AAM 3.91 Gears...Very Nice

[StreetStrip]

Well, as some of you may know I've been struggling to find a rear end setup that's strong, quiet, and efficient. I started with Richmond 4.11's in the stock diff, we setup the gears 3 different times and never could eliminate the whine completely. Frustrated I decided to try the DSS 9", it turned out to be as noisy as the Richmond setup, reduced effective power, and added weight.

So, finally I decided to try AAM gears from Lingenfelter and other upgrades to the stock differential.

• JRE Posi Clutch Upgrade
• AAM 3.91 Gears
• LPW Heavy Duty Cover with Carrier Cap Supports

We finished the setup yesterday and I put about 20 miles on the gears. The AAM gears are dead silent! There's a reason GM uses them for OEM parts. Finally I have a rear end setup that works!

We noticed during setup of the AAM gears that they have a much larger tooth contact pattern than the Richmond gears, and were wondering if the relatively small contact pattern on the Richmond's contribute to their noise.

[camaro1]

yes the small contact area makes the setup more critical than factory cut gears

[Petersimov]

can u pm me the cost for this setup

[NinoSS]

I want these gears and a cam...

[StreetStrip]

Originally Posted by Petersimov

can u pm me the cost for this setup

I bought the gears and setup kit from Lingenfelter for a ridiculous price of $1K. The LPW cover was $250 and the posi mod was $185 from JRE. Gear oil and LS additive was another $30 for a grand total of $1,465

I did the install myself; as a mechanical engineer I told myself my degree wasn't worth the paper it's printed on if I couldn't learn to setup a ring and pinion. You could probably get the gears installed for $400-$500.

[StreetStrip]

Originally Posted by Ovenmitt

Anyone who carries American axle can get you those 3.91s. My local ring+pinion sells them, and they're over $150 cheaper then the lingenfelter price, plus you don't need to buy an install kit since any reputable shop will just use the individual pieces they need to install the gears. Just saying it pays to shop around sometimes. It's not like this is a lingenfelter exclusive gear.

That's right, and something I should have done.

[RUMBLBE]

Can someone provide a contact for these gears outside of Lingenfelter? I have been calling all of the AAM suppliers on the east coast and they are unable to help.

[camaro1]

Originally Posted by RUMBLBE

Can someone provide a contact for these gears outside of Lingenfelter? I have been calling all of the AAM suppliers on the east coast and they are unable to help.

ya, i tried also to get a set of the aam 3.70's,, i called and e-mailed several large aam dealers and none of them could get the aam camaro gears,,,

lingenfelter must have some type of deal with aam,, aam is not giving them to thier standard dealers

any pics of your aam contact pattern?

[2010victoryred]

last time i checked you can get the 3.70s from rpm transmission you could either get the gears themselves or they sell an assembled differential which when all said and done would probably cost around the same unless you could do it yourself me personally id rather bolt on and go because i dont know of any shops in my area that do this besides maybe the dealer and im definately not going to them

[camaro1]

Originally Posted by 2010victoryred

last time i checked you can get the 3.70s from rpm transmission you could either get the gears themselves or they sell an assembled differential which when all said and done would probably cost around the same unless you could do it yourself me personally id rather bolt on and go because i dont know of any shops in my area that do this besides maybe the dealer and im definately not going to them

i think rpm gets them from lingenfelter, none of the actuall aam gear dealers can get them, at least they couldnt when i was checking.

[jrh@lpe]

I can understand the possible frustration with the cost of these differential gears compared to what you may be accustom to paying for other gears but these are a low volume product that we have made by a high volume manufacturer to OEM component standards. AAM puts these through all the same QC checks they do the OEM gears. No other vehicle applications use this gear set so we can't spread the cost across many years of production and many potential customers. As you can probably imagine when having small volumes of parts produced by a company used to making 10,000 or 100,000 of parts, the setup costs are a significant percentage of the cost when you are working in low volume products. What we in the aftermarket consider to be production volumes are prototype volume levels for a company like AAM. We try to get them made in large enough batches to help keep these costs under control but that then causes us to have to hold significant inventory and have a lot of money tied up in inventory for a longer period of time.

Our retail and jobber level profit margins on the 3.91 5th Gen Camaro gears are less than our profit margin on the 3.70 gears for the Camaro and most of our other products. We did this to try and keep the retail price down.

We are very pleased to have AAM as a business partner in producing these gear sets for us along with the 9.5" differentials for the Camaro. Not many OEM automotive manufacturers and suppliers are willing to work in these small volumes. Having AAM produce these parts for us has allowed us to provide 5th Gen Camaro owners with a product of a level of quality that would not exist otherwise.

Originally Posted by RUMBLBE

Can someone provide a contact for these gears outside of Lingenfelter? I have been calling all of the AAM suppliers on the east coast and they are unable to help.

[blazzin1]

While I certainly enjoy paying less for something of equal quality, I am a firm believer in "you get what you pay for". I think it has been proven time and time again that these AAM gears are far superior to the "other" brand out there. I have absolutely no problem paying for a quality product. My only problem.....I want 4.33's in my M6!!! I don't plan on ever having 700hp, so I want all the gear that I can reasonably put in my car. Hey LPE, can you talk AAM into making some "bigger" gears?? At least a 4.11?? That seems to be the industry standard for "performance" gears anyway. Any chance of something bigger than 3.91's coming from AAM in the future???

[Badger]

....what he said

[StreetStrip]

Originally Posted by jrh@lpe

I can understand the possible frustration with the cost of these differential gears compared to what you may be accustom to paying for other gears but these are a low volume product that we have made by a high volume manufacturer to OEM component standards. AAM puts these through all the same QC checks they do the OEM gears. No other vehicle applications use this gear set so we can't spread the cost across many years of production and many potential customers. As you can probably imagine when having small volumes of parts produced by a company used to making 10,000 or 100,000 of parts, the setup costs are a significant percentage of the cost when you are working in low volume products. What we in the aftermarket consider to be production volumes are prototype volume levels for a company like AAM. We try to get them made in large enough batches to help keep these costs under control but that then causes us to have to hold significant inventory and have a lot of money tied up in inventory for a longer period of time.

Our retail and jobber level profit margins on the 3.91 5th Gen Camaro gears are less than our profit margin on the 3.70 gears for the Camaro and most of our other products. We did this to try and keep the retail price down.

We are very pleased to have AAM as a business partner in producing these gear sets for us along with the 9.5" differentials for the Camaro. Not many OEM automotive manufacturers and suppliers are willing to work in these small volumes. Having AAM produce these parts for us has allowed us to provide 5th Gen Camaro owners with a product of a level of quality that would not exist otherwise.

Thanks for taking the time to explain! The pricing makes sense now; I must say that after having the gears for a little while I would have paid even more for them. I was at my wits end trying to resolve the gear whine issue.

Thanks for bringing those gears to market!

[SilverSS3108]

I'm on the fence on these 2 set ups (4:11 & 3:91)and since noise doesn't bother me I'm curious as to how much time each of these will knock off at the track and what kinda milage loss I can expect with each... Oh and I have an A6 with all the normal bolt ons... Big cam, 150hp shot and 3200 stall converter coming in the next year or so.

[marticus24]

Bump... I too am curious if there is a big difference between going with the 3.91 ratio vs the 4.11

[Nvincent4708]

Originally Posted by marticus24

Bump... I too am curious if there is a big difference between going with the 3.91 ratio vs the 4.11

I know in the C5 Vettes 3.91 was more desired than 4.11.

I think that with a 6 speed 3.91 should be the perfect gear. with the 4.11 i think 1st would be practically useless in most racing due to how short you would be in first.

just my opinion, no flaming please

[BlackRS/SS]

I just put the 3.91s in two weeks ago and I think these are the gears that should have come stock with the M6. They are great

[Tshepp]

Originally Posted by marticus24

Bump... I too am curious if there is a big difference between going with the 3.91 ratio vs the 4.11

Debating this as well...I want to do gears on my cammed SS and wondering how big of a difference there is between these two setups. Do you guys think there is a noticeable change with gears as well? I have heard both sides that it can increase or decrease mpg...Hoping it doesnt decrease too much since my new cam/tune already dropped significantly.

[LBV]

I'd love to know if these 3.91 gears would fit my GXP ... stock my car comes with 3.70.

[camaro1]

the g8 rear is smaller than the camaro, even the gxp diff

[mike25]

i plan to do these..how is the gas mileage etc with these and how does it change seat o the pants/ ride quality etc?

[puertoricanfont]

I still can't decide if I want the 3.73 or 3.91 for my v6. And I don't care about gas mileage just the better of the two for v6 application . We v6ers def need more get up and go.

[ipimpthisc]

so if u dont care then go 4.27 4.44 or even 5.13..I had a 5.13 in a rotary powered..my et went done .8 secs...thats a big margin but i was high in the cruising range on the highway.

[summitss/rsls3]

4.11 in our cars will be a better gear than 3.91 mainly because of the tall 20 in tires we run.