Vibration over 75MPH

[Dan Vincent]

This has been bothering... when driving over 75 MPH, I get this strange vibration under the seat area (it goes up through the seat too). I'm ruling out alignment and wheel balance, since those were done recently. Could this be something driveshaft related? Or has anyone else had a vibration like this?

[eyeeatryce]

Mine did the same thing. It was a problem with my rotors.. They were warped!! So i replaced them and it was all fixed!

[BLLDOGG]

my front rotors are warped and my car doesnt shake at all, and i have done the alignment yet on my car. got 74K now and got her at 63K

[Dan Vincent]

Originally posted by eyeeatryce:
Mine did the same thing. It was a problem with my rotors.. They were warped!! So i replaced them and it was all fixed!

I have all new rotors, so this isn't it. This isn't when braking, either, it's during acceleration or cruising.

[ravenp]

have you recently swapped in a 1 pc driveshaft?
i've heard many people having this problem when going to 1pc... i was lucky.

[ellik]

I had that problem with my old 2-piece driveshaft. started at like 75 mph. after time, it will start vibrating at lower and lower speeds. swap it out for an aluminum, just make sure the new one has good u-joints.

[CARdiac]

I am thinking DS.

I have a lot of movement in my DS joint, tho no vibes now, I would expect to feel some soon

[RallyRed 98]

an easy way to get rid of the vibration is to index your DS, especially if it's an aluminum one. it is a little time-consuming, though...

[94TeaL]

Driveshaft, when my u joints started going bad for the 2nd time it did this. Highway driving was alomst impossible.

[Dan Vincent]

I haven't swapped in a new DS recently... but it looks like it would be a good time to pop in an alu one. Thanks for confirming my suspicions.

[FireFighter]

Wheel balancing maybe?

[saved1]

I would still look at the tires even though you just had them done recently. A weight could have come off, or even something like tire pressure could do it.

[PiercedJD]

wheel balancer could be fubar also. ( I worked in a shop and those things go down all the time.)

the driveshaft should have a balance weight on it. it will look like a little square lobe or possibly like a washer that was welded to the tube. if you don't see one on yours it's possible it came off and your driveshaft is unbalanced. You can have a driveshaft balanced for like $30 or less. I have had them shortened and balanced for $70. just call around to find someone local that does driveshaft shortening/ lengthening.

jack the front of it up and with the car in gear and the rear wheels on the ground try to turn the tube and check for play in the universals, as well as prying it up and down.

[ReodDai]

I have alot of vibration. If no one sits in my passenger seat you can see it bouncing around everywhere. Thought it was tires, mounts and suspension just getting stiffer.

[C.O.Jones]

Originally posted by ReodDai:
I have alot of vibration. If no one sits in my passenger seat you can see it bouncing around everywhere. Thought it was tires, mounts and suspension just getting stiffer.

Doesn't suspension and rubber mounts loosen and break down over time?