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I’m getting a “shimmy”, that’s the best way to explain it I guess, between 30ish and 40 mph. Usually, I can feel it leaving my neighborhood b/c the speed limit is 35 so I’m cruising in that speed range or when gradually slowing down. I can tell as soon as I hit 40mph and it goes away around 30mph. Instead of feeling it in the steering and steering wheel though, I feel it in the front of the car. Steering wheel doesn’t move, but front of the car does.
Everything has been replaced. I don’t remember if this issue was there when I bought it b/c I didn’t really drive it much before putting in the new suspension parts. Current set up is Koni struts, Hotchkis springs, Baer bump steer kit, Adj upper strut mounts and stock a-arms with polyurethane bushings. Car only has 52K miles on it and inner tie rods, center link, etc are all tight. We’ve taken the bump steer ends off and put stock tie rods back on (then went back to the bump steer kit after not seeing a difference), I added the a-arms with new ball joints and the poly bushings and added the adj strut mounts, and this shimmy remains. I also added a WS6 steering box. Alignment is fine. My brother works at a garage with a rack so we’ve reset it each time. We even took it to my buddy’s shop who has a really nice alignment rack, tweaked it some, but it made no difference. Only think I haven’t changed out is the Jeep steering arm but again, I’m not feeling it in the steering so I don’t see any reason to mess with it. Looking for feedback/suggestions…
What kind of tires are you using.. Wear rating? Size? Have you noticed if there are sertain spots in the road that it does it more? And did you check your wheel bearings? Even if they swam good. Jack the car up and pull off the dust cap. See if there is any end play at all in the wheel bearings? Usually it's something very simple and easily over looked. What's your caster camber and toes set at?
Sumitomo HRZ 275/40/17's on 17x9.5 at all 4 corners. 160UTQG. Now, when I first noticed this way back, maybe a year and half ago, we noticed that one of the tires looked to be out of round while on the balancer. At the time, I was running 315/35's on the rear (same Sumitomo's) so I bought a new pair of 275's for the front. Both new ones appeared fine on balancer, shimy remained. I've autocrossed this car 3 times this summer and put the old pair on the rear b/c I was getting some fender rubbing under severe cornering with the 315's. Slight butt vibration at highway speeds even though they balanced fine, but no difference in shimmy.
I'd say the shimmy is probably most noticable on a smooth, straight surface; however, with this suspension setup the car basically rides like a dump truck so not sure how noticable it would on a bumpy road. lol That said, I don't think the road surface makes a difference. Wheel bearings are good. It's a Flynbye (I think that's where they're from) C5 set up, originally on my Iroc, with well under 10K miles. Only 2K of which are from this car. All was good when they were put on.
Here are a couple pics of last alignment print out...
Hmm .... Are you maxed out on caster? What's your tire wear look like up front. I wish I could ride in the car . Shimmy is a hard word to break down lol what wheels and back spacing and off set are you? Does it wander at all? How else could you describe this shimmy
Maybe shimmy isn’t the best term. I used it b/c it reminds me of my dad’s ’70 Dodge 1-ton with straight axle kingpin steering from when I was a kid. The pins were worn and the truck had a horrible shimmy around 50 mph. I replaced them eventually and truck was smooth after that. But the truck itself would shimmy/shake, not the steering wheel.
Caster isn’t maxed, there’s a good bit of adjustment all around with the adj upper mounts. Tire wear is even across on the fronts. No wondering on smooth roads either, car tracks relatively straight. All steering components are tight, at least last time I checked. I’ve only put maybe 2500 miles on it in the 2 years I’ve had it. I do drive it hard though. It’s currently up in the air so I can replace header collector gaskets so I’ll check everything out again.
Wheels are 17x9.5 Racestars with (I think) 4.5” bs. Not sure of offset but know several others are running same combo on TGO. That said, it is now occurring to me that other than my initial test drive of the car in a parking lot, I’ve never driven it on any other wheels or tires b/c the seller kept what he had on it. We put my wheels on it in the parking lot, loaded onto the trailer and headed home. I’ve never rotated front to rear either b/c I had been running the 315’s on the rear. I can try swapping now that I have 275’s on all four; however, I would think that a bad tire/wheel would be felt in the steering wheel, no?
It's honestly hard to say... And also maybe if some one else drove your car they wouldn't nice. But because you drive it all the time.. Your feel of the car is much more magnified. I would check every nut and bolt. From control arm bunching bolts to ball joints. Even the sway bar end links . Take a pry bar between you cross member or any other hard point and pry against the bottom of the idler arm. When I drove heavy on canyons regularly I would wear out idler arms. Because I was on stock lower control arms and stock geometry even though it was lowered a bit. Now I don't have an issue at all because I re designed the front end and over built it .. I don't have one bushing in my front end. It's all heims and sphiracle bearings. That being said. I wish I could ride in it and feel what you feel. But I would double check EVERYTHING and maybe give it a bit more caster... I think you will like it if you do ... Sense I get the idea that you like to drive it .... With spirit lol
Came across this old post of mine and thought I'd provide an update. I determined my issue to be wheel related. I rotated front to rear a little while back and my issue went away. I haven't put the wheels that are now on the back onto the balancer but when I had switched out tires this spring, I recall them all balancing nicely. However, I have the wheels marked and later realized my brother had put the wheels/new tires back in same location as the old ones which was why the issue never went away initially.
09-29-2015, 03:31 PM
