S_Johnson

So, my (manual) car makes this incredibly annoying clunking/rattling sound at 1-5 mph, when in neutral.

I've looked underneath, and the only thing I can find, is that the pinion gear seems to have a lot of rotational play in it. I can turn the driveshaft a fair bit back and forth, before it starts to move the diff/tires. Now, I know for a fact that the carrier shims are good, it has just the slightest hint of lash, the last time I changed the diff fluid. But I'm wondering if from the other end (moving the pinion instead of the ring gear), it has a lot more lash?

It's driving me crazy, and it sounds HORRIBLE. My question is, should the driveshaft have a lot of rotational play in it? Thank you!

big gear head

I'm guessing that you have already checked the u joints.


The pinion nut can back off and cause the pinion to become loose. If rotation is the only movement that you have, and you can't move it up and down, or in and out then it's probably fine.


I see that you have changed the gears in it. If you have 2 rear ends set up with exactly the same backlash at the ring gear, one has a 2.73 and the other has a 4.10, the rear end with the 4.10 will have more pinion movement than the one with the 2.73 due to the size of the pinion head.


You are also probably feeling slack in the axle splines and the gears in the Auburn differential. The Auburn probably has wear on the cones and that has caused the clearance in the differential gears to increase a bunch. Add all of this up and you will feel a lot of rotation at the drive shaft/pinion.

S_Johnson

Crap, I never updated my profile info.

My gears are actually 3:43 (I think, I'll have to check), and it's a yukon dura-grip.

I had a shop install the diff/gears, and recheck the gears when they changed the fluid. I also checked them myself, that's why I know the ring lash is good at least.

I don't think the ujoints are loose, I remember that the pinion yoke itself was moving.

big gear head

Is the pinion moving in any direction other than rotation?

S_Johnson

I don't think so, but I haven't had a chance to get underneath it the last couple days. But I'm 90% sure it's just rotational.