Re: alfa-digest V8 #52 - L-Jetronic Flywheel Trigger Pin

[AlfaNeely@domain.elided]

       I have an 85 engine with flywheel in the garage.  Measuring from the 
ring that the pressure plate bolts to, the flywheel teeth project 
approximately 15 mm.  The little magnetic button or trigger projects 
approximately 9 mm.
       I say approximately as it is not real easy to measure.  Plus I was 
using a cheap plastic vernier caliper marked in mm.  If you need closer 
measurements, I will move a bunch of Alfa parts so I can get to it better and 
use my dial caliper.

       How did you remove the trigger from the flywheel?  I am curious as to 
what holds it in place.  It has to be more than a press fit or centrifugal 
force would remove it.  Or I would think it would.  I know from experience 
that the Bosch L Jetronic engine will turn at least 7400 RPM.  

Ciao,
Russ Neely
Oklahoma City


In a message dated 09/15/2001 8:24:11 PM Central Daylight Time, 
owner-alfa-digest@domain.elided writes:


> Date: Sat, 15 Sep 2001 18:24:01 -0700 (PDT)
> From: "charles.slayman" <Charles.Slayman@domain.elided>
> Subject: Another Question on L-Jetronic Flywheel Trigger Pin
> 
>     I think I've figured out how to set the depth of the flywheel trigger 
> pin on
> the L-Jetronic Spider.  In case you missed my earlier post, I have my 
> flywheel
> lightened.  So I wasn't sure how much to shim the trigger pin to get back to
> the correct clearance between it and the spark sensor.  I could find no
> reference in the Workshop Manual either.
>     I tried waiving a screwdriver in front of the sensor to see how 
> sensitive it
> is to gap.  I could see the ohmmeter deflect a little with the screwdriver
> several mm away.  But not knowing the sensitivity of the trigger circuitry 
> in
> the spark box, this doesn't tell me much.
>     Then I noticed that the spark sensor and engine speed sensor align with
> different parts of the flywheel!  The spark sensor aligns with the trigger 
> pin
> and the speed sensor aligns with the ring gear.  I then looked at the depth
> each sensor (the sensors are identical but the bosses on the bellhousing 
> they
> bolt into are different).  The speed sensor is flush with the inside of the
> bellhousing and the spark sensor protrudes about 4mm into the bellhousing.
>     So that tells me that the trigger pin must be recessed about 4mm from 
> the
> ring gear teeth to account for the different sensor depths.  And the depth 
> of
> the ring gear teeth are about 4mm also.  So that means the tip of the 
> trigger
> pin should be flush with the bottom of the ring gear teeth.
>     If any of the digesti has an L-Jetronic flywheel sitting around and 
> could
> confirm this, I would greatly appreciate this.  After all, if I screw it 
> up, I
> have to pull the transmission to get at it.
> 
> Thanks,
> Charlie S
> '89 Spider - soon with lightened gears and flywheel!

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