peep

Dare I?
I'll start with two cumbiah's and post in the morning.
Our 95 ZJ has developed death wobble.(300,000km)
Did driver side ball joints couple months ago, passenger side ball joints were solid and are still.
All tie rod ends are firm, all control arms seem firm.
The toe is approx 1/16" in. Wheel unit bearings feel good, rotors appear to run true without warp.
I haven't confirmed the track bar, seems firm to my prying from underneath, but will still have to confirm with a helper to move the steering back and forth while I take an additional looky.
I did find both motor mounts have failed (the rubber failed and is free in the steel loops). Explains the driveline vibrations I'm feeling thru the chassis and steering.
Tires (kP235-75R15)are getting older, can't confirm balance is true.
Springs are original, sag a little, lower control arms, no longer level, they are a little inclined from the spring sag but less than 5 degrees. Shocks have 70K km on them, no leaks, haven't disconnected for hand feel/test but bouncing the truck by hand the shocks seem to control quickly.
This is one of my daughter's trucks so I don't see it but couple times monthly, when she returns from abusing my Peep I'll get her to help with further diagnosis.
My question is the motor mounts, would these seem a reasonable cause for the wobble? (I do know the difference of DWobble vs from just vibrations).
For normal troubleshooting when results of a sytem/process performance change; you look for what's different. The broken mounts weren't there when I did last inspection when doing the ball joints, and no DWobble at that time.
So the mounts are my prime suspect.
However with my Peep, there is often more than one item failing at any given time and I have become suspect of things that seem the obvious.
Any thoughts on the motor mounts, just coincidence, or perhaps they failed due to the wobble? Is there more I should inspect for?
Perhaps I should get daughter helper back here for additonal trac bar testing. Then take two motor mounts and post back results?
I am not going to just shotgun repair and replace everything, that method won't identify the root cause.
Am I overlooking something seemingly obvious?

dave1123

One quick suggestion. Try swapping the front tires for the rears and see if there is a difference. If there isn't, you can eliminate tire balance.

peep

That's a great suggestion Dave, thanks! She'll bring the ZJ back mid week, I'll try the front rear swap then.
At least she primarily drives around town, no hi way.
I'm also looking at replacing the failed motor mounts during the holdidays.
Appreciate your feedback.

dave1123

If the motor mounts are that bad, be sure to check the trans mount also.

twinkiedooter

My 94 ZJ had a horrible death wobble. Seems that anytime I went into a pothole doing around 50MPH or better the car would shake so hard I had to immediately slow down and pull over to stop. The 2 engine mounts were shot. Once they were changed no more death wobble. Fix them before engine falls out!!!

peep

The ZJ has been parked until we can do the engine mounts fix (after Christmas)
I wonder what Santa will leave in my daughters stocking?
Thanks for the info
Merry Christmas

dave1123

Actually, after 1969 the NHTSA required manufacturers to redesign their engine mounts to a "capture" design so that if the mount breaks, it still contains the engine. It won't fall out but will rattle around a lot! Every time you hit the throttle, the driver's side of the engine will lift up and the weight will shift on turns.

twinkiedooter

Dave - Everytime I would be at a stop sign and take off too quick my 94 would have the engine go and body catch up split second later. If I would hit a pothole at say 50 or 55 all hell would break loose and have it shake and shudder and scare me half to death. Yes, I know the engine mounts prevent engine from falling out as I asked my mechanic when he was changing them out if indeed the other 2 would break would the engine fall out and he said no. Phew big relief to me about that.

dave1123

I've got some horror stories to tell about broken early mounts, like my Camaro going full throttle when it broke one, but I'll save them for another time.

I bought a pair of Anchor mounts on rockauto.com for about $50 each.

exjay1027

please do tell

peep

I'm off thru next week so hope to have the ZJ in for mount service.
Had a 67 Chev Belaire, 283 V8, 1st car, non capture type mounts, when the driver side mount broke the engine would try to roll over. With the mechanical linkage back then the gas pedal would drop to the floor and she'd take off. Turn it off, roll to a stop. Would restart. Zoom Zoom, would rev no problem. Back into drive, start off, no problem, accellerate, whap, gas pedal would drop to the floor again and she'd take off. When your 16 and mechanically inept, you look at it for an hour before finding the problem. Then you learn a little when you install the new mount. Back then you could climb under the hood right in with the engine. I think it was about 69 when the capture type engine mounts became a factory install design. Remember having a dealer recall and they put a metal cable tie from the frame mount around the exhaust manifold to prevent the roll over. The 95 ZJ remains captured but definately both sides the rubber is done.
I'll post a followup on the new mounts and the wobble effect.

dave1123

Yeah, GM had a major recall of ALL V8 cars manufactured before 1969 for motor mounts. To satisfy the NHTSA, if the mounts were broken, they had to replace them. If not, they were allowed to install a restraining cable from the frame to the first exhaust manifold bolt on the driver's side. GM got out of spending MILLIONS that way. I had already replaced mine so I got ZIP! I had used the new style Corvette mounts which WERE capture mounts. I was drag racing my Camaro at the time so I thought it was MY fault. That car would hook up so well on the launch that the rear window seal broke from the body torque.

One thing I learned, don't race your everyday wheels, you may be walking to work! Same thing goes for wheeling.