[TR] [Spits] a new clunking noise

[Clark W. Nicholls]

Put the top up and close the windows, you may be able to hear the noise
better. I keep the top down to avoid this!

Here's a new one for me I experienced last fall... 74 Spitfire.

Last year on my last run of the summer (as it turned out) I noticed a
rotational clicking from the rear, similar to a u-joint. The axle U-Joints
were  both recent, considering the miles I drive, but I figured, oh-well...
I slid underneath and by feel I determined the click was on the driver side,
so I did that u-joint.  It looked fine on removal, but it's out so a new one
goes in. 

Back on the road, still there, so I did the passenger side. Same deal, old
looked fine.

Noise still there... Hmmm... Driveshaft feels fine, but perhaps? I really
don't want to do those as I've had experience with ruining the balance
before. 

I disconnected everything from the diff and twisted and turned the stub
axles and input, I could still feel a clicking. After much hesitation I
removed the diff. Turned out that the shims behind the spider gears were
worn out and there was slop there which causes this.  Never heard of such a
thing.

Ted Schumacher wasn't too surprised.  Apparently it does this when one wheel
is turning faster than the other and the spider gears are doing their thing.
Straight line they should be still, but that's really straight!

I put in a spare diff and spring. The old spring had worn out the rub
buttons between the leaves and into the leaf below and was at least an inch
shorter than the spare. All is well, now. 

It took me over a month to think this all out and get the job done, It's a
big decision to swap the diff (and it's heavy too!).

The whine from the diff I lived with for 25 years is gone as a bonus!

Clark