Hey, another broken disconnect thread!

[Philberto]

Pending further investigation (tomorrow on what is coincidentally my only day off ), I have come to the conclusion that my 4WD disconnect has blown up. I guess it was finally my turn.

How did I reach this conclusion, you ask?

Well, after coming home about 30 minutes ago, I decided to check front brakes, suspension, and all that jazz due to a grinding noise that I noticed at low speeds from the passenger side wheel.

Here is the initial picture:



All that grease, seems to be coming from the boot right? Wrong!



At least I don't have to worry about getting the CV axle out of the disco assembly. Here's hoping that I don't break the housing during removal.

So my day off gets to consist of removing the passenger side CV axle and disco assembly and looking for parts. woo hoo.

[DirtyBacon04]

is the housing broken, too?

[Philberto]

It doesn't appear to be so. I'm not sure how long the disconnect gears were broken, but the only damage to the housing is a bit of aluminum ground off of the end of it where the cv axle was spinning against it. Fingers crossed for tomorrow to check it out.

[DirtyBacon04]

You gonna go with the AWD sleeve, too?

[Philberto]

Not sure yet. I'm rather dumbfounded that this broke, as I do not frequently use 4wd, not in the past year anyways. Have you noticed a drop in mileage using the AWD sleeve?

[Philberto]

Parts diagram and part numbers for those who want to convert to AWD sleeve, since apparently nobody here has ever posted them:



001 12479302 SEAL. Front Axle. Front Wheel Drive Axle Shaft.

002 26053326 BEARING. Front Axle. Front Wheel Drive Axle Shaft. (3 required)

004 12471625 WASHER. Front Axle. Front Drive Axle Shifter/Lock. Front Wheel Drive Axle Shaft.

005 12471636 SLEEVE. Front Axle. Front Wheel Drive Axle Shaft.

006 12471623 WASHER. Front Axle. Front Wheel Drive Axle Shaft.

008 15801507 SEAL. Front Axle. Front Wheel Drive Axle Shaft.


The following aren't needed, but are just here for reference:

003 12479197 HOUSING. Front Axle U Joint. Front Wheel Drive Axle.

007 12471633 HOUSING. Front Axle U Joint. Front Wheel Drive Axle.

009 12471634 PLUG. Front Drive Axle Shifter/Lock

[Trail X]

First of all, how did you come by those numbers!? What is your source? I'm green with envy!

Second, that is the MOST worn out disconnect I've ever seen! Your gears may be intact still, but your bearings are going to be nonexistent. What happens, is the bearings go dry, and don't spin. Heat gets built up between the CV axle and the bearing, which burns through the bearing. The CV axle then wears down into the aluminum casting. Internally, the gears begin wearing through their steel wear plates and into the aluminum housing.

Basically, you will probably need an entirely new disconnect (at least outer housing, outer gear, fork, bearings seal) and a new CV shaft.

A failure like that does not happen overnight... that's something that has been broken for like... months!

[navigator]

sounds like if he had tried to use the 4wd in the past few months he would have noticed it.I guess that is a good reminder to cycle through the 4wd occasionally even if we aren't using it much.

[Mudwheelin]

Hey man, that looks fun...not. If your housing is broken let me know. I have a spare one sitting in the garage. You can have it if yours is broken. Just pay the shipping.

[Philberto]

whew, finally drivable again! Okay, here's the rundown, and I'll have pics up when I get back later tonight:

1) Outer housing is toast, as is outer bearing. Big surprise there.
2) CV axle is, surprisingly, perfectly fine. Steel vs aluminum = steel wins.
3) Gears and fork look fine, but I have an AWD sleeve on order anyways.
4) inner housing, bearing, seal, washer, all fine.


Also, I didn't have any issues getting either a) the CV axle out or b) the disconnect detached from the pan. For a), there is a circlip holding the axle in the gear assy of the disconnect, and for b), one should simply be able to thread in a slide hammer into all 4 bolt holes that are threaded on that side of the disconnect. The key is to disassemble the disconnect while it's still attached to the car, taking the outer housing out attached to the CV axle, and then remove the inner housing. See ya guys in a few hours.

[arl120384]

whew, finally drivable again! Okay, here's the rundown, and I'll have pics up when I get back later tonight:

1) Outer housing is toast, as is outer bearing. Big surprise there.
2) CV axle is, surprisingly, perfectly fine. Steel vs aluminum = steel wins.
3) Gears and fork look fine, but I have an AWD sleeve on order anyways.
4) inner housing, bearing, seal, washer, all fine.


Also, I didn't have any issues getting either a) the CV axle out or b) the disconnect detached from the pan. For a), there is a circlip holding the axle in the gear assy of the disconnect, and for b), one should simply be able to thread in a slide hammer into all 4 bolt holes that are threaded on that side of the disconnect. The key is to disassemble the disconnect while it's still attached to the car, taking the outer housing out attached to the CV axle, and then remove the inner housing. See ya guys in a few hours.

I like the idea of disassembling the disco first. Seems to be less of a headache. Also, if you opt for the sleeve, do you have to take the inner housing off at all, or can you re-assemble as is?


ARL

[DirtyBacon04]

If your inner housing/bearings are fine then yea, you should be able to do it w/ the disco installed.

Oh and Phil, make sure you put the sleeve on the correct way (beveled edge out, towards axle).

[Philberto]

Parts are on their way, currently driving with empty disco attached (inner bearing is in place to support intermediate shaft). Pics when I am more sober.

[fishsticks]

Parts are on their way, currently driving with empty disco attached (inner bearing is in place to support intermediate shaft). Pics when I am more sober.

Wad some paper towels or something up and shove it into the disco. That bearing isn't going to support the intermediate shaft and the shaft will walk.

[Philberto]

Done.

[Trail X]

2) CV axle is, surprisingly, perfectly fine. Steel vs aluminum = steel wins.
3) Gears and fork look fine, but I have an AWD sleeve on order anyways.

Detailed pictures please!

Yes the steel shaft will win against the aluminum housing, but it has to burn through the hardened steel casing of the bearing, and the steel reinforcement of the seal first. My CV had a concave ring burned into the bearing surface. Your bearing surface needs to be smooth, and the proper diameter all the way across it.

[Philberto]

Alright, now that I finally have time to breathe, here's the more detailed information:

First of all, how did you come by those numbers!? What is your source? I'm green with envy!

Second, that is the MOST worn out disconnect I've ever seen! Your gears may be intact still, but your bearings are going to be nonexistent. What happens, is the bearings go dry, and don't spin. Heat gets built up between the CV axle and the bearing, which burns through the bearing. The CV axle then wears down into the aluminum casting. Internally, the gears begin wearing through their steel wear plates and into the aluminum housing.

Basically, you will probably need an entirely new disconnect (at least outer housing, outer gear, fork, bearings seal) and a new CV shaft.

A failure like that does not happen overnight... that's something that has been broken for like... months!

James, I got those numbers and the diagram from that Nalley GMC site that we were discussing in the parts lookup thread as a replacement for Compnine. It's not the best, but it works well enough until I get a download of AllData or a pirated version of some dealer's EPC.

My inner bearing is in perfect shape; my outer bearing, however...







Nice lighting image of the gear assembly. You can see I've started to detach the circlip for the CV axle.


View of the inner CV joint. I believe that James is correct, and I will need to order a new CV axle too. You can see the wear on the bearing surface.


and another view:


Outer housing sort of cleaned up:


Thrust washer:


Gear 1:


Gear 2:


Fork:




Inner Housing:





I removed everything except the inner bearing (it's fine, and doesn't contact the intermediate shaft) and the inner seal, reinstalled the whole housing with a liberal application of wd-40, and fashioned this little lid/nitrile glove combo to seal the housing end:


Parts are coming from gmpartsgiant.com, actually a division of Rydell Chevrolet in Van Nuys, so they are due to arrive on Monday. I will pick up a CV axle at the same time, since that groove you can see on the second picture worries me.

The most interesting thing to me is that this did not present any apparent symptoms for so long, and then the blame rests on me for not checking regularly. That's what happens when you don't go offroading for a while, so go offroading frequently everybody!

[Trail X]

That outer housing is toast! Also, good call on replacing the CV, that would cause your bearing to fail faster.

Did you rebuild this previously at some point?

Regarding posting part numbers, we need to start making that a habit, whenever we are working on a system of the truck. Post pictures (hosted yourself, or as an attachment) and part numbers. Just in-case we lose access to the new parts database.

[Philberto]

No, I never rebuilt this before. Last check I made on it, everything was A-OK, but that was quite a while ago.

I second the motion on posting part numbers, and was shocked that 5 people replaced their parts with AWD sleeves, but no mention was made anywhere of the part numbers. We may be ORTB and expect Google-fu, but still, having part numbers makes cross-shopping much easier.

Also, major thanks are due to Mudwheelin, for helping me out with an outer housing. If I ever make it up there, or you down here, you're definitely getting some beer.

Total spent on parts for the internals of the disconnect is only a measly $165, and adding the CV axle will likely push that to around $210, still vastly cheaper than the reportedly poorly designed ATP disconnect (rough edges, improperly machined areas, etc).

This, plus tires once my tax refund gets deposited, and I should be wheeling-ready again.

[Trail X]

Are you not purchasing a new outer aluminum housing? I do not think you would have any luck reusing it.