hurley711

iTrader: (5)

Nah man no worries at all keep it alive! There's not alot of info with the 3.90s I'm hoping more guys will jump in! I don't track race and tend to baby the car so I hope they will hold up fine!

2000TransAmWS6

iTrader: (12)

with a 10 bolt in a 600hp car you are asking a boy to do a man's job.
IMO if you're going to keep the 10 bolt in that car i'd stay with the stock 3.42s and put a girdle on it. one of the major problems to overcome on a 10 bolt is that the carriers just don't hold up, the small clutches and spider gears just don't stand a chance.

fatmat80

Yeah i was told that as long as the wheels are spining it should not break. But i spin so much that I am barely beating cars I should be destroying. Guess im gonna have to break down and get a 9 inch. Just did not wanna spend 3 grand yet.

RealLiveMD

iTrader: (1)

3.90s feel like a 50 shot over 3.42's However, after 4 different installs, I still get whine esp. at about 50 to 65mph. However, 72 mph has very little whine. So, I just simply speed. The 50hp feeling allowed me to beat my nemesis by 1.5 to 2 cars when we usually are neck to neck or he beats me by a fender. He thought I sprayed him. I run GSd3 275's in the rear. Great hook on the street above 70degrees

2002 T/A

OK, guess I am looking for moral support before I over react! Two issues, 1- the Motive Orange box gears are as loud as the stock 3:42 minus the slop, backlash set at .006 by seasoned GM tech. 2- is 1st through 4th ever close now, seems like a different M6? I know the 4:10 guys will think this is a joke but bear with me relating to driving style, I am questioning weather I should have gone with a GM 3:73 for noise and a wider gear spread?? I am really surprised how loud these wine, is this normal for the F-body, would a GM 3:73 be better??? I want to fair to Jaws Gears as they only sell the product, but I am disappointed! Thanks for your feedback, Les>>>

Tobias05

iTrader: (1)

^i'd take it back and have him readjust it. it seems in my experience (4 sets of gears) gear whine is 75% installer, 25% luck of the draw on the gears themselves.

I took my 87 the second time around to the "seasoned GM tech" that everyone recommended, and was told they couldn't get my gears to fit. seriously? lol... got charged labor twice over. took the same exact set of gears to an RPM (garner,nc) employee, and they're 97% quiet. granted my car took him to lunch but he got it done.

2002 T/A

OK, what was your backlash when completed? Motive says between .004 to .010 and my guy set it at .006 (2nd attempt). Also, once its driven is that not it? Thanks, Les>>>

96lt4c4

iTrader: (5)

Look at my gear install thread, I did mine myself. I have built a few rears using Yukon gears and have never had any problem. But, these danm things sound like ****. I am going to try changing pinion depth tomorrow and see what happens. My backlash is .009. The instructions that came with mine say BL should be between .007 - .009. I have always set Yukons up .006-.010 on BL. If they dont calm down I am yanking them out.

2002 T/A

Are you saying then that some noise is expected? From most of the posts I read there is always noise, some guys have none? The Motive Orange in my case are worse than the OEM 3:42. My guy said the pattern is very good and in the middle, even he was dissapointed! So is there a solution to this setup?

hurley711

iTrader: (5)

Gears going in tonight fellas. Hope to have updates by wed-thurs bro in law is installing at his dealership after work hrs so it might take a couple days on his free time!

hurley711

iTrader: (5)

ahahaha oh well it's always something right fellas??? HE took the gears out and.the diff fell out with the gears. Broken, gear pattern out of place he and another mechanic said they don't even know how the car was driven. Ordered an Eaton diff for $430 should be here Fri

RedWS6 00

I have the Motive 3.9's in mine, from Jawsgear. Also put in an Eaton Posi at the same time. Acceleration does feel a lot harder now. I didn't want to go for 4.10's as worried it was too bigger jump. 3.90's is a nice compromise.
Soon after it was done I done a 270mile highway journey on less than a full tank of fuel. I used to get 27mpg on 3.42's now I get about 24mpg on 3.90's. both were going between 60mph and 70mph, and slowly accelerating. I did have more weight in the car when doing the 24mpg run.
I'm certainly pleased with the added fun factor.

hurley711

iTrader: (5)

Thx for the response! MPG doesn't bother me the car is a weekend crusier only sees 1200-1500 miles a year. The Eaton I am chalking up to good maintenance and it obviously will be a nice upgrade over the stock POS in there. Part comes fri so hopefully updates by this weekend

hurley711

iTrader: (5)

Hey does the Eaton diff need the GM additive fluid or just the Auburn??

Black96z28

All limited slip differentials with need friction modifier for the clutch packs.

hurley711

iTrader: (5)

Cool thanks 1 bottle or 2? Or how many oz is needed?

therobman

iTrader: (39)

1 bottle

hurley711

iTrader: (5)

So 2 guys working, installed the Eaton diff and gears in 2 hrs flat.........and the pinion seal sent with the kit didn't fit. WTF. Shop closed so now he has to wait until tues because of the holiday. Should be spending entire holiday weekend breaking in the gears but nope, wait again. Such BS. The seal doesn't matchup with the original, so the wrong one was def sent.

Midnight00SS

I just got my Motive Thunder Racing 390s in a month ago and love them, much more accelaration, car is alot quicker, fun to drive, u get into 4th real quick now, i highly reccomend them, but beware as the pinion seal i got in the Thunder Racing Kit was the wrong one, so be sure to get urself a factory one or a reg one from the autoparts store, cause i had to pull apart my rear twice

hurley711

iTrader: (5)

ahahah did you read my post??? It WAS the wrong seal and since they didn't have the right one handy the car sits all freaking holiday weekend because the shop closed. NOT happy with the sponsor on this one. Surely theyvre had complaints about this before?