so i recently been doing lots of work with my diff after it kept breaking so diffs have been in and out if my car like crazy. i noticed that from all of this a small rubber fitting inside the drive shaft is all outta place (this is where the diff connects and goes in the drive shaft) but i just crossed my fingers and put the diff in. so when i finally put my new locked diff on my sc i noticed that if i go past 20-30 i get mad vibrations from the back tires. it feels like going over thousands of little speed bumps at like 50mph. so i got the car back home, jacked it back up so the tires where off the ground and gave it some gas. As the rpms increased the vibrations came back, so i had a buddy look at the diff while the car was doing the vibrations and it didnt move at all (so its not the diff right?) i thought maybe it could have been moving at bit but no. So then he look at the driveshaft and saw it shaking so im assuming that it is the driveshaft? plus of what i saw before the diff was in. if someone can narrow this problem down and tell me what i need and how to get it fixed i will greatly appreciate it, i just want my SC back .

 

Have you looked at the flex coupler thats by the diff towards the end of the driveshaft?

 

Is that the rubber peice around the drive shaft that has the bolts in it?

 

Yes, how is that? do you have like a grinding whilst your driving also?

 

no cant say i do. all that happens is a horrible vibration at 20/30 mph. do u think this could be my drive shaft or something else? i believe its the rubber piece not on outside of the shaft but inside. i doubt its my welded diff, they just dont do this. i might try going over every thing again and try tightin up where the shaft meets the diff.

 

get the shaft balanced, check the condition of the rubber couplers, consider replacing the center bearing.

 

So is there mulitple center bearings? When I took my diff out I Stretched out a rubber fitting inside the driveshaft where the diff connects in. Is this something I can fix? Or should I leave the to the shop that's taking care of the balance? Also Does a driveshaft need to be balanced once the diff is removed I know it's good to but I thought that only had to be done if you didn't put the drive shaft in the same spot as you removed it?