I have recently installed a 13b-RE with a 88 turbo tranny, custom drive shaft, with stock GSLSE rearend, ACT 93 lightweight flywheel, ACT 88 TII clutch and pressure plate. . Tranny mount is a Solid mount, so yes...vibrations from the engine will come into the car."Something that will be fixed soon".
The feel of the vibration is like having 1 or 2 tires with a bald spot on them,"It has a rhythm." thump...thump.....thump
My problem seems to be at its worse at 50mph in 5th gear, as I increase in speed it speeds up as well. If I put it down into 4th gear, this vibration seems to dissipate to the point where I dont really feel it.
I have taken the driveshaft back up to a driveline shop to have it rebalanced, and they replaced the yokes on the new one cause they mentioned the ones that were on it were already going bad.
Tires are brand new, never sat for any period of time to generate a flat spot.
Rims have been refinished since ive own them...and I've never hit a bump.

I can not for the life of me figure out what this is or what I should look into to resolve this problem. Hopping some of our very knowledgeable rotor heads can chime in here.
I can post pictures if need be.


cheerz,
-vern

 

Drive shaft...check the bolts back there on the rear end...I had the same problem...i learned the hard way, and the end result was a drive shaft blow out tearing through my floor inbetween my seats...

 

I Personally tightened all 4 with a 14mm wrench, with car in gear.

 

Guess I'm not the only one that can't figure this out...
PLEASE someone help me out here!!!

 

go through the whole under chassis...motor mount, tranny mount, drive shaft bolts, exhaust bolts, it could be anything that makes that noise bro...and it's kinda hard to say since were not there with you to hear the car feel what the car feels like when driving and stuff... another thing people over look are the wheel studs check those...

 

Yea, its hard to explain what is going on. If anyone needs further detail of something, just ask ;]
The noise I hear is associated with the vibration.
The motor mounts are brand new as well.. ordered from Racingbeat (using their stiff set) used on a 13b front cover.

 

Are your tires aligned?

 

check your tranny mounts. i am having the same problem with mine

 

does it vibrate only when you are on the gas? mine vibrated when i accelerated, but when i let off, it was smooth.

 

Mine is a little opposite of yours, when decelerating there is a different vibration that comes through the car. Which I know it more so do to the solid tranny mount.
My vibration has a rhythm....
A buddy of mine told me that being it is a custom driveshaft and all...that the angel of the reared ham is off and that I need to extend the top arms that hold the rear end to bring the nose of the ham up.

 

somewhere something is lose bro...

 

great idea!!!!
Take the drive shaft off put the tranny in gear and rev to about 3,000rpms, if the vibration is present this will eliminate the driveshaft, rear end, front end.
If the vibrations isnt there it breaks it down to 3 parts, driveshaft alignment, rear end sway, diff hop.

It is common in rear wheel drive cars that the LSD if Posi unit has hop-along the fluid is thick enough or dirty enough that the clutches or ring gears fail to release right and you feel a vibration in decelaration and corners.