vibrating and shaking when it goes over 45mph?

Hello
Check the tires you may have one that is seperated. Also do you notice any pulsation in the brake pedal?

John

Hi Most likely the steering damper a shock absorber thing see diagram. Thanks for donate

We were talking about the rear, or trans... How did you make the leap to "STEERING" ? NO ! return donation and let someone else answere!!!! iI said i replaced rear u-joint........... why . never mind! DUH!!!!

It could still be a tire that is seperating.Does it make any odd noise or does it just vibrate? is it a side to side shimmy or a regular feeling vibration? How are the rear end bearings? any excessive play in the pinion?

you could be on to something. We went ahead and replace the front u-joint and the problem perist. my on looked up the problem in the service manual "trouble hooting" and the talk about replacing the rear axle bearings....... Doe this sound right to you? What would caue this problem? (Van was used by a tile company for 18 year)

I have personally never had an axle bearing in the rear cause a vibration.More likely the rear end bearings/gears themselves.Have you cheked the tires for any seperation (bubbles) in the tread?Tile is heavy and can take its toll on all the bearings that the van rolls on.Also look real close at thedriveshaft, see if there are any spots wherea balance weight may have flown off, this will cause a vibration like you describe.

We replaced all four tires and went back to service station and had them take each tire off and show me that they were balance, and they were.

Knowing what you know about the van now , do you think I need to replace the rear? and how much play in the pinion is too much?
I appreciate your help....

peace
tim

The play in the pinion is measure in thousandths. using a dial indicator. Did you check thedriveshaft for a rusty spot where a weight may have been at one time? I would go there before the rear end, just to be sure

I really appreciate your follow-up! We decided to take it to a Chevy Dealer to have them tell us what is wrong, this way we can be sure we fix it once and for all ! We will pay for their time but we intend to do all the work ourself. I think you are right on about the drive shaft and i told the dealer to look at the that first.

I will let you know, if you are intereted, what the problem is .

Thanks again!
tim

Yes, I would love to know what it was, thank you.The info may help someone else down the line

the verdict is in .....

A broken leaf spring! The noise was from the excessive movement in the spring. Though you were not right about the drive shaft you were right that it was not the rear! You even made the comment that "Tile is heavey" that, and rust, is what leed the spring failing.....

Thanks again
peace
tim

Cool, glad the problem is gone and you are back on the road vibration free..... have a good one