So while doing my monthly little mini inspection, I came across something that I don't know if it's normal or not.

So I'm checking the wheel bearings, spinning the wheels gently by hand, seeing if the wheel gas lateral play or give. Then I get to the rear...

So I'm pretty sure we're all familiar with we're solid axles, and which you turn one wheel one way and the other one goes the opposite way, just a natural part of a differential.
Well, when I do this there's a noticeable delay and tiny bit of noise between the other tire moving. As in, let's say I turned one rear wheel left, the other will obviously turn right but there's a noticeable delay and little clunk. The clunk doesn't sound heinous or anything, just sounds like something two faces meeting gently.

Basically, my question is should there be a little bit of play like this? Or should they move one to one with each other?

On the off chance that it should not be like this, what should I do?

Ur feeling the backlash, its norm 4 the to be a little play, if its excessive then there could be an issue but as u didn't go looking to solve a problem my guess is ur fine...

Backlash, interesting. Should it still be there even when the differential is locked?

I guess if it was a problem I'd have to replace the internals or something huh? Hopefully that shit holds together haha

when setting up gears (ring and pinion) there is a prescribed spacing (backlash), the locker has nothing to do with said, so yes even locked. The only diff will be both tires will be turning in the same direction when u free the "play".

I think its normal but if its too excessive than something has to be wrong with the gears inside the diff.

More interesting, so how do you know when it is excessive?

When you turn the one wheel and the other wheel engages and spins very late with obvious play. This is my guess though. I remember spinning my wheels when adjusting the drums and it engaged right away. 225k on 2000 4Runner.

This is just a rough guess, and it has been several hours, but I'm gonna say they had... Maybe 0.5" to 0.75" of rotational difference.

Hmm

If your backlash was excessive. The gears will grind excessively and you will hear the differential howl.

To me backlash is for the ring and pinion.

He’s talking about the spider gears. It’s a shame he can’t just pull a Diff cover and check the diff pin and spider gears for ware.

When you spin only 1 wheel for a long time it galls the diff pin that the spiders spin on.


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Technical what his feeling is a combine of axle shaft spline, spiders, ring and pinion, and a little driveshaft tcase (if 4x4) but to get into explaining tolerances of every component and how they interact seemed a bit much.

Having a 3rd member that drops out and can be rebuild on a bench or just drop a new one in is a plus for me on this vehicals

It is nice being able to pull out the carrier. But if his rear is in the air and in park the only thing going to rotate is the spider gears.

If the trans is in neutral and he spins one wheel without a posi and the drive shaft tries to spin to me those spiders are shot. They are easy to replace though. Or pull them and put a lunch box locker in their place.


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I'll try to get a video today to see what you guys think, honestly I don't really know if it house or anything because it may have been this way since I got it about a year ago, maybe? I'm not sure.

The only noise that I think is new is, what I guess is the front diff, making noise in four wheel drive.

Let me go take that video and upload it

You also have to remember you are looking at a 360 degree wheel. A half inch of movement at the tread side of the tire is roughly ~1.5 degree of movement of lash when cold. These parts operate at a much hotter temp than ambient cool. Go drive an hour and then see how much the other tire moves when you turn the other one.

Because of the high variance in temps and the way metal reacts to heat if the gears were "tight" when ambient cool they would hand grenade at operating temps. Some things need a little play to work right.

But in my opinion I think you are chasing windmills, Don. I have been in more than a handful of trucks that had gear problems and not once did we have to wonder about it. You know from the banging, grinding, popping, or other crazy ass sounds coming from the 3rd member.

That little bit of rotation before the other wheel rotates is completely normal. If the backlash were excessive you would be experiencing other symptoms while driving like loud clunking when going between gears once the engine is warm or howling/whirring noise when driving. Nothing to worry about.