All seemed to be going well. Got the differential out in 20 minutes, the tubular crossmember and coilovers really speed up the process. I drained the fluid out, found a broken snap ring. That would explain the excessive (more so than normal worn out yokes) end play on one yoke.
Put it up on the bench and started looking at it. Both yokes has some sort of a cap on them. The one yoke with no snap ring does not slide out. It has very little left of this cap. The other side has quite a bit left of the cap and the snap ring is still on there. I'm basically stuck as to how to get these yokes out with these caps on them (unless they are so mushroomed as to only appear to be caps). I'm following gtr1999s guide and there is no mention of these. If these are not stock yokes, was this rear end rebuilt at some point? Any way to tell? The ring and pinion were set up very nicely with excellent wear patterns.
What parts do I need?
I figure I need the bearings, seals, and side yokes (the rebuilt/reman ones are the best to get, correct?). The posi clutches may or may not be good. This is an L48 automatic car... I just don't see it having the power to wear anything out. I'll mic them as per the guide though. I've got a set of 4.11s on the way.
Where is the best place to get said parts?

Also, the posi tuning thing. No springs. I don't quite understand. How does it work without the springs? I thought they were there to provide tension across the spider gears to allow for the posi action to work. I'm not doubting that it works, I'm just curious as to how.

The most important thing though is getting the side yokes out. I'm thinking of going in there with a die grinder and grinding on them, but it probably won't work because I can't reach the back anyways.

 

The yoke probably worn down to the snap ring and it fell off and got chewed up in the gears. You might have a rebuild set of yokes already but they should have been harder then the posi pin. If the end is really mushroomed over then grind off as much as you can. Otherwise drive the yoke out with a long brass rod and then drive out the opposite one. Look at the yokes to see how muc is left from the end,should be .187"(3/16"). I'm guessing you have over .100" endplay. Look at the housing where the yokes go in they will hit and grind it down,just like facing stock in a lathe. I have been able to reuse housings that worn down close to .125", I didn't like it all that much but I didn't have to try and replace the housing and the seal didn't leak.
You can use the 4 springs if you like, the procedure is in the GM overhaul manual. I use the springless method and it does work. I certainly make no claims to be idea, Tom's has been building them like that for 30 years and Pepe Estrada for years before that. I have the 1979 issue of PHR scanned with the "tuning article" procedures in it. I set them up using a surface grinder to get them right where I want them. Centrifugal action forces them to work without the constant binding the 4 springs produce and the common posi chatter along with it. If you were to compare a stock setup to the springless side by side you would see and feel the difference. With the 4 springs you can not easily rotate the yokes in opposite directions. With the springless setup the yokes will move without little effort against each other. The first time I set up a posi like this I did have my doubts as to how well the rear wheel would lock up and corner.Tom and his son assured me they built hundreds if not thousands of 10 and 12 bolt Eatons this way. The first time I dropped the clutch at 2,500 RPM there was a good 40' double line behind me! The clutches have never chattered hot or cold since I set them up like this. Going around a sandy corner I felt the posi engage as normal as one wheel started to slip. There are various load setups that can be used with this procedure, the drag setup is much tighter and I wouldn't recommend it for a street car. If you have a Tom's Catalog you'll see the rear ends they build and they all are springless.
Did you mark the caps before removing them?
Gary

 

Haven't removed the caps yet. We know to mark them. I read briefly through your directions, but I'm still really stumped as to how to get the side yokes out. Both are stuck in there. Should I just hook the slide hammer on there and pound away? Can I do any damage this way?

What should I buy from Tom's for this rebuild?

 

Make sure your 4.11s are for a 3 series carrier or you have a 4 series carrier. Do not use a spacer on a 3 series carrier, it will break. Talking from experience here.

As for getting the yokes out, sometimes the ydo have to be pounded out due to the mushrooming of the ends. Its doubtful you will damage the gear but if you do you have to get them out somehow. You can't proceed without getting them out.

 

A pointed carbide burr in a die grinder or dremel type tool will allow you to remove much of the peened over stub axle material . Rotating the axles in opposite directions will expose the areas that are hard to get to . Clutch pack friction in the springless units is achieved by the concave shape of the driving clutch plates in the center section . These can be a bit of a stinker to remove and install if they are in good shape .

You should have no problem if just remove enough material from one stub to remove it and drive the other side out . The axle gears them selves are quite hard and will not usually suffer any damage .


Geo

PS I may have some pics stored away of a rebuild

 

Norval is selling me his barely used 4.11s. It requires a spacer. If it survived behind his engine for a little while it should be fine behind my L48.

Do I just want the installation kit from Tom's? Part# C10V-IK
So that kit should be enough, and maybe posi clutches, and I shouldn't need to buy any more parts, right?

 

Mine lasted quite a while. It was not until I started to drag race, just street tires, that they broke. I was told under "normal" driving conditions the ywould be fine. What actually broke on mine was it sheared off all the bolts holding on the ring gear and then the yjust wedged themselves and locked everything up. Surprisingly it did not show up until I was on the return road making a turn. Never hinted anything until it was running slow. An L48 you should be safe. Just don't be dumping the clutch at 5000 rpm to much.
I see you have an automatic, you should be fine

 

So, should I just call Tom's and ask them what I'll need? Is there another place I should call instead? Is the installation kit all I'll need to do the gear setup?

 

For kits you can use anybody. I use kits from Bairs or Randy's both are fine, the carrier bearing shims are a little difeerent between the two but that's about it. Use the solid steel clutches I just bought a set for $79 but was told that Eaton is raising the price tomorrow,1/3/05?
If you decide to shim the posi, get the posi shim kit Tom sells. You'll find about a $30 window on the Master kits. You'll need 4 bottles of posi additive- 2 to start and 2 for the 500 mile oil change. Coat the clutches with it too when assembling.
Gary

 

Well, the gears I'm using are used already, so will I have to do the 500 mile oil change?

And the GM overhaul manual, what is this? I have the GM shop manual for '77 and '64 cars and it doesn't have anything in it about rebuilding the differential.

Okay, my list of parts then (all from Tom's, keeps it easier)
C10V-IK Installation Kit
Includes center bearing set, crush sleeve, pinion nut, gasket, locktite, marking compound w/brush, super side shims, and some aftermarket pinion shims.
C12-PSS Posi shims
Posi shims are necessary for the proper tuning of your posi. Available in a kit which includes 2 each in thicknesses: .010, .015, .020, .025, .030, .035, .040, and .045.
C12-PP 18S Posi clutches/plates
18 Solid disc and plate set

They have 14 solid pyrolitc carbon disc's for much less, but I'm assuming I should just stick with the solid steel ones.

Side yokes
Lube
Posi additive

 

GM Overhaul manual is different then the service manual. Try ebay or a swap meet to find one. Any of the 69-72 issues will work.

I like to drain the oil after a rebuild,you probably could let it go though.

Stay with the solid steel clutches. BTY, the prices just went up 12% from Eaton this week. I last paid $69 for solid clutch sets that's now up to $78.00. 2 years ago they were $51 per set.
Rebuild kits from Yukon are going up 5% this week too.

If you don;t want to use the crush sleeve Ratech sells a solid sleeve and spacer kit to setup the pinion bearign preload. About $30 for the kit.

Gary

 

Okay, I ordered the parts from Tom's. The guy was kinda difficult to understand, but I got it all ordered. Now I just need to hammer out the old side yokes, tear the case down, clean it up, paint it, wait for the parts, and put it all back together.

 

I got the side yokes out. Some grinding on the ends and the finally slide through. One had to be persauded with a maul though. All the spider gears are out. Now the next step is to remove the caps (already marked them) and then pull out the carrier, do the pinion, press out the bearings and I can start cleaning it up for paint.
Any tips on cleaning the case up for paint?

It appears to have nice roller bearings on the side, do these ever wear out?

 

Cleaning tank, bring it to a car wash and use the high pressue engine wash, or just clean it with simple green and hot water.

The carrier bearings do wear out and you will not be able to save them anyway if you try and remove them. They are in the kit so replace them. I use a Craftsman 2 jaw puller and impact gun to pop them off. Look at them before you remove them and you'll see the carrier hub protrudes a little beyond the bearing race ID you have to get the bearign fully home when installing and get the hub in that position otherwise you won't get the carrier bearing preload correct and have problems down line.

Gary