24v swap transmission+diff. question

[Wanganstyle]

In my E30 with 6 speed I ran 2.93, 3.07, 3.15, 3.23

I liked 3.15 or 3.07 (z3 3.0 m54b30 has this) the best for some weird reason. It wasn't any slower than 3.23

In my e36m grocery special I have ran 3.23, 3.38, 3.46

I like 3.46 in this s52 car as its hilly where I am. If I had a 6 speed I'd run a 4.10 or 4.27

[4door30]

honestly if you drive them all in the same car (I have):

3.15 - 3,23 - 3,38 - 3,46 is all about the same.

For mountainous regions the shorter numbers will provide more smiles.

if one cares about fuel economy pick 3,15 or 3,23 - the 3,15 ring gear is lighter than the others.

IF one has a pure track machine then 3,91 is the popular CA track choice

3,64 - 3,73 - 3,91 - 4,10 for s54+6mt+8krpm ++

That's some good info! I found a setup I am going to try to snag up next week!

S50, zf320, 328i driveline, 3.15 lsd!! And then if I want more, I can go more, but seriously, thanks for the real world info. It is a huge help!

[Wanganstyle]

Yeah that would make sense why the s52 is AMAZING with the 3.38 diff. rather than the stock 3.23. I did that diff. swap in my e36 m3 and the car rips...

honestly if you drive them all in the same car (I have):

3.15 - 3,23 - 3,38 - 3,46 is all about the same.

For mountainous regions the shorter numbers will provide more smiles.

if one cares about fuel economy pick 3,15 or 3,23 - the 3,15 ring gear is lighter than the others.

IF one has a pure track machine then 3,91 is the popular CA track choice

3,64 - 3,73 - 3,91 - 4,10 for s54+6mt+8krpm ++

[4door30]

Thanks for the input! I am now leaning toward a 3.46 lsd, I found one for 395 shipped and it is re-sealed under 100k miles!

[Roysneon]

I run an m50 with a ZF behind it and a 3.73 diff. It's fine for city driving or even highway. Top end speed is pretty limited, though. I hit rev limited in 5th gear at about 195km/h when I had 225/45R17 tires. Now I have 215/40R17, I'm sure top speed will be even a bit lower.

[4door30]

Yeah that would make sense why the s52 is AMAZING with the 3.38 diff. rather than the stock 3.23. I did that diff. swap in my e36 m3 and the car rips...

[Wanganstyle]

It think it depends too on whether your running an S50 or an S52. I know that the S50 (1995 M3) came stock with a 3.15 diff, while the 96 and later came with a 3.23. I know they are different engines and everything but after driving my buddies 99 M3 for a month or so, i did like the power it gave out with the stock 3.23 but just wished it would spool up through the gears faster... like with a 3.46 or something. So in my S50 swap i wanted to go higher than the stock (3.15 for a 95 s50 engine) to try and get that, so I'm going with a 3.25 torsen or LSD. Plus I'm in Vermont, so road are windy and hilly and more fun up here.

The smaller engine will only desire an even shorter gear.

3200cc > 3000cc with lower brain processing power.

There is a really good reason all the serious e36m3 track cars in norcal are going to 3,91 final drives; they all need it for elevation.

[zcenterb]

It think it depends too on whether your running an S50 or an S52. I know that the S50 (1995 M3) came stock with a 3.15 diff, while the 96 and later came with a 3.23. I know they are different engines and everything but after driving my buddies 99 M3 for a month or so, i did like the power it gave out with the stock 3.23 but just wished it would spool up through the gears faster... like with a 3.46 or something. So in my S50 swap i wanted to go higher than the stock (3.15 for a 95 s50 engine) to try and get that, so I'm going with a 3.25 torsen or LSD. Plus I'm in Vermont, so road are windy and hilly and more fun up here.

[4door30]

Yeah so far I'm looking at either a 3.15 lsd or a 3.25 lsd, and if I'm swapping the diff, either it will be rebuilt before I buy it, or I will rebuild it myself.

[Wanganstyle]

It's good to hear all of the actual situations people are in with their builds... So far I'm looking at s52 (staying obd2), zf320 trans (e36 m3), 328i driveline w/e30 csb, and either a 3.25 or 3.46 diff... The main reason I want to possibly go all the way up to a 3.46 is because I am usually around town or cruising at no more than 65 all day, I'll have a chance pretty soon here to drive an s50 e30 with a 3.25 so I will for sure make my decision after that!

Thanks for the help guys, I appreciate it.

My daily grocery special is a 1998 m3. Stock DME and 100% original engine

I fit a 3.46 final drive; I have every option avail on my shelf.

My 2002 325i-5mt e46 also had a 3.46 fitted

a 100% s52+5 speed + 3.46 final = 23MPG combined.

With 3.23 it's about 24-25mpg combined at best. Never going to get much better

IF the swapped e30 footwork is not corner balanced well you won't be able to put down the power.

Stock e36m has a 3.23 and it's pretty much spot on for 95% of people. Don't buy a Hella old rotten 3.25 from a dirty e28, buy one from a modern z3 or order one custom built if the budget is there.

[4door30]

It's good to hear all of the actual situations people are in with their builds... So far I'm looking at s52 (staying obd2), zf320 trans (e36 m3), 328i driveline w/e30 csb, and either a 3.25 or 3.46 diff... The main reason I want to possibly go all the way up to a 3.46 is because I am usually around town or cruising at no more than 65 all day, I'll have a chance pretty soon here to drive an s50 e30 with a 3.25 so I will for sure make my decision after that!

Thanks for the help guys, I appreciate it.

[butters]

Everything agent said.

I would have gone for the ZF anyway (I think) but it came with my S50, and I also have a 318 so I never had a G260 to begin with.

I went with a 2.93 LSD because it's relatively easy to find, and I wanted to start out with taller gearing and see how it went rather than going with 3.25 or above and then wishing I had less revs on the highway. I don't like cruising above 3000 rpm (weird mental thing, idk), and I'm happy with the gearing because that puts me at 75 mph indicated in 5th. I'll be pursuing a rebuild on the diff, so I've had to think about it and map out my options of speed/rpm in a spreadsheet, and at this point I plan on staying with that ratio.

[mpowerful]

My opinion leans the other way and ill explain why i decided to stay with g260. First and foremost i am cheap (not stupid though). G260 is plenty strong and should easily handle n/a s52 power even. No need to buy another tranny, a driveshaft, or a diff. Those are expensive ventures....much more expensive than buying at minimum a 70 trans brace. Anyway bending the shift selector rod takes about two minutes and is essentially a very minor tweak. Also you can use m20 single mass flywheel. It has to be cut down on backside to clear oil pan bosses which cost me 40 bucks with the benefit of going down to 14lb flywheel. Clutch can be a potential make/break too though. The stock m20 clutch is weaker than stock zf clutch setup. Many people run an aftermarket setup. Ive been on stock setup 3000 miles now with no issue but when i do have to replace it i am going with the m3 disc and pp which is plenty strong and nearly same price as m20 clutch kit.

[M3PO]

I have the ZF from an E36 328i in mine with a 325es "big guibo" driveshaft and a 3.25 40% lockup LSD from a 6-series (I think it's from a 635csi). I'm using the E36 M3 shifter. I was basically trying to mimic an E36 M3, but lighter. I like it a lot. Only thing I'm not too find of is spinning ~3750 RPMs at 80 mph (205/40/16 on there now).

[4door30]

Thanks for the input, sounds like staying right in the middle of that will be the best idea for me...