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Distributor shaft washers - why fiber? Alternatives?

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The distributor uses one fiber washer on each side of the housing.  My guess is that the fiber washer soaks up oil and provides lubrication but does it also dampen axial shocks as the shaft moves up and down?  How critical might that requirement be?


From what I can tell by reading the FAQ and other Bosch applications, the fiber washer on the top side almost always fails.  This makes sense, given that it does not get regularly lubed, unlike the lower one.  The question, then, why did Bosch not use and oilite washer instead?  They certainly were around.


Having taken apart two spare distributors, I measure the total axial clearance as between 3.0 and 3.1 mm, with no shims or washers installed.  Therefore, the added washers have to take up all of that, leaving the requisite .005" clearance.  My thought was to use a 12 mm ID oilite washer and ream the ID to fit the shaft.  Those are available in 1.5 mm thickness.  Add the large shim and the smaller shim to complete the top end stack.  That would permit the use of metal shims at the bottom end for a stack of 1 mm to get the correct clearance.  Preferably, at least three shims should be used to lower the relative rotational speeds.


This should result in a very durable assembly, no?

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To hazard some guesses:


1.) They have limited lifetime as well, but are much more difficult to re-lubricate and probably do not simply absorb the oil that passes over them

2.) They may break down faster in the hot environment

3.) They may be too brittle given the changing axial force applied when shifting and revving.

4.) The fiber ones probably re-lubricate from the oil that gets pushed up into the distributor. And the cloth sponge thing that is supposed to store some oil around the shaft.


I mean... all bushings eventually fail, and for the fiber ones to last so long in those conditions is kind of impressive to me. I wonder if oilite would last that long...


You should try replacing them with roller bearings or thrust bearings!!

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