Thread: Vibration after changing Universal Joints

Hi Jonn, I recently replaced all my uni joints due to a vibratrion very similiar to what you are describing.
While the new uni's definitely made things smoother, the vibration was still present.
I also got all 4 road wheels balanced, which also helped improve things, (this is a fairly inexpensive place to start, might be worth a shot before delving deeper).
I did a lot of reading and investigating, even took my front drive shaft in to get checked by a specialist, indeed there was a slight wobble in that shaft.
I got the shaft balanced, which was part of the problem, but the vibration was not as bad, but still present.
In the end, it turned out to be a partially seized viscous coupling.
There are a few tell tail signs...
Have you noticed any front wheel chirping during cornering?
Has your turning circle become similar to that of the Titanic?
In your case it might not be the vc, I would investigate the easy stuff first, but if it is your vc, I replaced mine myself, also did a how to with photos if you are interested in having a look:
P38 viscous coupling replacement in photos.
Hope that is of some help.

Thanks for the reply. I had no vibration before I changed the uni's. I only changed them because I ran them dry once and they started making noise. I think my vc is ok because I can still do the lifted wheel test and my turning circle is still nice and small. Also no chirping even on smooth concrete. I also had all four tyres replaced and balanced about 6,000 k's ago. Thanks for the link all the same though. As with all cars of a certain age (1997 for mine) I'm sure its only a matter of time.
Cheers
John

Originally Posted by johnyrover

Thanks for the reply. I had no vibration before I changed the uni's. I only changed them because I ran them dry once and they started making noise. I think my vc is ok because I can still do the lifted wheel test and my turning circle is still nice and small. Also no chirping even on smooth concrete. I also had all four tyres replaced and balanced about 6,000 k's ago. Thanks for the link all the same though. As with all cars of a certain age (1997 for mine) I'm sure its only a matter of time.
Cheers
John

I experienced a similar thing with mine. Replaced the front uni's as they were worn. Turned out to be the wheel balance. I only had a balance and alignment not long prior, my P38 had thrown a weight after only 800km.


Cheers
Keithy

Long shot, but did you by chance pull the prop shaft in half to check the splines when you were doing the joints? And if so, when you slid the two pieces back together, did they go back in phase? IE, the yokes and flanges have to be in the same plane at each end. If not, that's you're vibration. The other thing to check. When you fitted the new uni joints and circlips, did you then give each cap housing a belt to make sure they're seated against the circlip? This makes sure that there's equal/no resistance within each joint. If one was tight, this will also cause the vibration you describe....
If my garb about phasing does not make sense, then this will help explain it...

[ame]https://m.youtube.com/watch?v=gmV4qwLfOMY[/ame]

I wont rule out the wheel balance, but it was only directly after changing the uj's that this happened. Sitec, I did not pull the splines apart, but I did give the yokes a knock. I only did this till I got free movement of the joint. I'm thinking that maybe I did not give it a hard enough wack. I'll give that a go.
Cheers
John

Originally Posted by Sitec

Long shot, but did you by chance pull the prop shaft in half to check the splines when you were doing the joints? And if so, when you slid the two pieces back together, did they go back in phase? IE, the yokes and flanges have to be in the same plane at each end. If not, that's you're vibration. The other thing to check. When you fitted the new uni joints and circlips, did you then give each cap housing a belt to make sure they're seated against the circlip? This makes sure that there's equal/no resistance within each joint. If one was tight, this will also cause the vibration you describe....
If my garb about phasing does not make sense, then this will help explain it...

https://m.youtube.com/watch?v=gmV4qwLfOMY

Except for P38s!!

Sometime in the late 80s /early 90s the front axle was modified (slightly tilted) in production to increase the castor on the front wheels to improve directional stability.

This put the UJ thrust angles almost at their limit at normal driving height for vibrationless operation. Instead of fitting the front shaft with a double cardan joint to make it a true CV joint, they took the "easy" way out and changed the phasing of the shaft. Also, an "elastomeric mass" was added to absorb/counter vibration (the heavy 'discus' with the wire retainer on each axle -a similar setup is sometimes used on helicopter rotor heads).

As a result, the front drive shaft is now phased such that the flange closest to the transfer case "leads" the front diff flange (IIRC) by 2 splines in the normal direction of rotation. Later model drive shafts I've seen are actually machined to ensure correct fitment. The rear shaft is as per Sitec's post.

EDIT: When you grease the UJs immediately after fitting don't forget to force in enough grease to 'purge' the UJs so that the grease weeps freely from each arm of the UJ. This is very important.The UJ seals are designed for this to happen. Also make sure the sliding joint is well greased

I'd best be pumping more grease through mine then :-o

Just a thought, but your old uni's may have been worn and allowed just enough movement to mask a vibration from another source.
So by fitting the new uni's, the driveline is now tighter and the vibration has now become noticeable.
I hope it is just the uni's not quite seated properly.
Cheers, Pete.