vibration after transmission rebuild

[Big Dawg1]

Just had my automatic transmission rebuilt and the rear drive shaft Ujoint replaced (it had a lot of slop). The car has 177,000 miles on it.
Now the car has a vibration at between 40 to 50mph. Took it back and they said they took the entire drive shaft out (both halves) and had it re-balanced. They tell me that once put back together, that the vibrations were better but not gone. I asked it they checked the center carrier bearing and they said it was fine. Now they tell me they need to remove the rear axles to inspect to see if that is the cause of the vibrations.
Has anyone ever experienced having the rear axles start causing a vibration after a transmission and rear shaft repair?
This doesn't sound logical to me.

[t.mcginley.jr]

I doubt its your axles. Was there any vibration before getting this all done? Not to rub salt in the wound, but you would've been better off (and probably cheaper) to just get a new 1-piece driveshaft than spending money fixing your stock 2-piece one. Also after the trans rebuild, did they replace the transmission mount? It could be shot after that many miles

[Big Dawg1]

No I've never had any vibrations before the rebuild. I've been told by Z1 that the one piece can cause some vibrations that the two piece doesn't create.
As far as the mounts...I don't know...but could that cause a vibration at a specific speed?

[Ace2cool]

Yes it can. So can wheel balance, as well as misclocking the driveshaft. Try rotating the DS 90 degrees.

[Big Dawg1]

Ace2cool:
I had the wheels rotated and balanced and had a 4 wheel alignment just to be sure. No change. They then removed both shafts and replaced both Ujoints and rebalanced them. It is much better now, however, I can still feel some vibration above 40mph. I asked if they were sure that they put the two halves back together in phase and they said yes...so don't know. I also asked them to check the center carrier bearing, but they said it was fine.
I've been told conflicting stories about using a single shaft. Some swear by it, but others (including Z1) said the single shaft might create a very slight vibration that the dual shaft configuration doesn't.
Anyone have any experiences with the single shaft for the 1990 2+2 NA with vibrations?

[nissanfreak12]

I have the Z1 platinum on a 2+2, zero issues. Do not spend the money on a center carrier bearing, put it toward a one piece, you will not regret it.

Personally, I wouldn't trust too many shops that rebuild shafts, as the u-joints in a OEM shaft are not meant to be replaced. Did they put the spacers back with the center carrier bearing?

[Big Dawg1]

nissanfreak12:
You say th u joints are not meant to be replaced? Then how do they get repaired? The rear Ujoint had a lot of slop in it (177,000 miles) so I thought it should be repaired along with the Transmission. They sent the rear shaft out to a drive shaft repair shop that takes the old ujoints out and presses in new ones. Are you saying that can't be or shouldn't be done that way?
As far as the center bearing...I don't know about the spacer. I would assume they put it back. Is there a visual way to tell without having to remove everything?

[nissanfreak12]

nissanfreak12:
You say th u joints are not meant to be replaced? Then how do they get repaired? The rear Ujoint had a lot of slop in it (177,000 miles) so I thought it should be repaired along with the Transmission. They sent the rear shaft out to a drive shaft repair shop that takes the old ujoints out and presses in new ones. Are you saying that can't be or shouldn't be done that way?
As far as the center bearing...I don't know about the spacer. I would assume they put it back. Is there a visual way to tell without having to remove everything?

The only way to repair is to replace, all they basically are needle bearings. The 300zx DS was never meant to have u-joints replaced nor repaired, they are a very specific u-joint, which were non-serviceable. They designed it that way so you would just buy a new DS or to bring to a nissan dealer for them to tell you you need a new one. Some have gotten them repaired, but generally they fail soon after.

The spacer, yes you can visually see if they have one, but they are not always supposed to be there. They look just like thick washers.

U-joints in general can be replaced, like in my Jeep, easy to replace. Just the Z they are not serviceable. Hope this helps.

[Big Dawg1]

Thanks for the help.

[Z Prime]

Hey guys! This is my first post. I've had quite a few problems with my Z over the years that I have been fixing... This seems to be similar to a problem I am having.Not sure if this is 1 or more problems. I get my car up to 40 mph and my car shakes violently pretty bad. Now...Sometimes when I speed up to 50 mph it will slow down but still shake and other times going to 50 mph makes it worse and the only way to get it to stop is to get it down to 25 mph....that is my first problem my second one is my wheels wobble. I have had them balanced I did wheel bearing trick with trying to move the wheel up and down, it wouldn't move. I really notice it when I'm stopping my wheels wobble alot when I almost come to a full stop. Any suggestions on that one? Any and all help would be greatly appreciated. Thank you!

[Z Prime]

Well I fixed the shake in my steering wheel. It was a mix of the carrier bearing being gone on the driveshaft as well as the rack and pinion bushings being almost completely gone. So now all of that has been fixed. I still have the wheels wobbling badly. I've checked the suspension and cant find anything wrong, the tires have been balanced recently. Anyone have any suggestions on this problem?

[nissanfreak12]

Well I fixed the shake in my steering wheel. It was a mix of the carrier bearing being gone on the driveshaft as well as the rack and pinion bushings being almost completely gone. So now all of that has been fixed. I still have the wheels wobbling badly. I've checked the suspension and cant find anything wrong, the tires have been balanced recently. Anyone have any suggestions on this problem?

When does the wheels wobble? Braking? Certain speeds?

If under braking-
Tension rod bushings are bad
Rotors are warped

Under speed-
Rotors are warped

These are the main issues that ALWAYS cause these issues, not just once and a while.

[Z Prime]

Hey Nissanfreak thanks for the reply. Well I'm not sure if it would be the rotors. I just replaced all of them 3 years ago with brand new ones. I can feel them wobbling when I'm stopping at red light whether my foot is on the brakes or not. Then as I speed up it will cause my steering will to start to shake. This is the best way I can explain it. I really dont want to take my car to a mechanic who will charge me an arm and a leg for things I dont need.

[nissanfreak12]

Go back and have them check the front tires again. That sounds like tire separation or a bubble in the tire.

Just because you replaced the rotors three years ago does not mean they are not warped, and yes, you can feel it with your foot on or off the brake pedal. Do not shrug off the rotors, a very misdiagnosed issue with steering wheel shake/wobble.

[Z Prime]

Alright I'll have the rotors checked out. I appreciate the help.