in mid OK. Snapped all the lugs....of course the local shop blamed it on the wheel spacers. I limped it the rest of the way to Tx and got two new front rims, then bearings etc... to try to figure out what it was. It is better but still has the shimmy around 60. Wheels/tires that are on the front were balanced in ohio. I'm out of parts to change....any ideas?
Last edited by Turbogtu; Mar 10, 2011 at 06:38 PM. Reason: editing
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I have a front end shimmy that at times can get severe. I did multiple searches to see if I could find a similar situation but found none.
Car:
- 87 coupe
- GenIII iron block (weight difference?)
- Ball joints ~2yrs old
- tie rod ends - new
- front wheel bearings - new
- front rims are from a C5(rear) with 285/30/18 and 1" spacer
Also I just aligned it, put the toe to within .01 on both sides and the camber was in the green. The caster was not in the green but like 5.3 and 4.7 ish where it wanted 6....I was told that doesn't really matter.
The car has had this shimmy for a long time, but we all know how it goes when your building up a car, you kill one thing at a time. So I just put up with it. Recently I had to drive the car from Ohio to Texas and I dropped the right front rim in mid OK. Snapped all the lugs....of course the local shop blamed it on the wheel spacers. I limped it the rest of the way to Tx and got two new front rims, then bearings etc... to try to figure out what it was. It is better but still has the shimmy around 60. Wheels/tires that are on the front were balanced in ohio. I'm out of parts to change....any ideas?
Car:
- 87 coupe
- GenIII iron block (weight difference?)
- Ball joints ~2yrs old
- tie rod ends - new
- front wheel bearings - new
- front rims are from a C5(rear) with 285/30/18 and 1" spacer
Also I just aligned it, put the toe to within .01 on both sides and the camber was in the green. The caster was not in the green but like 5.3 and 4.7 ish where it wanted 6....I was told that doesn't really matter.
The car has had this shimmy for a long time, but we all know how it goes when your building up a car, you kill one thing at a time. So I just put up with it. Recently I had to drive the car from Ohio to Texas and I dropped the right front rim in mid OK. Snapped all the lugs....of course the local shop blamed it on the wheel spacers. I limped it the rest of the way to Tx and got two new front rims, then bearings etc... to try to figure out what it was. It is better but still has the shimmy around 60. Wheels/tires that are on the front were balanced in ohio. I'm out of parts to change....any ideas?
If it drives well with the other tire/wheel combination you've got bad wheels/tires or the adapters/spacers are your problem.
I would think you'd have no problem coming up with tires/wheels for a "test" if you posted your needs and why! There's many Camaro/Firebird wheels that I believe are in the 40 - 46 mm offset that would likely do for a driving test. There's likely a few sets of tires wheel already mounted in Forum members garages in your area that you could probably gather!
Check your rotors for balance?
You mention you "dropped" a wheel and without seeing what you've got for spacers/adapters I'm guessing they're not a "quality" product!
Snapshots?
Last edited by WVZR-1; Mar 10, 2011 at 07:58 PM.
Thread Starter
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Joined: Dec 2007
Posts: 52
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From: Waynesville Ohio
I thought it might be the tires or rims so I got another 2 18"ers so that I could somehow try to capitalize on the situation. Put some wider tires on the new rims and put the rear rims and tires in the front.
I just did a C5 brake swap on the front so I've had old and new rotors on the front now with no change in vibration.
When I dropped the rim the lugs snapped off at the hub...but what that makes me think is that I have not tried moving around the spacers to see if the vibration moves with them. I will try that today.
The .01 toe was per side but the total was still well within spec (it was in the tenths for the tolerance).
I just did a C5 brake swap on the front so I've had old and new rotors on the front now with no change in vibration.
When I dropped the rim the lugs snapped off at the hub...but what that makes me think is that I have not tried moving around the spacers to see if the vibration moves with them. I will try that today.
The .01 toe was per side but the total was still well within spec (it was in the tenths for the tolerance).
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Joined: Dec 2007
Posts: 52
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From: Waynesville Ohio
I was thinking it might be the rack because mine is crap, but I hadn't seen anyone claiming that a rack will produce a vibration, I was hoping through the thread someone would say yeah a rack fixed mine...but
at any rate I started moving the damn spacers around and think I found the issue, I found that one appeared to show signs around the lug of being worn oblong. I guess that you need to be careful when tighting them down (like much more than a rim) because they will seat not square. F! Put them all back on carefully to ensure a good symmetrical seat and it seems to be fixed. I don't even want to think about the amount of $ and time that damn spacer stole from me. Good example of why not to assume that there are any givens (good parts) when diagnosing no matter how new or old.
at any rate I started moving the damn spacers around and think I found the issue, I found that one appeared to show signs around the lug of being worn oblong. I guess that you need to be careful when tighting them down (like much more than a rim) because they will seat not square. F! Put them all back on carefully to ensure a good symmetrical seat and it seems to be fixed. I don't even want to think about the amount of $ and time that damn spacer stole from me. Good example of why not to assume that there are any givens (good parts) when diagnosing no matter how new or old.
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Joined: Apr 2003
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From: moraga ca
A shimmy can result from any part of the suspension with play or slop. The steering wheel is held for the car to go straight, the wheels with play in the steering can go a degree or two to the left and right causing shimmy.
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I was thinking it might be the rack because mine is crap, but I hadn't seen anyone claiming that a rack will produce a vibration, I was hoping through the thread someone would say yeah a rack fixed mine...but
at any rate I started moving the damn spacers around and think I found the issue, I found that one appeared to show signs around the lug of being worn oblong. I guess that you need to be careful when tighting them down (like much more than a rim) because they will seat not square. F! Put them all back on carefully to ensure a good symmetrical seat and it seems to be fixed. I don't even want to think about the amount of $ and time that damn spacer stole from me. Good example of why not to assume that there are any givens (good parts) when diagnosing no matter how new or old.
at any rate I started moving the damn spacers around and think I found the issue, I found that one appeared to show signs around the lug of being worn oblong. I guess that you need to be careful when tighting them down (like much more than a rim) because they will seat not square. F! Put them all back on carefully to ensure a good symmetrical seat and it seems to be fixed. I don't even want to think about the amount of $ and time that damn spacer stole from me. Good example of why not to assume that there are any givens (good parts) when diagnosing no matter how new or old.
I'm NOT criticizing the use of adapters/spacers, I use 16mm spacers that I had done to my specifications that allow me to use 11" @ 50mm offset wheels on the rear of my ZR-1.
Inexpensive spacers/adapters generally aren't quality and "expensive" doesn't necessarily justify the "assumption" that it's a quality product.
Hardware is important. I'd guess a hardware problem or installation error created the situation in Oklahoma.
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Had a similar problem.
Replaced the rotors. Fixed
Always torque the lug nuts, then retorque after a few miles.
Not doing so WILL cause the rotors to warp, and the front to shimmy.
BTW, the brake pedal did not pulse.
Replaced the rotors. Fixed
Always torque the lug nuts, then retorque after a few miles.
Not doing so WILL cause the rotors to warp, and the front to shimmy.
BTW, the brake pedal did not pulse.