Flywheel Shims

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trundletruc
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Flywheel Shims

Post by trundletruc »

I have just been looking at the design of the end-float shims behind the flywheel for a DJ engine and have been wondering how they are supposed to work? Obviously they fill up the space between the flywheel and crankcase to stop the crankshaft going backwards and forwards too much, but are they thrust washers as well and therefore subject to wear? Hopefully some expert will tell me what each component does. Do the shims rotate with the flywheel or are they stationary. Having only seen diagrams I am not sure of their diameters and what moves against what.
1. Firstly there is a thrust washer with a tab which stops it turning on the crankcase which it is next to.
2. There is a large shim which must rotate against the Thrust washer 1.? What is it fixed to in order make it rotate with the flywheel? Is this where the 2 surfaces rub and wear when you press the clutch?
3. There are 3 shims to give the right end-float. If 2. (above) is made to rotate with the flywheel? these shims should rotate also along with the flywheel. If 2. is not made to rotate the shims 3. (possibly quite thin), could remain stationary or rotate and start wearing. Is there a minimum thickness for any of these shims?
4. Then comes the "shim retainer" what does this do? Is it supposed to hold the shims so that they rotate with the flywheel or does it just hold them together as a block?
5, Lastly comes the oil seal which bears on the outer surface of the flywheel boss.

My interest is what actually happens to 2. 3. and 4. Often rear oil seals fail because they are damaged by the shims breaking up. Is this because they are too thin to provide a bearing surface when the crankshaft is forced forward by the clutch pedal, when in fact they should turn round with the flywheel and transmit the pressure to the surface between the large shim and the thrust washer?
It seems a funny system to me as most engines I have rebuild have had shims which are clamped solidly in place either behind a thrust washer or between the flywheel/front pulley or crankshaft.

Can anyone tell me what is supposed to happen?


 
Trundletruc 1984 DG-DJ Devon Moonraker

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