8.25 IFS swap for 9.75 or regear?

[Offroad Tahoe]

I am wondering if anyone has seen a swap for the 9.75 IFS to upgrade from the 8.25 or should I just go ahead and regear my front to match my 4.56? sorry if it has been discussed before I am new here. My 2012 Tahoe is sitting on 35's with a 7.5" lift and just had the rear end fully rebuilt with new axles, bearings, eaton posi, and 4.56 gearing. I would love to just swap in a front end that already has the 4.56 but haven't found one yet. I also have been trying to research what front ends i can go to for a little more durability. any assistance is greatly appreciated.

 

[rdezs]

I think your best bet is the 9.25 front axle assembly. It's the same found in the GMC 2500 and up pickups, and all Hummer H2's. I don't think there's any OEM 4.56 ratio that were delivered.... But many were shipped as 4.11. I know they can be re-geared for a 4.56.

It would require some custom work, shortened axles with CV joints; probably a shortened bolt in crossmember that's underneath the back of your engine. The 2500 and the H2S have a mount point in that crossmember. The front driver side mount may be the same as your current set up, but may also need to be relocated. The passenger mount appears the same, it may or may not need to be relocated left or right.

No problem clearing the LS motor. It is substantially heavier than the 8.25 you currently have. I raise and lower them strapped down to a transmission jack... It's one that you definirisk don't want to risk dropping. It's about 33% heavier than the 8.25 in.

 

[Charlie207]

The factory 1500 8.25" front differential is about 95lbs wet.

 

[rdezs]

I'm thinking the 9.25 is somewhere around 150 to 170 lb? But it sure feels heavier when you're wrestling it around!

 

[Offroad Tahoe]

I think your best bet is the 9.25 front axle assembly. It's the same found in the GMC 2500 and up pickups, and all Hummer H2's. I don't think there's any OEM 4.56 ratio that were delivered.... But many were shipped as 4.11. I know they can be re-geared for a 4.56.

It would require some custom work, shortened axles with CV joints; probably a shortened bolt in crossmember that's underneath the back of your engine. The 2500 and the H2S have a mount point in that crossmember. The front driver side mount may be the same as your current set up, but may also need to be relocated. The passenger mount appears the same, it may or may not need to be relocated left or right.

No problem clearing the LS motor. It is substantially heavier than the 8.25 you currently have. I raise and lower them strapped down to a transmission jack... It's one that you definirisk don't want to risk dropping. It's about 33% heavier than the 8.25 in.

Wasn’t there some of the avalanche and suburban models that came with a 9.25 front for the gmt900 models?

 

[strutaeng]

Yeah, probably the 9.25 IFS. It's what came on anything 8 lug...so 2500/2500HD/3500 truck or 2500 SUV GMT800. I believe it was unchanged in the GMT900 8 lug, at least until they changed the 8 lug nut pattern (?)

How would you keep the 6 lug to match the rear though? Adapters? If the IFS 9.25 involves any moderate fabrication, why not look into a "SAS" swap? That gets dicey though with all the wheel speed sensors and stuff, tho... IDK

Maybe the GM 9.25" IFS IS the "better"/, most economical swap?

What is your truck duties? Daily driver and off-road rig? Or dedicated off-road rig?

 

[Offroad Tahoe]

It’s a daily driver and off-roader I’ve been piecing it together but just had the rear end fully rebuilt after bending the housing. And now it’s time to re gear the front but have been having a horrible time finding the right ring and pinion kit for a GM 8.25 09+ and have been looking into a beefier front because the foam is for it to be a full time off roader eventually. As for the 8 lug to six lug I’ve been looking into custom end shafts of the CVs to get the proper spline count for the 6 lug hubs.