Driveshaft goin crazy

[Hypr5]

Hey guys,

Recently my car had bad vibrations and shakes when torque was applied. At 129k miles, the center bearing was completely torn. I replaced the bearing and it was back to being as smooth as glass. ~800 miles later, its starting to get that SAME vibe back under acceleration wheather it be light or heavy. Same speeds / RPMs as before too.

Now I would suspect that something is making the center bearing wear out, are there any ideas out there? This is !

[Jeff N.]

When you removed the driveline did you:

- check the u-joint for slop?
- check the guibo for cracks?
- check the aft coupling for slop?
- reassemble the driveline halfs in the same position you took them apart?
- possibly knock off a weight?
- preload the center bearing as described in bentleys?
- make sure everything was lined up?
- torque the driveline bolt that holds the halves together?
- torque the aft bolts that hold the driveline to the diffy?

Bet one of those is your problem. Gonna have to come out again for an inspection. Personally, I start by checking the aft bolts. Easy to see without pulling anything and they tend to work loose, especially if you reuse the nuts.

Jeff

[632 Regal]

wow Jeff, think that about covers it? Nice stuff there!

Bet its the guibo not tolerating being shaken to death or the bolts got loose.

[Hypr5]

Thanks for the help.
I know for sure it's not the guibo. How? Well, my car doesn't have one. lol.
Also, Im pretty sure the bolts didn't come loose because I bought all new self-locking nuts, but I'll check.
I did check the u-joints and the CV that connects to the differential. They all SEEMED okay, but maybe I'm not looking for the right thing here. I did notice that the u-joints were notchy at the direct on-center position, but only mildly. Otherwise, they seemed tight.

I did preload the center bearing and make sure everything lined up and I'm sure I did that properly because like I said it ran as smooth as glass for about 1100 miles. It just started acting up again and today got too bad to drive.

<confused>

One last thing - I noticed that when I back reverse it makes a CLICKING noise that is CLEARLY rotational as it speeds up with speed. It did this before I swapped out the center bearing last time too. It was totally gone until today.

Thanks again!

[bahnstormer]

might need a new driveshaft

[Jon K]

might need a new driveshaft

very doubtful.

if it was fine the day he put it back together and now its shaking again, its more than likely the pre-load on the center bearing. My center bearing was shot, i drove with it that way for like 3 months. I thought it was just worn, but when i took it out....



but my drive shaft is fine, even having knocked around for months.

[Hypr5]

Okay, I got under the car today after it's been parked for a while and what do I find? The transmission mount nuts had come almost all the way off, they had unscrewed to the very end of the bolt.

I thought maybe that was my problem so I tightened them up and took it for a ride. It killed about 60% of the shake that it had but it still has the shake. I'm starting to think maybe my driveshaft was okay, but the mounts coming loose caused shaking and maybe ruined my new center bearing. However I'd hate to go throw more money down on a center bearing and tranny mounts and find out that the driveshaft is still bad. Either way I don't think the center bearing should have failed that quickly... ?

What would you guys do?

[Bellicose Right Winger]

If you're u-joints are notchy then driveshaft alignment is very important in eliminating vibrations. Proper alignment depends on condition of center bearing, trans mounts, and engine mounts to some degree. Your center bearing is new and I doubt this recent experience ruined it, but you need to check it to be sure. How old are the trans mounts and have you checked them for separation? Support trans, unbolt trans cross member and pull to check for separation. If they're intact, and original I'd still change them since they tend to collapse in height which lowers the trans and changes the driveshaft angle, upsetting the alignment the factory intended.

Paul Shovestul

Okay, I got under the car today after it's been parked for a while and what do I find? The transmission mount nuts had come almost all the way off, they had unscrewed to the very end of the bolt.

I thought maybe that was my problem so I tightened them up and took it for a ride. It killed about 60% of the shake that it had but it still has the shake. I'm starting to think maybe my driveshaft was okay, but the mounts coming loose caused shaking and maybe ruined my new center bearing. However I'd hate to go throw more money down on a center bearing and tranny mounts and find out that the driveshaft is still bad. Either way I don't think the center bearing should have failed that quickly... ?

What would you guys do?

[Hypr5]

Thanks for that advice, I'll get under and check their condition closer.
They are 130,000 miles old, never replaced.
Thanks again.

[Hypr5]

Thanks for that advice, I'll get under and check their condition closer.
They are 130,000 miles old, never replaced.
Thanks again.

The mounts look okay, but I'll just replace them anyway, they're cheap enough. As for the vibration coming back, do you guys think that this could be something other than the driveshaft? The clicking noise when I back up is really making me wonder. People have mentioned axles / cv's, but I am not sure how to check for those... Can anyone advise me on that?