Axle problem

[mendelmax]

Hi guys.

It's not stroker-related, but I have a problem and I know I can count on your knowledge here, so maybe you can help me.

My 2004 WJ 4.0 requires new rear axle. Therefore I have to get some used one in good shape, give it a good tune-up with all new bearings, seals and new ECTED locker.

Today I have seen a really cheap axle, but some runout tests that I did with my dial indicator were not too encouraging:
Right wheel is perfect for an used part, runout of 0.04mm (0.0016"), but the left wheel has a runout of over 0.5mm (0.02"). Now the question is- is this kind of runout still acceptable? I guess it's not? The measurement was taken with mitutoyo digimatic on magnetic stand attached to the axle tube, and the axle was out of vehicle. I was spinning it by hand through the pinion yoke.
When dial indicator was placed vertically, to the hub edge, it shown also about 0.5mm variation. Swinging the shaft up and down returned 0.3mm of bearing freeplay (0.012"), which I thought was fine, isn't it?

What do you guys think, take it or not?

[yuppiexj]

It sounds like the left shaft was bent in whatever calamity caused to get junked.

You MIGHT get away with a new axle shaft and the rebuild you detailed.

I'd try for a better one from the junkyard.

[mendelmax]

I decided to take a chance and I bought it. Trip for another one would cost me 1/3 price of this one, not knowing if the next one will be any better, so I thought it's worth trying.

So far, I took the shafts out, and the axle runout remains at 0.5mm (0.02") in the left one, so I guess it's the axle shaft that is bent, not the housing (may be both though- how to check the housing, has anyone any idea?)

The problem that I have now is that the right one, which has only 0.1mm (0.004") hub runout after taking it out of the tube, has 0.3mm (0.012") runout when measured in the medium of axle length, making it a banana . Is this acceptable, or is this shaft also worthless? I guess that 0.1mm hub runout isn't much, but how about these 0.3mm? My physics knowledge tells me, that with radius that small, and being something like 1% of whole shaft diameter it shouldn't matter much, but am I right?

Anyone has any advice? Help me please, because I desperately have to bring my WJ back on the road- I start my studies next week and have no rig to drive there

[MrShoeBoy]

You are getting way too excited over the measurements. If all you are doing with this axle is offroad or general everyday driving it will be fine. If its more than a 1/32" then look for new shafts. I have seen and ran shafts with a 1/16" of runout but with big mud tires it wasnt noticable

If you want a high speed racer then 1/64" is about all the flange runout you want.

AARON

[mendelmax]

Yeah, you are probably right, I'm perfectionist.

As for now the axle is completely dissassembled, and I laser-tested it for straightness. The test was done with 4 bearing-sized discs (2 for axle bearings spaces and 2 for diff)


Then I set the cheap laser pointer on one side


And finally, the laser gone through


So I calculated, that the maximum axle bent is 0.15*-0.2*. I think that makes it fine to use. I'll just replace the worse axle shaft, and I'll start assembly.