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11.5" AAM Rear end fitment

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Lonnie P

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Are any of these newer rears compatible with the 73-87 chassis. I havent had any luck finding the perch & overall width of these. Apparently there are cab & chassis rears that are narrower.

Any ideas?

Thanks in advance.
Lonnie
 
With the inexpensive cost of a 14B FF, why would you even consider going this route?:confused:
 
hardly any choices for diff swaping of gears and traction devices yet. get the 14ff. and if you want wider go van 14ff its the widest. c&c is the narrowest.
 
While the 14bolt is relatively strong, the modified Duramax conversion I am doing will put out roughly twice the torque of the built 427 big block that I am removing.

I already have a few 14B rears, but it would be very convenient to drop in a larger latemodel takeout rear with low miles if it actually fit correctly.

Anyone have dimensions of the various 11.5" models?
 
No deminsions, but my friend has an 01 Silverado HD with the 8.1 liter and the AAM rear. I have the same truck with the 6.0 and the 14bolt. So logic would assume it has the same spring perch spacing as the 14 bolt, which is different from the earlier trucks.
 
the 11.5 is a beast of a rear axle, i actually worked on the assembly line for a few days making them as my intro the the AAM plant that i worked at for the summer, there are a few different tube configurations for them, you have your wide trac and narrow track single wheel and you have a narrow and wide track dually. so there are 4 different widths, as for the spring perches i do not know if the 2500 and 3500 still use a different width but the 11.5 is going to have the same perch width as a newer 14 bolt. For gearing you have the same options as the normal 14 bolt except the 5.38's, you can get a locker from a dodge with the 11.5 which is a lot better than the Eaton that the chevy axles use
 
Well, I found a pickup to measure. Give or take a 1/4", the width is 68-1/2" (to mounting face of rotor) & the perches are 48-7/8" apart ... it's definitely wide.

I would like to get the measurements on a narrow single rear wheel application. I'm told the chassis cabs had the narrower frame & axle widths. Hopefully someone can confirm.

The Dodges may also be an alternative.

I got my Duramax driveline wired up & running on the garage floor today & I have a bare painted 3/4 ton '74 frame sitting next to it.

I'm worried about the torque output of this motor. With mods, it should put out around 500rwhp & 900rwtq.

I've broken 14 bolts (broke the front bearing carrier out of the center section) dragracing before with a lot less torque.

I'll need to make a decision on the rearend soon.

Lonnie
 
One thing to consider about choosing a rear axle application is that GM ( or who ever ) decided on how much beef was needed they had a service factor built into the equation. The application was to endure HEAVY towing duties along with high miliage service life without fatigue. The smaller FF rear axles just might suit your needs even with real high torque numbers because most likely you won't be at full load and full torque output at the same time.
I am all for having extra beef for durability but just wanted to point out that sometimes our applications don't see the same stress that real world towing application do for the same time frame. Food for thought when you decide on what to get .....

HTH's Tom
 
I've already broken 14FF's with less power, that is why I'm nervous. Overkill the first time is often cheaper than buying parts, fixing, buying parts again.

If I can do it once for a reasonable amount & be relatively sure it is reliable, it may be worth the effort.

Lonnie
 
Lonnie P said:
I've already broken 14FF's with less power, that is why I'm nervous.

Lonnie
Click to expand...


Than by all means go for the axle beef !
Have Ya' thought about a Dana 80 model rear axle ? I am not sure of the "chunk" drop but it seems to be less than the AAM 11.5" axle.
The D80 comes in at 11.25" and is stout as can be and a lot more common in the bone yards used than the AAM big stuff.

Tom
 
No good pictures yet. Still a lot of loose parts, but I'll post some once I get further along.

The frame is done & the cab is being painted next week. I have to start building engine & trans mounts next.

Lonnie
 
I'd like to hear how it turns out. I've got the AAM axle under my '03 2500HD Sierra (8.1 w/6spd manual) and really like it. I'm planning on putting one under my '89 Blazer.

Good luck.
 
Well, if you are putting one under your Blazer, then we need the same one. I'll share any info I find.

Lonnie
 
Check car-part.com for one in your area. I have seen them for as cheap as $800-900 near here. I wanted to swap in a newer 14 bolt 10.5" to my 97, but the 11.5" 14 bolts are cheaper.

Question for those with trucks with the 11.5". Could you measure your U joints? For some reason 6 speed manual 11.5" rears are different then those from Allison autos, and I think it may be the size of the U joints. Please let me know if anyone knows the answer.
 
jac6695 said:
Check car-part.com for one in your area. I have seen them for as cheap as $800-900 near here. I wanted to swap in a newer 14 bolt 10.5" to my 97, but the 11.5" 14 bolts are cheaper.

Question for those with trucks with the 11.5". Could you measure your U joints? For some reason 6 speed manual 11.5" rears are different then those from Allison autos, and I think it may be the size of the U joints. Please let me know if anyone knows the answer.
Click to expand...

theres are only two sizes of ujoints used on the GM 11.5, one is the 1410 and the other was the 1480, no the nice thing is that the pinnion yolk on the 11.5 is the same as the 14 bolt ff, and if you do not like the pinnion yolk you can get a flange from a Dodge 10.5 or 11.5 and it is the same also
 
That is what I thought. Sort of makes sense that the manul trans trucks would get the 1480, and auto's get the 1410.

Same yoke though? Thats good. I'll just slap a 1350 in there for little wimpy diesel. Thanks.
 
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