Diff question

[maybs]

Here goes... I removed the third member from the rear of my samurai and the first thing I did was check the backlash. The service manual says it should be .004" - .006". I measured it to be .009, but I only measured in one location (I realize now I should have spun the ring around and measured in multiple spots). I also should have checked the run-out of the ring gear to see what it looked like before I disassembled it.

I took everything apart (including removing the ring gear), but I left the pinion alone. The side gears and spider gears were then welded to the carrier. Upon reassembly, I found that when I tried to adjust the backlash to be within spec, the ring and pinion would bind up at one certain point in the revolution of the ring gear. I checked the run-out of the ring gear and it was .014" (spec is no more than .004). So, I disassembled it again, checking to make sure everything was clean and flat with no burrs or welding spatter getting in the way. I also reassembled it without the ring gear on so I could check the run-out of the mounting face of the carrier. This told me the problem is with the carrier, not the ring gear. So with it fully assembled, the backlash varies between .002 and .008 depending on the rotation of the ring gear.

The question is, what should I do with it?

1) just run it till something wears out (or will it grenade the first time I try to take it to 50mph?)
2) find another carrier
3) swap the front/rear third members, welding the remaining one by filling in teeth on the side gears instead of heating up the carrier

Option 3 would leave me with a welded front and rear, but if I put the out-of-round third in the front, I would think it would be okay since it would not be seeing high speeds.

[TerryD]

since you're thinkin toyo axle swaps......run the piss outta it........backlash is only something you have to overly concerned with if you're wanting it quiet at highway speeds......

[maybs]

Thanks for the input! I'll probably just do that and see how it goes. Like you said, I'm not too worried about it since I've got the yota axles on standby... I'm just hoping to get in a good bit of wheeling on the stock axles before diving into the swap.

[Slinkey]

You should be fine, most of the specified tolerances are for new parts before they are broken in. A couple thousandths increase in backlash when the gears break in is no big deal.

[maybs]

That's cool, although this was more like ten thousandths than just a couple. The main thing that had me worried was how much it varied (ring not turning true). I can be pretty anal sometimes (no Cody, not the way you're thinking) as far as wanting to do things by the book. Since most of this is new territory for me, I just don't know which things are actually a problem.

[TerryD]

only thing the ring not turning true will do is create a harmonic rining at highways speeds.

[Billet Benny]

It may break and it may not.. There is no for sure answer and just because your carrier has a little more than called for runout doesn't mean it won't run for ever.... but it also doesn't mean it will. Run it and have fun, it's not something to stress over especially if you've got plans for better (relatively speaking =]) axles. Backlash does contribute to gear strength as well as some noise issues, but given your case the gear strength shouldn't be significant unless you're already borderline on having them hold up or they're on the last leg of their life.

For the record, it's 100% pointless and a waste to weld any part of the gears in the diff to the carrier. It forms a very weak connection and puts unnecessary heat directly into the carrier. You will have the best luck correctly welding spider gears to side gears if you know what you're doing with the welder, the metals, and the joint. If you JUST welded gears to the carrier, your welded diff will not hold up long. But run it anyway to see the effects first hand.