well, i dont know if yall have kept up with my build or not. i have a 08 GMC Sierra CCSB. it has a 6.2/6L80e/4:10s, nothing too special. i had a MadMan carrier mount made and have not changed anything else. the truck never vibrated until the new driveshaft, and carrier mount. i took it to MadMan today, and he double checked my pinion/driveshaft angle...said it was 2.2* and it wouldnt cause a decel vibration when i let out (anything over 100). the transmission is at 3*. it had spring clamps, and it was like the driveshaft was about to come out, i took them out and it's no where near as bad as it use to be.

talked to the driveshaft shop and they said it wont be the driveshaft, and talked to MadMan who said its not the pinion angles. well guess what it never did it before the trans/driveshaft swap. i have a feeling it is a crap *** driveshaft balance but we'll see when i get it back up there to see what they say. if that doesnt fix it then im going to MadMan and see what he can do. if he cant fix it then im buying a new driveshaft and setting this one on fire.

just wanting some info from someone that knows what they are talking about bc i am not a suspension guy.

 

To arrive at Proper driveline working angles ... " equal and opposite " angles ....if you drag racing and get alot of rotatiobn on launch then you may want to adjust pinion down say 1-2* .bottom line you dont want trans down 3* and pinion down 2.2* .if trans is 3* down and pionion 2.2 up then it sounds fine FWIW

 

http://www2.dana.com/pdf/J3311-1-DSSP.pdf

page 17 is where i read that the trans should be down 1-1.5*....mine is 3* down, and the rear shaft/pinion is down 2.2* also.
so you are saying that the rearend should actually "roll up" to match the 3* of the transmission since they are suppose to cancel each other out. -3* with a +3* or am i misunderstanding that. i wish i had more knowledge in this

 

Sori did not read link on holiday in Mexico so have to get off computer wife is calling lots of misunderstanding on thios topic .......... do not confuse pionion angle numbers you hear ton the net for drag racing as opposed to good working angle for a driver ......so yes Equal and opposite meeans if trans down 3* then pionion should be up 3* with 1-2 degree variation ....... if the trans down 3* ( which sounds fine ) and pinion up say 2* the working angle is the difference 1* key is oposite angles

 

ok, i'll try rolling the rear end "up" to make it be 3* also when i get my truck back