tom3

Can a driveshaft be put front-back reversed? I mean is it symmetrical?

since I got the rear end rebuilt, I get heavy driveshaft vibrations around 65mph, but the balancing weight is still there (and it was balanced properly before).

So I am just wondering if it is possible they put the front to the back. And would that affect the balance?

Injuneer

No, you can not put the front of the driveshaft in the back. The front has a "slider" that inserts into the tailshaft housing of the tranny. It wouldn't attach to the pinion yoke on the rear end.

What you can to to try and eliminate vibrations is unbolt the u-bolts at the back end, that hold the rear u-joint in the pinion yoke, slide the DS forward to disengage the pinion yoke, then rotate the DS 180-deg (1/2 turn) and put it back in the pinion yoke and put the u-bolts back on. Sometimes that will reduce/eliminate vibration.

tom3

unfortunately I just moved to an appartment with no garage/tools, so I have to go to a shop to tell them what to do. So far, I spoke to a couple that, given a description, have already tried to BS me into two different expensive rebuilds without even taking a test drive so I didn't leave the car there.

So, if I understand, this rotates the DS 180deg and reattaches it into the u-joint? and this would change the DS/U-Joint coupling by 180deg, is that correct?

here are a few facts to make sure I don't miss any details:
- DS was balanced before rear end rebuild; weight is still on it.
- Went from 3.73 to 4.11, so DS does rotate faster now. Car was in storage over a year after rebuild, end I did not notice it as I drove it shop->home->storage after the rebuild.
- The Vibration starts to be noticeable at 65mph and will increase with the speed, will still happen in neutral.
- Tires are brand new (< 300 miles) and wheels balanced.
- If I shut the engine off and go downhill in neutral (low speed), it is totally silent (no whining, etc noise at all).

But, also:

I know something is loose below the car as it 'clunks' when I go fw and stop, or accelerate from a stop. It is not a u-joint clunk, it feels too 'solid/full' to be the the exhaust; it is inconsistant (will not always do it, but 80 percent of the time). It seems to come from behind the transmission (and it doesn't feel like a broken mount) or further back depending on the time, it is very inconsistent.

So I am wondering if something could be loose and a small vibration could amplify by not being dampened/absorbed by something else.

Unfortunately, right now I don't even have a garage or even a jack anymore, so I need to either find a trustworthy place or come armed with a very good guess and tell them what to do :S -- you can imagine the frustration!

Injuneer

Is it a stock steel DS? If so, balancing them is usually not sucessfull in eliminating the vibration that is typical with them, at high DS RPM. I believe they were manufactured with the front yoke assembly not centered correctly.

The clunk on accel and decel can come from a worn torque arm bushing. If you have the stock torque arm, the bushing is mounted in a bracket on the tailshaft of the tranny.

Is it possible your new gears were set with more backlash than the originals? That would produce a more noticable clunk.

RUDEDOG

I have the same clunk. Never could figure it out.

Wild Willy

+1 on the torque arm bushing, or excess play in the ring and pinion inside the differential- both likely places to look

See if there is some lash in the driveshaft- can you turn it back and forth a bit before the wheels start to turn?

The torque arm moving would be most noticeable going from accell to braking, putting torque loads on the rear axle housing-

tom3

It is the stock DS, and there doesn't seem to be much slack at all in the drivetrain.

The clunking noise sounds 'outside', not in the tranny/diff, but it really sounds like something 'full' and 'heavy'. I do have the stock torque arm and that did not cross my mind.

Now that the torque arm idea has been brought up, there is another problem: I have bought Nittos NT-01, they seem to stick better than the NT555R, in fact they seem to stick better than anything I ever had, but if I accelerate/shift hard, I get consistant and instant wheel hop, no squeel or anything.

For the vibration, there is something I do not get: before I had 3.73 and they lost a tooth, so I moved to 4.11, so it is about ten percent increase. Before I would start to feel the car vibrating around 90-100mph, now it's 65mph.

Is it possible that an issue with the torque arm makes the vibration noticeable (by not absorbing it for example) or should I consider there are two distinct issues?

tom3

new info:

I discovered today that under heavy load, the vibration almost diseappears to come back as soon as I let off the gas.

would that confirm the torque arm?

taylorcrzy

I had the same problem when I installed 4:10's in mine. I tried balancing the steel driveshaft and it didn't get any better. I swapped to an aluminum driveshaft out of 98-02 WS-6 and vibes are gone.

Injuneer

Hopefully he solved the problem in the 15 months since his original post.