Update: Someone has suggested motor mounts. I'll do a check on that after work. Someone else asked if I had an electronic differential (interesting idea). To my knowledge we have just plane old open-cage, non-limited slip type diffs - don't we?

Hi Guys,

This is a weird one. Almost always in 6th gear (sometimes in 5th, but less), when the tranny is warm, and when I "just" press the accelerator down a touch - the whole car wobbles from side to side. It doesn't "shake" - the frequency is too low - but it's more than just rocking. My head will actually rock from side to side and I'll bet the guy behind me can see it (and worry!).

BTW: A recent trip to the Jag dealer for diagnostics (following a couple of Transmission Fault annuciations) turned up a code for "wrong ratio 5th gear" (or something like that).

OK, you tranny gurus, .... WTH is going on?

Thanks!

 

Update:

Someone has suggested motor mounts. I'll do a check on that after work. Not sure how I would check the rear (i.e., Tranny) mount.

Someone else asked if I had an electronic differential (interesting idea). To my knowledge we have just plane old open-cage, non-limited slip type diffs - don't we?

 

Don't remember where I read it, but the article said that rear wheel adjustments can cause an oscillation as the wheels induce steering on the rear axle.

 

Thanks Bob,

Yeh - I was planning to give the rear suspension a good inspection the next time I had her on a lift, but that was before I realized the wobbling only occurred at moderate speeds and in the higher gears. For the life of me of can't figure out why I wouldn't notice this while accelerating in lower gears. I guess it could have something to do with tire rotation speed (at the lower speeds they might not have as much authority to rock the car).

I seem to have other tranny quirks that I hope are just electrical, otherwise it may be time for a rebuild. YIKE$$$$$.

We'll see.....

 

Scardini,
A couple of months ago after having a rear wheel bearing replaced, I picked up the car, drove to the freeway with no problem, got on the on ramp and accelerated, and almost lost control of my car. The rear end felt like it wanted to come around the right to the front of the car and drive sideways. At first, I thought maybe there was some grease on the on ramp, but ANYTIME I accelerated on the freeway, the same thing happened. It was the most frightening feeling I have ever had driving a car (including many times at the track). I kept the speed below 40mph and limped back to my mechanic and described what had happened. He pulled the rear wheel and found that the hub had been damaged during the bearing replacement and was able to fix it the same day. It was only upon acceleration at freeway speeds where it happened. You might start at the hub/bearings first.

 

Thanks Tberg! That sounds so much like what I'm experiencing. In my case though, the onset has been gradual. I first noticed a telltale wiggle a couple of months ago. No work has been done to rear other than new brakes, and there aren't any sounds pointing to a bearing breakdown. But your experience sounds so similar that it MUST be suspension/axle related. And onto the lift she goes (again).

 

You nailed it TBerg.

Left rear wheel is loose in its hub. I've resurrected your original post on this to continue the conversation. It obviously does not have anything to do with the trans.

THANKS!!!!

 

I'm glad you found the problem. It was positively frightening driving the car with this problem, and I don't know how you could have driven it that way for more than a few minutes. Too scary! Let us all know how you repaired or replaced hub.

 

I think the difference between your experience and mine is this:

Your hub carrier must have been significantly damaged during the bearing replacement. (Nothing wrong one day; VERY wrong the next). If my problem is in fact the hub carrier, its failing has been gradual. I first sensed something a little weird going back there a couple of months ago, but obviously couldn't nail down what it was. Initially, I thought it was my tires going bad.

But I cannot thank you enough for your story. The car is still quite drive-able right now and I might have continued to drive her, but after reading about your experience, I won't chance having it go dangerously bad all of a sudden while on the road in the middle of nowhere. So Kitty will sit in the garage until I get this resolved.

 

Hi All,

I replaced the entire hub carrier assembly with a rebuilt unit. There is a separate thread with my lessons learned from that experience. This post is to discuss the failure.

First: You must keep in mind that at a minimum, the hub shaft is press fit into the ABS sensor ring. When I laid the removed carrier down, the ABS ring just fell to the ground! Later, while I was carrying the assembly to the work bench, the hub itself fell out!

Second: There was never any audible indication that the bearings were going bad or approaching a possible disintegration. I had no idea anything was wrong until the effects to my car's handling were bad enough to notice.

To tell the truth, I believe that the only things that were holding my tire even remotely in-line, were the brake calipers, the ABS ring itself (spinning within the aluminum carrier), and what was left of the inner wheel bearing.

There seems to be evidence that the hub shaft was rotating within the inner bearing races.

I bring these to your collective attention, because this potentially catastrophic failure could easily exist without you having much indication / warning. Next time your car is on the lift, try to wiggle your rear tires from the top and bottom. Top/bottom will expose the problem sooner than a side to side wiggle because the brake calipers can hold the disk in place.

Mucho thanks to TBerg, as it was the telling of his own frightening experience that lead me down the path of enlightenment. Despite the car being "mostly road worthy" I thankfully just parked her until I was ready to effect the repair.

Kitty Rides Again!!!