Well front diff bad news I think

[05Mudiak]

Our 08 alpha front end started grinding. I drained the front diff and lots of metal shavings. I'm guessing pinion bearing?How difficult is it to rebuild? There's gotta be a you tube video maybe?

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[rsc]

I haven't got a clue, repairing the front diff for me means tossing this aluminum one for the steel front diff with lockers.

 

[4speedfunk]

They're not too tough...same as any other Corp GM diff (but much smaller). You'll need all the normal set-up tools. I have some brass drifts I made that fit the races so I can knock new ones into the pumpkin. I also have an inner pinion set-up bearing that has an oversized ID that allows me play with pinion depth shims without pressing a new bearing on & off several times. Both a good idea if you want to do it right (with minimal cussing).

Shavings probably mean new carrier bearings and ring & pinion too.

 

[4speedfunk]

Or just cut off the IFS and go solid!

 

[05Mudiak]

Definitely want to go solid, but probably heading to Afghan in a couple months so the timing is bad, just want to get it back drivable for the wife while I'm gone

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[Highatop]

Or just cut off the IFS and go solid!

Funny, I knew that would be part of your reply...Upgraded gears, would be the way to go. Good luck

 

[SuperBuickGuy]

you're going to price gears, locker, and a rebuild kit and say "oh, for a few hundred more I could go solid"

I cut a lot of corners by calling in favors but I was still a cheeseburger away from $2000 when I rebuilt mine

I haven't got a clue, repairing the front diff for me means tossing this aluminum one for the steel front diff with lockers.

it's an Alpha, it already has a cast iron differential.... which also means cheap e-locker "while you're at it"

 

[rsc]

you're going to price gears, locker, and a rebuild kit and say "oh, for a few hundred more I could go solid"

I cut a lot of corners by calling in favors but I was still a cheeseburger away from $2000 when I rebuilt mine



it's an Alpha, it already has a cast iron differential.... which also means cheap e-locker "while you're at it"

IIRC, Alpha's were from 2008-2010, but the cast iron front diff was installed in 2009 and 2010 models when the front lockers became available. Maybe I'm wrong, but not all Alpha's had a cast iron front diff, right?

 

[SuperBuickGuy]

cast iron was in all alphas, and all h3s in 2009

my 2008 Alpha is an early 2008 (sold Sept 2007) and has a cast iron front differential

 

[05Mudiak]

yep all alpha has iron diffs.

Ugh I'm dreading pulling this this to see how expensive it's going to be. Hopefully I can just get away with a rebuild kit. I hope, because when I return I am planning axle swap, possibly depending how everything goes.

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[SuperBuickGuy]

the cost will depend on whether or not you can save the gears. Believe it or not, the bearings, seals, even getting it rebuilt isn't that terribly expensive... especially if you remove the center section yourself and take it to the differential shop. I'll have to look up receipts, but I think the bearings and seal kit was less than $200.00 from Yukon gear. A word of warning, though, their instructions have the wrong torque spec for the bearing caps - it's way high.

 

[SuperBuickGuy]

Here's some reading material
http://www.hummer4x4offroad.com/forum/showthread.php?5816-Search-and-Rescue-H3-Alpha-build/page11

It starts on page 10 on post 144 then goes on for several pages with commercial breaks for other crap that happened.

 

[4speedfunk]

A word of warning, though, their instructions have the wrong torque spec for the bearing caps - it's way high.

True! The H3 front axle gearset is robbed from a earlier, full-width, rear axle. Most of the rotating parts are the same, including the ring & pinion but, the IFS housing is much more "dainty" than the full-width rear-drive version. My guess is that Yukon robbed the torque specs from the original rear 7.625, not realizing there are different torque specs for the IFS housing. So don't try to torque the AAM-7.625 IFS main caps to 65 ft/lbs. (especially on the alum. version). Many axle guys have little experience the IFS version (or even know it exists)...so make sure you are using IFS info and not the 70s-80s rear axle info.

This same gearset (and differential) was installed in many 70s-80s era rear axles (Malibus, Camaros, S-10s, etc.)....so you can get gears, bearings, and diff parts from almost anywhere. But there are some items special to the IFS version, and a lot guys have a hard time finding them. You can get the gearset from any source...Yukon, USA-Gear, Richmond etc. But NOTE: Most aftermarket gearsets will be 5-cut and they require more lash than the factory 2-cut. Make sure your set-up guy is aware of this. If he sets the backlash from the GM manual, using aftermarket gears...it will be too tight. To my knowledge...GM (AAM) is the only source that is making 2-cut gearsets for the 7.625.

I have found the best source for IFS parts is directly from AAM. They offer several sub-assembly "kits" for whatever part of the differential you need to repair. Fantastic quality....much nicer than Yukon.

http://www.demandaam.com/axle-results?vm=GM&q=7.6"+IFS+-+Front+Axle