distributor rotor question

Bernie Benz b.benz at charter.net
Mon Dec 8 18:48:15 EST 2003

> From: QSHIPQ at aol.com
> In a message dated 12/8/2003 3:15:12 PM Central Standard Time,
> b.benz at charter.net writes:

-Big snip-
>> ...
>> IMO and from inspection, the plastic gear does not wear to significantly
>> increase its gear train backlash.  (It had high backlash to start with,
>> which was no design problem, until poor servicing allowed the cam drive
>> system to develop its torsional vibration problems, which greatly agravated
>> the catastrophic plastic gear failure. A design's deck of falling cards)  If
>> it did so, the distributor timing mark position would require readjustment
>> to compensate for this gear tooth wear, which is not the case.  i.e. IMO,
>> gear tooth wear is not a factor in plastic gear distributor failure.
> I think high backlash IS the issue, and MORE of it comes as it wears.  Take a
> brand new plastic gear vs one with miles on it.  I don't agree that timing
> adjustment would necessarily be required if the "wear" is an increase in
> backlash.   Lots of sloppy distributors still start without codes, including
> metal geared ones.
Scott, inasmuch as the distributor timing marks must be in alignment within
a degree or so, any appreciable wear on the driven side of the plastic gear
would alter this static timing adjustment.  IMO, such wear is not the case.
Excessive dist gear backlash is normally no problem, inasmuch as the driving
cam gear is always doing so and the backlash is out of the loop.  Only if
the cam drive system has a low frequency resonant torsional vibration (the
20V dist rattle) will the dist backlash be a factor in instantaneous dist.

> SJ

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