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Spitfire Spitfire differential question

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billspit

Jedi Knight
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I was trying to reassemble my Spitfire differential this weekend and ran into a problem (Surprise!). When I dissaembled the spider gears a while back, I noticed there were no brass shims behind the horizonal gears (are those the planet or sun gears?). The factory manual shows shims there. I ordered a set install, as well as the cupped bushings behind the vertical gears. The cupped bushings were only available in .041" and it looks like .039" were previously in there. When I tried to put it all back together, the gears would not all go back in. If I removed the horizonal shims, it went together fine. This would replicate what came out.

I guess my question is, is it normal for there to be no shims behind the horizonal gears? Or do i have to hunt down thinner shims all around.

EDIT
Just did some checking on line with Rimmer Bros. The horizonal gear is called a sun wheel. The vertical gear is the planet gear. The shims are listed as copper not brass and are actulally thrust washers. Only one size is shown behind the sun wheel. Several are shown behind the planet gear, but only one size is available (0.041"). How do people sell rebuilt units if there is such a limited supply of thrust washers?
 
FWIW, they are also known as "side" and "spider" gears.

The thrust washers are important IMO, so I wouldn't leave them out. They only turn when you're going around a corner, but do take a fair amount of force if you're on the throttle while doing so (especially in first gear). OTOH, I guess if it worked before ...

Since they are just copper, I'd guess it's fairly easy to work down the cupped thrust washers with crocus cloth or similar. Certainly it should be easy to dress down the flat ones.

Did you try the new flat washers combined with the old cupped ones ?
 
I have nothing very constructive to add... other than I agree the thrust washers are probably required...

All I've read about assembling Spit diffs: difficult to get right... easy to get wrong... and why we jumped at a rebuilt one from Quantum Mechanics for $375 at Carlisle. I installed it a couple of weeks ago... the rear of the car is nice and quiet now... :cooler:

John did mention it usually takes about a half-dozen assemble-check-disassemble operations to get the gear lash set correctly; 2-3 times for the pinion gear and 2-3 times for the ring/spider assembly. This pretty much jives with tech articles about changing R&P gears and installing lockers I remember reading in old 4x4 magazines.

Hopefully, I'm not telling you anything you didn't already know... I'm still interested in how you do as we now have an extra diff sitting around... :smirk:
 
I am familiar with multiple attempts to set the gear lash and all. That's why I paid somebody $200 to do it on another differential that I bought all new parts for. The pinion on this diff has not been removed and the shims on the carrier bearings are going back in just as they came out. I'm just diddling around with the stupid spider gears in this diff. They seemed to be a bit loose to me when I checked them.

I seem to recall it would barely go back together with the old trust washers behind the sun gears and the planet wheel trust washers in place. I will check again. But they are in bad shape and that's why I was repacing them. I guess its time to find some crocus cloth (whatever that is).
 
Perhaps he means emery cloth?
 
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