Alright guys, I've been dealing with getting rid of this vibration for quite some time now. Pretty much ALL the suspension is new, it's been lowered, yada yada, and I don't really know what else to do.

Originally, with a stock torque arm, I put a transmission spacer in and it helped the problem, but didn't fix it. My thoughts were that this confirmed the pinion angle was off after lowering the car. Yesterday, I installed the Spohn adjustable torque arm and set it to -2 downangle. The vibration has now gotten worse again, not better. Twice I messed with pinion angle, and twice it's effected the vibration, so I'm confident that's my problem. Question is, since it's technically now exactly where it should be, where do I go? Since adjusting is pretty easy, I'm gonna try a few different angles, but does anyone have any suggestions???

 

Is the spacer still in the car? Perhaps try removing it and resetting the pinion angle. Mine is set at -1 and my car is lower than yours so -2 should be good. Maybe try -1 on yours and see what happens.

 

sounds to me like the driveshaft is out of balance moreso than a -2 or -1 pinion angle. I'm guessing the poly trans mount made it more apparent and now the torque arm is transferring more vibrations as well.

 

If I remember correctly he's had the driveshaft checked out and maybe even replaced it with an aluminum one some time back. I know he changed the torque converter some time back and this vibration started sometime later.

 

I took out the poly mount because of roadnoise. I didn't really effect vibration one way or another.

I DID remove the spacer when I installed the torque arm, but I think I'll try -1 and see what happens.

I've been through 2 steel driveshafts that I was told were good, but of course, who knows. I should suck it up and go with an aluminum piece.

Some have suggested the torque converter could be the culprit too. I can't rule it out. I have the T5 swap in my possesion, but like so many others, I have certain other things that need money at the moment. We'll see.

 

but like so many others, I have certain other things that need money at the moment. We'll see.[/QUOTE]

Amen to that, that's one reason the '92 conversion hasn't happened yet. Hope to see you at AF.

 

Maybe, maybe not. ....not sure how I feel about limping 2.5 hours at 60mph.

 

Any luck with the vibration?

 

humm,
2 degrees of angle will not cause a vibration. It may change how much the vibration is amplified, but that little angle is not the cause. I've run as much as -6 w/o any problems. Yes, that's excessive, but that's where my car hooks the best, so that's what I run.
Since you have changed the ds, I'm at a bit of a loss. Have you had either shaft checked for balance and/or run-out? Did either have new joints? Is there excessive end-play in the trans tail-shaft bushing? Is there any end-play in the pinion?

Vibration comes only with speed, not rpm? Comes and goes? Only at certain speed(s)?

 

get your shaft balanced, don't bother with another steel one because it's probably out of balance too. the steelies go out of balance without any visual trauma all the time

either that, or get a new aluminum one, they are alot less prone to becoming unbalanced without seeing the actual damage thats causing it, but have it balanced too

 

in my car having the drive shaft balanced and even one built didn't help a thing.


the cheapest way i fixed mine was go to a junk yard, find a V6 auto (that still had the metal tab intact, that hold the two free rear bearing caps in place. which seemed to be the key, to tell if it was vib or not) pay my 20$ and be happy for 6months. after a while it would start to vib again and slowly get worse till i went and got another. this was a stock hight car and went thru many different rear end parts and trans mounts looking for it.

after swaping to a t56 i noticed the shaft goes into the tranny farther and seemed to cut down on alot, so i picked up a alum shaft out of a 4th gen and its pretty much gone. not totaly but it doesn't seem to have came back like it did with the stock ones. but also isn't as good as when i first would put a stock one in.


hell my 02 z28 has had a tiny bit since it was new off the lot...