Driveshaft fix gone bad

[Calan]

I pulled my driveshafts (propeller shaft) and filled the center bearings with window weld. (bearings are good...rubber was shot). When putting it back in, I noticed that the 2-piece rubber isolators that support the center bearings were non-existent, so I found some rubber grommets and thick washers at ACE that were very close in size and used them.

Long story short... I now have a HORRIFIC vibration at anything above 30mph. I didn't remove U-joints or anything to change the shaft balance, so I'm guessing that I solidified the carriers too much and maybe a bit out of alignment, since I did it out of the car (I just kept them centered on the shaft and perpendicular to it while the goop dried). I also may have lost any isolation by going the ghetto hardware route on the bearing isolators.

Anyone else seen this or had any issues like this when using window-weld to fill the bearings? I really can't up the bucks for a new driveshaft assembly right now, but buying the new bearings/U-Joints/Lobro kit and doing it myself is almost just as expensive.

Any other alternatives or thoughts?

Thanks much

 

[PieEyedPiper]

I don't see any indication that you've ruined your driveshaft...just the carrier bearings. Replacing them should fix your problem, unless I'm misunderstanding you.

 

[Calan]

Turns out that the car has been bottomed out on something... one of the studs that the rear center bearing mounts to is bent; and after I cleaned the gunk off, I see that it is also knocked upwards and fatigued at the point where it is spot-welded into the frame. And both studs have fubarred threads; to get the nuts up far enough to hit good threads, the spacers were (are) left out, causing the bearing to be cranked up into the floor pan and at an angle to the driveshaft...thus a nasty vibration. (Before my WW fix, the shaft still rode at an angle to the bearing, but it wasn't as noticable since it didn't have any resistance from the worn out rubber. Now that the bearing is rigidly perpendicular to the shaft, it's really being stressed.)

So... I need to figure out a way to cut the existing studs off/out and weld some new ones in.

I was hoping I could cut a bit of sheetmetal away on the inside and get to them from the top... drop a new stud in, bolt up the bearing and then weld from the top. but no such luck. The bearings sit right under the main rear x-member, and are impossible to get at unless I cut away a lot of structural metal..which ain't gonna happen

Anybody have any experience with this?

 

[wishihadatalon]

Turns out that the car has been bottomed out on something... one of the studs that the rear center bearing mounts to is bent; and after I cleaned the gunk off, I see that it is also knocked upwards and fatigued at the point where it is spot-welded into the frame. And both studs have fubarred threads; to get the nuts up far enough to hit good threads, the spacers were (are) left out, causing the bearing to be cranked up into the floor pan and at an angle to the driveshaft...thus a nasty vibration. (Before my WW fix, the shaft still rode at an angle to the bearing, but it wasn't as noticable since it didn't have any resistance from the worn out rubber. Now that the bearing is rigidly perpendicular to the shaft, it's really being stressed.)

So... I need to figure out a way to cut the existing studs off/out and weld some new ones in.

I was hoping I could cut a bit of sheetmetal away on the inside and get to them from the top... drop a new stud in, bolt up the bearing and then weld from the top. but no such luck. The bearings sit right under the main rear x-member, and are impossible to get at unless I cut away a lot of structural metal..which ain't gonna happen

Anybody have any experience with this?

Just get a 1pc unit for the rear 2 pieces. I have seen this a few time and the cars I have seen work well. Any axle shop should be able to make you a 1pc unit

 

[PieEyedPiper]

This problem doesn't merit hundreds of dollars for the repair ( a new dirveshaft), in my opinion. And he'd still have to remove the carrier bearings either way so simply replacing the carrier bearings would be the cheaper and quicker solution rather than replacing the bearings and the driveshaft..just because it feels left out.

 

[wishihadatalon]

This problem doesn't merit hundreds of dollars for the repair ( a new dirveshaft), in my opinion. And he'd still have to remove the carrier bearings either way so simply replacing the carrier bearings would be the cheaper and quicker solution rather than replacing the bearings and the driveshaft..just because it feels left out.

The studs that are welded to the car are bent. They are really hard to access and to fix. There are a few ways to do it, such as seeing how 2g guys convert to awd, because they have to weld these in. But I would call a local driveshaft shop that can make a steel piece and see how much it would cost. It would likely be easier than drilling out spot welds on 2 cars and re-welding a new mount onto the bottom of the car.

 

[Calan]

I fixed the stud problem, but still have a bit of vibration around 35-50mph.. which I'm pretty sure is because of the way I mounted the carrier bearings (hardware store grommets and washers) and the extra firmness from the WW. But it's nowhere near as bad now that the carrier bearings are in alignment.

For those interested, I fixed the studs by (sorry... no pics):

1. Cutting off the existing ones with a die grinder and hacksaw.

2. I used a punch and hammer to knock the remaining stud pieces upward into the frame, creating about a 1/4" deep bowl-shaped depression.

3. I welded a 3/8" fender washer to a 1-3/4" long piece of 3/8" all-thread rod, with about 1/4" of rod sticking through the washer on the side that was welded. (quantity 2). I used a nut threaded onto the rod to make sure the washer stayed flat while tacking it. I then sanded it down and rounded it as much as possible without weakening the weld. I ended up with maybe 1/8" to 3/16" of rod sticking through.

NOTE: The washer for the side closest to the ground had to be flattened on one side with a belt sander, because the original stud was bent back and up pretty badly, and the frame angles upwards there so a fully round washer won't sit flat.

4. After cleaning all the frame metal with a drill and wire brush, I located the new "studs" by centering them over the old ones, so that the welded sides of each washer/rod set into the bowl-shaped depressions... and tacked them in place.

5. I welded them to the frame in 3-4 places around the edges of the washers and ground the flat surfaces flush. (BTW - It's REALLY hard to tack these up in 12" of space on your back with only two hands, working around suspensions and stuff ... and without getting burned )

It was a bit of PITA because of not having a lift, but other than that it's not that bad. The studs are now straight with plenty of thread, and the bearings went back up nicely. Also, it turns out that (oddly enough) the lock nuts for the 3/8" rod I bought are exactly 14mm, which is the same size as the factory lock nuts.

I have factory spacers and bushings on order, so hopefully next week I can get those in and see if that lowers the vibration. If not, I'll save up some money and replace the bearings and U-Joints... or just go with a 2-piece aluminum shaft.

Now as long as my welds hold...