Another Front Differential Bites The Dust

[Maintcon]

This last Thursday, heard a couple of 'Clunks' from the front end and then, the god awful 'Gear Wine' of unsupported ring and pinions. Yep, the '05 has succumbed to the GM anti quality gear demons. Only 54,000 miles.

 

Friday, got me a used front differential center section from the local bone yard (2000 Chevy PU), ordered a Timken Bearing Master Kit and a new set of 4:10 gears and like they said about the bionic man, I'll Make It Better!!!!

 

Will repost as the rebuild progresses.

 

P.S. - The folks at 'Drivetrain.com' are the best. They have the info you'll need to rebuild or replace the POS AAM gearbox that Chevy installed in out trucks.

 

Timken Master Bearing Kit P/N: MTR8.2RIFSLMKT

Ring and Pinion P/N: GM885411 IFS

[smoothdime]

sounds like you got it all planned out. let us know how it turns out. good luck. gary

[AK4.8SS]

Haha, love the enthusiasm. Post up pics of the rebuild if you can!

[Maintcon]

So I take the 2000 differential apart, the one I got from the bone yard, and it was vary clean on the inside, very little use. Besides the split axle on the passenger side plus the solenoid, I noted that the spider gear (the ones inside the carrier) on the long axle side had no 'C' clip or even a groove to put one in. This could be a problem because I had thought that the AWD versions needed the 'C' clip to secure the long axle in the diff.

 

What's really odd is that all of the parts manuals and exploded views I have looked for these differentials (AWD and 4WD) show the spider gear sets are the same from 1988 on. Has anyone else converted a 4WD front diff for AWD use that could comment on this??? I can buy a new set of spider gears, but would like to find out if I'm missing something in the meantime.

[Bear]

The axle will need the spring clip.

Here is a link to a write up a fellow wrote doing exactly the same thing your trying to accomplish:

 

 

You can download the AAM parts manual here:

 

 

Here is a parts breakdown from Comp Nine:

 

[Maintcon]

Thanks Bear

 

Yep, The Denali Guy’s found the same issue. Must be that prior to 2001 (first AWD GM Trucks in 2001) they only cut the ‘C’ ring groove in the left (drivers side) spider. What a 'cheap skate' deal, save a few penny's per prodution unit. GM needs to separate from AAM, maybe impove their quality issues. I will be ordering a new set of spider gears Monday.

 

Drive Train Specialists had the best price at $114. Their P/N: AAM 74045936. Most other pricing ranges from $185 to $250 plus.

 

Last Note: the AAM Parts catalog you directed me to is one I posted a year ago.

[Bear]

Last Note: the AAM Parts catalog you directed me to is one I posted a year ago.

 

I know the whole ordeal isn't, but that's too funny.

[Maintcon]

It is pretty funny. I've been listening to front of this truck growl, howl and wine for about 2 years now. Been collecting info on the front diff and transfer cases for a while not knowing exactly when or where the thing would finally grenade. I had it pretty much planned out what I wanted to do, e.g. rebuild a used 4WD unit. However, did not expect the spider gear ‘C’ ring issue. Now everyone is informed, if you’re going to convert and early 2001 or older 4WD differential to AWD, you’ll need to order a set of spider gears that have grooves for the ‘C’ ring. Also, verified that the AAM 74045936 P/N for the spider’s is correct (‘C’ ring grooves).

 

I had gone through the transfer case on my 05 this last summer. At the factory, an improperly installed front drive shaft seal allowed water it into that lower bearing causing it really make some noise. Replaced both lower bearings on the front drive shaft output shaft and replaced the drive chain, just because.

 

Next year I plan on rebuilding the front diff I’m pulling out of the SS and keep it around as a spare or maybe changing to 3:73 gears. If I went to 3:73 gears, this would give me an excuse to tear down that crappy G80 in the back and installing a Detroit Tru-Trac (also by Eaton). The Tru-Trac would cure a good part of that god awful push that’s dialed into most trucks and made worse by cheap ‘friction’ posi’s.

 

The only reason for the 3:73 gears would be a bit better economy.

 

Gotta’ love the SS; most other vehicles would have been traded by now if they gave me this much headache.

[Maintcon]

Just a quick update on the progress of my 4WD to AWD front diff conversion. Got all of the parts except the new spider gear set. Should be here early next week. Besides the parts listed in previous posts, I also ordered and received a carrier adjusting nut spanner. Got it from Seven Springs Customs for $49.95; P/N YTA08. Also, once I had looked through the Master Bearing Kit from drivetrain.com noted that the carrier adjusting nut lock tabs and the axle C rings were not included. I picked these up at the local Chevy dealer. GM Part numbers are 15588312 for the lock tabs and 26056600 for the C rings.

 

I finally got the 2000 diff fully disassembled and learned a new lesson and that is; another oddity on these front GM diffs that any of you would be builders should note is that the ring gear bolts are LEFT HANDED threads.

 

I kinda found this out the hard way. To remove the carrier and front pinion bearing, I took the parts to a friend of mine who is the shop manager of a local electric motor rewind shop; they have a pretty good size arbor press. To get the carrier to fit on the press we had to remove the ring gear.

 

So we chuck up a ¾ inch impact gun and commence rattling off the bolts. We stripped the threads on all 10 bolts. Once we smacked off the old ring gear and pressed off the bearings I took the whole mess home. Once at the house, I was messing with the new ring gear and ring gear bolts (that came with the bearing kit) and after a couple of trys of righty tighty and no thread engagement, I tried a quick turn to the left and the bolt started to suck itself into the ring gear. Wah La, solved the stripped bolt mystery!!! Left handed threads.

 

Ill take a few snap shots of the 2000 differential as its assembled and I update the posting.

Edited December 18, 2010 by Maintcon (see edit history)

[misterp]

...So we chuck up a ¾ inch impact gun and commence rattling off the bolts...

More Power!!! Ruhh Ruhh Ruhhh

 

I'll have to admit I've been guilty of that move a couple times myself :doh:

 

Mr. P.

[Maintcon]

Over this last weekend, finished tearing down the bone yard 4WD diff. The only parts I’ll be using from the 4WD unit are the carrier adjusting nuts/sleeves, the carrier, the aluminum housing, the drive shaft yoke, the pinion shim and the left side stub axle. All other parts will be new.

 

Another pointer on disassembly, besides the left handed ring gear bolts; the carrier adjusting nuts are screwed into sleeves pressed into the side of the aluminum housing and one would assume removal would involve bending the lock tabs out of the way and unscrewing the nuts. Not so, just ‘knock’ them through from the outside in; the sleeves are not pressed in all that tightly.

 

From the pictures, you will note that my new pinion shaft is sitting next to my holiday Cinnabons (picture 2). The carrier is sitting under the Cinnabons. Freezing the shaft and the carrier overnight shrinks them down a bit and after cooking the new bearings at 400°in an old deep fryer (picture 3), the bearings more or less slip right on; in theory anyway. As the brass and the hammer in picture 4 suggest, you still need to get a bit medieval on the unit to ensure the bearings are seated. Picture 4 is the new pinion with the front bearing installed with the shim from the 4WD unit. Picture 5 shows the pinion installed ‘without’ the crush sleeve for the initial backlash and pinion depth adjustment.

 

To see the pictures, click on the following link;

 

http://picasaweb.google.com/102438165407566385617/SSDifferential#

[Maintcon]

The new spider gears were delivered yesterday and this evening I did an initial assemble of the gearbox just to see where the pinion landed on the ring gear. Remember from the last post that I had reused the shim from the 2000 4WD differential. Well it looks like I need to ADD shims. The reason, the pinion is riding high on the ring gear. If you follow the link to the photos, you will note that the scrub marks on the bluing (yellow goo) are high on both the coast and drive side of the gear tooth.

 

This means pressing off the front pinion bearing and adding shims. Now, just in case I hose up that bearing (remember press off and heat/smack on) I went ahead and bought another Timken cone assembly. This is the roller part of the bearing. Since the cup was never used, a new cone assembly is all that is needed; e.g. cups and cones sold separately. Timken Front Pinion Bearing P/N; M802048 for the cone and M802011 for the cup.

 

Picture 6 shows the Coast side pattern and picture 7 shows the Drive side pattern.

 

http://picasaweb.google.com/102438165407566385617/SSDifferential#

Edited December 22, 2010 by Maintcon (see edit history)

[T-Bag]

MMMMMMM Cinabons

[Maintcon]

Finally, got the beast assembled and ready to swap out. Setting the pinion depth only took THREE tries. Spent Christmas day and the day after fussin with the thing. Anyway if you click on the link below it will take you to a series of pictures. Pictures 8 and 9 show the ring gear pattern from too many shims and picture 10 and 11 show what I consider a good pattern, especially on the drive side. The coast side on the final adjustment is still a bit low but I think shell be O.K.

 

Picture 12 shows how I was pressing the pinions back out of the housing; pretty crude but it gets the job done. I also used this arrangement with a Harbor Freight bearing splitter to get the pinion lower bearing off the several times needed to get the correct shims in place. I had bought the Porta-Power several years back for industrial fan work and Im grateful I kept it around for this challenge.

 

Picture 13 shows the beast fully assembled and ready for installation.

 

A couple of assembly notes;

 

1) The spider gears need to be installed before final installation of the ring gear; the pin that goes through the carrier will not fit with the ring gear installed.

 

2) When adjusting the backlash and setting the final torque on the carrier adjusting nuts, a second set of hands is helpful. It youre by yourself, it will be like wrestling a pig to hold the thing while tightening up the carrier adjusting nuts.

 

3) You will NEED to purchase a spanner tool to tighten the carrier adjusting nuts. Do not believe the guy who says; just knock then around with a screw driver. Im glad I bought one earlier or Id be waiting another week to finish the job.

 

4) A ½ inch electric impact wrench will eventually smack down the pinion nut against the crush sleeve to get the final pre-load on the pinion, itll just take a while.

 

http://picasaweb.google.com/102438165407566385617/SSDifferential#

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

[misterp]

Very cool, thank you for sharing - I will refer to your notes here when I get into mine.

 

Mr. P.