I have a bad vibration starting at 45mph and increases as speeds goes up...70mph --> and up, cars is ready to destruct.... I replaced and fixed the following:

Rebalanced DS and replaced Ujoints
replaced opti
replaced plugs
replaced wires
replaced coil
replaced torque converter
replaced rims
replaced tires (brand new)
balanced the brand new tires twice

My vibrations occurs infront mostly but after 85mph,,the whole car shakes below 85mph,, I can only feel it in the front,, steering wheel shakes a lilttle bit but mostly the whole front...what else can it be.

I checked (just visual) tranny mount, and it looks good.

what else could it be?????

engine mounts?
warped rotors?
DS?
alignment? (have not done yet)
if its alignment, can someone explain how can an alignment problem cause such vibrations? thank you

 

I've got the same problem. Two things come to mind. 1 - driveshaft and 2 - control arm bushings.

However, I don't have a dime to prove either theory correct. heheh...

anyone else confirm or deny the above? (the vibration problem, not that I'm broke)

J

 

Could be rotors are warped. Also tie rods ends worn or wheel bearings. Warped rotor(s), I would suspect first.
A wheel alignment would determine if any of your suspension parts are out of tolerenace.

 

ball joints or even the pitman arm will cause instability in the front steering. Unbalanced tire(s) or the weights fell off one tire e.t.c.

 

i have the exact vibration also. form older posts and a couple of rags i read the vibration comes from the stock steel driveshaft around 90 mph. i just bought a used ls1 aluminum and i am putting it on with some tranny mods next weekend. they do have a resonant rpm that they all vibrate at. the stock steel was around 85-90. the ls1 aluminum will still vibrate but its not until some really high speed (170 ish). i also read in one post that turning your driveshaft over would reduce or remove the vibration. i personally dont see how. if its out of balance or was never balanced in the first place a 180 shift wont change anything but i am no physics major soooo.... i will post after the driveshaft swap and let you know if that fixed my vibration.

david

 

i put in the new ls1 driveshaft and all vibration was gone.

david

 

Could be the front hubs. How many miles does the chasis have? I never have liked NOT being able to grease the bearings and suspension parts on my 4th gen.