///M1.5 Build Thread

[amg6975]

Last summer my trusty 2012 135 spun a rod bearing, likely due to constant track use. This left me with a hard decision on what to do with it, rebuild the N55, get a "new" N55, or other. Looking at the financials, and goals for the car being a 90% track car with some cars and coffee use, with the approval of the wife (also a track junkie) I decided to just shelf the car and save my pennies to buy a wrecked donor M3 and do "the swap." By the time I fixed the N55, addressed oiling issues, sorted out the massive cooling requirements, I may as well just spend the money on a silky smooth NA S65.

I decided that this project needed to be complete this winter since I didn't want to spend another track season without it. I have several other fun cars but nothing that performs like the 135 and track days just wern't the same.

So a couple weeks ago I finally pulled the trigger and brought home a 52k mile 2013 E92 M3 DCT.

Got the thing home and I really don't understand how it was totaled out. The only thing really wrong with it was the DCT cooler was bent. It ran and drove perfectly once I peeled some damaged panels off. I really almost didn't have the heart to tear it down as a donor. I wanted to fix it and drive it, but then I'm even deeper in the project and still have a useless 1 series shell. Onward we go.

The 135 is already almost completely stripped. The plan is to strip both cars into individual piles of parts and then reassemble using the best of both worlds. It's really staggering how similar the two cars are. No one is ever going to convince me they didn't intent to put the S65 in the 1M.

My goal for this thread is to document the "hard" parts. I'm not going to post much about the tear down, or the things that simply bolt on. If there's anything specific you're curious about fire away and I'll try to document it as I go. I'm going to make three posts below this and just update them as I go to create a continuous historical record that people can reference. Hopefully I can document all the small things that other builds have skipped so more people can make this happen!

 

[amg6975]

Engine and Drivetrain

Obviously here everything is coming directly out of the M3. S65, DCT, Rear Diff, etc.

First Step is remove the Engine and start to evaluate what parts need to go where.

Engine is out

I wanted to delete the AC as it's not really necessary for a track car, it's just more things to break, and zaps a couple HP even if it's off. Issue is, the S65 (2007.5+) has a goofy belt routing where the power steering pump spins backwards and needs the AC compressor to wrap the belt around the PS pump so it's not as easy as just taking off the AC compressor and using a shorter belt.

I tired to see if an N55 PS pump, that spins the "right way" could some how be adapted but definitely no such luck. I could make a whole bracket and such but I just can't be bothered. I'll just leave the AC alone. I would buy an AC delete bracket if anyone knows of anything but I couldn't turn anything up.

*Update: I don't know why I didn't think of it sooner but the S85 never changed belt directions and still has a clockwise PS pump. $30 on eBay latter:

The bracket is different between the two, and the input port is at a slightly different angle. The S65 bracket fits on the S85 pump, and the input tube angle doesn't seem to be an issue. The hose is just slightly bent. If it leaks or anything I'll just replace the tube with something slightly more flexible and worm gear hose clamps. Now I can eliminate AC and save about 35 lbs I think. 2999lbs here I come!

Looking at exhaust set ups, I got lucky the M3 already had the secondary cats and resonators chopped out so I have a nice clean slate to work with. Just need to cut the M3 mid pipes and weld on flanges and then just bolt on the 135 mids and muffler sections. Easy peasy:

Saturday was rod bearing day. The M3 has 52k miles but I figure while the engine is already out I should probably do them. I went with BE Bearings and OEM bolts. If I had to do it again I'd by the ARP bolts just to avoid doing the OEM torquing procedure. What a pain.

Bearings were totally fine, someone took really good care of this car. Oh well, peace of mind.

 

[amg6975]

Chassis, Brakes, etc

Honestly I think this is where all the fussing around is going to be. There are some things that need to be modified to swap over so I'll document that as I go:

• Heat Shields and undertrays
• Brake Lines and Fuel Lines
• Fuel Pump
• Airbox

First Project is to see if I can salvage my trusty 17" wheels. I've been running 17x9 et42 ARC8s on the 135 and I really dig it. I have a lot of track friends that run E36s so there's an abundance of similarly sized wheels amongst us. Also, the tire cost is quite a bit lower, the ride is better over curbs, etc. I have been running 335i brakes on my 135 for several years and have no doubt they would be up to the task on the M1.5 so that's my goal. Keep the brakes, keep the wheels. The front is no issue, the 135 hubs with 335 brakes will bolt right on with the 135 tie rods. This is basically exactly what I already have since I had an M3 rack and control arms in the 135 already.

Issue is then the rear, the balance would definitely be off with 335 front brakes and M3 rear brakes. I tried every combo I could think of to get the 335 brakes bolted onto the M3 rear hub with no luck. There is also a toe arm difference between the 135 knuckle and M3 knuckle/subframe so it looks like I'm stuck with the M3 rear brakes, which means M3 front brakes, and 18" wheels. I could go to a 355mm Stoptech set up that would allegedly fit in the 17's but I just don't have it in the budget. Oh well, hopefully that's the biggest disappointment of the project so far...

What do you suppose the odds are the M3 carbon crash structure will work with the E82? They're close enough I'm 100% going to try it. They look like they're different sizes in this picture but they really aren't. The M3 may be just sliiiiightly "longer" but the 1 series bumper should accomidate that.

First minor snag I ran into is there are two studs for attaching the rear front fender liners that interfere with the V8 subframe:

I just zipped these off and applied some rattle can bed liner. Not yet sure how the fender liners are going to fit. The M3 has two pieces (actually three total) so the subframe can be exposed without removing the whole wheel liner. Maybe I can hack those to work.

 

[amg6975]

Electrical

The idea here is to pull both complete wiring harnesses and swap the whole M3 harness into the M1.5. I think the NFRM module has to stay but all the other modules will come over from the M3. I believe I also need to splice in the tail light connections from 135 since they are one piece vs split on the M3.

I've already deleted most of the audio, airbags, sunroof, seats, and such from the 135 so I'm also going to remove all that wire from the M3 harness.

First thing is data log as much as I can think of to make sure I can get M Drive and all that working in the M1.5.

A lot more wires in the DME box compared to the N55 1 series:

First "Electrical Mod" is installing the new washer reservoir. I'm going to run pre-LCI 128 halogens to save some weight at the front, so I don't need the washers, so I don't need the washer pump, lines, or wires. The other thing that struck me was that my car does not have heated washer jets as an option, but it does have heated washer jets and the wires. I'm going to remove those wires. The last thing to note about the washer jets is it's one of the differences, the M3 has them in the cowl, and the 135 has them on the hood. Should be easy enough to take care of though since I'm removing the heater wires, but if you weren't they would need to be extended to go in the 135.

My initial plan was just take the whole harness out of the M3 and put it in the 135, then change the couple things here and there as needed. Not going to work... It's amazing how much more stuff the M3 has than the 135. I'm not sure exactly what my plan is, I need to tear apart the M3 a little more and open up the harness and look at it for a couple of beers. I think I need to dig apart both harnesses and mix and match. My current line of thought is pull everything out of the 135 harness that isn't currently attached to anything, then pull all the missing pieces from the M3 harness and wrap it all back up.

Things right now that I know are different:

• Most of the ECU connections, including the power button
• Some of the DSC connections
  • Extra brake pad sensors, DSC OFF button
• EKP (Fuel Pump) module wiring
• Extra Battery + cable from the battery to the JBBF Radiator Fan
• GWS wiring is close enough it could be converted but I'll just use the M3 wiring.
• Several Engine bay things need to route to the opposite side, or are just slightly different:
  • Vacuum sensor
  • Fuel Pressure sensor
  • Aux water pump
  • Servotronic
  • Horns
  • Outside temp sensor

Modules I'll be swapping, everything else will stay from the 135:

• ECU (duh)
• DKG
• DSC
• CAS
• KOMBI
• JBBF
• EKP
• DSC sensor under driver's seat
• GWS
• Radiator Fan Relay

Thing's I'm eliminating while doing this:

• ABG module, all airbags, and sensors (track car)
• Combox
• Rear speakers, Driver's side subwoofer
• FZD
• All interior lighting
• Seat modules
• Brake pad sensors (connect wires at DSC)
• RDC
• Adaptive Headlights, washers, etc

I'm an Electrical Engineer and this is going to suck.

I've identified everything I need to get rid of in the 135 and everything I need to swap from the M3, now it's just matter of picking apart the harnesses and mixing and matching. Honestly not as bad as I thought it would be, but I swear someone took extra time to tangle these harnesses...

 

[derekgates]

holllllyyyyyy shit! Awesome!


Yes, those crash bars fit. I have been trying to snipe some one Ebay for the weight savings. https://www.e90post.com/forums/showthread.php?t=1282179

 

[amg6975]

holllllyyyyyy shit! Awesome!


Yes, those crash bars fit. I have been trying to snipe some one Ebay for the weight savings. https://www.e90post.com/forums/showthread.php?t=1282179

Interesting. Hopefully it's the same story with the 1 bumper. I didn't think the weight difference was all that much but hey, 5-10 lbs is 5-10 lbs. I'm already swapping to 128 non-LCI halogens to save 10lbs out over the front so that's 15-20 lbs all the way out over the front. Removing the bulky CSF intercooler and replacing it with the M3 oil cooler is probably another 20 lbs. Couple that 40 lbs with the S65 sitting way lower and farther back than the N55 and hopefully I can move the balance rearward quite a bit... removing rear weight is easy.

 

[derekgates]

Agree with your sentiments. I am also trying to reduce front weight; that bar saves a little bit but then I am installing an oversized intercooler and... sigh.

There is also a thread on the subframe 'brace' that the M3 uses. Talks about rigidity and how to fit it to the triangle bar setup our cars have: https://www.e90post.com/forums/showthread.php?p=26613054#post26613054


[EDIT] I keep forgetting that 1series !== 3series in all regards, so hopefully this stuff is applicable...

 

[amg6975]

Agree with your sentiments. I am also trying to reduce front weight; that bar saves a little bit but then I am installing an oversized intercooler and... sigh.

There is also a thread on the subframe 'brace' that the M3 uses. Talks about rigidity and how to fit it to the triangle bar setup our cars have: https://www.e90post.com/forums/showthread.php?p=26613054#post26613054


[EDIT] I keep forgetting that 1series !== 3series in all regards, so hopefully this stuff is applicable...

All that will be a direct bolt on from the M3 since I'm using the whole V8 subframe and everything. The rear braces are slightly different 1 vs 3 series so I'll just keep the 1 series set up rather than hack together the 3 series braces some others have done. One of my major goals is to use as many unmodified off the shelf BMW parts as I can so I can A) find parts later and B) build it like BMW would have.

 

[derekgates]

All that will be a direct bolt on from the M3 since I'm using the whole V8 subframe and everything. The rear braces are slightly different 1 vs 3 series so I'll just keep the 1 series set up rather than hack together the 3 series braces some others have done. One of my major goals is to use as many unmodified off the shelf BMW parts as I can so I can A) find parts later and B) build it like BMW would have.

ohhhhhhhh derp! Yes you are absolutely correct.

This is a very similar project to @martymil https://bmw.spoolstreet.com/threads/teaser-tuned-s65-dct-powered-1m.6981/

 

[martymil]

You don't need the front brace like the e88 the m3 belly pan is the actual brace.

You will need to mix and match the heat shielding but it fits.

You will need to change the front brake lines but I left the middle ones stock and wrapped them in heat shielding and made a bracket to hold them away from the exhaust.

Have fun and cut your hair short so you don't pull it out. LOL.

This is the ultimate conversion to the 1 series chassis, nothing even comes close.

I would leave the metal front crash bar it stiffens the front end a lot compared to the carbon fibre version.

That's why I never changed it, weight saving is not everything when you go backwards in chassis stiffness.

 

[aus335iguy]

With respect to rear brakes. I’d compromise and use non m subframe, knuckles and brakes but take all of the diff, and all the arms etc. What specifically do you need the M3 knuckles for ?

 

[aus335iguy]

Also this thread needs an update.

 

[amg6975]

With respect to rear brakes. I’d compromise and use non m subframe, knuckles and brakes but take all of the diff, and all the arms etc. What specifically do you need the M3 knuckles for ?

I need the M rear subframe for the diff. There's a knock on effect, M diff means M subframe, which means M control arms, which means M knuckle. It's fine, I'll just suck it up and run 18" wheels.

Also this thread needs an update.

Not much progress, been too cold to work in the garage... propane heater barely takes the edge off if it's really cold. Engine is out of the M3 and all the maintenance parts and such are showing up so progress is creeping along. Balmy 39 today so I'm hoping to knock out some more stuff, probably just the last little bit of 135 engine bay dismantling now that I can get in both engine bays to see exactly what's going and what's staying. After that it's just going to be more M3 dismantling to get the wire harness out.

 

[aus335iguy]

I thought m diffs fit non m subframes ?

 

[amg6975]

I thought m diffs fit non m subframes ?

I didn't think so but I'm not really all that sure. I'm not all that worried about it to be honest. The only reason I wanted to keep the 335 brakes is to run 17's but I'm over it. The M3 brakes will be nice to have.

 

[martymil]

I run 20's on mine and handles much better with no traction issues, the m3 brakes are surprisingly very good unless your tracking than I would look into
a brembo setup or the like but the stock setup works really well.

 

[amg6975]

I run 20's on mine and handles much better with no traction issues, the m3 brakes are surprisingly very good unless your tracking than I would look into
a brembo setup or the like but the stock setup works really well.

I'm certainly not going to run 20s the car is 95% track use, so the main issue is the cost of consumables, I go through at least one set of track tires a season. I was running E9x 335 brakes with Bimmerworld bushings, Stoptech rotors, and PFC08 pads and never had an issue with the brakes even when pushing as hard as the car could. I don't anticipate any issues with the M3 set up.

 

[martymil]

Not saying to run 20's just saying there wont be any issues with traction with the s65 setup even with a supercharger.

The way the motor makes power is very linear unlike n54 which is fighting for traction at the hint of boost.

 

[amg6975]

Hey @martymil how does the 1M rear portion of the front wheel liner fit with the V8 subframe? I had to cut the two little studs off to seat the subframe, curious if the 1M had the same issue.

 

[martymil]