1985 A-Body Front End Wobble

[Blue Cherry]

Hi all, just joined, very nice site.

I have a 1985 Blue Century Wagon in good condition with 47K original miles. After being on the latest alignment systems, etc no one can figure out why it shimmys at certain speeds like 53mph, 63mph mainly. The dog bone motor mount on top was recently replaced and seemed only to focus the effect at certain speeds. They tell me that the other motor mount could use replacing. But this is becoming an expensive process of elimination. It also shimmies under braking but this might just be a rotor issue. Thank you in advance for any ideas.

[CieraSL92]

Are the wheels balanced properly?

[Blue Cherry]

Thanks. They had it on one of the newest machines - all checked out. Could they be missing a bent rim? These guys are pretty sharp. It was the proverbial granny wagon until I got it, parked for ten years thus the low miles. I wonder if something dried up that wouldn't normally under wear

[CieraSL92]

I'll let some a little more knowlegeable than myself chime in, but a couple things would be helpful. If your driving at 63 and you shift to neutral, does the shimmy stop? A bent rim is a possibility too, but that would be fairly obvious by looking at it.

[Blue Cherry]

I'll take a cruise and check that out. Thanks. I wonder if granny ran over a curb or such before parking it and something is bent just enough to show up at high wheel rpm.

[notsoslimshady76]

Have someone follow you on a 4 lane highway. Let them run along side you and see if any wheels shimmy. Then switch lanes and have them look at the other side.

Congrats on owning such a hard to find car

[86euro]

Are the tires old? Could be a separated tire on the front.

[Blue Cherry]

Thanks everybody. The tires are all new, service all up to date. That's part of why this is frustrating.

I took it for a drive and shifted into nuetral and the wobble shimmy was still there - in fact it made it easier to discern from road feedback so that will be helpful if anyone new takes it for a test drive. That was a good idea.

Also, good idea about having someone drive alongside and watch. I'll try that in the next few days.

If anyone has web links to views of this front end - parts and exploded views that would be cool.

Thanks - not sure how to post a pic from my hard drive, it seems to want a web URL to choose from but I don't have any pics posted of the car. I probably just have to learn how to use this great web site/blog better.

Thanks again

[GatorsFan38]

Been happening to my Dad's Ciera since it was new, have no idea what it is either. It happens at about 55mph-60mph

[SCREECH]

...1985 Blue Century Wagon in good condition with 47K original miles...it shimmys at certain speeds like 53mph, 63mph mainly. The dog bone motor mount on top was recently replaced...They tell me that the other motor mount could use replacing...It also shimmies under braking but this might just be a rotor issue...The tires are all new...I took it for a drive and shifted into nuetral and the wobble shimmy was still there...

It sounds to me like you're referring more to a vibration (a shaking of the car) rather than a side-to-side kind of shimmy, correct? That's what I'll have to assume for the rest of this post anyway.

Ok, so let's start ruling things out here - you've got new tires on the car, and the alignment shop checked out the wheels and said they checked out ok. Even if a wheel was bent, if it showed up as an imbalance on the machine they would have compensated for that with weights. You've confirmed that it's nothing in the drivetrain prior to the transmission by shifting to neutral while rolling down the road and confirming the presence of the vibration. It would therefore seem to be something within the transmission, or something between the wheels (if they truly are not the problem) and transmission.

My suggestions:
1. Get a different set of wheels bolted on and go for a drive. Does the vibration feel exactly the same? If so, put your original wheels back on as there's nothing wrong with them. If the vibration no longer exists, get a new alignment and tire service shop.

2. Check your drive axle support bearings in the transaxle, where the axle enters the transaxle. If you are able to move the axle around (ie. up and down, not in and out of the transaxle) then you may have found your problem right there. If the bearings seem fine, proceed to suggestion 3.

3. Check the boots and clamps on the drive axles - does everything appear to be as it should? The boots are not ripped nor are any clamps hanging off of the axle or missing? If this all checks out, see suggestion 4.

4. Grab a set of drive axles from the wreckers. It'll take you probably an hour per side to change them if you haven't done it before. The biggest part of the job is separating the balljoint from the lower control arm. I always find it best to remove the sway bar as the control arm can then often be pushed and held down by hand to do this. If you get this far and want more details about changing the drive axles then post it here and we'll help you out.

If you go through all these steps and have not successfully identified the vibration (ie. it still exists regardless of doing all of the above) then, sadly, it would seem to be something within the transaxle. I would hope that if that were the case that you wouldn't hesitate to get it fixed and continue driving the car - I would hope it would take more than a tranny problem to have someone give up on a gem like the one you've apparently got! I'm sure it would. Anyway, let us know how things are going.

[Prospeeder]

my 6000 seems to "shake" just abit when around 55-60 but you slow down, it stops, and you speed up it stops, if you had an old lady car, they looooooove to ram into curbs.

[glasspilot]

Guys, I might have the answer. I had a shimmy on my '88 Ciera. Long story short; it was a worn out rack and pinion. There was a recall on it way back when it was new that I never took it in for. The recall fixed a "stiff when cold" steering. I just always put up with it, once the steering "broke loose" it worked just fine.

Might have been better for me to have taken advantage of the recall. The same thing that caused the stiff when cold steering also caused it to wear out. The mechanic that replaced it said it could have been dangerous, the little teeth in the rack were getting smaller and smaller. At some point it would have given way and I would have no steering!

Check that rack!

[notsoslimshady76]

That's a good idea glasspilot. I've had a bolt loose on the rack before that lead to a "whap whap whap whap" when the wheel was turned a certain way.