E92 M3 Rear Subframe + Diff upgrade

[John_01]

The cog icon normally means there is some issue related to the DCT gearbox. A mechanic will be able to scan the errror code and tell you more precisely what the issue is.

[drwillb]

Originally Posted by DR-JEKL

It remains the same, the wider track on the M3's is due to the wider/lower offset M3 spec rims (so whatever offset works on a 135i)

I've got a 2010 e92 full rear end and front end sourced and will be doing the conversion to my 2012 135i in the near future.

It seems that apart from the driveshaft, this will be a direct bolt-in upgrade. However, I still don't see how the wheel fitment will be the same. I thought that the hubs and rear rotor hat thickness were big contributors to the 135 having the crazy 52mm offset. So, unless the rotor faces on the M3 rear end up with the same side to side width (rear track), how can the 135 wheels still fit?

Thanks in advance.

[houtan]

Originally Posted by drwillb

I've got a 2010 e92 full rear end and front end sourced and will be doing the conversion to my 2012 135i in the near future.

It seems that apart from the driveshaft, this will be a direct bolt-in upgrade. However, I still don't see how the wheel fitment will be the same. I thought that the hubs and rear rotor hat thickness were big contributors to the 135 having the crazy 52mm offset. So, unless the rotor faces on the M3 rear end up with the same side to side width (rear track), how can the 135 wheels still fit?

Thanks in advance.

i thought you have to upgrade to the m3 master cylinder if converting over to the M3 brakes. Either way, hopefully you will have some spare time to share your experiences on how the conversion goes, would be great to know.

[drwillb]

Originally Posted by houtan

i thought you have to upgrade to the m3 master cylinder if converting over to the M3 brakes. Either way, hopefully you will have some spare time to share your experiences on how the conversion goes, would be great to know.

Has anyone done the M3 master cylinder swap? I've read that they have different part numbers and everyone assumes the M3 part has a bigger piston but do we know what the actual (in numbers) difference is? Is it a direct bolt on swap for the master cylinder as well?

I guess I'll just throw that into my order list.

[houtan]

Originally Posted by drwillb

Has anyone done the M3 master cylinder swap? I've read that they have different part numbers and everyone assumes the M3 part has a bigger piston but do we know what the actual (in numbers) difference is? Is it a direct bolt on swap for the master cylinder as well?

I guess I'll just throw that into my order list.

I honestly have no idea. I just remember reading it in the past. hopefully someone who has done the conversion will chime in or you can find the info if it is available from a prior thread.

[drwillb]

Found a very thorough write up on the full M3 front and rear swap here:

http://www.babybmw.net/viewtopic.php...e647b939fa2333

[houtan]

Originally Posted by drwillb

Found a very thorough write up on the full M3 front and rear swap here:

http://www.babybmw.net/viewtopic.php...e647b939fa2333

oh nice! are you MT, AT, or DCT?

[drwillb]

I'm 6MT

[DR-JEKL]

Originally Posted by drwillb

I've got a 2010 e92 full rear end and front end sourced and will be doing the conversion to my 2012 135i in the near future.

It seems that apart from the driveshaft, this will be a direct bolt-in upgrade. However, I still don't see how the wheel fitment will be the same. I thought that the hubs and rear rotor hat thickness were big contributors to the 135 having the crazy 52mm offset. So, unless the rotor faces on the M3 rear end up with the same side to side width (rear track), how can the 135 wheels still fit?

Thanks in advance.

no your wheels will sit in the same position as stock (well thats the case on my E92)

FWIW I run genuine M3 ZCP/comp pack rims on my E92 335i with no issues (running 245's up front and 275's in the rear) oh and I have the M3 driveline retrofit.

[drwillb]

Jekl, I've found 2 different numbers for driveshaft length after Frankenshafting the two halves. Do you have a spec for this?

Also, thanks to the track width answer. I found the same info elsewhere: rotor face to rotor face, the M3 and 135 are the same, the difference is wheel offset on M3 wheels to push the wheels out and bodywork that is 100mm wider to create the wider track.

[houtan]

Originally Posted by drwillb

I'm 6MT

Do you have to use the m3 diff? Or will the stock 135i housing work? For a dct n55, the m3 ratios aren't close to the 2.56 dct rear end

[drwillb]

I'm planning on a full M3 rear end swap from a salvage car. The DCT diff has a 3.15 ratio so that's a nice, small bump for a 6MT 135.

You can easily find the ratios for the other M3 diffs with a quick search but the DCT is the only one close to our cars.

[froop]

The driveshaft length will vary on a few things and I wouldn't recommend making one without measuring the actual length required first.

N54 and N55 gear boxes are different so there can actually be a total of 8 different lengths depending on what combination you use.

[berne]

i am going to buy a car that has M3 LSD, and wonder if the wheels size are chaning? for ex ET and styff like that?

[froop]

Originally Posted by berne

i am going to buy a car that has M3 LSD, and wonder if the wheels size are chaning? for ex ET and styff like that?

No. It was confirmed just a couple of posts above that the hub to hub (rotor to rotor) measurements are exactly the same on all 135 and M3/1Ms etc. The only change in track width is due to wheel offset.

[Traf]

Just finished the conversion, except the fact that my diff is almost dead, it fits nicely.

[houtan]

Originally Posted by Traf

Just finished the conversion, except the fact that my diff is almost dead, it fits nicely.

So you did the full m3 rear subframe with brakes too? What about the front?

[Traf]

Originally Posted by houtan

So you did the full m3 rear subframe with brakes too? What about the front?

I only did diff conversion, so axle shafts, prop shaft and LSD only.

You can do the whole subframe but i don't think its worth the trouble, at least it wasnt for me since i had M arms already and adjustable toe arm.

Everything is a direct swap, but if you keep M3 brakes then you need to swap the master cylinder too.

[houtan]

Originally Posted by Traf

I only did diff conversion, so axle shafts, prop shaft and LSD only.

You can do the whole subframe but i don't think its worth the trouble, at least it wasnt for me since i had M arms already and adjustable toe arm.

Everything is a direct swap, but if you keep M3 brakes then you need to swap the master cylinder too.

I thought the m3 axel didn't fit into the 135i hub?

[Traf]

Originally Posted by houtan

I thought the m3 axel didn't fit into the 135i hub?

They fit no problem

[juld0zer]

Re: M3 master cylinder.
It's on my list for this year along with the booster, which despite being M3/1M specific all threads suggest it is no different to the stock E82 one.

Master swap in Australia is expensive. Alternative is to fit a LHD one and ditch the hard lines to the DSC valve block. Get some stainless braided lines custom made instead. The M3 master is rumoured to be more front biased. Piston/bore diameters remain unknown.

[houtan]

Originally Posted by Traf

They fit no problem

oh, nice.

So does that mean if one wanted to, they could use the M3 rear spindle, rotor, and brakes, with a 135i axle?

I know the master cylinder may need to be upgraded but just trying to understand if the rear is a direct fit with the stock axel.

I know the m3 front spindle will work with my tcklines if I get the adapter they use for the front strut for m3s.