Vibration over 70mph 1989 325ix

[bikerguy71]

Hello- Need help. I have a vibration when my car reaches 70mph...and it gets really bad at 80. Car runs smooth at lower speeds. Very weird. I have replaces the rear drive shaft, have a rebuilt transfer case, guibo was replaced with the drive shaft. Could it be the front guibo on the front drive shaft? It looks good, but who knows. I am thinking about bring it to a shop to investigate, but would like to know if anyone has any ideas?

[NeedaE30]

have you checked the balance on the tires? could also check the control arm bushings

[ak-]

Look into your front suspension.

[bikerguy71]

Tires were all dynamically balanced. Front end has all new bushing and rebuilt axles. Rear end has new drive shaft, new guibo, rebuilt transfer case, wheel bearings, but stil has vibration. I jacked up vehicle and ran with all 4 wheels off the ground. Got it to about 80 and could hear the vibration.....definately in the rear end of the car. Thought that is could be the rear axles.....so I disconnected them from the diff. Ran it again jacked up, but still vibrates in the rear of vehicle. Seems to be coming for the rear of the drive shaft by the u-joint, where it hooks up to diff. Why or how could this be? Its brand new? Could the drive shaft be out of balance. Not to noticeable below 60mph, but it gets much worse over 70. Help!

[KVF]

Sounds like you've narrowed the issue down to a bearing within your rear diff starting to go south.

[jlevie]

Tires were all dynamically balanced. Front end has all new bushing and rebuilt axles. Rear end has new drive shaft, new guibo, rebuilt transfer case, wheel bearings, but stil has vibration. I jacked up vehicle and ran with all 4 wheels off the ground. Got it to about 80 and could hear the vibration.....definately in the rear end of the car. Thought that is could be the rear axles.....so I disconnected them from the diff. Ran it again jacked up, but still vibrates in the rear of vehicle. Seems to be coming for the rear of the drive shaft by the u-joint, where it hooks up to diff. Why or how could this be? Its brand new? Could the drive shaft be out of balance. Not to noticeable below 60mph, but it gets much worse over 70. Help!

I've seen new and rebuilt drive shafts with binding u-joints, but with the car on a lift and the drive shaft spinning you should see a bit of wobble in the drive shaft if it is the cause.

[bikerguy71]

Hello- It appears that it was the driveshaft

[bikerguy71]

Replaced drive shaft with a used one I had laying around. Vibration is gone. So it appears that my new driveshaft was not balanced. Makes me mad. Paid around $380 for it. I will probably send it out or find a local shop to balance it. For the moment, I am quite happy to have my car back to normal.

[nando]

where did you get it?

the slip yoke on the rear of the ix driveshaft comes apart. It's possible they didn't line it back up before putting it together. There should be two white painted dots, see if they match.

[KVF]

where did you get it?

the slip yoke on the rear of the ix driveshaft comes apart. It's possible they didn't line it back up before putting it together. There should be two white painted dots, see if they match.

And I learned that they sometimes paint their own dots during rebuild and mistakenly put them together 180 degrees opposite. If the dots are aligned and it seems out of whack try aligning the dots exactly opposite of one another. Mind you that's a ton of troubleshooting to go through.