ibanez7

iTrader: (7)

This is my setup: (suspension related/drive line related)
2001 Z28 m6 119,xxx miles.

-all bolts ons
-cam
-strange dana s60
-spohn adj. torque arm/DS loop
-bmr adj pan hard bar
-spohn rear sway bar
-rear comp eng. drags shocks
-front suspension and bushings stock
-slp subframe connectors
-cut springs (1 coil cut at all 4 corners)
-wheels AR TT2m
-tires front = nitto 555 275/17, rear = NT05R 315/17
-rearend and transmount = all poly bushings
-front stock rubber bushings


Here is the issue, the whole car starts to vibrate at 60mph and gets worse as I go faster.

So far this is what I have fixed:
-Upon inspecting my car, i saw the torque arm lost its nuts, where it connects to the rearend. I fixed that and adjusted the pinion angle to -2/-3
Some vibration went away.

-re-balanced the wheels at all four corners, some vibration went away. Steering wheel shake is gone (only left front was out of balance)

-checked the tie rod ends and wheels bearings, they are fine.

here is my remaining thoughts:

-the cut springs - were never an issue but could be now

-rotors do feel warped upon braking and make noise when spinning the wheel by hand. (rotors can make your car vibrate while driving, not just braking)

-pinion angle, -2 seemed to be the general consensus for these cars, and seem to work fine before.

-worn input shaft bushing. (doubt it would vibrate the whole car)

-busted engine mount

Any other thoughts or suggestions before I start throwing money in buying new parts. I did do a search here, however read pretty much what I already knew.

rck2004

I would inspect the pan hard bar for damage. had one crack once at the top and there was a wicked vibration. Also could check the rims and make sure they are true. Drive shaft?

ibanez7

iTrader: (7)

good point on the pan hard bar. will check

DS - is balanced.
wheels are true.

JUSTINSWS6

My lower control arm bent and did this. Is your steering wheel shaking worse then the car body.

It'llrun

How about the u-joints and bearings?

ibanez7

iTrader: (7)

u-joints have less then 10,xxx miles on them.
I will still check.

mikh338

iTrader: (16)

OP-i lost the nuts off my torque arm to rear end housing as well and had a crazy vibrations around 70-80 also. do you remember what size those 2 nuts were? my new s60 rear end comes in friday and want to have everything ready to go. i also saw you had the same torque arm as myself, did you have to do much trimming to get it to fit?

black00TA

iTrader: (3)

start with wheel/tire. just because they were balanced does not mean they will not cause vibrations...

a balancer will balance a square, it will just tell you where to put weight, does not mean its going to ride good down the road...see what i mean?

Azar_Hawke

iTrader: (5)

Do you have a manual transmission? This sounds like a bent output shaft. It's a common problem with the T-56.

ibanez7

iTrader: (7)

manual trans.... good point about the output shaft

ibanez7

iTrader: (7)

didnt have to trim at all.
the torque arm does hit the floor of the car sometimes. Need to add a dent to the floor to allow for room..

UMI and spohn both make a bolt and nut kit for this setup, its about $18. make sure you order it. Dont use the stock bolts, they are way too short.

mikh338

iTrader: (16)

you gotta be kidding me about the stock bolts not being long enough!!!! i have never heard that anywhere and carl didnt mention it either. wtf!!!! its always something.

mikh338

iTrader: (16)

just spoke with carl on the phone about the rear end bolts and he said the stock ones are perfectfly fine

blackmaverick

my truck does this all the time after 70. Also hear a loud clank when I turn the wheel very hard at a dead stop. I had everything checked out but nothing was found

bwkmaro

drive shaft harmonic balencer... and look at your weights on the tires if there's alot in one spot itll vibrate and if you drive with them out of balance itll wear them outta balance. and you cant fix them except by getting new or dealing with it.

bwkmaro

you pitman arm is most likely bad and they didnt check it. that noise it common to the pitman arm bad just put a new one in its 2 bolts and 40$

DarkblueTA

Did you perform a shake down test to verify that the ball joints and tie rods are good?

speed_demon24

iTrader: (6)

The only way I could get rid of my vibration was ditching the poly trans mount for a stocker.

ibanez7

iTrader: (7)

update on the OP...

-wheels and tires balanced.
-driveshaft balance checked
-new spicer 1350 ujoints
-pinion angle is -2 degrees

vibration still present.
detail of vibration
:
50 to 70+mph
-seat back rest vibrates like a massaging seat
-center consoles vibrates like its about to blow up (it is screwed down)
-steering wheel has the shakes (guessing its because the rest of the car shakes)

so now Im left to think its one of these two things:

-poly transmount is 6-8yrs old, never was an issues but maybe it crapped out/hardened up if that is possible.

-rotors are warped extremely bad...

any other ideas. would like to keep this thread alive until the issue is solved.
Could be helpful to other chasing down a vibration

JohnnyBz28

iTrader: (12)

I'm having the exact same issue as you and still haven't figured it out lol