vibration problem

[twneels]

I have a2013 chevy tahoe that I recently installed a used transmission. It was not shifting right and I had felt a vibration so I had it reprogramed. The mechanic told me everything was fine. It now shifts right however between 50 and 55 mph the is a slight vibration in the rear of the car. I had also changed the rear u joint and its still they're. I know it needs rear shocks but everything i has read says that would have nothing to do with a vibration. I need help to figure out why it is vibrating. Could it be the transmission, the torgue converter, the other u joint the tires the driveshaft all I know is it never did it before the transmission went out. please help

[chippie]

Your best bet is to take it to a transmission shop, have them check out the full drive train, from the auto box thru to the rear wheels….

Btw, this is a UK based forum, but we like to help where we can..

I like the Tahoe/Suburban range and the more exotic Escalade….😃

[wightdiag]

If you would like to see if you can identify it yourself you might find this technique helpful

[valhalla]

Was it yourself that changed the transmission, or was it done by a garage?

It would be useful to know how the transmission was removed, as some garages employ a technique of separating the propshaft to get the gearbox out - it's quicker than undoing the drive-flange fixings on some cars. The sliding joint on the shaft is usually keyed, so it cannot go back out of alignment, but sometimes the shaft gets pushed back together in a different orientation (front portion versus rear portion of shaft), and this gives stiffness in the sliding-joint that can give vibration issues at certain speeds.

The other scenario, where the drive-flange has been disconnected from the back of the gearbox directly, can also lead to problems, especially if the gearbox has been replaced - there's nothing to realign against, and therefore its "trial and error" to find the best orientation of shaft to gearbox.