Lost pinion preload

[Jeepsinker]

My intermediate axle has lost the pinion preload and given me a vibration. I've done about 800-900 miles in the past five days and the bearings have not burned up on me and it hasn't gotten any worse so I'm fairly sure the bearings are not bad, just lost the preload. I understand that this is fairly common for these axles.
My question is, how do I tell which pinion nut I need to tighten up, front or rear? I do not want to pull the gear pattern out of alignment and eat up the gears. I guess I need to remove either the side cover or top cover and just look and see which way it needs to go?

 

[doghead]

It's covered in, TM 9-2320-361-24-2.

 

[Jeepsinker]

Took the rear seal retainer off and inspected the bearing. No sign of failure, no metal dust or shavings, oil was clean. I went ahead and replaced the rear pinion seal on this axle because it has been leaking. Put it all back together and went to town on both pinion nuts with my 1" impact, but only got a very marginal improvement. I guess if I can't get it to stop vibrating this way I'll just have to buy a shop press (I'm sure I need one anyway), then remove the pinion cross shaft and press the bearing retainers farther in.

 

[doghead]

The pinion nuts do not adjust the shaft, shims do.

Did you read the TM I posted?

 

[Jeepsinker]

Yes I did, thoroughly before I took the first fastener off. The shims adjust the preload, but the bearing retention collar presses onto the cross shaft to retain the tapered bearings against the shims. My rear pinion nut was installed loosely and it looks like that gave room for the collar to slide aft under force until it contacted the yoke. This happened when I was jerking my wrecker out of the mud. I thought it was a bad u-joint ( I did have a bad one), so I replaced it directly before leaving for the Texas rally. Still had a vibration and found the pinion suspect when I arrived at the rally.

Just got some more uptake on the rear nut, which is the one that was most loose. I'm going to try and get another 1/8 turn on it and that should do it. Very little up/ down, in out movement left now. I know there should be some fore and aft movement, but certainly not the 3/8" it had. And there should be no up/ down play. If it burns up I'll swap in one of my spare carrier assemblies.

I appreciate that link to the TM section by the way. I needed that.

 

[Jeepsinker]

Well I tightened it as much as I am comfortable doing, and it still has more movement than I like. I must have battered the bearings out of spec. I did not think to get the number off of the race while I had the seal retainer off either, and the bearing and race numbers are not in the quick reference guide or thread.

Anyone have the Timken or SKF numbers for them?

Edit: Nevermind, I found them with the handy dandy search tool.

 

[doghead]

My first thought was to get the NSNs out of the parts tm.

Then I tried a general search for pinion bearing numbers and nearly instantly found this thread. http://www.steelsoldiers.com/showthread.php?54205-Pinion-Bearings-Napa

Maybe it can help you.

 

[Jeepsinker]

Ha, you posted before I could edit. That is the thread I found, and has the part numbers.

 

[rustystud]

Well I tightened it as much as I am comfortable doing, and it still has more movement than I like. I must have battered the bearings out of spec. I did not think to get the number off of the race while I had the seal retainer off either, and the bearing and race numbers are not in the quick reference guide or thread.

Anyone have the Timken or SKF numbers for them?

Edit: Nevermind, I found them with the handy dandy search tool.

Jeepsinker, the rear shims adjust the pinion depth into the ring gear. The front shims adjust the preload of the bearings.

 

[jasonjc]

Why not go a head and post the bearing numbers here also. And pic's we have to have pic's.

 

[gimpyrobb]

So you guys are saying that if you pinions are good right now, we should pull the nut, add some red loctite, and re - assemble?

 

[rustystud]

So you guys are saying that if you pinions are good right now, we should pull the nut, add some red loctite, and re - assemble?

I would pull the yoke and seal housing and check the shims to make sure they are not damaged. If the nut had come loose and allowed the bearings to hammer at the shims they could have broken (especially the very thin ones) the shims causing the extra end-play. I have rebuilt many differentials that have had the same problem. You can find a small piece of metal in the oil that used to be a shim that got hammered out of place.

 

[Jeepsinker]

That's funny. I found a piece of a shim in the rear axle when I changed the oil in it, but it has no problems or end play yet. Nothing in the oil on the intermediate.

 

[rustystud]

That's funny. I found a piece of a shim in the rear axle when I changed the oil in it, but it has no problems or end play yet. Nothing in the oil on the intermediate.

A lot of new mechanics when rebuilding differentials (or transmissions for that matter) forget to shield the thinner shims by placing them in the center of a shim pack. Shims that are .002" to .010" are really easy to damage.

 

[Hainebd]

Shims set the preload, play up and down/ in and out. Shims between the seal retainer and carrier on the front.if you have up and down but no in and out, you may have bad shaft. Now for the real bad news. Both bearings cups and cones need replacing. How do I know, previous owner of Brute installed to many shims and drove loose. Both nuts were so tight a 1" impact could not move. No reason for that much torque. Just stretching the threads. So get under there and pull that shat, replace bearings and seals. Figure a whole day to do right. Yes you will find more stuff to fix.

 

[Jeepsinker]

I'm just going to change the whole chunk out. I'll pull the bed, lift the chunk out with my wrecker, drop the new chunk in, then put the dropside I have back on there.
Just have to order a third member to housing gasket.

Ill fix this one later, when I'm not relying on it for transport.