shimmy/ alignment question

awilson40 · 02-24-2001, 02:13 PM

I've had a shimmy in the front of my 1982 924 sense I bought the car... I repacked the wheel bearings and tightened per specs, That greatly reduced it, I have had all 4 wheels balanced and have tried rotating the wheels/tires to different positions. Still a slight shimmy around 55 mph. Everything in the front seems good and tight, no play. I've repacked the CV joints and they look OK. This weekend I replaced the front springs and struts with Weltmeister 250lb progressive springs and Boge struts, and KYB Gas adjust rear shocks. While the car handles and rides great (the old parts were well worn) I still have the shimmy. I set the front Camber to neg .5 deg using an inclinometer... I checked the toe using a tape measure and measuring across the front and rear of the tires, It was at 1/8 in toe in, I tried 1/4 in, 0 in and 1/8 toe out... made no difference so I put it back to 1/8 toe in. Then I checked the rear... Its at a bit under 1.5 deg neg camber on both sides but is TOED OUT about 3/16 in. The car tracks straight and doesnt wear tires funny any all. Could this toe out on the rear cause a front shimmy?? Any thing else to check or could it just be the tires. After all the fiddling it now is smooth up to 60 mph before it vibrates, the vibration goes away around 70 mph.
Thanks for any help you can offer.
Andy

lm6y · 02-24-2001, 03:30 PM

I read somewhere that this is a common problem on the 924/944's. Some do it, some don't. But the suggested fix was having the tires balanced ON the car. You might have to look around to find a tire shop that can do it that way, but it balances the whole rotating assembly, and seems like it might help. It's worth a try.

Pilot_951S · 02-24-2001, 08:28 PM

Your porblem sounds like a harmonic imbalance and that usually signifies an out of balance or out of round tire. It could however also be a warped (not bent so hard or immpossible to spot when the wheel is staionary) rim.

The best way to check is to have the tires balanced by a GOOD shop that will pay attention to things like lateral and vertical runout of the wheel, as well as wheel weight positions etc etc.

Actually if you can find a shop that has one you can get everything measured accurately with a HUNTER GSP 9700 Anti-Vibration machine.
http://www.hunter.com/pub/product/balancer/4159T/index.htm

http://www.gsp9700.com/pub/news/4412T.htm

vas deferens · 02-24-2001, 11:12 PM

control arm bushings........that's the key word here........control......arm.......bushings. notorious for this symptom........vas

Lawrence Coppari · 02-25-2001, 02:36 AM

Raise the front wheels off the ground about 3/32 - 1/8 inch (small amount). Put a flashlight on the engine side of the wheel on the ground and slowly rotate the wheel. That way you can see if it is out of round. I have noticed that much over 1/16 inch can cause problems on some cars. Some makes are more troublesome than others.

awilson40 · 02-25-2001, 03:03 AM

Thanks for all the input, I will check the things you pointed out. But, what do you all think of the Rear Toe Out condition I found?
Thanks

vas deferens · 02-25-2001, 03:42 AM

control arm bushings........replace them.

Pilot_951S · 02-25-2001, 01:43 PM

I think you should bring the rear toe back to zero. Having toe out in the rear can make for some very scary handling, and even scarier tire wear.

Also I'm not convinced that your Contral Arm Bushings are bad as VD believes. The fact that the vibration stops at a certain speed points to some sort of harmonic issue, and if the bushings were bad the vibration would continue to get worse, same thing with wheel bearings or bad alignment.

Another thought: You may have a brake rotor that is out of balance.

[This message has been edited by Pilot_951S (edited 02-25-2001).]

awilson40 · 02-26-2001, 02:20 AM

Pilot... good point. I've ordered a set of Poly Graphite bushings... several people have pointed to the bushings and its not to expensive to try. I had a bent rim (looks like someone was heavy handed with a tire changer) I used a mallot to straighten it, but no matter where I put the wheel, frnt, rear, left or right... the shimmy stays so I doubt its the wheel. Also some days its just noticable, other days its worse. I will also look into that rear toe.