That run was before the diff and I actually did do a victory donut on it on accident, I spun the car and just put the pedal to the floor and turned it around. Lol. It should cut 3 seconds or more off my track times I think, the rear feels so much more predictable after the bushings too. Not many people have done this swap but I'm just trying to put more info out there so it will help people in the future trying to do it. Also now having the m setup I can get a carbon fiber one piece driveshaft and delete the guibo and also get stronger axles. One day I will be upgrading them after I get a smaller supercharger pulley and cams.

 

The mounting points for the subframe brace are not on the non-M chassis and need to be welded, right? or are you talking about the reinforcement bracket?
Also, you're saying that the M3 axles work whilst reusing the non-M trailing arms as long as you space out the ABS sensor by ~3/8", right?

Very nice.

 

I'm not sure about for the v brace that attaches to the little brace that runs between the front mounts but that small front brace on the front two bolts up as well with the rear subframe. You will need new hardware for mounting the diff but all other hardware can be reused. Yea for spacing it out you need to space them roughly 3/8 of an inch to have the right clearance, I bought half inch spacers and grinded them down some and longer m6 1.0 bolts, I believe they were 35mm long. But the axles will fit perfectly with the non m subframe and I don't have any abs lights or anything from spacing the sensors out.

 

noticed you're using the "solid" subframe and diff mounts, how would you rate the nvh level for others possibly using those?

also how would you rate the 3.62 ratio for others?

you might want to review the pros/cons for others doing the swap nowadays. :bow:

 

With the 6spd, the 3.62 ratio is awesome I think, still good on the interstate. The 5 spd I still wouldn't mind with the 3.62 if I was someone that didn't drive 100 miles a day and such but for a second car or for driving in back roads it would be good, only like a 200 rpm difference from the 3.46 diff that I had in my car previously. There is some noise from the diff but I think it's mostly from the solid diff mounts and I have no insulation under my back seat and the rear trunk is also fully gutted to bare steel. Driving down the road though it feels a lot tighter and more predictable than how my rear suspension was before. I would maybe do derlin or poly diff mounts if I had to do it again but the solid subframe mounts helps keep the whole suspension squared up better. The car has poly engine and trans mounts and it has some vibration from them as well. Going down the interstate though the car is pretty quiet and rides amazing, it is alittle tighter feeling but it is quiet.

 

I am curious as to why you installed a m3 3.62 over a zhp 3.64 with a new lsd unit? A m3 subframe and diff is heavier, has a used worn lsd, and costs a reasonable chunk of $. A zhp 3.64 on ebay goes for an average of 250$ and a m-factory or wavetrac brings you up another 1k$ give or take. The zhp 3.64 is lighter weight, is a direct bolt in for a 330 with no mods, has virtually the same ratio and gives you a freshly rebuild diff for a few bucks more, plus it has a warranty. i personally can't see going to a m3 diff with mandatory subframe based on these options.

 

I am curious as to why you installed a m3 3.62 over a zhp 3.64 with a new lsd unit? A m3 subframe and diff is heavier..

everything on the M3 diff swap is stronger; gears, axles. also the mounting design of the diff carrier is better. the differential also holds more fluid along for better heat dissipation(also better designed finned cover). and yes i know there's the non-M finned cover. i installed it on my custom Turner Motorsport LSD on my 323Ci many years ago.

 

From what I have seen there's a lot better aftermarket support for the m3 diff and also for the m3 drivetrain. My car is supercharged and I plan on going for more boost eventually and I know the 330s can bust output shafts and axles and u joints. the m cars all that can be upgraded so your not out your car on a track day or stranded somewhere. I could see doing the 330 diff if I was n/a and wasn't supercharged with the plans of adding more boost and internals. The m3 swap if I didn't do all my performance goodies would have only costed about 1k-1100. I've seen them go for less if you can find the right deal. It's also something different that you don't really see, not many non m cars out there with anything from the m power train

 

The weight gain is not very much, maybe a max of 20 lbs. the diff is heavy but the subframe is actually alittle lighter. I know you probably gain some rotational mass as the diff unit is larger. I haven't seen any ring and pinion issues or diff issues out of the non m diff or heard of them other than lack of maintenance but people have snapped cv joints and u joints when making more power, especially if you get traction and wheelhop etc. the m3 guibo is a lot bigger than the non m one as well, I actually installed one on a 323 not long ago as pelican sent me the wrong one and I was in a pinch to get the car done and the m3 one fit perfect. The bolts need to be alittle longer than the non m bolts but I just used some red picture to be on the safe side, the bolt still goes to the end of the nut, just no excess thread hangs out. My 3.46 non lsd I had in mine had the finned cover on it as well

I will agree though that for most people the non m diff with an lsd will be more than enough and they will never have issues busting one, especially if they stay n/a like most. A lot of the boosted cars don't see very much track use, there are some people on here that do but the majority have added a supercharger or turbo just for the fun factor which is completely ok. My car doesn't see a lot of track but it sees enough to make me worry about my next weak link, the car has a Kevlar clutch and flywheel so I know the clutch will not slip, the transmissions aren't known for any real issues other than synchros, so the next would be driveshaft failure and axle failure. And to have those custom made for a non m would cost a lot more than to buy some that have already been r&d for the m3. At one point I will upgrade the m3 unit for something better but I'd rather take this one step at a time, I've already got close to 2500 in the swap from all new bushings and a turner sway bar and uuc lower arms

 

Here's some random pictures from throughout the build over the past couple years. This car is definitely one of those money pits/black holes. Lol

 

Been thinking about this swap for awhile now since I want to get my manual swap done by next summer. I knew it was possible, but I haven't done a whole lot of research on it, so forgive my lack of knowledge.

As far as I knew, I thought the Getrag 420G transmission from the M3 was required to mate the gearbox to the M-diff without any custom fabrication. You said you're using an M3 drive shaft? I'm assuming your car is a ZHP, so you have the ZF 6 speed. If so, that's great news to hear it bolts up fine.

Did you run into any major issues during installation, or come across anything you'd do differently if you could do it over? Curious as well why you didn't use M3 trailing-arms / rear suspension setup since the subframe would allow it. Great work on the swap and glad to hear it's working out great, makes me excited to do the same at some point in the near future!

 

Yea my car is a 2005 330ci zhp with the stock 6spd in it. It is using a stock m3 6spd driveshaft with a m3 guibo. The bolts for the m3 guibo need to be longer but mine work for now. If I had went with m3 trailing arms it would mean I would also have to run m3 rear brakes or for me I would have to have some new brackets made to fit my wilwood calipers onto the m trailing arm.

the trailing arms would work with the swap though, just would be more costly for me, I do have e46 m3 rotors on my trailing arms though for the calipers. If I did it again I would probably go with a derlin diff mount instead of solid but the solid really isn't that bad, alittle noise in the cab but the radio makes it go away. Lol. The one main issue I found was the trailing arm issue with the speed sensor. I researched it and apparently the m3 speed sensor is different and people were having to space their stock speed sensors anyways. The m3 one is shorter but runs on a different frequency or something. I haven't tested this for sure, but just what I found info wise on it. There's very little info on the speed sensor delima. From what I found the lower camber arm is the same as with the upper control arm is the same between non m and m3