Help with an auto to manual swap

E28 technical advice asked and given! Troubleshooting, modifications and more.
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mrvedit
Posts: 19
Joined: Jul 26, 2017 10:52 PM
Location: Ann Arbor, MI

Help with an auto to manual swap

Post by mrvedit »

I purchased a well preserved '86 535i with an automatic and am in the process of swapping it to a manual trans.
A BMW JY owner friend, very experienced with these cars, removed "everything" he said I would need from a '85 535is that had a very marginal body. This included the trans, shifter, driveshaft, brake & clutch pedals, clutch master and slave cylinders and associated hardware.
I bought a new clutch kit, shifter repair kit, new clutch slave cylinder and lines, clutch master cylinder rebuilt kit and assorted more.
Having recently swapped an E32 (M30B35) engine and manual trans into an originally manual E28, I know this process pretty well.
Not related, but I also stripped down the engine to the long block, and replaced/rebuilt or cleaned/painted nearly every part, replaced every hose, thermostat housing, etc.
I will ask specific questions in the following posts, but these pictures show were I am now. (Yes, I have a hoist in my home garage.)

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mrvedit
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Re: Help with an auto to manual swap

Post by mrvedit »

My first question related to how to mount the bearing needed at the rear of the shifter. Originally manual trans cars have a bracket bolted/welded (?)
to the tunnel to hold the bearing. The E28 has one type type of bearing in a mini-bracket which needs to bolt to the body bracke; later models have a better bearing and I don't know how that mounts.
Anyone swapping to a manual trans needs to solve this.
Any help available please?
mrvedit
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Joined: Jul 26, 2017 10:52 PM
Location: Ann Arbor, MI

Re: Help with an auto to manual swap

Post by mrvedit »

My 2nd question...
The RealOem.com diagram shows a compression spring on the clutch pedal. I cannot yet figure out how that all mounts. (My previous manual E28 is not readily available.)
Thanks in advance for any advice or pics of all the parts mounted on the clutch pedal.
dsmith
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Re: Help with an auto to manual swap

Post by dsmith »

#1: Make the bracket out of sheet metal and weld to the tunnel. If you are missing the piece that attaches to the rear of the shifter, get this:

https://www.turnermotorsport.com/p-3926 ... 8-e30-e34/

#2: Look at the replacement in this link. Try to buy this one if available.

viewtopic.php?f=4&t=149057&start=25
mrvedit
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Joined: Jul 26, 2017 10:52 PM
Location: Ann Arbor, MI

Re: Help with an auto to manual swap

Post by mrvedit »

Thank you for the reply and suggestions dmsith.
I do have the piece you mention in your #1 reply.
I will follow the link you mention in your #2 reply to see if I can get a better compression spring; the one supplied to me is broken and they cost about $80 new.

I got the automatic shifter out, approximately aligned the trans on a trans jack and that brought up two new questions related to the below pics:

Q3 - Since the manual trans is much shorter, it appears I need a different trans mounting bracket. Perhaps my friend forgot to include that part.

Q4 - The new shift boot seems to be designed for a 4" hole, but my hole is only about 3.5". So do I enlarge it? Centered or offset to front or back?
(I approximated the trans position by measuring 16" back from the engine mounting holes.)

If another thread already answer all these questions, please let me know of it. I searched but couldn't find it.

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Thank you again.
mrvedit
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Re: Help with an auto to manual swap

Post by mrvedit »

Quick update, I have figured out that a totally different trans crossmember is used with the manual trans.
Unfortunately the ones listed on ebay are in Europe. Hopefully my JY friend can pull it out of the trans donor car.

I am still hoping that someone who has done this swap can confirm the shifter hole in the tunnel has to be enlarged and how.
Mike W.
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Re: Help with an auto to manual swap

Post by Mike W. »

In case you are unfamiliar with it, Realoem.com is a great resource. Not perfect, there are errors, and they list more what came on what year, not what fits or is interchangeable, but still invaluable.

Realoem should confirm, but I believe that dust boot was universal across the years.

Tranny crossmember was not just A/T or M/T specific, but transmission specific. One for say a G265/6 will not fit what appears to be a G260/6. Nor will the rubber mounts. 260/5 and 260/6 may or may not be interchangeable on those parts, check again with Realoem.
demetk
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Re: Help with an auto to manual swap

Post by demetk »

Dust boots are the same.

You will also need the manual TPS and some rewiring to add the WOT signal to the ecu.
mrvedit
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Joined: Jul 26, 2017 10:52 PM
Location: Ann Arbor, MI

Re: Help with an auto to manual swap

Post by mrvedit »

Thank you for chiming in Mike.
Yes, I am familiar with RealOem.com and have been checking it daily during this swap, but didn't think to look up the trans mounting bracket.
RealOEM shows it as 23711175731; none on ebay and new ones are a painful $190.
Thanks for pointing out that I need to verify the trans model # when buying on ebay.
My trans # is 260.0.1302.90, so presumably a Getrag 260.

Wow you have 24,500 posts. Do you recall any other trans swap threads? If not, perhaps I should document mine better.
BTW - I have "only" 6500 posts on the ls1tech.com on which I am a moderator.

Demetk: Thanks for info on the dust boots. I will measure it carefully with calipers and then enlarge the tunnel hole. Also curious if anything sits on top of the rubber boot for sound insulation. The last E28 I worked on was our "24 Hours of Lemons" car which has most sound insulation stripped out.
It appears that this automatic car had an additional switch on the TB which I have not seen on a manual trans E28. I will check the wiring differences.
Mike W.
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Re: Help with an auto to manual swap

Post by Mike W. »

There are a ton of threads on auto to manual swaps. Although none the other way that I know of. Yeah, a lot of posts, I've been here almost 20 years now and I'd been playing with BMWs long before then. Anyway, this thread may be of use. viewtopic.php?f=3&t=61367
mrvedit
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Re: Help with an auto to manual swap

Post by mrvedit »

Thanks Mike.
I had already found the thread on transmission types. Mine appears to be a G260/6. Interesting the the '85 535i had a different trans.

I enlarged the tunnel hole and installed the dust boot.
I figured out that the trans crossmember I need is # 23711128517; hopefully my dealer can get it.

For now I don't have any further questions or issues. Thanks for the help. I'll post if I need more.
dsmith
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Re: Help with an auto to manual swap

Post by dsmith »

You will also need to make a bracket for the clutch rubber hose and weld to the frame rail. It should be the same as one of the front brake hose brackets for reference.
mrvedit
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Re: Help with an auto to manual swap

Post by mrvedit »

dsmith wrote: Nov 01, 2020 12:57 AM You will also need to make a bracket for the clutch rubber hose and weld to the frame rail. It should be the same as one of the front brake hose brackets for reference.
Thanks for the guidance. Our "Lemons" E28 is up on a teammate's hoist and I will ask him to send me pictures of that too.
brickwhite
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Re: Help with an auto to manual swap

Post by brickwhite »

Crossmember can be purchased online...

https://www.ecstuning.com/b-genuine-bmw ... 711128517/

but if you ask around you should be able to find one under $100.

As the shifter hole, It does not need to be enlarged, that is a rubber mount and fits no problem...

did you get the manual drive shaft???

clutch line bracket I made on my last swap...

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welding on the rear bracket for shifter:

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mrvedit
Posts: 19
Joined: Jul 26, 2017 10:52 PM
Location: Ann Arbor, MI

Re: Help with an auto to manual swap

Post by mrvedit »

Although I only work on the swap occasionally, I have made good progress.
* The clutch master cylinder and hose are installed; screwed a HD clamp into the frame to hold the hose connection.
* Found the trans crossmember (# 23711128517) on ebay from an overseas seller; about $100 which beats the $230 new price.
* Clutch and brake pedals are installed (but see below); new sleeve bolts bought from dealer for the clutch pedal connections.
* Entire electrical diagrams printed and studied for auto to manual differences.
* Start Relay removed and bypassed to agree with manual-trans diagram
* ECU pin #28 will be grounded
* Existing TB microswitch for "Closed Throttle" should work; I may skip the "WOT" micro switch, but did order a used manual-trans TB switch #280.120.320
* Tried to remove the entire TCU harness but gave up because the subharness to C238 is hard to separate around the heater box.

Nothing to do with the swap. but glovebox latch was broken; took a lot of effort to drill/cut out the latch mechanism without ruining the glove box inself. This gave me access to the ECU and let me pop out the engine harness. Easier to install the engine harness with engine out of car.

My next puzzle is how to install the clutch compression spring; I bought a new one ($80) and the special sleeve-bolt. (Solved below)

Brickwhite: Thank you for your informative pics, especially for the shifter rear bracket.
* Yes, I have the longer manual driveshaft. I just had it cleaned and painted.
* I did enlarge the shifter hole a bit and the rubber mount now fits perfect.
* I found the crossmember on ebay from an overseas seller.
==> If you have any pics or description about mounting the clutch pedal compression springs, that would be greatly appreciated.

Thank you all.
Last edited by mrvedit on Nov 15, 2020 2:34 PM, edited 1 time in total.
maybeillbuyit
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Location: Vancouver BC

Re: Help with an auto to manual swap

Post by maybeillbuyit »

mrvedit, I just googled " BMW e28 manual pedal box" and lots of stuff comes up. Heres a video of someone looking at a manual and auto pedal box. About 3 min in it shows how the clutch return spring is situated

https://www.youtube.com/watch?v=tIIo2x__CMQ

Theres also this on the forum:

viewtopic.php?f=4&t=149057
duggi
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Re: Help with an auto to manual swap

Post by duggi »

Mike W. wrote: Oct 31, 2020 8:24 PMThere are a ton of threads on auto to manual swaps. Although none the other way that I know of.
Mike you know of at least one...but there is no thread on it, for obvious reasons. :laugh:
Mike W.
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Re: Help with an auto to manual swap

Post by Mike W. »

duggi wrote: Nov 14, 2020 1:06 PM
Mike W. wrote: Oct 31, 2020 8:24 PMThere are a ton of threads on auto to manual swaps. Although none the other way that I know of.
Mike you know of at least one...but there is no thread on it, for obvious reasons. :laugh:
Well, E28 specifically. I thought about mentioning the E12 but I didn't. :rofl:
mrvedit
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Joined: Jul 26, 2017 10:52 PM
Location: Ann Arbor, MI

Re: Help with an auto to manual swap

Post by mrvedit »

Thanks.
After I cut some of the sound insulation away behind the clutch pedal I quickly figured out that the clutch spring simply fits into a crease of the firewall and is held in only by the weight of the clutch pedal; the clutch master cylinder prevents the clutch pedal from releasing too far and dropping the spring. Very simple, just not what I expected from typical German "overengineering".

Instead of trying to remove the entire auto-trans harness (which near its C238 end was stuck around the heater box), I instead unwrapped it from the shifter all the way to the TCU connector. I cut off the TCU connector and the dash lights connector. This let me pull out all the unwanted wires, leaving just the WOT throttle switch wire (Grey/Yellow) and the 10 wires from C238, the connector near the ECU.

This let me make all the necessary electrical changes behind the instrument cluster instead of all over the place. Just 3 splices are needed:
ECU Pin 28 to Ground to bypass the Park/Neutral safety switch. - Splice Brown/Violet to Brown, both from C238.
ECU Pin 3 to WOT throttle switch under the gas pedal. - Splice Brown/Violet from C238 to the Grey/Yellow from the shifter area.
Cruise Control enable - Splice Blue/Brown wire (cut from dash lights connector) to a new ground wire running to the ground connection under steering column.

Another benefit of leaving the C238 connector and its wires in the dash is that it gives me signals and wires I might want to use in the future.
* +5V from the ECU Pin 10 (Brown/Green)
* +12V from the main relay (Red)
* Tach signal (Black/Blue)
* Fuel Rate signal (White)
* 3 wires that terminate near the TB where the Rheostat used by the TCU used to be (Orange/Black, Yellow, Brown)
Obviously I put tape over all the unused wire ends. And labeled each wire and splice. It finally looked like this:

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LarryM
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Re: Help with an auto to manual swap

Post by LarryM »

Might be a little late but here are a couple of helpful threads I found when doing research for my E24's manual conversion.

tech/DaveKanTransGuide/

http://www.bimmerforums.com/forum/showt ... n-Swap-DIY
cek
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Re: Help with an auto to manual swap

Post by cek »

This is a Good thread.
mrvedit
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Re: Help with an auto to manual swap

Post by mrvedit »

Yes, that is a good thread on the E24 trans swap, but as you suspected, perhaps a bit late.
Nonetheless, if anyone searching for info on an auto-> manual E28/E24/E30 swap finds this thread in the future, it would be good to have links to other threads, especially more comprehensive ones.

In that E24 swap thread, it appeared that the author swapped the entire pedal box, which is the preferred way to go assuming the manual pedal box is available. My swap "kit" from the JY did not include the pedal box and I therefore struggled to figure out where and how the clutch compression spring mounted. Fortunately another member emailed me an excellent picture of the spring behind the clutch pedal. From that I figured out that the manual trans pedal box has a extra "finger" on which the spring mounts, but my auto trans pedal box did not have that. (That "finger" is barely visible in one pic of the E24 swap thread.)

I therefore had to add my own "finger" to hold the spring as seen in the following picture. I found a suitable bracket, bent it a bit to fit and let one end extend between the pedal box and the firewall; I had to loosen the pedal box to install it. I then used two self-tapping screws to keep it in place.
After reassembling all the pedals, it seems to work just fine.

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