8.25 Cross Shaft play

[Bjorn86]

I just picked up a used 29 spline 8.25 with 4.56 gears and an Aussie locker, and decided to convert it to disc brakes before I swapped it in. Everything went smooth, but upon reassembling the Aussie, I noticed the cross shaft has some play up and down when i push on either of the exposed ends of the shaft. This is with the retainer bolt installed and tight. There is no play side to side.

How much, if any, play is normal? Could this be a worn cross shaft or retaining bolt?

 

[cda xj]

I would say none to very little I have no experience with one with a Aussie but I had a ford ranger with a 8.8 I took the cross shaft out when I was re assembling it I noticed I had play with the bolt in. A week later I was doing some snow drifting at about 35mph and the diff just locked up well it sherd the dam bolt and the shaft came out and hit the pinion just my experience with this problem.

 

[GrimmJeeper]

there should be NO play whatsoever. without seeing it in person I can't speak to what your problem is but it should be solid and tight in there.

 

[Bjorn86]

Maybe I can explain it better. With the cross pin installed in the carrier and the retaining bolt tight, I am placing one finger on either end of the cross shaft, which I can wiggle lengthwise. The cross pin fits snugly in the holes in the carrier (no side to side play).
I just ran down and picked up a new retaining bolt. Still have play in the shaft. I would estimate it as about 1/16" or less. It seems like the hole in the cross shaft that the retaining bolt passes through is slightly too large and that's where my play is coming from.

 

[kastein]

I would recommend a new cross pin retaining bolt. The unthreaded portion sometimes gets worn spots on it that allow play... and I have had not one but two of them break off (with no real provocation) partway down the threads recently, leaving a partially threaded section in the carrier holding the cross shaft in place, which is a real barrel of laughs to deal with.

The part number for the replacement is 3507724, can be bought at any chrysler/dodge/jeep dealer, and should run you 3-8 dollars depending on dealer markup.

Do yourself a favor and use a 5/16 6 point box wrench or socket ONLY when removing/installing those bolts, or at least when torquing them and breaking them loose. I've had them round off due to 12 point sockets before.

 

[Bjorn86]

I would recommend a new cross pin retaining bolt. The unthreaded portion sometimes gets worn spots on it that allow play... and I have had not one but two of them break off (with no real provocation) partway down the threads recently, leaving a partially threaded section in the carrier holding the cross shaft in place, which is a real barrel of laughs to deal with.

The part number for the replacement is 3507724, can be bought at any chrysler/dodge/jeep dealer, and should run you 3-8 dollars depending on dealer markup.

Thanks for everyone's input. I already tried a new retaining bolt earlier this morning, although I just grabbed one from O'Reilly right next door to my place; Dorman part # 81048. Didn't seem to make any difference, which is what leads me to believe the hole in the cross shaft has become enlarged.
I did notice some difference in the overall length as well as the length of the threaded portion between what I pulled out and the new Dorman replacement. Assuming what I pulled out is in fact a factory retaining bolt (it's used, I don't know the history of the axle), I suppose I could try an OEM replacement. Think that would make much of a difference?

 

[kastein]

You might need a new cross shaft, I wouldn't be too surprised, I just figured the bolt was more likely.

The threaded length shouldn't matter as long as overall length is the same, the replacement's threads aren't longer, and the underside of the head has the same contour. As I recall, that bolt has a special conical shoulder to keep it locked in place better.

 

[Bjorn86]

Everything is the same except overall length. The Dorman replacement is shorter than whatever it replaced, but seems to be long enough. I can take a picture in a few minutes as I plan to pull it apart again. I think I'll order a new cross shaft since they aren't all that expensive and I don't have a clue how many miles are on this one.

 

[Bjorn86]

So I pulled the cross pin again, definitely has a slight oval shape in the retaining bolt hole. The pic is the Dorman replacement next to the old one. You can see where there had been movement based on the wear on the old bolt. The difference in length is not a problem, as I reinstalled the bolt with the cross pin removed and it easily spans the gap.

 

[kastein]

Yeah, that looks fine length wise. Bolt looks OK too but replacing it is good insurance.

 

[Digger87xj]

make sure the unthreaded end of the lock bolts are the same diameter.. then, call Aussie or a distributor and get a new hardened cross shaft. Ask them for a lock bolt too if they have them.

 

[Bjorn86]

make sure the unthreaded end of the lock bolts are the same diameter.. then, call Aussie or a distributor and get a new hardened cross shaft. Ask them for a lock bolt too if they have them.

Already have a cross shaft on order. The lock bolt is the same diameter and seems like it is easily long enough. Think that difference in length is significant enough to need another new one? I'm no expert by any means, just want to fix it right.

 

[Digger87xj]

As long as it spans the gap, use it. Save the old one for a spare.

 

[Bjorn86]

Thanks for the advice everyone. I'll report back once I get the new cross shaft in.

 

[Bjorn86]

New cross shaft and retaining bolt are in. The same amount of play is there. With the cross shaft removed, the retaining bolt has no play when installed in the carrier. The play seems to be between the retaining bolt and the retaining bolt hole in the cross shaft. I don't understand, both are new.

 

[kastein]

The hole may be large enough to allow play and none of us ever noticed it... entirely possible.

That bolt shouldn't actually see any significant loading during normal use - it just has to keep the cross shaft from sliding out and hitting the pinion. I guess I'm not too surprised, though it does seem a little odd.

 

[Bjorn86]

I could see how it could go unnoticed. I'm not really sure what possessed me to wiggle it. I guess it's just me being overly meticulous. I'll just have to try to forget about it.