vibration ?

[chatcher]

up around 80+ mph i notice a pulsing vib from the rear of my car i have replaced virtually every thing i can think of back there but have not fixed it my last areas of concern are the wheels and rotors i believe i over torqued the aluminum wheels when i first got them i used to use the crank on it till you cant crank any more method but i have had them off and taken to a tire place and rebalanced not sure if anything i would have done to them would have shown up on the balancing machine or not also the rotors behind the wheels of cousre were subjected to the stress of my ignorance of torque specs the thing that confusses me is that it is not a constant vib but a pulsating one it has new polyurethane bushings on the rear end itself new upper and lower control arms new aluminum driveshaft new springs replaced axleshafts new shocks and updated sn95 brakes if it is the wheels is there any way to tell other than getting new wheels i have rotated them to no avail what else could it be? any help will be greatly app

[KiltedBanshees93GT]

Have you tried taking the car up to that rpm in another gear to rule out something in the drivetrain? Other than that, borrowing a set of wheels is the only thing I can think of. Though the rotation kinda ruled that out, unless there is something wonky in the axle/hubs.


J

[grey88gt]

I know this sounds silly. But you might take the driveshaft off and rotate it 180 deg at the pinion. My old 75 Cougar would get a vibration in it at about 75 mph. I replaced axle bearings , balanced tires ( Idont know how many times) . After I did that the vibration was gone.

[smokedchevy]

Have you tested to see if the vibration is there while revving the engine in neutral? The reason being, I thought I had drivetrain vibrations, but instead it was a broken bolt holding the alternator bracket. Shook the whole car!!

[chatcher]

tried reving in neutral and i have turned the driveshaft i think i need to borrow some ones wheels because i am noticing vib in the front also and everything up front is new within the last year also has anyone expierenced or heard of over torqued aluminum wheels causeing this kinda prob?

[smokedchevy]

Is it at a certain RPM or just 80mph? Does it do it any other gear?

[chatcher]

it is just a high speed prob not realatd to rpm

[smokedchevy]

Just how many ft lbs. were your aluminum wheels torqued too?

[chatcher]

i used to use a breaker bar and crank on them till i started noticing this prob ( i dont get to do a lot of high speed driving ) and its been really crappy this week so far and its not looking better in the forecast for the rest of the week so i prob wont get to drive it for a while but i tried rotating the drive shaft again and rotated the wheels again what are some of the causes of this type of problem that i may have overlooked any one else out there with any guesses

[procharge94]

Do me a favor, get the car up to speed. You mentioned that 80 mph was a speed at which the vibration seemed the worst. Rip up real fast, to about 90 or so, and then put the car in neutral. Tell what if the vibration changes at all.

[grey88gt]

Where do you fell the vibration? Is it the steering wheel, do you feal it just over all in the car, you might try a spare tire one at a time to rule out the tires and wheels, or like KiltedBanshees93gt said borrow some tires and wheels and see what happens. Have you checked the crossmember bolts and trany mount? A buddy of mine had a trans mount broken and his car would vibrate at high speed, but it wasnt a Stang.

[chatcher]

unfortuanatly snow has covered me again so it may be a while before i get the car out again but when i do if at 80+ i take the car out of gear and the vib changes what would that indicate to you and the trans has a new poly mount and new ford racing crossmember with poly mounts all installed after i noticed the vibration (not because i thought it may be a potential cure though just as maitence/upgrade)