Grinding and vibrations from rear end

After wheeling a few weeks ago I had some slight vibes at speed, now after wheeling again the vibes are worse and very loud. They seem to be coming from my rear end, chyrco 8.25 29 spline with a powertraxx and 4.56 gears. The gears and locker worked fine since I got the whole axle off another club member this past fall, there was little to no vibes and now its getting worse and worse.

I had a SYE and am running a 231/AW4 on bfg 33 inch KM's.

I am going to check the fluid level tomorrow but as of now the U joints dont have any play in them, and also when I let off the gas the grinding and noise stops totally but as soon as I hit the gas it starts up again.

-Alex

I am dealing with this on a friends (just bought it from him so I guess it is mine now). Pop the dif cover and look for metal in the oil. tiny flakes are ok, not good but normal. any more than that and you could have a bearing or race going bad. If you are sure it is the rear it is probably the pinion bearing/race and if yo run it with that bad it will damage the gears. A vibration in the drive line is hard to do diagnose becasue it travels from one end to the other under torque. It could be as simple as a motor mount either bad or out of line putting presure on the joints and making bad noises and vibrations.

Thanks, if the bearing race is bad can I fix that by myself or do I need to reset the gears after I do it? Also I know my motor mounts are going out right now, but they aren't in horrible condition yet.

-Alex

I recently installed a JY 44 that had a bad pinion bearing, slight grinding but no vibration. Easy to do all the diff bearings, just be careful not to mix up the shims, keep them separated, and reinstall them exactly as you removed them. If you don't have a bearing press, stick the bearings in the oven for a few, and the carrier and pinion in the freezer(or outside if a significant other will yell at you), and try to work fast when putting them on, the faster you work the easier it will go. Shouldn't need to reset the gears, but still run a pattern on them when you're done.

As for the vibration, you might check the d/s u-joints and c/v. I was getting horrible vibes up front when my c/v went out.

I just pulled the DS, it was the last joint (one that goes on the pinion). It was frozen up pretty bad and doesn't like to move very much.

-Alex

Ba-Riedo said:

I just pulled the DS, it was the last joint (one that goes on the pinion). It was frozen up pretty bad and doesn't like to move very much.

-Alex

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I was gonna suggest u-joint issue, but you stated in earlier post they seemed OK. I had to put mine up on a lift & put it in gear to realize mine were toast.

Yeah there was no play in it while it was still attached, once I pulled it off I realized there was no play because the joint was toast.

-Alex

Sometimes it is better to check u-joints with vehicle in neutral. That way, there is no driveline bind to mask a loose joint. Learned that the hard way. Usually a dry one will show some rust around the cups.

There was no rust or anything around the caps and it didnt move at all. Once I pulled it out I saw that the caps were cracked and the needle bearings were totally destroyed.

-Alex