AAM 9.25" IFS Differential

AssBurns

Member
I am looking to use an AAM 9.25" IFS differential out of the GM HD, 3/4 and 1 ton 4wd trucks for an IFS rock crawler/pre-runner build and I am looking to see if anyone had a CAD file for this differential that they would be willing to share. I've know some of the pro4 trucks use these diffs, and figured someone here might have a CAD file they would be willing to share to help me with my build.

Thanks!

Pic found from google
1570676505447.png
 

AssBurns

Member
Another question that I had. I need to narrow the diff as much as realistically possible to fit in my chassis constraints, so the ADD system needs to be eliminated, and the passenger shaft and ADD tube need to be shortened to whatever length I end up needing. What would be the best way to go about this? I am assuming the guys building the Pro4 trucks are doing something to narrow this diff quite a bit. Does anyone have any insight or pics on what they did?
 

michael.gonzalez

Well-Known Member
Have you looked into the IRS differential from a 2003+ expedition.

It's a 9.75" ring gear and doesn't have the long tube side.
 

partybarge_pilot

Well-Known Member
There was a thread a while back on how to narrow them. A little machining and a little welding is required. Then run the same short stub on both sides. I have done the same thing on an 8.8 diff, not sure if it's easier or harder on the AAM diff.
 

partybarge_pilot

Well-Known Member
There was a thread a while back on how to narrow them. A little machining and a little welding is required. Then run the same short stub on both sides. I have done the same thing on an 8.8 diff, not sure if it's easier or harder on the AAM diff. With the removable sidecover, I would think the AAM would be easier to machine.
 

AssBurns

Member
@michael.gonzalez I haven't really looked into the 9.75" IRS diff yet. Only things that I can see as a negative are it's a low pinion diff and standard cut gears, so it'll be riding on the coast side of the gears. Not the end of the world, but it does lose a little bit of strength there. And the gear ratios only go to 5.13. Not a huge issue, but I was hoping for 5.38 gears which the AAM 9.25" offers. Pair those together, and it makes the 9.25" a little more attractive. Another thing to consider, is I'll still most likely have the axle offset, to clear the oil pan, so I'd just be narrowing the ADD tube a lot, not necessarily eliminating it. Not 100% on this yet though. Since the diff is so much bigger than the stock 7.5" diff, it'll be sitting quite a bit lower than the stock diff, which might give it just enough room for the driveshaft to clear the oil pan. If that happens, then I might just be able to center it and have even better suspension geometry. I got some things to really think about now. Thanks for the idea! Now that leads to another diff I need to either buy for measurement purposes, or find the CAD file for it.
If anyone has the CAD file for the Ford 9.75" IRS diff, please let me know.

@partybarge_pilot I'll have to find that thread. Thanks! If you have the link, can you share it here?
 

partybarge_pilot

Well-Known Member

 
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