Rear driveshaft u joints?

ok blew out my rear driveshaft and just got a junkyard one put new u joints and now it shakes going 40mph why?

Thanks Erik

It may be out of balance or you have the phasing wrong on the driveshaft.

make sure the u joints are not in a bind, did they move freely after installing them? i just had the s ame problem after installing new u joints i had a vibration between 35 and 45, u should be able to look at he sanp rings and tell if one is pushed out a little more than the other one, if so just smack it with a hammer, i did not even have to remove the driveshaft to free the joints up just smakced the shaft until the snap ring was centered and no more vibrations, but oculd have a bad srive hsaft also hth

Durango-Bob said:

It may be out of balance or you have the phasing wrong on the driveshaft.

Click to expand...

X2
unbolt the driveshaft (at the rear diff) and rotate it 180 degrees then bolt it back up and go for a drive. See if that helps. Then let us know.