3.91 gears on M6

[BAH2SS]

I am planning to get the 3.91 gears for my M6 2010 camaro.

car currently has TSP 1 7/8 headers and x-pipe, GMPP axleback and airaid CAI.

put down 424 whp 426 lb.ft (cold day)
417 whp 426 lb.ft (hot day 94 degree)

anyone tried AAM kit (part# 40098654). it is the cheapest of them all.

https://www.ebay.com/itm/2010-2015-C...sAAOSwxKtYB8RD
250 USD on ebay.

Or anyone tried motive or GM kit?

I mostly do 25 & 50 roll races and take it to the track from time to time.

[Black_SS10]

I love mine, although it is difficult for me to keep traction sometimes. I believe AAM makes the gears for GM.

[CamaroFred]

If you have a GM dealer the GM kit contains a code to re-calibrate the speed/odometer.
Otherwise your speed/mileage will read 13% high.
A tuner can do it at a cost to you.

[BAH2SS]

Originally Posted by Black_SS10

I love mine, although it is difficult for me to keep traction sometimes. I believe AAM makes the gears for GM.

Are you using AAM? do they make noise?

[BAH2SS]

Originally Posted by CamaroFred

If you have a GM dealer the GM kit contains a code to re-calibrate the speed/odometer.
Otherwise your speed/mileage will read 13% high.
A tuner can do it at a cost to you.

Tuning is not an issue for me & i think its not required for the manual trans.

[frankwjr]

You will need a tune, not just for speedo otherwise why do it in the first place? Any gear change has the possibility of being noisy, all depends on the installer.


I have a tiny bit of noise on decel (.002 backlash) but I also have the LPW cover and the delrin bushing so all of the sounds come straight thru.


What is the mileage? I went ahead and replaced all bearings and I highly recommend replacing the axle seals at the same time...save a little grief down the road.


I was able to do all this in my garage on jack stands incl redoing the posi. If you can drop the pumpkin and take it in should save you a couple of $$.


good luck


Peace

[PepeLePew]

I have the GM 3.91 1LE set installed less than a week ago. I can't seem to figure out if the AAM set is the same as the GM set personally. I know that AAM was sold by GM a while ago and they've been operating independently of GM for some time now. That doesn't mean that GM doesn't source OEM parts from AAM though. But the part numbers for the GM ring and pinions aftermarket is different than the part numbers for the AAM sets.

My gears are silent so far (although my car is very loud with cutouts open so it is hard to tell). I am sure if you change the bushings to delrins like others said, you will get some NVH though... but that is not a bad thing in my mind.

I agree 100% with CamaroFred that you will need to get your tune updated to correct the speedo. You will read 13% faster than actual speed if you don't. If you don't care about that and you do the math while driving to know your actual speed then there will be no adverse effects, but you will start to acumulate 13% more miles on the odometer without a tune update.

Lastly, I totally recommend the 3.91s. If you never have any future plans of boosting the car, you could even go as aggressive as 4.10/4.11s and really maximize the potential. Gears will make your NA car feel 500-700 pounds lighter so acceleration will be awesome. If you go boost in the future, you are probably limited to a centrifugal blower or a turbo setup with lower boost off the line that won't blow the tires. Otherwise, if you go positive displacement blower, you may want to stick with stock 3.45s since the boost comes in right off the hit.

You're gonna love it!!! let us know what you do!

[rdavis]

3.91s are the best mod out there short of getting into the engine. I have gm 3.91s and they are quiet. I do believe that the gm kit comes with a voucher to get the speedo programed properly. In my opinion the gears make the car much more driveable. Also I remembering reading an quote from the late great John Lingenfelter, He stated that in his opinion the ideal overall first gear ratio for a street car is 12/1. An SS camaro ( except the 1LE) with 3.91s has a ratio of 11.77/1 Almost perfect according to Lingenfelter.

[BAH2SS]

Great, thanks for tge input guys. I've decided to go ahead and place an order for GM kit from amazon and i have a 200$ gift card which i will end up paying 300$ for the kit.

[Benman]

I just ordered my AAM 3.91 gears, P/N 40098654, found on eBay for 250 free shipping. I also got the AAM master install kit thru Gears Unlimited for 290 +35 shipping, P/N 74060018/74010007. All these parts are from the OEM which was AAM when my car was built, probably still is. I was able to also get the Jannetty posi mod kit for $150 shipped from a forum member, Now if I can find a good deal on a LPW cover I will have all I need to make my diff as strong as it can be. I may also get the billet carrier bearing caps from Jannetty. As with all my junk I will do the install myself. Dynosteve will update my SCT X4 for the new gears.

[Benman]

As it turns out the master install kit from AAM has been discontinued, but the guy at Gears Unlimited was able to supply me with a Motive master install kit for the same price. It has virtually the same pieces, except it does not as many shims to adjust things as the AAM kit. I don’t think this will be an issue though, most of the rear ends that I have worked on ended up reusing the shims that were already in the assembly when I took them apart.

[STALKER]

You're going to love them. 3.91's totally change the car.

[frankwjr]

Originally Posted by Benman

I just ordered my AAM 3.91 gears, P/N 40098654, found on eBay for 250 free shipping. I also got the AAM master install kit thru Gears Unlimited for 290 +35 shipping, P/N 74060018/74010007. All these parts are from the OEM which was AAM when my car was built, probably still is. I was able to also get the Jannetty posi mod kit for $150 shipped from a forum member, Now if I can find a good deal on a LPW cover I will have all I need to make my diff as strong as it can be. I may also get the billet carrier bearing caps from Jannetty. As with all my junk I will do the install myself. Dynosteve will update my SCT X4 for the new gears.

DynoSteve can get you the LPW cover, it's where I got mine. Forget the billet caps...not needed IMHO and you need them machined for proper fit. And don't forget axle seals!


Any any gear fluid will work..most already have the posi-lube...I just stick with Mobile 1 LS now.


good luck!


Peace

[Benman]

Already have the billet caps, machining isn’t an issue, I worked as a machinist in the past. The caps need only to be faced on surfaces where they mate to the case. I will check with Steve, but the LPW girdle shows something like a mi September delivery date when I looked at it the other day. And yes, the gears help wake these big girls up.