Another Front Differential Bites The Dust

[Maintcon]

Well we got the new front differential installed last night. 3 hours flat, just rolled the truck up on 4X4’s pulled the original and installed the rebuilt 2000. You can do this WITHOUT dropping the steering arm or tie rods, just remember to turn the wheels fully left.

 

If you look at picture 14 and 15, the 2005 unit is positioned next to the replacement. I left the long axle installed during removal so that I wouldn’t be fighting gear oil running down my arm at the same time as wrestling the gearbox out of the truck.

 

Picture 16 is the ‘hole’ under the truck where the front differential resides. During installation, I installed just the center section 1st and then installed the long axle. It made it a lot easier to ‘bench press’ the unit back into the mounts with just 2 ends to aim and worry about the 3rd leg later.

 

Pictures 17, 18 and 19 are the best, they show what ‘usta-be’ a carrier bearing. What’s interesting is that the rollers are on the WRONG side of the carrier adjusting nut. The ‘goo’ you see surrounding the bearing pieces is the consistency of past; a ground metal gear oil past. There won’t be much salvageable I’m afraid. I’ll take pictures and re-post once I get the thing apart so all can admire the carnage.

 

Also from pictures 18 and 19 you will note that there is no roller bearing installed in the carrier nut. On the 4WD units, there is a small roller bearing installed in BOTH carrier adjusting nuts to support the stub axles. On the AWD units, the long axle is supported by the spider side gear and the bearing at the end of the long axle housing. If you do install a roller bearing here it wont be supporting anything because the long axle is ‘undercut’ (smaller diameter) just past the splines. So the last difference between the 4WD and AWD differentials is revealed; no carrier adjusting nut roller bearing on the long axle side.

 

The best part; when I road tested the rig – NO NOISE, quite as morgue. Hopefully it will stay that way. We’ll change the oil at 500 and 1000 and hope for the best after that.

 

As far as dollar savings by doing this yourself; in the $1200 dollar range based on $2000 for a dealer or transmission shop completing the work or, about $300 to $500 if you were to buy a rebuilt unit and install it yourself.

 

Link to Pictures; http://picasaweb.google.com/102438165407566385617/SSDifferential#

Edited December 28, 2010 by Maintcon (see edit history)

[misterp]

Sounds like a job very well done!

 

So let's recap - you took a front diff from a 2000 4x4 truck, rebuilt it, and used the passenger-side axle tube & axle from the SS, right? Did you choose the 2000 4x4 diff because it was stronger, or because it has better internal axle & carrier support on the passenger side?? Apologies for the newbie Q's, I've not dove into differentials before...

 

Mr. P.

[Maintcon]

I chose the 2000 4WD unit because it was AVAILABLE; e.g. a matter of convenience. With the exception of the spider gear ‘C’ ring groove and the lack of a carrier adjusting nut roller bearing on the right side (long axle side), the center section of 1998 through 2006 AWD and 4WD front differentials are the same.

 

For me, rebuilding the bone yard unit was easier than removing the one in the SS, hoping major components like aluminum housing and carrier were O.K. or repairable, disassembly, ordering parts, waiting on delivery and hopefully getting it back together and out of my garage in a short period.

 

With a rebuilt unit I could work on it at MY convenience and still have the SS at least semi drivable.

 

Also, I plan on rebuilding the original differential and keeping it around; “just in case”.

[misterp]

I hear you on that one, I have a front axle from an '04 SSS in my truck now and my original in the corner of the garage (it was making noise). The '04 unit is now whining, the colder it is the more gear whine it's making. I'm pretty sure that's a sign I need to overhaul my original axle and R&R it again. 'Funny' thing is that on both units they leak/drip gear lube at the pinion seal, not enough to mark the driveway but still I have always suspected the condition of the pinion bearings.

 

A far-out question - in your research have you heard of anyone running a TruTrac in the front diff?

 

Mr. P.

[Bear]

A far-out question - in your research have you heard of anyone running a TruTrac in the front diff?

 

Mr. P.

 

Unfortunately there are no solutions for a locking differential for the 8.25" axles. The aftermarket has deemed them too weak to handle one. It's funny that they offered for the 7.25" in the smaller trucks and they are offered for the 9.25" in the 3/4 and 1 Ton's, but notta for us. There has been a few people that have swapped to the larger 9.25" units in 4WD's, but it's far from a bolt-in and would require a decent amount of fabrication to mount one, but it is possible.

[Maintcon]

Agree with Bear, there aint nothin out there as far as a Tru-Trac or a Friction Plate Posi for these units. However, I did find that Richmond Gear has a product called a PowerTrax. It replaces the spider gear assembly and acts as a locker of some sort. I think (but not positive) the spiders for the 8.25 IFS are the same as the standard 8.5 10 bolt rear diffs.

 

I do not think or would I ever suggest you install something like this in the front of anything that drives on pavement and has to negotiate a turn. Even on the drag strip, making only minor correction to keep it straight, I think it may be unstable. It would PUSH like bulldozer; e.g. keep going straight, lots and lots of under-steer. These trucks already have a tremendous amount of PUSH dialed in by the GM designers. It keeps the unknowing from falling off freeway entrance ramps, ass end first.

 

A REAL locker in the back (manually engaged air or electric) and in general, friction plate posis, would do the same thing, keep the truck from turning. Although going straight, more power to the ground. A progressive locker, AKA Tru-Trac, AKA Torsen Differential may actually improve handling a bit by shifting torque to the OUTSIDE rear wheel (when the inside lifts in a turn) and help steer you into the turn. Just ask any of the left hander circle track boys what they think of Gold Trac diffs. Theyre just an expensive version of the Eaton Tru-Trac.

 

Thats my 2 cents anyway.

Edited December 30, 2010 by Maintcon (see edit history)

[Black04SSS]

Great write up! I think you have me convinced to try this myself... Mine is making more and more noise and I desire to keep the down time to a minimum as well.

 

Would it be too much trouble to ask you to make a list of what parts need to be switched if one gets a 4x4 center section, where you got it, and an approximate cost for each part?

 

EDIT: Also, do you remember what the measure of the pinion depth shim(s) you ended up going with was in the end? I am just thinking it would save time to start with that one to see how it looks. I do have some experience in setting up ring and pinions (only done one IFS GM one though - and that was 13 years ago in school...lol) so I know they are never identical from one to another, but they also aren't usually terribly far off if the application and manufacturer of the parts are the same.

 

Thanks!

Edited July 15, 2011 by Black04SSS (see edit history)

[iregret]

I still don't quite understand why you can't just put the long axle and tube on the 4x4 differential. Would it work if it were a later front end? I know it didn't work on yours because your 4x4 front end was from a year 2000 truck.

[dendrizzi]

I know this thread is a little old, but it is a great write up Mainton! My 2003 SS is whining pretty and I was wondering if I could grab a 2001 or newer 4x4 diff and switch out the long axle and tube with my AWD unit in my truck. Is that tube/axle the only difference in the diffs 4x4 and AWD diffs?