torkmonstr

So are all the motive gears just junk. I have now gone through two sets of 3.90 gears. First set had two teeth shear off the ring gear. Motive warrantied them and git the second set all set up. Broke in and they were quiet nd smooth till last night the exploded taking out the case too. We teally need a quality gear set for these cars

0Shane@RPMtransmissions

Unfortunately the C5/C6 corvette takes a very unique pinion gear and lots of tooling changes to forge and machine the gears and Motive is the only company to take this task on. Saying that we have had really good luck with the gears they do have some power limitations but we see lots of other issues before the gear becomes the weak link.

HardcoreABN

here is hoping my 3.90s are quiet....

torkmonstr

Mine were quiet too until they exploded. Pics to come. Its coming apart now

v98roadie

Read my thread on changing the gears in my 02. Went through 3 sets and several adjustments before getting the noise to an acceptable level. Best of luck.

torkmonstr

The aftermath of 3.90 gear failure

HardcoreABN

the hell kinda power are you making?

torkmonstr

Only just over 600 to the wheels

HardcoreABN

6k launch with a manual on drag radials?

torkmonstr

Nope. Gears were just past the break in period. No noise. All sounded great. And on street. If was on a track hooking hard i could understand.

HardcoreABN

odd....did you take it up with Motive?

torkmonstr

Ive called Motive. Had to leave message with no call back. Go figure. Now am going through the dealer they were purchased through.

frodo84

Sigforty

I had something similar happen to one of the built 3.90 diffs I had. Unfortunately, it broke the case when some broken teeth got between the pinion and ring gear.

torkmonstr

Oh this took out the case too. Massive damage

Sigforty

I see. I have also had the cross-pin fail in the first diff I broke. I eventually stepped down to 3.42 GM gears and things seem to be holding up better.

torkmonstr

That is my plan at this point. Have located a low mile diff out of a 03 z06 and goinf to swap im my stub axles and run that. Sucks cause i spent a ton on this with the billet pinion support upgrade too.

Sigforty

I am roughly doing the same thing. I have been riding on a stock Z06 diff now for a few years. I have some new GM gears and a 3.15 diff I plan on building up with what parts I can reuse from my last broken diff. I also plan on putting in some of the C6 Z parts to upgrade what is no longer usable.