Diff Spider Gears

Hi All,

I've bought a pair of gen 3 auto diffs from someone and checking them over I found that the spider gears turn a little 'clunky' on the rear diff, but smooth on the front diff. It's a smooth type of clunk, like they are meshed too tight.

I've partially disassembled it and got this video through the small window so we can see and hear, From what I can see through the tiny window the gears inside look healthy, perhaps this is normal or perhaps they are too close together?

Video is here, be sure to have the sound on.


Any help would be very much appreciated!

No, I don't like the sound of that! 

It's a very short video. but sounds like something is almost jumping?! 

Agreed that sounds very wrong.

Thanks!

After playing a bit more I found it does this when I try and turn the diff gears (fig 11) because I was applying pressure so I could grip them to turn. They are indeed jumping as each tooth meshes

If I pop this assembly on it's side and try and turn from both sides using my fingers whilst instead 'pulling' on these diff gears (fig 11), then it is smoother.

So I guess there is some play (lateral?) on the spider gears, perhaps the thrust washer (fig 15) is damaged/worn/missing, or perhaps that is normal? I am still pretty sure the front did not do this though.

Assuming we have established that all diffs don't do this and I haven't just been a fool by pushing down as I turn them, I guess I'll need to find a garage with someone strong enough to get those bloody bolts (23) out

Thanks again for your help!

I've just stripped and rebuilt a diff to replace the 22 spline side gears with 26 spline ones for HD Trail Gear shafts, I'm pretty sure they're still on the bench if you want them (for the price of just the postage), if you're going to the effort of replacing the thrust washers (Martin can get them, the shop on this fine forum - see top banner).. (Front and rear side gears are the same by the way)

The crown wheel bolts are loctite'd in, you'll need a socket and a breaker bar if you want to crack them out yourself... remember to get them loctite'd back in and torque'd to spec (in the BigJimny Wiki in the top menu)

HTH
Dave

Thanks Dave,

I'm now willing to bet this is normal, I have just rechecked the front and it does do the same after all! I must just have been applying a little more pressure to the rear as it has a couple of extra gears, thus a little extra resistance.

I'm pleased to say it can stay in one piece and I'll be getting them fitted confident that they should be ok.

Thanks again for your help and I very much appreciate your offer!

No problem! 

Glad you've got it sorted! 

Our 2006 Jimny had advisories on clicking rear diff in MOT test for several years now. It never makes a noise while driving. If the rear wheels are lifted and the prop shaft turned, still no noise. But if one rear wheel is turned while the prop shaft is braked, gearbox in park, the diff bevel gears click softly, as the other rear wheel turns in the opposite direction. Like you, I guess it is just the setup of the rear diff bevel gears. The front diff does it, but softer. A tin of Wynns helped dampen the rear axle clicking a little.

That sounds like a good example of a garage fishing for business through their MOT lane if ever there was.

My thoughts exactly. The next MOT test should be interesting.