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Differential Play Returns

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RJS

RJS

Jedi Warrior
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Ugh! I had my diff out 3 years and 3,000 miles ago for a rebuild. Despite new seals, new bearings, spider and pinion gears shimmed and clearanced, the play appears to be back as bad as ever. Crown and pinion were pronounced good at the time.

It was great after the rebuild but the "clunk" returned when I pulled it from winter storage this spring. I was under the car this morning and confirmed the play is inside the diff.

Is this even worth pursuing or do I just learn to live with it?

Bob
 
I'd go after it. If it is degrading that fast, total failure cannot be far away. There's also some small chance it's as simple as the input flange nut coming loose.
 
Hi, I rebuilt a couple (3's and 4's) years ago, but followed the recommendations for both late model Spits (Mark 4) AND TR 5 and 250, which say zero ("0") backlash in the differential assembly. Between the differential (suns, with the splines) and the pinion (planetaries). Now I did test heat one assembly with a heat gun (maybe 200 degrees) dry with no lube and it still turned. So I say zero is the way to go. Also recommend checking all splines on your outer axles first as I think that's the more likely source of your clunk on an IRS. Jack up that rear, put it jackstands, get a friend to hold the inner flange maybe with a pipe wrench etc, and rotate the tire back and forth. That clearance will make itself known if thats it. Could be the pinion / crown but doubt it. If there's a real problem inside the gears, it ought to show up in the oil, get a magnet. Good luck.

PS OOps reread yours and you did figure out its not the outer splines, but could be the inner and the axle splines have been known to fail on rare occasions. If that were the case change the splined gear also, they may seen OK but aren't.
 
Two quick things:

1) I adjusted my clutch so I can engage it much more smoothly now. This reduces the clunk from the diff quite significantly (actually it was more like a "bang"),
2) I measured the rotational play in the diff. I'd say it's about 3 to 5 degrees of play. Does that sound reasonable, excessive, or....?

Cheers,

Bob
PS: hot summer weather in CT. Perfect day for a drive!
 
Considering all the splines, gears, thrust washers and bearings involved, all of which wear and develop play, you are in good shape for an old rear end.
Bob
 
Very reasonable. The book calls for .004" to .006" backlash in the ring & pinion, but as Bob says there are many other sources that each contribute a little.
 
Update. I further worked on the clutch slave cylinder. I removed, cleaned. lubed and replaced the clutch slave fork. I added the spring on the spring pin (clutch fork clevis) and added the clutch slave return spring with the correct return spring anchor plate. Then adjusted clutch slave to 0.1" (2.5mm) play, per the manual (actually, I used the advice of Buckeye Triumphs and added 2.4 turns of play to the clutch slave push rod).

Well, I can report that it's like having a new clutch. The pedal pressure and engagement is dramatically improved. Before the clutch was incredibly heavy and acted like an "on-off" switch.

The end result is a clutch which works properly and no more clunk or bang from the diff. Engagement is smooth. It's amazing how sensitive the clutch is to slave adjustments.

Bob
PS: so, it appears my 3 to 5 degrees of rotational play in the diff may be within tolerance and acceptable.
 
too bad you cant put a Nissan diff in, I put one in my TR6 and its made a world of different, no more clunking and banging, Nice and quite plus its a limited slip unit
I have the original unit out and need to get rid of it, it was rebuilt about 2000 miles ago too

Hondo
 
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