Vibration...already replaced guibo, csb and ujoints.

[ParsedOut]

Just installed my newly rebuilt driveshaft, new input bushing, new guibo and new CSB. Now I get a vibration that starts at 50mph. Here's the funky part...it goes away once the car warms up. Vibration is in the butt, not the steering wheel.

Is it possible the new ujoints need a few hundred miles to loosen up or should I tear the whole thing apart and bring it back and have it balanced? Common sense tells me that if it were out of balance it would vibrate no matter the temperature.

Tire pressures are all at 30-35psi. This started as soon as the driveshaft was reinstalled, so I feel it has to be related...

[jlevie]

Who rebuilt the drive shaft and was it balanced after rebuilding?

[ParsedOut]

It was rebuilt by Phoenix Rack and Axle, they are well known around here especially in the bimmer community. They did not balance it because 1) i forgot to give them the csb and 2) they said it rarely needs it since there are factory alignment marks. But this goes back to my original point, if it were out of balance wouldn't it vibrate no matter if the car is warmed up or not?

[jlevie]

It the drive shaft were to be out of balance, it should vibrate all the time.

This could be tires. They may be flat spotting while the car is stitting.

[KenC]

I'd still take it back and have them balance it.

The fact that it goes away when the car warms up is beyond bizarre.

[Northern]

to test if it is the tires flatspotting, you could start the car and let it fully warm up before driving to see if the shake is still there.

[jlevie]

to test if it is the tires flatspotting, you could start the car and let it fully warm up before driving to see if the shake is still there.

A check to see if the cause is the tires flat spotting is to jack up the rear of the car immediately after driving the car (support it on jack stands). The next morning drop in on the wheels and immediately drive it.

[ParsedOut]

I did check the inflation on the tires but I haven't done anything to create flat spotting.

However...with that said. My first test drive after installing the new driveshaft it was smooth as butter all the way up to 95mph. The next day I was driving around kind of like an idiot (no full lockups to cause flat spotting) and then I noticed the vibration the following morning. I plan to jack up the car this weekend and see if anything came loose or looks out of the norm, if not then I'm still stumped.

[jlevie]

I did check the inflation on the tires but I haven't done anything to create flat spotting.

Parking a car over night in cool or cold weather can cause the tires to flat spot. Some tire are worse about this than others. Once the tire heats up while being driven, the flat spots will go away.

[ParsedOut]

Interesting! Living in AZ I've had no experience with that. I park in the garage also, doesn't drop much below 50 in there.

[ParsedOut]

Turns out I just threw a rear wheel weight... Rebalanced and good as new!

[scottinAZ]

Turns out I just threw a rear wheel weight... Rebalanced and good as new!

sounds about right, usually something stupid simple causing the major issues