The comprehensive DOHC engine swap thread.

[cheades]

Addissimo - If you have access to someone who can do a bit of welding for you they can modify the existing tranny brace to use the stock mounts. I did this because then both mounts sat nice and flush as I have read the e21 mounts sit with a lot of stress on them.

i3uller - Use either an e36 or e34 cable, I believe you only need the e30 M3 driveshaft if you use the e36 M3 tranny.

[Addissimo]

i3uller- go for the e30 tranny- the e36 might seem nice because its alittle closer ratio- but cruising with a 1:1 5th sucks man. Staying with a higher(number) geared diff will make acceleration much faster, and still allow relaxed cruising speeds. You also get stuck with a dual mass flywheel (unless ofcourse you got a lightweight one).

-Addis

[i3uller]

i3uller- go for the e30 tranny- the e36 might seem nice because its alittle closer ratio- but cruising with a 1:1 5th sucks man. Staying with a higher(number) geared diff will make acceleration much faster, and still allow relaxed cruising speeds. You also get stuck with a dual mass flywheel (unless ofcourse you got a lightweight one).

-Addis

Well I'm not on the freeway much and I already have an e36 5 speed with a LTW kit.

[i3uller]

Also...does anyone have a detailed graph of how to rewire the body to chassis wiring?

[Addissimo]

if you're looking for just the harness, AKG has a spreadsheet with all that info on it.

https://www.akgmotorsport.com

-Addis

[DEV0 E30]

I picked up a parts car for almost nothing, and I think I'm going to slowly piece together my dream of a 24v E30 with it. I see alot of later model guys are spending around 1-2k and upwards of 3-4k. I want to replace/upgrade alot the the maintence items before it goes into the car, what is this stuff about replacing plastic with metal? I gotta start looking around at junkyards for parts but I just got a few quick questions.

The 'E' tranny will work with a M50 correct?
And the driveshaft would need isn't it the 318 from an M10 E30?

I'm on break at work but a few tips and tricks would be nice.

[Beej '86 325es]

The 'E' tranny will work with a M50 correct?

Correct.

And the driveshaft would need isn't it the 318 from an M10 E30?

No, if you use the M20 transmission, you need the stock M20 driveshaft.

[Ferret]

I trial fitted the engine (m50)-tranny (e30 tranny) assebmly in my car (MY 1985). The assebmly doesn't sit paralel to the ground when viewed fro the side. the front of the engine is higher than the back of the transmission. If I try to raise the back of the transmission its top would touch the transmission tunnel and if I tried to lower the engine by using shorter engine mounts the sump would touch the subframe. Is it the angle everyones engine is sitting, or did I do somthing wrong? What are the normal transmission to tunner and sump to subframe clearances?

Thanks,
Avner.

[Bimmerfanatik]

Wow. 2 days later, I finished this monster of a thread, and boy did I learn a lot.

One question did go unanswered, and it directly applies to me:

I have an 85 325e, does that not have an engine plug? What wires would I be connecting and would it be worth it to get the treehouse racing connector?

Any word on this?

Thanks to everyone for the information. Us "wusses" who have waited it out will have a much smoother install thanks to the blood and tears you've put into it. Thanks for paving the way!

[86325e]

My car is a 85 325e. Just send me a PM when you're ready and I'll send you an exact diagram of what I did.

Wow. 2 days later, I finished this monster of a thread, and boy did I learn a lot.

One question did go unanswered, and it directly applies to me:

I have an 85 325e, does that not have an engine plug? What wires would I be connecting and would it be worth it to get the treehouse racing connector?

Any word on this?

Thanks to everyone for the information. Us "wusses" who have waited it out will have a much smoother install thanks to the blood and tears you've put into it. Thanks for paving the way!

[Addissimo]

I trial fitted the engine (m50)-tranny (e30 tranny) assebmly in my car (MY 1985). The assebmly doesn't sit paralel to the ground when viewed fro the side. the front of the engine is higher than the back of the transmission. If I try to raise the back of the transmission its top would touch the transmission tunnel and if I tried to lower the engine by using shorter engine mounts the sump would touch the subframe. Is it the angle everyones engine is sitting, or did I do somthing wrong? What are the normal transmission to tunner and sump to subframe clearances?

Thanks,
Avner.

As long as you are using the correct engine mounts, in the correct holes, it should be fine. Once you get your tranny mounted, it should even out a bit. The main concern is that your hood closes on it. I know when i first got the engine in, I was thinking the same thing as you, I just put my hood on and since it fit, figured it was good. Easy enough.

-Addis

[Jason89i]

if you're looking for just the harness, AKG has a spreadsheet with all that info on it.

https://www.akgmotorsport.com

-Addis

that wiring diagram is a great start.....but it is missing a few wires....and could be simplified. (oil level sensor, speed reference sensor, k5 relay (or is it k7). it is covered somewhere in this thread.

[Addissimo]

if you're looking for just the harness, AKG has a spreadsheet with all that info on it.

https://www.akgmotorsport.com

-Addis

that wiring diagram is a great start.....but it is missing a few wires....and could be simplified. (oil level sensor, speed reference sensor, k5 relay (or is it k7). it is covered somewhere in this thread.

I used an e34 engine harness, and an e36 body plug... It was a pain, and I didnt actually use AKG's diagram.

-Addis

[joshh]

That was quite a read. I had a ton of questions and have had most of them answered.
Its tough reading all this without actually doing any work and seeing how it all fits together. I'm new to BMW's and have done alot with Acuras.
Thanks to all of you who have pulled their hair out trying to get these working.
Funny thing happened. I started to read this thread and literally hours later a guy posted a 525i for sale....F yeah! You guys have added alot more to the honey do list...,thanks! ;)
I bought a wrecked 525i auto ($725.00). I'm keeping the my 86 E stock from the tranny back for simplicity for now. I'm still very fuzzy on the wiring but will get more into that with the start of the install.

I still have a couple questions:
1. Will the auto ECU and harness work? I read several things about the 525i harness working but not specificly the auto harness and ECU.
2. Why can't I use the stock E master and booster? I thought I read you can but it seems everyone is replacing them.


I'm sure I will have a ton more questions later. Thanks for any help and all your hard work in helping us noobs.

[motors4me]

To all those out there that have completed the swap already:
I am useing the e36 five speed trans and the e36 slave for the clutch. I was told by the Dealer parts guy, that used to have a s52 e30, that the e30 master would work for the e36 slave. I am not sure if there is still air in the system or what, but I have to push the pedal all the way to the floor and it still is not disengaging all the way.

Is it always necessary to use the E36 slave cylinder? I just got to this point while putting my trans. in and noticed that the E30 slave cylinder bolted right up to the E36 trans. I'm using.