11.50 Rear Axle? What is this?

[buggz]

Hello,
My window sticker is showing a 11.50 Rear Axle listing.
What is that?
I don't think it's a 4.11 misprint, as driving it doesn't feel like it revs up fast.

[jbarker]

That is the diameter of the ring gear and also how they refer to the type of rear end in the truck the gear ratio should also be listed on the sticker or in the glove box if they are still putting decals there

[Nitrous340]

Do they mean the AAM 11.5? Its prob your rear axle model, like ours have a dana 70, the newer trucks got a AAM (american axle manufacturers). I would think you most likely have 3.73 or 3.55 gears.

[runnin on empty]

mine doesn't say on my window paper and nothin in the glove box...i'm not really even sure what it is....any ideas?

[Rollin Coal]

it is an AAM axle. thats the same company that makes rockwells. the axles they make for dodge are they smallest axles they make

[buggz]

This pdf shows only a choice of 4.10 or 3.73
I'm thinking I have the 3.73, 'cause, I have a '69 RS/SS Camaro w/ 4.11, and know how that feels.
http://www.turbodieselregister.com/0...ifications.pdf

[Drew]

11.5 refers to the ring gear size. . .and for your auto you have a choice of two axel gears. if you cannot find the axel ratio on your build sheet, most likely you have 3.73's. 4.10's usualy carry a slight charge.

another way to tell what gearing you have is look and see how fast you are going with the engine turning 2K on the interstate. with the 48re tranny I believe 2K RPM equals around 70-75, 4.10's will get you around 65.

[antwan718]

Originally Posted by Drew

11.5 refers to the ring gear size. . .and for your auto you have a choice of two axel gears. if you cannot find the axel ratio on your build sheet, most likely you have 3.73's. 4.10's usualy carry a slight charge.

another way to tell what gearing you have is look and see how fast you are going with the engine turning 2K on the interstate. with the 48re tranny I believe 2K RPM equals around 70-75, 4.10's will get you around 65.

on 3.73 gears
1700=60 MPH
2000=72 MPH

Sweet spots for fuel econ are 64 & 69 they keep the turbo from spooling up

[hollingass]

i can concur the 69mph sweet spot, never tried the 64, i recently switched to 35" rubber, and recalibrated my speedo with my smarty, havnt figured the exact sweet spots yet.

[antwan718]

Originally Posted by hollingass

i can concur the 69mph sweet spot, never tried the 64, i recently switched to 35" rubber, and recalibrated my speedo with my smarty, havnt figured the exact sweet spots yet.

if you have a boost gauge look for when your pressure starts to dramatically increase while in OD. Back the throttle down from there. If you don't have a boost gauge listen for the turbo whistle, try and get the RPMs as high as possible without much audible whistle and that's the sweet spot.

[AH64ID]

Originally Posted by runnin on empty

mine doesn't say on my window paper and nothin in the glove box...i'm not really even sure what it is....any ideas?

AAM 11.5.. all HO's have the 11.5.. And only a few SO's had the 10.5.