defiance

My suggestion is to take it back to the shop. Friction modifier only will make the rear quieter, not fix any vibrations, that problem is something else.
Getting gears done right is such a pain it seems, I have 3.73s and I cant seem make them to shut up even after 2 changes of fluid with correct friction modifier. And mine were factory installed.
Good luck with it, keeps us updated!

07BLACKGT

Hrrrm. If it's pretty bad go back to the shop for sure. I remember mine had a very slight vibration at a certain speed when I first had them installed.. I was concerned about it, but it went away on its own.

alan0614

I just had 3.73's installed and it seems I have some sort of harmonic vibration at speeds above 50. The best way I can describe it is as being close to the sound of a car next to you with sub woofer and their volume is up, you kinda feel/hear the bass. That is what I feel, a deep sound/vibration. I can push the clutch in and I still hear it, so I know it is not exhaust, etc.

Any ideas?

Blacksmoke

You need to take it back.

Gear installation is a VERY sensitive process.
Even a tiny error can cause problems.

You should NOT be having this.

Widowmaker[X]

Spoke with the shop this morning. Says I should drive it for a few more miles (only have about 50 on it since the swap) to give things a chance to lubricate properly and see if it clears up.

alkemist

"A few more miles" won't clear up a problem like that. Maybe if it was just gear whine but not vibration issues. Most likely something was not installed correctly. There is almost no margin for error.

I can tell you, after my install, my installer and I went for a test drive and had no problems. They were smooth.

FrostByte

There should be no sound/vibration issues @ all, no matter how few miles are on them. Your just gonna damage some thing if you keep "breaking in" the gears.

I had 3:73s installed when I first got the car 6 yrs ago. That metal is so hard that even after 6 years of use you cant even tell there is any wear on the gears. (had it open to fix gasket leak) never had any sound issues, just a one-wheel peel last year. i changed dif fluid w/ new friction mod & its fine now, didnt even have to change the clutch pak.

Widowmaker[X]

Update!

Returned to my installer who put in a second bottle of friction modifier. Haven't experienced any vibrations since. Fingers remain crossed...