Centermount may be hard to do. Take a look at this build if you haven't
Dualsport Runner. Its difficult because the links are all expired to his photobucket but if you get on photobucket directly
Photobucket you can still see them. He used a centermount MK3 supra diff and had to do a bit of a drop bracket. Not really sure how it compared to the stock area so he may not have lost too much, but thats a small diff in comparison. Got this one off a different thread as a talking point but I would recommend getting onto his photos and checking it out.
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Definitely some inspiration from that build. I never thought about going directly to photobucket to view the pictures. I've never actually seen the actual pics of that build. It's always been the blurred out PB pics in the thread. Thanks for sharing those links man!
The basic idea of what he did vs what I am doing is about the same for the most part. Some of the things that I am going to do a little different from his is:
- 1 ton or equivalent differential. More strength = bigger tires and more HP without going kaboom!
- 1 ton or equivalent hubs. Longer lasting, and overall more strength by having larger axle options (35+ spline).
- 1 ton or equivalent steering box. Better steering capacity, longer life, and more strength.
- I will be pushing the axle forward, so pair that with a low pinion, and a rear sump oil pan, I can potentially have a larger differential with equal or better ground clearance (less of a drop bracket). Pushing it forward will also give me more room for bigger tires and better approach angle.
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I think I figured out that I might as well center mount rather than try to use the AAM 9.25" off to the side. I got a CAD file for the 9.25" yesterday, and after taking measurements and seeing where it can fit, I don't think that diff is the best candidate anymore for the following reasons.
- It's huge! I knew that, but the housing itself is just very large and bulky, especially with it being hi-pinion. The clamshell bolting ring makes the overall height pretty tall (About 11" tall. Stock is roughly 9"), and the bolt ring is offset further to the passenger side whereas our 7.5" is offset to the drivers side. This causes even further interference with the oil sump (whether its front or rear sump). This causes the need to push the entire axle either further to the drivers side or down under the sump. Both of those options suck. Pushing it further to the drivers side means shorter CV's which ends up being shorter control arms. That's a waste. No way i'm doing that. The other option is to go under the sump, but that means I'll have a HUGE drop bracket type lift for the housing to clear everything. I know I'll need to drop the diff a little, but I don't want it to be THAT much. So the AAM 9.25" is probably not a great choice.
- Being high pinion (good for strength, bad for packaging) means I have to push the whole diff down under the trans and engine sump, and if most of the diff is below the pinion, that means that the diff is going to hang WAY lower than I want. Same issue as above, but just another factor as to why. Even if the diff housing was smaller, the high pinion makes it hard to fit a diff up into the bulkhead neatly.
So I have come to the conclusion that I need to go low pinion, and the only two decent candidates for that is the Ford/Sterling 9.75" IRS diff or pay big money for a Ford 9". The 9" would be a better option because of the following reasons:
- Very low pinion means I can tuck the housing up further with the pinion being at almost the lowest point.
- Housing size seems to be smaller (both height and total width)
- Ability to have a 10" ring gear for further strength.
- 3rd pinion bearing means less deflection and more strength.
- HUGE aftermarket support. Probably the most supported differential platform available
The problem is a ford 9" is stupid expensive to get a complete IFS housing and 3rd member. For the moment I am going to pursue the Ford/Sterling 9.75" IRS until I can either afford a 9" or come up with a better option.