Front end shimmy?

[cougar9150]

Well guys, I'm still trying to get my MM fully recovered from my accident. I have rebuilt the driveshaft, replaced the front brake hardware w/new pieces(bent a caliper pin), same w/the rear brakes along with new pads all around (old one on there for a month before the accident), on my month old cryo-treated rotors. Now the constant vibration while driving is gone, same with the braking shimmy I was getting from a nearly locked up calipers and uneven pad wear. I have 2 brand new front tires, just got the wheels balanced, and an alignment to the factory specs (forgot to bring the other specs w/me).
Now I only get a shimmy starting around 40 mph, that stops around 60+ mph. When I brake at these speeds I also get the vibration in the steering wheel. Funny thing is it does not happen when taking turns at these speeds (on ramps w/a wide apex not standard corners), or under hard acceleration. It also does not do it at all at lower or higher speeds. I have looked at the upper ball joints, tie rod ends, rack bushings, sway bar bushings and end links. I cannot visibly see anything the matter with these components. My shocks all all brand new about 3 months ago also, w/no leaking or compression issues since the accident.
Again I hit the median in the middle of the road at about 45 mph when I was sleeping behind the wheel so I'm sure this was the cause of it since it did not do it before that point. I cannot determine what it could be unless I just start buying all of parts to replace everything up front. Please help with any info/suggestions you may have. It vibrates so bad at these speeds that if I take my hands off the steering wheel it bounces back and forth about a 1/4", but again as soon as go to turn or change lanes it stops until I'm going straight again.

[OneBADLsE]

Well guys, I'm still trying to get my MM fully recovered from my accident. I have rebuilt the driveshaft, replaced the front brake hardware w/new pieces(bent a caliper pin), same w/the rear brakes along with new pads all around (old one on there for a month before the accident), on my month old cryo-treated rotors. Now the constant vibration while driving is gone, same with the braking shimmy I was getting from a nearly locked up calipers and uneven pad wear. I have 2 brand new front tires, just got the wheels balanced, and an alignment to the factory specs (forgot to bring the other specs w/me).
Now I only get a shimmy starting around 40 mph, that stops around 60+ mph. When I brake at these speeds I also get the vibration in the steering wheel. Funny thing is it does not happen when taking turns at these speeds (on ramps w/a wide apex not standard corners), or under hard acceleration. It also does not do it at all at lower or higher speeds. I have looked at the upper ball joints, tie rod ends, rack bushings, sway bar bushings and end links. I cannot visibly see anything the matter with these components. My shocks all all brand new about 3 months ago also, w/no leaking or compression issues since the accident.
Again I hit the median in the middle of the road at about 45 mph when I was sleeping behind the wheel so I'm sure this was the cause of it since it did not do it before that point. I cannot determine what it could be unless I just start buying all of parts to replace everything up front. Please help with any info/suggestions you may have. It vibrates so bad at these speeds that if I take my hands off the steering wheel it bounces back and forth about a 1/4", but again as soon as go to turn or change lanes it stops until I'm going straight again.


I have the same issue on my GM ever since i bought it. Please post or PM me when a solution is reached.

Only difference is, mine was never involved in an accident (not being sarcastic).

[Blk Mamba]

Did you check the front wheels for run out, it only takes a little. When you hit the median, you may have bent the wheel a little.

[cougar9150]

One wheel was completely replaced after the acciden, but all of the others were checked for center and balance and said to be okay.

[Blk Mamba]

I'd check again

[Local Boy]

Road force balanced?

That will rule out the tires...

ALOHA

[Dragcity]

Sounds like you did everything on the corners. If you are certain the wheels, tires, calipers, and steering are perfect, I would look into the entire drive train.

Man, there are a LOT of components that can cause that.... I guess I would focus on the drive shaft and wheels.

Could it be in the Transmission Tail shaft? If the driveshaft was bent (said you rebuilt it). Is the driveshaft true? Did the pinion Shaft in the differential take a hit too? Could you have a bent axle? Not sure how you hit the median.....

[Krytin]

I just had an issue with mine. 70k+ miles and since November I had clunk in the front end at low speeds and car would "pull" when on one side of the crown in the road or the other. I was sure I had a major component going bad but I could not find anything loose!!!
This was really starting to p*ss me off!
I tracked the clunk down to the passenger side - with the hood up and rocking the car up and down a very distinct metalic clunk couold be heard.
I got down on the ground and had a friend bounce the car. I reached in and felt the end link on the sway bar and sure enough, the bar end had some play in it! Now I had already checked this with the wheels up and I could not get any play out of it but with the car on the ground and bouncing you could feel the play. I replaced the link and all is well! There was about a 1/16" play in the ball joint of the sway bar end of the link - go figure?

[cougar9150]

I hit the median falling asleep driving after a long ass week of work. 90+ hours will do that sometimes.
I rebuilt the driveshaft as a precaution. I was getting minor drivetrain vibration before I had the accident (around 60k miles) and was considering it anyway. I wanted a new PST one for an upgrade but could not afford it at this time. The heavy duty u-joints were only $40 vs $500+.
The only part that took a real hit was the passenger side front wheel. The rest of car didn't get touched at all. No under body scrapes or hits. Took it to a quality body shop for the insurance claim and then had my own shop I always use check the wheels and alignment again. Tires are brand new...
No pulling but I think I will try the end-links next since they are not that expensive but after that I'm thinking new hub assemblies, steering linkage, misc. bushing etc. Cannot enjoy the car this way. Somedays the only reason I get out the door for work is because I enjoy my ride when I'm in my MM. It's not even fun now.

[shawn.criswell]

I had the same issue with a '96 cougar. Checked out everything I could and couldn't find anything out of the ordinary. Then one day while working under the hood, I noticed where the left strut mount had actually broken a couple of the welds loose. Took it in and had it repaired and it fixed the porblem.

[JMan]

Cannot enjoy the car this way. Somedays the only reason I get out the door for work is because I enjoy my ride when I'm in my MM. It's not even fun now.

Alright, emergency help merited! If I PM you my phone number, will you call me? I might be able to assist in the diagnosis of the problem.

JMan

[cougar9150]

Jman. Any help would be great.

[ParkRanger]

I like to watch Jessica Biehl shimmy. :D

[cougar9150]

That is a fact but not relevant. ;)

[Stranger in the Black Sedan]

Oh hell's yeah

[cougar9150]

I took the MM into a shop I go to for basic work out of desperation after spraining my elbow and pulling a bunch of muscles in my arm to get the shimmy fixed. I didn't care about the cost I just wanted it fixed since I'm sidelined for about 6-8 weeks. They told me never go back to where I went ever again if I liked my car at all. The dumbasses at the Tires Plus In my area had put weights in like 4 different places on the wheels and basically screwed it up worst than the collision shop who replaced the wheels after the accident. I usually will not go to these type of shops but it was a Sunday and I needed an alignment after screwing around with the suspension and before my Monday drive into work. They rebalanced the wheels (third times a charm I guess) and it is like night and day. I love her again. Something so simple almost became so costly.

[Krytin]

Glad to hear you got it right - nothing worse than starting to hate the ride you love!

[cougar9150]

Just happy to have her back. I'm going to replace the front hubs soon anyway, just to be proactive. Since the front driver side took the hit I just want to be carefull and make sure I didn't screw anything else up. I'd rather be proactive than reactive...