Calling all 12-Bolt experts

[1oldtruck]

O.K., this is my first axle rebuild but I think I've studied and researched enough that I'm pretty confident in what I'm doing. The problem is that I can't seem to pull the front (small) pinion bearing up enough to contact the crush sleeve. I've got a brand new Richmond ring/pinion set and brand new Timken bearings. Shouldn't the front bearing be a slip fit onto the shaft? I test fitted the bearing with a press and it goes on easily but of course, must be removed to assemble the rear end. Both the new and old bearings slide with ease over the old shaft but not on the new shaft. I polished the shaft with emery cloth to remove the phosphate coating and it helped a bit but not enough. Should this be a slip fit or a very slight interference fit? Should I keep polishing? Do I have a bad ring and pinion?

Thanks in advance for any helpful comments!

Mike

[Imperial Kustom]

First of all, Richmond gears are a pain in the arse to set up for the street. It takes some time to get them to run tolerably quiet. Second, yes, the outer pinion bearing should be a relatively tight fit. I think what you are encountering is the crush sleeve itself. I am guessing that after tightening everything, the pinion is still moving in and out? The crush sleeve takes an immense amount of pressure to crush. A very powerful impact is a big help. Otherwise run a bar through the yoke with U-bolts or bolts and straps in place, and rest the nd on the driveway. Then use a big breaker bar to tighten the nut. DO NOT OVERTIGHTEN!!!!! Then you have to get a new sleeve and start over. There should be a slight amount of resistence when you spin the pinion after all is tight, but it should not freespin but still turn fairly easy by hand.

[1oldtruck]

Yep, just a bit of pinion movement like you described. I would think that with that much movement I wouldn't be on the crush sleeve yet. But maybe you're right - perhaps my impact is too wimpy! I can't see what's going on inside so I'll give it another try on the bench without the crush sleeve to confirm that the bearing will pull up far enough with the nut. If that works, then I'll have to find a bigger impact somwhere!

[Captainfab]

Just like Imperial Kustom said...it takes a crap load of pressure to compress the crush sleeve. It sounds as though you have the diff out of the truck, so you'll probably be needing a real good 1/2" impact or maybe even a 3/4" impact.

It's been a while since I've worked on a 12 bolt, but it seems like somewhere I've seen that some people have switched from the crush sleeve to a grind/sand to fit sleeve. That would mean assembly and disassembly a few times to get it right.

[1oldtruck]

My impact is a 1/2" Ingersoll Rand rated at 449 ft-lbs. Is that not enough?!?!?

Mike

[blackedoutharley]

The IR gun is plenty sufficient for the job...... so long as you have enough compressor to power it to its full potential.

Think of it as an electrical part that requires 12 volts but your system only puts out 9; it won't work too well. It's the same with the impact gun/compressor combo.

[1oldtruck]

Imperial Kustom, Captainfab,

You guys are right! I assembled the pinion shaft assembly out of the housing to see exactly what's going on. Just as you suggested, the bearing runs right up against the crush sleeve and everything comes to a stop. I do now understand why I still have a small amount of slop - it's because I need to crush the sleeve to remove the last of it and then go a bit further to get the preload. I should have realized this!

I guess I'll have to find a more manly impact from somewhere now!

Thanks for the help,

Mike

[1oldtruck]

The IR gun is rated at 449 ft-lbs @ 90 psi. I have a vertical, 60 gallon, 5 hp compressor and I'm running 100 psi. I would think that would be sufficient but still no dice!

[Fred T]

Can you set the air up to 120? Also, lube the threads, preferably with anti-sieze. And torque on impact wrenches is grossly overstated. At 100 psi most 1/2" guns will hit about 100 ft-lb of torque.

[wild one]

Well, my 1/2" snap on gun is rated at 600+ lbs/ft of torque, and it in conjunction with my 60 gallon 5 horse upright air compressor set at 120 psi did not have the beans to completely collapse the crush sleeve. I had to resort to fabricating a fixture to hold the pinion yoke in place then use my 1/2" breaker bar with a cheater bar (1" pipe, 3' long) to gain the needed leverage to set the crush collar. Good Luck,

Pete

[Imperial Kustom]

Working at a differential repair shop, we use Nitro Cat impacts at 120 psi on crush sleeves. Those things are about the most powerful impact on the market plus the factory will hop them up if you send them back. Then they really cook!!! Whichever companies are manufacturing these crush sleeves (like Ratech) have made them much harder in the last couple of years also.

[Vaughn]

If you use a hydraulic press to start the crush sleeve, it makes life a lot simpler.

You can only "start" the crush sleeve bending - you have to be careful not to do more than that.

The initial amount of pressure to start the bearing crush will be high - but as soon as the "crush" or bulge of the bearing starts, the amount of pressure needed drops off significantly.

Makes it a lot easier to install.

[1oldtruck]

Originally Posted by Vaughn

If you use a hydraulic press to start the crush sleeve, it makes life a lot simpler.

You can only "start" the crush sleeve bending - you have to be careful not to do more than that.

The initial amount of pressure to start the bearing crush will be high - but as soon as the "crush" or bulge of the bearing starts, the amount of pressure needed drops off significantly.

Makes it a lot easier to install.

Thanks for the suggestion. I actually thought about doing this but was afraid of taking it too far. I suppose that if I'm very careful I could make it work.

Another suggestion I got from a co-worker is to get a couple of Y-connectors or tees and run two air hoses in parallel, doubling the flow area and improving the flowrate. The thought is that I may be losing significant air pressure through the hose and don't have enough to maximize the impact gun's capability.

It will have to wait for a while as vacation and other things are taking priority.

Mike

[1oldtruck]

I got it! A crusty old Field Service Engineer from my work gave me some larger bore industrial air line fittings to replace my cheesy little 1/4" Home Depot fittings. This combined with shortening the air hose from 50 feet to 3 feet did the trick. My impact gun took care of that crush sleeve with minimal effort once I got the airflow/pressure at the gun up. Amazing how much is lost through the fittings and hose.

Mike