Z4 35is M3 DCT Conversion

NoQuarter

Lieutenant
Nov 24, 2017
867
Indiana
#1
Getting started on the DCT conversion to M3 DCT

First thing is to make the shifter look like it belongs.

The Z4 shifter on the left. M3 on the right sitting on top of the trim.

The M3 shifter leather looks large enough to change its shape from the "triangle" to the "square".

Unless anyone has a better idea, My plan is to use a heat gun to remove the blue plastic frame/leather you can see on the Z4 shifter (and also on the M3 shifter)

then fit the M3 leather over the Z4 frame.

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Nov 18, 2017
780
#2
Looks like it’ll work I’m going to use an m5 knob and surround which has less leather. I was going to buy an eBay leather boot and adapt it. Like you I’d have to heat gun the leather off the knob.
 

doublespaces

Administrator
Oct 18, 2016
6,758
AZ
#3
Looks like it’ll work I’m going to use an m5 knob and surround which has less leather. I was going to buy an eBay leather boot and adapt it. Like you I’d have to heat gun the leather off the knob.
What is the difference? I did a search and didn't find anything. Speaking of boots, it would be pretty sweet to get rid of the leather entirely:
 

NoQuarter

Lieutenant
Nov 24, 2017
867
Indiana
#4
Right... I was thinking the same thing on that style with no leather. I was looking at the M4 shifter because of that but the box required 2 PTcan connections instead of a LINbus.
 

NoQuarter

Lieutenant
Nov 24, 2017
867
Indiana
#5
I just got an opening at my body shop I have been waiting for. I will take the Z4 in tomorrow so I won't be working on the DCT coding until after.
 

doublespaces

Administrator
Oct 18, 2016
6,758
AZ
#6
Sorry if I missed it. What work are you having done?
 

NoQuarter

Lieutenant
Nov 24, 2017
867
Indiana
#7
Nothing too exciting. I been waiting a month to get in and finally got an opening.

My Z had been wrecked prior to me getting it and the headlights, hood, front bumper has an alignment issue that makes me a little disappointed every time i see it :frowning:
 

doublespaces

Administrator
Oct 18, 2016
6,758
AZ
#8
Ah, it happens I suppose. Get'r fixed and the party resumes!
 

NoQuarter

Lieutenant
Nov 24, 2017
867
Indiana
#10
Been waiting to see how the final drive ratio issue got sorted out.

It looks like now I can do a wavetrac or mfactory as those ratio's seem to be close enough according to results posted in the other thread.

Wasn't anticipating doing a diff swap. Being a Z4 I am not keen on having it down too much over such a short driving season so this will be a winter project I think unless I can figure out where to get this done "quickly".
 

Blue335is

Specialist
Dec 12, 2016
58
#11
Could you swap the lsd diff, as in the the actual differential, I to the case of the Z4 diff? I realize the casing is drastically different from something like a 335is but I've never understood if the internals could be swapped. If you could with a custom drive shaft it seems you would fix one of the weakest points of the e89.
 
Nov 18, 2017
780
#15
It's an e46 non m subframe but I dont know of you could easily get the right final drive.
There’s tonnes of old diffs on eBay for next to nothing. Maybe get a cheap one and play around with a ruler ?
 

Blue335is

Specialist
Dec 12, 2016
58
#16
Yeah you can get LSDs from different companies but it wont strengthen the weakest point of the e89 drivetrain which is the pinion coming out of the diff that the driveshaft slides on to.
 

NoQuarter

Lieutenant
Nov 24, 2017
867
Indiana
#17
Didn't know that was a problem. Just reading about broken axles but not the pinion from the diff.
 

Blue335is

Specialist
Dec 12, 2016
58
#18
Didn't know that was a problem. Just reading about broken axles but not the pinion from the diff.
Yeah we talked about it at length in my dct Facebook group. A friend of mine broke his twice. First time we went to a Mfactory LSD. After the second time we rebuilt it with the upgraded ring and pinion from mfactory as well as replacing all the diff and subframe bushings with stiffer units.
 

Stokes

Corporal
Jan 26, 2018
118
Houston, TX
#20
It's an e46 non m subframe but I dont know of you could easily get the right final drive.
Noticed BMW has an LSD unit in a e46 size listed under what could be a e92 page. I wonder... looks to be a 3.07 ratio (last one in the list). For some reason it is cheaper than the rest. Maybe a 188 case, which might explain the weak point.
https://www.getbmwparts.com/c-differentials-92
 

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