Vibration? How to tell where it's coming from?

[Tz44]

I was thinking I had a bad rear tire because at around 68-72 mph my car vibrates a lot, kind of bouncy. Below that speed I don't have as much of a problem and when I accelerate and get up to around 80-85 it rides just fine.
The vibration isn't felt in the steering wheel at all, I feel it in the seat. I get the impression that its coming from the right rear but I don't really have any way of confirming this. I ran my hand across the tread of the tire horizontally and it seems to dip in towards the center and swell towards the outer edge.

I was hoping you guys could give me some simple ideas on how to check some things that might lead me to the vibration. I appreciate any help.

 

[T-CHRGD]

Grab the driveshaft and try to rip it out by hand - to check the Ujoints.
That kind of tire shape can be caused by too wide a wheel, of over-inflation at one time, causing the center to wear.
Obviously check tire balance.
Also, bounce on the rear bumper. A completely worn out shock can cause the rear to "bounce" down the road.
And jack up the rear and spin the tires to check for out of round, or tread migration (belt separation)

 

[Tz44]

I can't really get the drive shaft to move at all when I'm pulling on it. It does give just a little either way when I twist it but not much at all. I can't really check tire balance right now but I plan on it as soon as possible, as well as jacking up the rear end and watching the tires spin, I don't really know what to look for there though. I jumped up and down on the rear bumper and I can get plenty of movement but the shocks have been replaced a couple of years ago (they are cheap though).

I tried driving up to the speed where I usually get the vibration and put the car in neutral but didn't feel any difference. Hope that helps.

 

[Tz44]

I'm sure it doesn't help anything either but just to add in a detail; the vibration is much worse at some times than others. It's mind of random. I'd like to say its worse when it's cooler, but I can think of times when it's been warm and I've been driving for a while and it still shakes.

 

[Mike T]

The dip in the center of the tire that swells at the outer edges sounds like a bad belt to me.

 

[pmoore4321]

If you can "drive" the vibration out, I would think your driveshaft is OK. Driveshaft problems get worse with drive train RPM.

 

[Tz44]

I jacked the car up the other day and let it run in drive to see if anything stood out. I didn't really see anything crazy but the vibration doesn't normally happen when I'm just idling around anyway.

 

[novaderrik]

I can't really get the drive shaft to move at all when I'm pulling on it. It does give just a little either way when I twist it but not much at all. I can't really check tire balance right now but I plan on it as soon as possible, as well as jacking up the rear end and watching the tires spin, I don't really know what to look for there though. I jumped up and down on the rear bumper and I can get plenty of movement but the shocks have been replaced a couple of years ago (they are cheap though).

I tried driving up to the speed where I usually get the vibration and put the car in neutral but didn't feel any difference. Hope that helps.

if you get ANY side to side movement when you grab the driveshaft, the u joints are worn out.. it might not be the cause of your vibrations, but they are ready to be replaced..

just to eliminate it as the problem, get under there with a grease gun and shoot some grease in each u joint and go for a drive- well, if the joints have grease zerks... if that fixes it, you've found your problem because the grease will temporarily take up the slack..

 

[Tz44]

The little but of movement I got was from twisting, just to be clear. I'm not sure if that's what you mean or not? I couldn't force the driveshaft up down left or right, I could grab it with my hand and slightly twist it.

Any other ideas of things I can check?


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[fitz3820]

I am having the same problem - I had the wheels straightened, tires balanced and driveshaft changed - I will jack it up and look for movement or something bent.

 

[Tz44]

Have you found anything yet?


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[fitz3820]

Not yet, been busy with work. I will jack up the rear when I get back from this business trip to see if I can find anything.


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[1KWIKSIX]

I was experiencing exactly the same vibrations as you Tz44. Was chasing my tail for years trying to fix this with out success.
I had my tires "road force balanced" & also had the transmission tail shaft bushing replaced.

Without success, I finally decided to take the drive shaft off & take it to a drive shaft service / repair vendor to check & re-balance.

Inspecting the original drive shaft I brought in, they found one of the U joints from the factory was not perfectly centred in it's yoke when it was pressed in at the factory (which would lead to a wobble type symptom)....also they found a slight bend in the drive shaft that they were able to remove by straightening the shaft in their press.

They replaced both original 26 yr old U joints with Spicer non-greasable HD 3R units & rebalanced the drive shaft.

Glad I did, what an amazing difference!
Turns out that this was the problem all along .....should of done this years ago....they even cleaned it up and put a fresh coat of black paint on my drive shaft!

As an added benefit......my loud "CLUNK" that I was hearing when shifting the transmission from Park into Drive or Reverse, has been greatly reduced & now pretty much disappeared. Guess the new U joints fixed that.

I'd recommend you take yours off & get it rebalanced & if you haven't done so, replace your U joints as well.

dave

 

[captndave737]

I had a vibration I couldnt get rid of at the same speed. Had the tires balanced, replaced te driveshaft and flexplate, rotated the tires and nothing worked. Someone suggested a road force balance and that took care of it after 2 years of chasing it.

 

[Tz44]

Road force balance? I'm not familiar with that. I haven't driven the car much lately so it hasn't been on my mind.


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[1KWIKSIX]

Do a google search on it & you'll see. It's not cheap, but does a much more thorough job of balancing your wheels. Computer gives direction as to best clocking of tire on rim for least amount of weight + so much more.
You'll have to search for a place locally that does "Road Force" balancing, but you will be happy with the service.

 

[Tz44]

I drove it a few minutes ago and it was really bad this time. It almost feels like the car is shaking side to side. I still feel nothing in the steering wheel though.


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[1KWIKSIX]

I'd suggest you check drive shaft for out of balance . THis is from my own personal experience where I was finding exactly the same as you. Took the drive shaft in for rebalance & all is good now!

 

[Tz44]

How much did all the driveshaft work cost you? If you don't mind me asking.


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[1KWIKSIX]

How much did all the driveshaft work cost you? If you don't mind me asking.


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Was quoted $60 for balancing & about the same again for a pair of new Spicer HD non-greasable 3R U joints installed.
Got mine done locally, but since your in the US....I bet prices will be alot less for the same work. Check a drive shaft shop to know for sure.