m3 diff swap

[martzman 0]

I am very keen on swapping the internals of my e36 m3 evo LSD with those of an e46 m3. This is a good mod, alot of positive feedback from those that have done this. I have done alot of research and crown wheel and pinion, viscous slipper etc all fits in with no machining neccessary. MY PROBLEM IS in sourcing the e46 m3 LSD internals. Anyone have any ideas on where to get these? They are so rare in NZ as I cant imagine too many m3's get wrecked. Any help would be great.

[antony 0]

Try here.

[greenday-rulz21 6]

Have you checked eBay? Bound to be some on there, but be prepared to pay a fortune. For the LSD and then for the shipping.

[martzman 0]

Have you checked eBay? Bound to be some on there, but be prepared to pay a fortune. For the LSD and then for the shipping.

Yeah it would cost a fortune thats why I would really prefer to source from within NZ. I might just wait it out as I dont want to spend much more than 2K on this swap. Some of the UK guys on bmwowner say they have seen internals go as low as $200US on ebay. Expect to double that with shipping but it still seems way too cheap so I'm a bit sceptical.

[*Glenn* 855]

May I ask what you are trying to achieve ? is it a different ratio that you are after ? or the LSD centre ?

I'm just curious as to why you are wanting to do this

[CamB 48]

May I ask what you are trying to achieve ? is it a different ratio that you are after ? or the LSD centre ?

I'm just curious as to why you are wanting to do this

Me too - I mean the ratio is slightly more favourable in the E46 M3 LSD (and I'd personally love a shorter ratio for mine), but for my money I'd take a freshened up and higher lockup plate diff to some fancy variable one.

Is the "Variable" part self contained? Or does it need to talk to the ECU?

Edited July 29, 2009 by CamB

[|ncary 0]

From reading about the M3, I'm pretty sure it takes it everything like steering wheel position, throttle pedal position, maybe even current G-Forces with an accelerometer, and adjusts the active diffrential to suit. Quite amazing really, can put down 100% of torque to the wheel with the most grip.

[Forrest 35]

^ off topic but Christchurch Stadt....LOL love your work.

Back on topic, surely the benefits vs time, cost, fitting isn't really worth it?

[|ncary 0]

I was going to say Christchurch Ghetto (like as in Warsaw ghetto in Poland 1939) but didn't think people would get it

[westy 614]

From reading about the M3, I'm pretty sure it takes it everything like steering wheel position, throttle pedal position, maybe even current G-Forces with an accelerometer, and adjusts the active diffrential to suit. Quite amazing really, can put down 100% of torque to the wheel with the most grip.

I think you're right.

Also, there isn't a speed signal from the E46 diff????

[martzman 0]

May I ask what you are trying to achieve ? is it a different ratio that you are after ? or the LSD centre ?

I'm just curious as to why you are wanting to do this

Trust me it is definitely worth doing, I know a few guys on bmwowner who have done this and they love it. Ratio in m3 evo is 3.23. Higher than standard m3 but still far too long ie. my car will touch 170 in 3rd gear. e46 m3 uses shorter 3.62 ratio. This ratio is far superior for performance. 100 in 2nd gear, just shy of 150 in 3rd, just shy of 200 in 4th. 0-100mph in the m3 evo takes 12.2 seconds. They reckon you can shave close to a second of this time with just the e46 diff mod. Will run with e46's comfortably. This is just what people who have done it themselves have told me. Much more effective (performance wise) than spending three grand on a genuine carbon plenum/alpha n setup. In the UK they are getting this done for about 700-750 quid. 300 quid for diff internals 400 quid labour. Obviously an e46 diff is much easier to source in the UK than here.

The other reason is that my diff has the tiniest leak in it that was picked up in an inspection. I am meticulous with my carcare so if I am taking diff out anyway I might as well give this a go if I can source the diff internals.

[martzman 0]

Try here.

Thanks mate very helpful ive contacted him

[westy 614]

Is it not possible to use a ratio from a different large case diff??

[CamB 48]

So, they only change the ring and pinion? Or the whole diff/insides?

Westy - its hard to find decent ratios. I'd go shorter again than 3.62, if I could find one. Maybe a 3.73 or even a 3.91 (6th gear would become as short as 5th, which is ok for me).

[2002 1]

Try http://www.diffsonline.com That's where I got the 4.45 ratio for the 2002. After talking to him Dan seems like a straight up guy. However it's not going to be cheap.

[*Glenn* 855]

UUC in the states recommend a 3.45 :1 from memory. Have a look through this site:

http://www.uucmotorwerks.com/

[martzman 0]

Yes one other gearset is compatible. The 3.64 ratio from the e34 535i manual. Other ratios ie. 3.91 etc are too short

[martzman 0]

So, they only change the ring and pinion? Or the whole diff/insides?

Westy - its hard to find decent ratios. I'd go shorter again than 3.62, if I could find one. Maybe a 3.73 or even a 3.91 (6th gear would become as short as 5th, which is ok for me).

[/quote

You need e46 m3 gearset. S

[martzman 0]

So, they only change the ring and pinion? Or the whole diff/insides?

Westy - its hard to find decent ratios. I'd go shorter again than 3.62, if I could find one. Maybe a 3.73 or even a 3.91 (6th gear would become as short as 5th, which is ok for me).

Oh sorry I stuffed that previous answer up. You need e46 m3 gearset so that is crown wheel, pinion, viscous slipper and 4 bearings and 2 seals. Gearset fits straight in you just adjust ramp angle from 30ish degrees to 45 degrees then seal it up I think thats pretty much it

[CamB 48]

Would be keen to read a link on it if you've got it handy. Cheers.

[*Glenn* 855]

Would be keen to read a link on it if you've got it handy. Cheers.

I'd like to see it as well please

[martzman 0]

Would be keen to read a link on it if you've got it handy. Cheers.

Heres some links guys. Problem is you will probably need to be a member of bmwowner.com. Only takes 2 minz to sign up and in my opinion is the best international bmw forum.

Heaps of info here

http://www.bmwowner.com/forum/viewtopic.ph...ff+donor+m3+evo

diff project here

http://www.bmwowner.com/forum/viewtopic.ph...ff+donor+m3+evo

Interesting stuff definitely worth a read if you are into your performance mods. Can also use 3.64 internals in medium case diff (type 188) for regular e36 m3. Only person I know who's done this is alan (morerevsm3) and his car is bloody quick.

[CamB 48]

Thanks for that - good stuff.

Its not entirely clear whether swapping to the Variable M Sport LSD is desirable - it seems that people have done both. I think I'd still prefer an uprated clutch pack diff (ie the Evo one) but then again that's what I am used to.

I guess put me in the queue for a 3.62/4 (or 3.73 preferably) if they become easier to get. I'm in no rush but might do it one day. I am keen for a lighter flywheel too if the gearbox ever comes out.

Note: A regular M3 should think about a 3.46 medium case - they don't have 6th gear and a 3.64 would be very short in top gear.

[martzman 0]

Thanks for that - good stuff.

Its not entirely clear whether swapping to the Variable M Sport LSD is desirable - it seems that people have done both. I think I'd still prefer an uprated clutch pack diff (ie the Evo one) but then again that's what I am used to.

I guess put me in the queue for a 3.62/4 (or 3.73 preferably) if they become easier to get. I'm in no rush but might do it one day. I am keen for a lighter flywheel too if the gearbox ever comes out.

Note: A regular M3 should think about a 3.46 medium case - they don't have 6th gear and a 3.64 would be very short in top gear.

Yeah sorry I did mean 3.46, 3.64 is too short unless you are regularly doing track/drag work and top end is not relevant. I would definitely use the 3.46 if I had the non-evo m3. The general consensus is 3.64 is a bit short for these and 3.46 is pretty much perfect.

I would like to try and source a whole bunch from UK and ship them (although they are very hard to get hold of). I wouldnt mind buying two or three of them if they were 300 quid each and then I may be able to onsell them, but its hard to find one let alone three. Never know I might get lucky.