Is this normal? Or am I risking damage by this?

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Sep 17, 2002
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Hey mudders,

Im in the process of rebuilding a 40 series, which has been in storage for too long. I have painted the frame and put in new differential seal but noticed the play in the diff, so in need of asking for your wisdom here. Do I need to worry about this play in the rear diff? Any help ideas are much appreciated
 

pjohnson

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Seems a lot to me. Looks like it moves in/out as you turn also. Did you properly torque the pinion nut?
 
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I will have to double check that, I did it a while ago as I was slowly building it up, and it wasnt until last week that I installed the shaft that noticed it.
 
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Is there originally a crush washer in there? I dont recall ever seeing one.
 

pjohnson

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Yes, there is typically a crush sleeve, sometimes replaced with a solid spacer.
 

pb4ugo

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In my experience most earlier 3rds have solid spacers as and shims. Idk, when they went to crush sleeves. A lot of the rotation is from the spider expanding and contracting against the inside of the carrier. I agree with pjohnson, it appears the flange is moving in and out. In shouldn't wobble side to side or move in and out. Usually a leaking seal is caused from bad bearings.
 
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I'm not an expert (just finishing only my second diff rebuild) so consume the following info accordingly:

My 1/80 40 has a shoulder on the pinion shaft that holds a thin spacer and shims, as did a pre '78 diff I recently re-built. Regardless of which type you have (solid/crush sleeve or shouldered pinion), if that flange is going in and out, as it appears to be in the video, I would think there is something majorly wrong. I had a fair bit of rotational play in mine before I rebuilt it, which is apparently normal with open diffs (spider gears have a fair bit of lash), but zero in-out play. If that was my truck, I would get to the bottom of that before driving it anywhere, especially anywhere remote.
 
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It's pretty easy to drop the end of the drive line to get access to the pinion nut so you can determine if it is torqued and if there is any in/out play in the pinion or flange. If there is in-out play, you could try removing the pinion nut and seal (you'll need a new one as removing destroys them) to get a look at the outer pinion bearing.

HTH!
 

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