Flywheel reference sensor magnet

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Notelect
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Joined: Jun 10, 2020 5:12 PM
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Flywheel reference sensor magnet

Post by Notelect »

I am manual swapping my 528, posted about it before, and when researching the speed and reference sensors I noticed the flywheel needs a pin for the reference sensor to play off of. However I don't see that pin on my flywheel nor do I see it on the diagram for it on real OEM.

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#8 is a dowel pin and there are three of them for the clutch to align. For manuals do the reference sensors play off of the dowel pins or am I missing something? Looking at pics of other flywheels I don't see anything save the dowels that the reference sensor could play off of
Notelect
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Re: Flywheel reference sensor magnet

Post by Notelect »

Think I found I actually

Found this picture elsewhere

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This is what it should look like on my flywheel, right?
1st 5er
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Re: Flywheel reference sensor magnet

Post by 1st 5er »

Yes.
I'm not aware of a separate # being that it's an integral part of the flywheel and specific to each application.
Notelect
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Re: Flywheel reference sensor magnet

Post by Notelect »

1st 5er wrote: Dec 29, 2024 9:08 PM Yes.
I'm not aware of a separate # being that it's an integral part of the flywheel and specific to each application.
I might try to weld on the piece from the flex plate from when it was an automatic.

Is there any specifics on how large the piece should be, or is there wiggle room? Piece I have is bigger than the piece welded on in the image above
BDKawey
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Re: Flywheel reference sensor magnet

Post by BDKawey »

for how archaic these efi systems are a few thou isnt going to make your engine explode. nail its location and make sure its welded good
gadget73
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Re: Flywheel reference sensor magnet

Post by gadget73 »

Whats it actually using the sensor for, just engine speed, or does it need an accurate timing reference for something? If its batch fire and not driving the ignition I'd assume its just speed. At that point its not super critical, just make sure its well attached. Don't want that thing flying off at 5 grand.
Mike W.
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Re: Flywheel reference sensor magnet

Post by Mike W. »

gadget73 wrote: Dec 31, 2024 9:43 AM Whats it actually using the sensor for, just engine speed, or does it need an accurate timing reference for something? If its batch fire and not driving the ignition I'd assume its just speed. At that point its not super critical, just make sure its well attached. Don't want that thing flying off at 5 grand.
The sensor is for ignition timing so it's got to be pretty close. However I don't know how much clearance there is between the tab and the sensor. I've always thought if I had one fail on a M/T car I'd try tapping a small hole and putting a small bolt in there. With red locktite. Never done it, but that's what I'd do.
Tone1633
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Re: Flywheel reference sensor magnet

Post by Tone1633 »

Does anyone have the correct position for the reference sensor block. I am in the same predicament and need to weld a tab on, but need the correct positioning. Either dimensions or a tracing..... Thanks
Mike W.
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Re: Flywheel reference sensor magnet

Post by Mike W. »

Tone1633 wrote: Jan 02, 2025 4:06 PM Does anyone have the correct position for the reference sensor block. I am in the same predicament and need to weld a tab on, but need the correct positioning. Either dimensions or a tracing..... Thanks
 
 
A/T or M/T?  I can probably measure it, but it might be a few days.  I measured one long ago for a guy in Australia, but gawd, that must have been 20 years ago and I doubt I can find the info anymore.  Ping me if I don't report in a few days, I'm not a flake but I am entirely capable of forgetting.
JohnH
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Re: Flywheel reference sensor magnet

Post by JohnH »

I went down this route when I fitted a manual gearbox to my 525e Auto. I used an E21 flywheel, but for the life of me icant find/remember how I worked the tab position out.

All I remember is thinking that the car was a bit gutless and the whole project was a waste of time. 

I would highly recommend fitting motronic M1.3, which dosent use the flywheel tab, rather a timing wheel on the front of the engine. You will want to do this anyway when you fit a 731 head on it anyway. 
Tone1633
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Re: Flywheel reference sensor magnet

Post by Tone1633 »

Thanks for the response, Mine is a manual...

Thanks
Mike W.
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Re: Flywheel reference sensor magnet

Post by Mike W. »

OK, took a reminder but I finally dug it out and took measurements and pictures.  The image a few posts up does look like what I remember, but not what I have, which I think came off an '82, E24.  But it was probably at least 15 years ago I pulled it so I might have the exact car wrong.  But it is a lightweight motronic flywheel.  Images didn't come out as clear as I would have liked, wow, like that's a first, but hopefully usable.  And I have the direction of the cutout by the tab facing in the wrong direction, look at the pic to be clear on that, not my scribbling.  And feel free to ask more questions.  Also, especially to the OP, don't forget the stiffener/spacer on the bolts and the bolts themselves are a different length than the ones on Autos.

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