Caprice Shudder at Hwy Speed

[Renken2000Classic]

While I'm logged in here...

I've got a noticeably annoying shudder in my Caprice that comes in frequent and regular waves, that I haven't been able to get rid of. It's not the same as a continuous vibrating like out of balance tire(s). It seems to travel front to rear and repeat.

I've got new tires on the front, had the rears (which had been on the front) rebalanced, and even put balance beads in those 2 (like 3oz each). I even went back to the stock rear brake drums that I saved after changing to new AutoZone ones a year or more ago.

No good. Shudder is still there. I'm wondering now if it's still in fact the tires, or something else going on like u-joint or front (brake discs?) or ???

I'm not 100% sure about the tires on the rear as they wore more on the inside (even though it was aligned when they were put on), and may not have worn evenly all the way around, though if that's the case there was something else wrong.

 

[ezbtr]

While I'm logged in here...

I've got a noticeably annoying shudder in my Caprice that comes in frequent and regular waves, that I haven't been able to get rid of. It's not the same as a continuous vibrating like out of balance tire(s). It seems to travel front to rear and repeat.

I've got new tires on the front, had the rears (which had been on the front) rebalanced, and even put balance beads in those 2 (like 3oz each). I even went back to the stock rear brake drums that I saved after changing to new AutoZone ones a year or more ago.

No good. Shudder is still there. I'm wondering now if it's still in fact the tires, or something else going on like u-joint or front (brake discs?) or ???

I'm not 100% sure about the tires on the rear as they wore more on the inside (even though it was aligned when they were put on), and may not have worn evenly all the way around, though if that's the case there was something else wrong.

Drive shaft weights? Check the ujoints for play

 

[briangcc]

Sounds like a motor or tranny mount if its traveling from front to back of the car. Could be wrong and it may very well be a driveshaft as mentioned above.

Any abnormal tire wear to indicate it maybe bad shock/strut/spring?

Mileage on the car?

 

[racerone]

year ?

 

[matt167]

Fwiw balancing bead’s and weights together don’t work. Cancels out

 

[Renken2000Classic]

It's a '93 with about 162k.

I wondered about leaving the weights on; I'll knock 'em off and see what happens.

I'll check the 2 older tires closer, but other than the inner wear, I don't think they are that uneven... Handles as I'd expect it to also, no bouncing or sagging or anything.

I have had a rear u-joint go bad before on a truck; didn't think of that as a possibility until when I was posting here. I'll look at the trans mount too.

I can throw it into neutral and it's still there, fwiw.

 

[ezbtr]

Has the driveshaft ever been out and perhaps reinstalled 180 off?

 

[jimmbo]

Ride Height can affect Driveline Angles, and that can create Vibrations. Can be difficult to track down as any change to the weight of the vehicle can and will cause the Vibrations to vary.
In the Mid 80s I had an Olds Regency, with a very odd vibration, varied in intensity, location, and could change after turning a Corner. Had the Tires balanced and rebalanced, several times, no change. One day I was at a Car Wash, and took the Wheel Covers off. These were Spoked Design, and at quick glance, looked fine. I didn't put them back on, for the return trip. On the return trip, the Vibrations were gone. I took another look at the Covers and found that 1/2 the Circumference was packed with Mud(maybe the car had gotten stuck in some Mud/Dirt/Clay, before I owned it). A thorough cleaning and reinstallation, and it was still Shake free

 

[Scott Danforth]

not a fan of balancing beads. if you use the wrong amount, you exasperate vibration.

 

[82rude]

Broken belt in tire?

 

[Renken2000Classic]

Has the driveshaft ever been out and perhaps reinstalled 180 off?

Don't know; not since I've had it.

 

[Renken2000Classic]

not a fan of balancing beads. if you use the wrong amount, you exasperate vibration.

Supposed to take 3oz per the Napa counter guy; all they had was 4oz, so I bought those and guesstimated.

 

[Renken2000Classic]

Broken belt in tire?

Don't think so.

 

[matt167]

So I have the balance bead calculator right on my phone. And 3 ounce would be right. But if you add 4 oz you effectively put enough beads in for a tire twice the size

 

[Renken2000Classic]

So I have the balance bead calculator right on my phone. And 3 ounce would be right. But if you add 4 oz you effectively put enough beads in for a tire twice the size

Cool. No, I poured what looked like about 1/4 out of each package and set it aside.

They were a real pain to get in through the valve stem too. Won't even try that again. Air kept blowing 'em back out... Nah, kidding.

 

[WIMUSKY]

Has the driveshaft ever been out and perhaps reinstalled 180 off?

Do tell????

 

[jimmbo]

Speaking of Driveshafts. My 86 Caddy Fleetwood Brougham had a Driveshaft that was a Tube within another Tube, with what looks similar to a rubber Prop Hub between them. One day, it developed an odd vibration. I had the wheel balance checked, U joints were fine, Driveline Angles looked okay. I had it on the Hoist at my Cousin's Tranny Shop, he noticed that the U joints at each end were no longer in Phase/lined up, there was a few degrees twist between them. A replacement Driveshaft solved that one

 

[Renken2000Classic]

All the torque this thing puts out mighta twisted mine too...

Of course I joke. It's anemic. I knocked off the weights from the rear tires, but it made no difference. I started going through the troubleshooting section of an older full size Chevy manual, and I think reinstalling the driveshaft 180 is a possible try at some point (like rotationally, not end to end, heh).

There were 2 weights on one side of the shaft and no noticeable missing ones, and the joints didn't seem to have any play. I didn't think about spinning the tires and looking closely at them all the way around the tread while it was jacked (dumb). My big floor jack scrapped out (something else to fix...), and I'm sick of the littler ones I'm having to use. Anyway... I'm half tempted to get 2 new tires for the rear and try that (more $ I don't have, sigh...).

 

[jimmbo]

A tread separation can cause vibration and wobbling

 

[matt167]

Put rear tires on front. If shake moves to front replace those tires. Ply separation may be visible on a balancer if so