Shake from rear on highway primarily between 61-78

[tyb323]

Hello ladies and gents. I've just gotten in from a 7 hour trip in the d and I noticed that the car was shaking for most of the trip. I have replaced and regreased all the axle joints and according to my mechanic, they are on nice and tight. The tires were balanced 2 months ago, and alignment is spot on. So, what would cause this and what should i be looking for?

[Michael]

It's very possible you lost a wheel weight....that's the first thing I would check.

[tyb323]

I'll check, but it shook before and after I had it balanced

[Bitsyncmaster]

Can you tell which side is shaking? Try swapping the wheels from one side to the other.

[tyb323]

It feels like the back right, but to be honest, it's resonating through the whole tub. It feels like it's coming from the back, that's pretty much all I know. Front is solid as a rock. There also don't appear to be any weights missing.

[DMCMW Dave]

It feels like the back right, but to be honest, it's resonating through the whole tub. It feels like it's coming from the back, that's pretty much all I know. Front is solid as a rock. There also don't appear to be any weights missing.

Lift the tires off the ground and spin the tires. Look for a bent wheel or loose/sloppy wheel bearing.

[stevedmc]

Trailing arm bolt?

[tyb323]

Nothing appears to be bent at a glance.m tomorrow I'll jack the back up and see if either wheel is wobbling. I'm kind of hoping that is what it is. Seems like a straightforward job

[tyb323]

Also, TABS are fine

[Ron]

Nothing appears to be bent at a glance.m tomorrow I'll jack the back up and see if either wheel is wobbling. I'm kind of hoping that is what it is. Seems like a straightforward job
Probably goes w/o saying, but look from both angles...it might be the tire is out of round.

[tyb323]

Seems to be a slight whine coming from the rear left tire at least. I'm not sure if it's the bearing or just tire noise/ transmission whine. And I have no floor jack. Gomna see if I can borrow one in a few days to see if I can move the back wheels. If it is bearings, how big of a job is that? Also, does seem to be some vibration under hard acceleration, not as prominent, but its there. For reference, it's a 3 speed autotragic

[sean]

You got a jack in the trunk dont ya? Id at least use that to get the wheel of the ground to see if there is any play in the bearing.

[David T]

Sounds like a rim that is bent, a tire out-of-balance or defective, or somehow not mounted correctly onto the hub. Raise the car, place a stick alongside a tire, and slowly rotate the tire watching if it moves away or towards the stick indicating runnout. I would also check and retorque the wheel lugnuts. With both rear wheels off the ground you can run the motor and listen to the bearings and see what shakes while an assistant steps on the gas to spin the wheels. While you are checking I would also check the front. Another "trick" is to have someone drive the car while you drive alongside and look at each wheel.
David Teitelbaum

[tyb323]

Another "trick" is to have someone drive the car while you drive alongside and look at each wheel.
David Teitelbaum

this is the trick I will use until I get my hands on a reliable not 30 year old jack

[Kevin]

A balancing machine should catch something like a bent rim or out of round wheel and report excessive runout, from my experience anyway. So, tire or rim may be unlikely, unless the place that balanced it ignored the error.

And if it were the lug nuts, you'd hear more of a knocking, I've had a lug nut gradually come loose like that.

But yes definitely check everything folks have mentioned, including any abnormal tread wear or wear around the inside of the hub once/if you take the tire off.

[David T]

I have seen kids try to balance bent stuff. They figure if they add enough weight in the right spot it will make everything OK. Amazing what can happen if you do not know any better! Most shops put their rawest, newest people on tires, batteries, oil changes, and exhaust work (all of the routine "dirty" stuff). If they come in every day and don't wreck too many cars then they are "keepers" and worth investing some time in training them. Unfortunately the quality of their work often leaves a lot to be desired. Look the car over yourself and if you do not see anything obvious take it back to the shop and ask for a more experienced mechanic to look it over. It *could* be a defective tire and that is not easy to spot. You did check the tire pressures, right?
David Teitelbaum

[Kevin]

I have seen kids try to balance bent stuff. They figure if they add enough weight in the right spot it will make everything OK. Amazing what can happen if you do not know any better! Most shops put their rawest, newest people on tires, batteries, oil changes, and exhaust work (all of the routine "dirty" stuff).
David Teitelbaum

Sadly true, now that I think about it. So, yes, could be a tire or rim. I've experienced the same vibrating symptoms you are from a bent rim on my daily driver. The problem was pretty obvious when I took the tire off, the lip was bent down slightly on the inside, but enough to cause some trouble.

But, sounds like you have plenty of leads to follow up on, let us know how it goes!

[DMCTek]

A balancing machine should catch something like a bent rim or out of round wheel and report excessive runout, from my experience anyway. So, tire or rim may be unlikely, unless the place that balanced it ignored the error.

And if it were the lug nuts, you'd hear more of a knocking, I've had a lug nut gradually come loose like that.

But yes definitely check everything folks have mentioned, including any abnormal tread wear or wear around the inside of the hub once/if you take the tire off.

+1 a bent rim or out of round tire can be felt best below 10 mph.

[tyb323]

New symptom! Clunk from somewhere in the back when reversing and turning hard over

[jawn101]

New symptom! Clunk from somewhere in the back when reversing and turning hard over

Hmm.. I would think a clunk would be CV joints but it's hard to go based solely on onomotopaeia. I am reminded of that Aamco commercial where it looks like all the customers are having seizures trying to describe symptoms to the tech :)

[tyb323]

CV joints are all freshly regreased, inspected, reinstalled and tight, so it ain't them

[Ryan King]

Mine used to have a horrible wobble at fast Highway speeds. I am still working on tracking down the problem as we speak. I am going to do an overhaul of my steering rack along with with adjustable lower links on the rear.

I believe the awful wobble is caused by the car being out of alignment.

[tyb323]

Aligned less than a week ago

[jawn101]

Did it wobble before the alignment? Maybe it was done wrong or you lost a shim off a rear wheel. I have read that the universal shims used at big box shops tend to fall out for some reason and that you are well advised to bring along some proper ones from a vendor.

[tyb323]

Just jacked up the back wheels, no fore or aft movement on either one unfortunately. It did shake before alignment, no better after, and the guy used the proper shims. So still clueless

[shortcircuit971]

I just found a loose spot on my rear end that may sound like what you have as well. Not trying to hijack the thread, but it may be your solution too.

On my passenger rear wheel, the trailing arm has play at the two bolts securing it to the hub carrier. At the moment I have the struts out and am waiting for new shocks to arrive. With the spring tension off, when I lift the hub carrier up and down I can see the trailing arm move at the hub carrier bolts which makes a good clunk sound.

Now my question is, does this mean my trailing arm bolt holes are worn out, or will re-torquing the two bolts fix my problem? The bolts themselves don't move, just the trailing arm on the bolts, as if the holes of the trailing arm are bigger than the bolts going through them.

[Farrar]

Maybe need new bushings?

[David T]

Typically a bent or out-of-balance rear wheel will show up as a shake in your belly and be more noticeable at certain speeds. It can also be a defective tire and you wouldn't always be able to see it. Run your hands around the sidewalls, sometimes you can feel a bump where the cords have shifted or separated. If it is a front tire you usually feel it in the steering wheel, especially on a Delorean because it doesn't have power steering to isolate you as much from the tires. Raise the car and put a piece of wood alongside each tire. Slowly rotate it and see if it moves in and out. Make sure all of the tires have the proper pressure and all of the lugs were tightened in the proper sequence to the correct torque.
David Teitelbaum

[tyb323]

Finally figured out my issue the other day, bushings are bad on my front right upper control arm. Stiffening my entire front end apparently made it worse. Another suspension disassembly is in the near future =(

[Farrar]

Finally figured out my issue the other day, bushings are bad on my front right upper control arm. Stiffening my entire front end apparently made it worse. Another suspension disassembly is in the near future =(

Are you going to replace them with polyurethane or standard rubber?