Reference sensor spacing?

[The Glademister]

So I figured out why my new SPEC aluminum flywheel was missing two of the trigger screws present on the OE flywheel yesterday through this thread and more research...

924Board.org :: View topic - Extra sensor trigger screws on 924S/944 flywheel?

And I installed the SPEC flywheel last night. But it appears the spacing on the sensors is going to need to be adjusted. I'm thinking that doing that now with great access to the sensor bracket in the bell housing tunnel, from below. I can adjust the bracket with the reference sensor temporarily installed by measuring from the trigger screw on the new flywheel. However, everything I've read says to measure .8 mm on the speed sensor and that, in turn, sets your reference sensor. So does anyone know what the reference sensor ends up at you you follow that procedure? Another reason I need to know is because the trigger screw on the SPEC flywheel is much shorter than OE. I suspect I'm going to have to back that out a ways to get the correct gap.

[The Glademister]

So here's what I'm looking at. Speed sensor set at .8 mm from the ring gear with no space. The reference sensor is off the pin considerably more. I set the pin height at 6 mm off the flywheel. That just looks really far away to me.

[Arizona_928]

use a credit card for spacing... ref & speed are the same btw

[The Glademister]

Originally Posted by AZ_porschekid

use a credit card for spacing... ref & speed are the same btw

Yeah, I was actually able to get a feeler gauge under the speed sensor. There's no way both could have the same spacing as the reference sensor mounting is raised probably 4 mm higher than the speed sensor which is flush to the bracket. Add the sleeve for the reference sensor and I suspect there's 4.5 - 5 mm difference in elevation. That might be different in the early brackets however. Keep in mind this 924S has a 2.7L transplant.

[9FF]

Originally Posted by The Glademister

...That might be different in the early brackets however. Keep in mind this 924S has a 2.7L transplant.

Just checking if you used the housing and bracket from the 2.7?

I found out the hard way that there are different housings and brackets for the different model variants, I now have quite a collection

[The Glademister]

Originally Posted by 9FF

Just checking if you used the housing and bracket from the 2.7?

I found out the hard way that there are different housings and brackets for the different model variants, I now have quite a collection

I didn't get the part number as I didn't pull the bracket. It does look the same as the late 944 PET diagram however.

[wildcat077]

I had the same issue when i installed mine ... turns out the outer diameter of the Spec flywheel is smaller than the OEM unit !
Took me half a day to figure out why my car wouldn't start, anyhow i ended up drilling a hole in the bottom of the bellhousing so i can adjust the height of the trigger screw and i used a vernier through the sensor hole to adjust the proper clearance.
Make sure to use red Loctite on the trigger screw after you set the right height !

[The Glademister]

Originally Posted by wildcat077

I had the same issue when i installed mine ... turns out the outer diameter of the Spec flywheel is smaller than the OEM unit !
Took me half a day to figure out why my car wouldn't start, anyhow i ended up drilling a hole in the bottom of the bellhousing so i can adjust the height of the trigger screw and i used a vernier through the sensor hole to adjust the proper clearance.
Make sure to use red Loctite on the trigger screw after you set the right height !

Good to know someone else had the same experience. When I compared the OE flywheel to the SPEC, I thought the SPEC was smaller OD. But measuring with tape revealed they're really close (within a 1/8"). I noted that the SPEC flywheel has two dimensions. The half closest to the engine has a slightly less OD than the half closest to the firewall. The sensor screw is tapped right in between the two.

Do you know what the gap between the trigger screw and reference sensor ended up being on yours?

[wildcat077]

It's something they fail to inform you about when you purchase an aftermarket flywheel ...
Anyhow , i measured the depth of the sensor from the housing and turned the engine over one turn at a time and kept adjusting the trigger screw accordingly until i got the right gap.

Drill a hole in the bottom of the bellhousing so you can get an allen key in there ,it makes
it a whole lot easier to adjust , just go a bit at a time till you get it right.
I don't remember off hand what the protrudance ( is that a word ? ) of the trigger set screw is though !

[The Glademister]

Agreed. The access hole is a good idea. If that trigger screw needs to be any longer I'm going to have to get a longer screw. The one that came with the flywheel is just grabbing the threads set at 6 mm off the edge. Thanks for your help!

[The Glademister]

Update - I finished installing the pressure plate, bell housing, clutch slave cylinder, starter, torque tube, header, new speed and reference sensors. The fuel tank is out but I wanted to confirm ignition before getting much further. So I shot a bit of ether into the MAF and cranked the engine. The tach bounced and the engine fired up. So that spacing on the reference sensor is correct as far as I can tell that this time.

[911tracker85]

LOL

I also had some challenges installing my SPEC alum flywheel. my main problem was self inflicted. but finally got it sorted out.