Volvo G80 Spider Gear Backlash (play)

I was digging into my 240 rear diff recently and contemplating my G80. I noticed that there seems to be a considerable amount of play in the spider gears. So I made a video.

This is the backlash that can be seen when rocking the right axle back and forth. The play that happens at the outer axle end (measured at the lugs) appears to be about 1/8 inch. It's hard to see in the video, but if you watch closely, you can see the the bottom spider gear is NOT turning as the axle is rocked. The gear is actually rocking to the right and left. This would indicate there is some play in the spider gear shaft.

I know some play is expected, but does anyone know if this is normal or is it more play than normal? Could this just be how loosely these diffs were made?

I've had a couple G80s and I think they had play.
Dave B

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That comes from snow belt cars when people spin one tire to 100 mph, the spider gears try to weld themselves to the pin and start to wallow out

freevolvos said:

That comes from snow belt cars when people spin one tire to 100 mph, the spider gears try to weld themselves to the pin and start to wallow out

Click to expand...

So that's an indication of wear in your opinion.
Appreciate that.

There's a lot of play going on, but it's not really a measure of backlash in the gears. In your video, you have slop from: axle to side-gears, lash from side gear to spider, spinder to shaft clearance.. and then all that to the other axle shaft. There's a lot of stuff moving about.

Are the spider gears wobbly on the cross-shaft? If so, that's no good. The spider will wobble about and gear contact stress will skyrocket.

To measure spider gear backlash you'll want to lightly preload everything, and then wobble one spider gear back-forth. That should be actually gear backlash.

culberro said:

There's a lot of play going on, but it's not really a measure of backlash in the gears. In your video, you have slop from: axle to side-gears, lash from side gear to spider, spinder to shaft clearance.. and then all that to the other axle shaft. There's a lot of stuff moving about.

Are the spider gears wobbly on the cross-shaft? If so, that's no good. The spider will wobble about and gear contact stress will skyrocket.

To measure spider gear backlash you'll want to lightly preload everything, and then wobble one spider gear back-forth. That should be actually gear backlash.

Click to expand...

Good to know. I changed the G80 to a different one before putting things back together. It seems better, although it seems to me there is still a little slop in the spiders on the new one.

Maybe I'll dismantle the old one and have a closer look.
Dave

You should be able to buy the cross- pin, and spider's new. The side gears on the end of the axel shaft, if they are in good condition shouldn't need replacement, as they aren't run in like a ring and pinion. I would pull the cross shaft and just check for wear. It will be obvious if things are bad, However if the cross pin is messed up it can turn into a big job as you can't get it past the part that's galled up. I have seen the spider's welded to the cross pin that spun in the case and broke the bolt that holds the cross pin in. Yours don't look that bad usually the gears will be a nice shade of cobalt blue in extreme cases

This is probably a good lesson on evaluating a used G80 before installing instead of just installing like most of us do.