Rear wheel bearing? - 99 Suburban C2500

[stutaeng]

From what I have seen on the 2500 Suburbans and C/K 2500s, the SBC got the 14 bolt SF 9.5" and the BBC/Diesel got the 14 bolt FF 10.5.

On the C/K 3500s, they all got the 14 bolt FF 10.5, regardless of engine.

This has been true for all the civilian vehicles I've seen on the late 96-00 style.

Only exception may be government-spec. trucks as far as I know, as well as the early GMT 400 (some had Dana 70s, etc...)

 

[HotWheelsBurban]

From what I have seen on the 2500 Suburbans and C/K 2500s, the SBC got the 14 bolt SF 9.5" and the BBC/Diesel got the 14 bolt FF 10.5.

On the C/K 3500s, they all got the 14 bolt FF 10.5, regardless of engine.

This has been true for all the civilian vehicles I've seen on the late 96-00 style.

Only exception may be government-spec. trucks as far as I know, as well as the early GMT 400 (some had Dana 70s, etc...)

Probably so, I know my old 90 square body Burb,R2500(2wd 3/4 ton, 350 TBI/TH400) had the semi floating axle. We had a 77 C25 square body Burb with a 454, and it had the full floating axle.

 

[Pinger]

The locking is working - I tested it with a wheel off the ground, forwards and reverse.

And then it sat until today and when I was reversing uphill full left hand lock on the steering it felt like the diff was locked. Scrabbling, wouldn't follow the expected radius of turn, and left a dark mark (from the driver side tyre) on the tarmac. (It was the driver side tyre I had off the ground when I checked the locking).
It's free now (I found some ground to turn tightly both sides and forwards and back) but is it expected that it would remain locked after my earlier locking test?

 

[Schurkey]

I wouldn't think so. As soon as the load came off the flyweights, I'd expect 'em to retract (spring-loaded retraction) which should release any load on the clutches.

I'd be more likely to believe that the rear axle re-engaged the lock when you went uphill, full left steering lock. Uphill would tend to unload the rear axle, full steering lock would maximize the speed difference between left and right wheels.

Wild Guess: totally normal, if unwanted, operation.

 

[Pinger]

Thing is though, it never broke traction to invoke the locking. Dry tarmac (and even when wet never a problem) with a lot of weight over the rear axle (Suburban body and 100 litres of LPG and tank).

 

[evilunclegrimace]

Thing is though, it never broke traction to invoke the locking. Dry tarmac (and even when wet never a problem) with a lot of weight over the rear axle (Suburban body and 100 litres of LPG and tank).

It does not have to break traction for the diff to lock, you only a speed differential between the wheels.

 

[Pinger]

It does not have to break traction for the diff to lock, you only a speed differential between the wheels.

Fair point (to which I'll add that as far as I can make out, if there's even an axial pull on one of the axle shafts, there's a degree of locking without the Gov 80 being activated) but, I was going so slowly that I doubt (very much) that the threshold speed could have been reached and, it's never done this before in the same (routine) manoeuvre.
Given I'd been checking if the locking was working (wheel jacked off the ground) as the last thing before it was exhibiting this behaviour, I'm wondering if the cam/ramp mechanism wasn't stuck in an engaged position. The thought of which kinda freaks me as for that to happen implies that it was at the cam/ramp's peak which itself implies significant wear of the clutch plates.
Weather permitting, I intend checking the axial play again tomorrow and see if there's any change.

 

[92GMCK2500]

@Pinger , you get this sorted?

 

[Pinger]

@Pinger , you get this sorted?

No, not yet.
I intend replacing the pinion cross pin and C-clips but can't currently get the cross pin bolt.
My hope is that that tightens it up, not least as clutch packs are hard to get. (Rock Auto list a set for the right hand side but no mention of the left hand side - the side I have the play on).
Meantimes, I'm keeping a very careful eye on it, checking that the play doesn't worsen.

One thing that came to mind when I was checking it the other day was that when I push and pull on the wheel it sounds distinctly metallic at its extremes of travel - like steel on steel. I'm wondering, given that clutch packs have alternate discs of friction material, that if it was wear in the clutch pack, that the sound would be more 'damped' ' less clicky steel.

 

[Pinger]

Good news and bad news.
The good news. End play on the passenger side is now 0.3mm (previously 0.9mm) after replacing the C- clips and pinion shaft.
The C-clip has 0.15mm of wear and appears to have been installed the wrong way round ie, with the bevelled side facing the gear (where the gear bears on the outer edge of the C-clip). There's marking on the pinion shaft but no measurable wear so it isn't obvious how I've lost 0.6mm of play by replacing a part with 0.15mm of wear. Driver's side C-clip didn't have any noticeable wear.

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Couldn't see anything too extreme on the passenger side clutch pack and as can be seen in the following photo, the C-clip was never in danger of falling out (it's edge is just visible flush with the edge of the axle gear)

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Another shot (from other side) of passenger side clutch pack below.

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The bad news. I can't withdraw the pinion shaft bolt to replace it.
I was rained off so didn't get the chance to see if rotating the diff so that the bolt is forward of the big bearing cap permits removal but so far, it fouls the cap and can't be removed. My diff (9.5'') has the adjuster (that saves having to spread the case).
Is there room for the bolt further forwards or does the cap have to be removed. If the cap has to come off, what's entailed in refitting it?

Just to certain my terminology is correct, GM refer to that bolt as 'Pinion Shaft Lock Screw' (page 4-103 of part 2 of the manual) and it's to be torqued to 25lb.ft - yes?