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Spyke

Help confirming a few M42 swap details?

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(edited)

Hey gents, if someone wouldn't mind clarifying the few things I am unsure of on the M42 swap, I'd be very grateful. I've tried to get through everything on my own using previous threads but I am hung up on the following:

 

There seems to be conflicting info I am finding on various wiring charts. Pin 6 on the c101 is for DME power, which already has a relay (white) in the engine harness. JakeB's chart shows that needing to be powered off another relay with 15 amp fuse. Another says no relay and a 20 amp fuse. With it already having a relay in place, it would make sense that this would only be a 12v signal, then it's jusy a matter of it being 15 or 20 amps.

 

Similarly, pin 7 is for the coil power. This also says to power from a relay, with no fuse. Another post I found states that this is a signal only, and given that the 91 318 did have an external coil, I am not sure which is right.

 

Pin 15 is labeled as Starting Signal, which I don't see being used anywhere, and I find that really odd...

 

Thank you in advance for anything that can be confirmed! I'm trying my best to wrap my head around all of this, and as much as I've stared and traced wiring diagrams I can't seem to grasp these last few details.

Edited by Spyke
remove answered issues.

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I see you aren’t getting a lot of response, and I can’t help you much, either. I would suggest you call the good guys at Classic Daily. They’ve done this swap numerous times; I’m certain they can help you. 
 

Ed Z

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I've not done the M42 conversion, but from doing 5- speed conversions,

the shifter details aren't hard to work out once the transmission's in place.

I usually cut and weld the plate and the rod, and twist the rod ends relative

to each other to bias the shifter towards me.  Because I have short arms?

 

That clutch line will work.  The E21 version should, as well.

 

What's your M42 donor car?

 

I've only worked on the E36 M42- it has coil- per- plug, and as such, 

you'd need a way to sum the switched negative of all 4 coils.  

If you have Brent's tach adapter https://www.autosportlabs.com/product/tach-adapter/

you'll want the negative from all 4 coils.

If you really only have 2 coils, yes, the negatives from them are enough.

 

Hope this helps-  

t

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(edited)

1

15 hours ago, Spyke said:

 

 

1) Shortened & redrilled e21 platform (for Getrag 240)

I ended up using the shortened 02 platform. Drilled and tapped the trans (per Clay @ http://tx02.blogspot.com) to use the stock mounts. The e30 platform didnt' have enough room near the trans side pivot when done this way.

This also allowed the use of the 02 brace and foam donut for semi-stock appeal. Just bolted the bottom of the brace to the new trans mount.

 

2) Clutch line

I used the rogers tii one. Looks really close to the same as the IE one, just a little different bends.

I know some people haven't had a good experience with him, but mine have been perfect. He even refunded some of my shipping cost. Of course I have only bought new parts.

 

3) Selector Rod

 As Tobyb said, I did this in place, no measuring, just eyeballed. I also used the threaded rod method for the minute adjustments..

 

4) Tach Adapter

I had the autosports tach adaptort. It is just the two wires. One in from the ecu ( wire 9 from the c101) to the spot marked "coil 1" on the apdaptor.  Then the other out from the "tach" marking to the actual tach. I ended up removing the adaptor as I was chasing a miss problem. The adaptor was not the issue, but apparently on the 75 and 76 you can run straight from pin 9 to the tach. I have, and it works fine.

Hope this helps a little.

I was just a jake B's site and saw the new headers. Wish he would've had those earlier.

 

Edited by GoGo Garnet

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Interesting... Still a lot of unknowns even though this hasn't been a new swap for 10 years or so.

 

I'll try and just keep driving the struggle bus and update with all the details I find out when I'm done with the swap.

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On 5/16/2020 at 7:35 PM, Spyke said:

1) Shortened & redrilled e21 platform (for Getrag 240)

The photo referenced by Jakeb/Clay shows the platform MUCH shorter after 12-15mm is cut off. My initial cut of 13mm ended just after the stock holes on the e21 platform. Referenced photo shows this initial 12-15mm cut falling more where the crudely drawn line is in this picture.

49876758017_21fe325b26_b.jpg

 

Cutting the e21 platform down was a mistake. As usual, trying to do things before hand to make it go faster and easier did exactly not that. It should have been left just as it was stock, as once in place it was already too short to make any minor adjustments. I can see no logical reason to use Jakeb's mounts and shorten the e21 platform. That said, I was exasperated at making it work, getting everything in place, and then finding out I could not install the pin on the selector rod/selector rod joint. The half-moon shift platform bushings and their mounting bolts (that go into the tapped transmission bosses) are in the way. So, I found two more e30 airbox bushings, chopped the shifter platform down to just the area around the cup, and mounted it up. I trimmed down the e21 foam piece (it has a metal core) as well to fill the void. Now it's a semi-rigid body mounted shifter, which I will probably be much happier with anyways. (The trans mounts are Delrin.)

 

50031594312_930600dcbf_b.jpg

50031603857_c95b3be896_b.jpg

50031597802_cac9a21c29_b.jpg

50030792693_02aba38a1e_b.jpg

 

On 5/16/2020 at 7:35 PM, Spyke said:

2) Clutch line

I'm sure this is an easy one, I just don't see it mentioned anywhere in the swap threads. From viewing what's available on Ireland's page, it would appear the line I need is the "Long Clutch Line for 5-Speed Conversion" as it has both small male threaded ends.

Link: iemotorsport.com/product/long-clutch-line-for-5-speed-conversion/

 

IE 5 speed conversion clutch line is in hand, looks like it will work perfect. Fluids will be the last thing in of course, so not officially tested.

 

On 5/16/2020 at 7:35 PM, Spyke said:

3) Selector Rod

The only recommended measurement I've seen for center-to-center of posts on the selector rod is 8.5" or 216mm. This would I believe lead me to the e30 M3 selector rod which is noted at 215mm center-to-center. However I've seen the e36 M3 rod called out more than once so again just wanting to confirm.

 

The selector rod is indeed 8.5" (216mm) center-to-center, using Jakeb's mounts.

 

On 5/16/2020 at 7:35 PM, Spyke said:

4) Tach Adapter

I've got the Autosports Lab adapter to boost signal to the stock 2002 tachometer, and given this is a 4 cylinder wasted spark setup, I should only need two wires? If this is correct, I assume I must intercept the signal before the coils?

 

The adapter I will not incorporate unless the tach doesn't work when it's up and running. I am hung up on a couple details in the wiring, as again I am seeing conflicting info.

 

#6 on the c101 is listed as the M42 ECU Power in Jakeb's list, however in the wiring diagram this is listed as "12V to Diagnostic Connector from Fuse 11 / Ignition Switch". This leads to pin #16 on the Diagnostic Connector. The white main relay which is incorporated into the engine wiring harness already, is what I believe powers the ECU.

 

#15 is skipped over in Jakeb's list, but in the wiring diagram it's labeled "Engine Starting Signal" which seems odd to ignore. This goes over to the Starter, at contact 30h.

 

The rest is very straight forward.

 

 

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For the tach adapter, one wire from the tach to the adapter and another to the ECU wire off the C101. Simple. See my old post here.

 

For the shifter platform, I used the stock 2002 one, but had the E21 in hand just in case.  I did use the E30 shifter which i like better.  

 

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Bump, I think I have almost everything figured out besides two wires and one questionable wire that I may not need at all.

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(edited)

(Updated first post) 

Edited by Spyke

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Yup, that's  one of 3 that I have, but it conflicts with Jakeb's writeup, which is why I am in limbo on 6 and 7

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Damn, I wish I could remember how I did it, I am sure JakeB can help you, he was super nice when I did mine.  Unfortunately I would have to rip apart the loom I made to see what connects to what.

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1 hour ago, Lost&FoundDept said:

I found this helpful when I did my swap. 
https://www.r3vlimited.com/board/forum/e30-technical-forums/24v-engine-swaps/m50-52-s50-52/128000-love-your-c101
Adams autosport tach adapter worked great for me. 
 

it’s a super fun engine in the car. 

That's massively helpful. Looks like pin 6 and 7 are indeed just signal only, so I'll be ignoring Jakeb's call for relays. 

 

Thank you very much, I'm not sure why that didn't come up in all my forum searches, but I am saving the shit out of that link. Thank you kind sir!!!

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3 minutes ago, Spyke said:

That's massively helpful. Looks like pin 6 and 7 are indeed just signal only, so I'll be ignoring Jakeb's call for relays. 

 

Thank you very much, I'm not sure why that didn't come up in all my forum searches, but I am saving the shit out of that link. Thank you kind sir!!!

 

Glad it helps. A mechanic friend showed me that thread. I will say I still definitely followed JakeB's writeup. Pretty sure I added 2 relays, 3 if you include my fan relay. And 4 or 5 fuses.

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