Rear End vibration

[steveplym]

Spent a few hours on the interstate this weekend and noticed my vibration problems. Here is what I've got.

I replaced the driveshaft with modern u-joints and it was balanced and manufactured by a reputable shop.

Overdrive is all rebuilt and I have replaced the rear leaf springs brand new from espo with all new shackles and shocks.

Engine mounts have been replaced as well.

I have not done any work to the rear end yet. That is my next part of the car to tackle. About 62 mph it the noise and vibration starts to get bad and gets worse the faster it goes. Also gets worse on decel from any speed over 55mph. My guess here is I have a pinion bearing worn out, it is leaking a bit, and I know the seal is bad. Could it be anything else?

If I tear this thing down I'm going to pretty much just replace all the bearings and seals to do it right, I just wanted to see what you guys thought. Thanks!

[TodFitch]

I assume that you've already checked that your wheels are true and balanced?

[1941Rick]

Steve....I am experiencing the same problem....I put the old style driveshaft back in and vibration went away.....the new drive shaft will be going out for balancing soon. Hopfully the vibration will go away....If not I will be looking at the input and output angles...Always something when you try to update these old girls.....

[steveplym]

Yeah Rick, you never know.

Tod I replaced the wheels and tires this year and had them checked before I mounted the tires to make sure they weren't bent.

I guess the question I have is this a symptom of worn bearing and parts in the rear end or should I be looking elsewhere?

[greg g]

Try indexing the drive shaft + 180 degrees. Can't hurt and it's easy. If it doesn't solve the problem, it may mitigate it some.

[suntennis]

I have had a harmonic with my car starting at 60mph and am on about the last thing I can think may cause it. When checking the driveshaft angle to the trans and rear end, there is about a 3 degree difference. I do no know if this is enough to cause the problem, but I am in the process of installing 2 degree shims to see if it makes a difference.

[greg g]

Is your harmonic balancer delaminating??

[steveplym]

I just changed it Greg, about a month ago. The vibration is definitely coming from the rear. Can feel it through the floorboards and seat rather than the steering wheel.

[Niel Hoback]

Have you considered swapping wheel/tire assemblies front to rear just to make sure its not a tire or wheel problem? I'm just doing my natural thinking of "cheapest first".

[Greenbomb]

I don't know if this relates to your problem, but earlier today I had a little rear end vibration followed by a really terrible smell. I couldn't tell if anything had delaminated, though.

[mikemaker]

Drive shaft boots can cause the type of vibration you are experiencing if they have distorted or if you are using the leather boots. This has happened to me in the past.

[55 Fargo]

Have you considered swapping wheel/tire assemblies front to rear just to make sure its not a tire or wheel problem? I'm just doing my natural thinking of "cheapest first".

A bad tire, bent rim, unbalanced wheel will create viration big time at Steve's mentioned speed.

I would check the back wheels.

I have this type of symptom time and again on my modern vehicles, as I live on a gravel road, and when it rains, the gravel sticks insdie of the wheels, making the wheel beocme unbalanced with a bad vibration at the 55-65 mph range.....

[JIPJOBXX]

The main pin that holds the universal together was loose on mine (Its suppose to be pressed fit). Anyway I had a machiest drill tap to set screw hole to keep that main pin from moving back and forth and it worked! I had the same problem it sounds like you and now that is gone. That pin is suppose to held with .005" from side to side and so if your pin is moving back and forth this can cause a heap of problems. Jon

[TodFitch]

The main pin that holds the universal together was loose on mine (Its suppose to be pressed fit). Anyway I had a machiest drill tap to set screw hole to keep that main pin from moving back and forth and it worked! I had the same problem it sounds like you and now that is gone. That pin is suppose to held with .005" from side to side and so if your pin is moving back and forth this can cause a heap of problems. Jon

Except his first post mentioned that he'd replaced the drive shaft with a modern one....

[steveplym]

Well a small update here.

I put back in the old driveshaft today just to see how it runs as it has been over two years since I have changed it out.

Pretty much the same issue, just starts at slower speeds. The only thing I can think of now is to eliminate the wheels then look at pinion angle.

I just put brand new wheels and tires on the car in January. Guess it wouldn't hurt to check that, only problem is I had this issue before and that was one of the reasons I replaced the wheels and tires. Tires were 10 years old and needed replaced and the wheels I thought would look neat on the car.

Otherwise to look on the bright side of things I drove the car about 8 hours on the interstate this weekend and it ran great. Temp never got over 190 degrees and it purred right along.

[Alshere59]

I think your original thought about the pinion bearing needs looked at. Drive it for a bit at highway speed then back it up some ramps. If the pinions hot you have a problem. check the fluid level while your down there as well. Just suggesting it as that what mine turned out to be. Your pinion angle should be good from what you have said you have done. What would change it?

By the way my vibration got a lot better just by adding the lube.

Edited May 24, 2011 by Alshere59

[suntennis]

Steve, Just finished putting in 2 degree shims on the rear axle. The good news is the drive line alignment looks better but the bad news is that it had no improvement on the harmonic problem. Now I need to lift the rear end off the ground and run up the drive train to get the harmonic, then get under the car and try to pinpoint the problem area.

[steveplym]

Thanks for the tips guys. Now I just have to find some time this week to check a few more things. I'm thinking about going ahead and having the driveshaft checked and balanced just to make sure all is okay there.

[MarkAubuchon]

Steve, I have the exact same problem. We had our drive shafts done by the same place. My 47 has 16 inch rims with Coker white wall radials. swapped my 15 inch wheels with goodyear radial, vibration went away. Took all my 16inch wheels for rebalancing two of them have are "hub bent" causing them to wobble creating a vibration. I have bought three more 16 inch rims and am planning to take all 7 of them to a tire shop that balances those big oh 22's low profile tires. Find the best 4 and balance them

[steveplym]

Thanks for the tips Mark. I've taken the driveshaft to a local machine shop to check and make sure it's balanced. Haven't heard back from them yet. Hoping tomorrow. If that turns out okay then will probably check the wheel balance again. Just bought new wheels and tires, I would think they would be okay, but who knows. Process of elimination I guess.

[steveplym]

Well another update. I had my driveshaft checked and balanced. Helped the vibration issue a bit, but still a lot of noise in the rear and a slight vibration above 62mph. So my next step was going to be work on the rear end, but at this point I have decided on a rear end swap.

After talking with several forum members who have been quite helpful I think I'm going to go the Dakota rear end route. Hoping to get something done the next month or so and will post the progress here.

[Don Coatney]

This thread might or might not help.

http://www430.pair.com/p15d24/mopar_forum/showthread.php?p=258310#post258310