WAY MORE: distributor rotor question

[SuffolkD at aol.com]

Bernie:
I read this and laugh.
I have no expertise in this area....but I'll forge on.
Scott is stating, quite clearly, that crossfire at high HP is the "result" of 
the wider tip AND plastic gear (slop).  

"In this case it was poor design and materials selection." (which you mention 
correctly (IMHO) Bernie), as does each other person on this thread.  Scott 
just refers to it as:
"I think these plastic gear electrically arched pretty early in their service 
life, but that a bit of arching really didn't tax the really strong rods in a 
stock motor."
(referring to plastic gear and wider tip. IMHO)

THEN
Scott's line(s), one of which quoted below is a SCREAM: (like POPCORN)

"In terms of "how it would 'otherwise' manifest itself?"  By a rod exiting the
> block in a prejudicial method.  I think these plastic gear electrically
> arched pretty early in their service life, but that a bit of arching really
> didn't tax the really strong rods in a stock motor.  Add some software HP 
into the equation, like popcorn..."
AND
"Every single 20vt 3B I service, has that plastic gear inspection done unless
> documented so already.  I think that was the stupidest idea someone at audi
> had to reinvent the toothbrush."

Phil chimes in with:  pjrose at frontiernet.net writes:
>"...guess what I'm wondering is: yes, the plastic gear begins to wear and 
>presumably to develop "slop", but how does that show up in engine 
>performance so as as to force Audi/Bosch to develop a metal-geared 
>replacement? My guess is that it was the gears' catastrophic-failure 
>mode ( and not simply the gear wear) which led them to the 
>replacement gear.

A reference, (As I read it) as the second and most common reason the plastic 
gear was replaced:  A broken GEAR........
(even I have a BTDT WithRegardsToThat.)
...............not cross cap/rotor contact arching, which by this thread, is 
the #1 plastic distributor "catastrophic-failure".  
#1 only because it COULD set your 3B motor back $$$$$$$$$$$$$$$$$$$ at high 
HP and RPM on a plastic gear and wide tip rotor.
But THIS #1 reason is an extremely LOW percentage of total 3B distributor 
failures.

A little different from (plastic gear) breaking at a stop light, needing a 
tow to a shop. 
(which is the most common #2 reason of "catastrophic-failure" and why 
Audi/Bosch has gone wide to narrow tip to accompany plastic gear to metal.

Neither is this an ECU mod factor or "software" application.
Plain and simple its about the materials at the top and bottom of the "dizzy" 
and what they do/have done to 3B motors in the field.

Bernie says:
"Ditto this paragraph.  Are you trying to say that you think the plastic
geared 3B/7A distrubutors suffered cross fire to the wrong plug early in
their service life, and that this was a fault of the plastic gear?  I just
don't believe it!"....................

Here its just what I say above. Early plastic gears HAD the wide tip-ed top.  
Here its YES to "Are you trying to say that you think the plastic
geared 3B/7A distributors suffered cross fire to the wrong plug early in
their service life, and that this was a fault of the plastic gear?" because 
the gear helped the WIDE tip (that came on top) come closer to crossfire 
contact.

Its okay not to "believe it." Bernie, but from these posts and this list "I" 
do. 
Crossfire HAS happened once - mentioned long ago. to a ~450/500HP 3B as I 
recall.

-Scott by BOSTON not trying to whip the "froth" up any higher............
#1 rarest most expensive failure result.  Spark Arc
#2 most common plastic gear failure (BREAK)  
$3/400 replacement. (~$200 part & 1 hour labor) 
Please correct me if I was wrong or did a poor job in cut and pasting these 
threads together into an explanation.


In a message dated 12/8/2003 11:25:39 PM Eastern Standard Time, 
200q20v-request at audifans.com writes:
> > 
> Ditto this paragraph.  Are you trying to say that you think the plastic
> geared 3B/7A distrubutors suffered cross fire to the wrong plug early in
> their service life, and that this was a fault of the plastic gear?  I just
> don't believe it!
> > 
> > Every single 20vt 3B I service, has that plastic gear inspection done 
> unless
> > documented so already.  I think that was the stupidest idea someone at audi
> > had to reinvent the toothbrush.
> Nothing basicly wrong with a plastic gear in this application.  In this case
>