poor alignment after motor mount RR?
 

I am currently having some problems with my suspension and I need some guidance.

Recently had an alignment completed as well as new front tires. I also recently finished up a motor mount replacement. Left for a road trip last week and I am surprised at how poorly she rode.:mad:

Up to 60 MPH, not bad, but still not good. 60-80 was bearable but much worse; over 80 MPH was violent. Steering wheel shakes, and the entire car just bounced. First thought was maybe I left something loose after the MM work, but I KNOW I went back and torqued everything.

She was has never been smooth, but I felt is was due to a poor alignment and subsequent worn tires. Those issues should have been resolved with a proper alignment and new tires. This is now much worse!

Could I have impacted the alignment removing the lower control arm bracket or letting the tierods and steering rack hang? Or could it just be that the tires are not properly balanced? I want to get a handle on this before I just start throwing money around while not fixing the root cause.

Any thoughts will be appreciated.

Did you drive it after the alignment, and it rode fine? Then when you did the MM job it started to shake?

Thanks, guys.

Yes, I drove it after the alignment, but the front tires were worn pretty bad, so I did not get it up over 60. At that speed, felt fine. Since I had the front tires off for MM, I had the new tires put on... did not drive until everything was put back together. The shaking was essentially after new tires and MM. Rims should be okay.

The alignment was fine, on a drive up Hunter machine. The tires did not leave the ground.

I'm just wondering what I could have screwed up during the MM change that could cause this. Otherwise, a road force balance may be needed.

Torque tube is okay for now.

I would start with a careful check of the wheel and balance.

just to post a follow-up:

I inspected tie-rods, upper and lower balljoints, and wheel bearings. Found considerable play in driver tie-rod and torn boot on both uppers. Lowers and bearings were fine.

Well, I decided to replace the driver and passenger upper a-arms (mine are not rebuildable), lower bjs, and tie-rods. Took a while and some $$$, but I finally finished. Got another alignment and .... no improvement. :mad:

Out of frustration, I took all four tires/wheels in for a road force balance. According to the computer, 3 were sorely misbalanced and one rim is out of round. The results were astounding. Smooth ride into double digits (can slightly feel out of round tire in the seat), but night and day all the same.

So, if your ride is less than smooth, look into a road force balance. I went to the Hunter website and found someone local with their balance equipment. Well worth the $80 I spent. SmileWavy

I would probably get that out of round rim taken cared of before doing 3 digit runs.

you know, I hadn't really thougth about it but I guess I should get that rim taken care of.

any thoughts on a repair or is it better to replace?

Tweaking a bent wheel at the places I have looked at is around $125, seems like a flat minimum charge kind of thing. I've been twisting over doing it with my wife's Continental vs buying a used wheel and having it polished and chromed to match the rest for $225.

OTOH I would not knowingly buy or use a repaired wheel on my 928, other than cosmetic only repairs. 100+ MPH is a lot of stress on a wheel, and aluminum doesn't really like being bent. Besides good 928 wheels are cheap.

Amen Sir! That sounds like a good idea. See if you can find one that is used and perfectly round.

good advice. I'll search all the usual suspects for a used rear Cup II. Any body have one lying around?

when buying a used rim, is it possible to have a PPI done? sounds silly, but the ones currently on the car were supposed to be perfect.

You could always ask the seller to check the wheel, especially with an expensive one like a Cup II. With cars changing hands so many times good chance you would never know if a wheel has been repaired in the past unless the repair place puts some mark on it.

Did they try rotating the tire 180 degrees on the wheel thats "out of round"? Most of the time its the tire thats out of round.

I'm in the middle of it right now on my wife's car, and not much you can do except throw money at it until its ok.