S54 w/ 6 speed. Which diff

[Staszek]

I know this is an old thread but I bought a 3.73. I haven't finished my conversion yet but I thought it was the perfect compromise, slightly more aggressive then the stock 3.64 but not as crazy as the 4.10.

[jink0619]

373 the perfect choice

[superleggeram3]

373 the perfect choice

You running a 5 or 6 speed box ? Im doing a S54 conversion in my e30 but have decided to run a 5 speed box with a 3.64 diff but wondering if 3.73 would be better.

[Jb325is]

I had a ZF with a 3.73 and it was awful on the street. That will be fine if it's a track only application

[agent]

^ Agreed. 3.73s are fine for Getrag 5 speeds or possibly a 6 speed box. With a ZF 5 speed you really need a 3.25 or higher for the street.

[Staszek]

I had a ZF with a 3.73 and it was awful on the street. That will be fine if it's a track only application

You have the 5speed though right? I will be running it with a 6 speed. My E93 M3 has a stock 3.85 diff.

[gills]

Any thoughts on the 3.46 torsen LSD from the Z3 3.0's? I never knew BMW made a torsen diff until the other day. I may try to source one myself.

[Jb325is]

You have the 5speed though right? I will be running it with a 6 speed. My E93 M3 has a stock 3.85 diff.

Yeah, that should be fine. I was responding to the guy talking about running the 5 speed and 3.64/3.73

I now run a 3.23 and it's really good on the street, not great for autocross with my torque dip (hopefully thats fixed this week), but will probably be fine on the track

[agent]

Any thoughts on the 3.46 torsen LSD from the Z3 3.0's? I never knew BMW made a torsen diff until the other day. I may try to source one myself.

I'm running a 3.15 Torsen with a ZF 5 speed. It's the perfect balance for street and track.

[e30polak]

The ZF 5 speed has pretty much identical gearing 1st through 5th when compared to the 6 speed 420 Getrag out of the M3.

I ran a 3.46 with the ZF on my s54 e30 m3, with a 245/40/17 on 17x9.5s out back and it was a BEAST! Even in 5th gear on the freeway, it felt almost as torquey as my old s52 e30 with the 3.46 in 3rd!

All that being said, I switched to a 2.93 with the ZF and still LOVED the way the car drove. To anyone saying the s54 hates long gears, it really depends on your set-up and tune. My car made 317whp/264wtq and the car felt very similar to my friend's tuned C6 non-Z06 with the 2.93 gears, and felt like a C6 Z06 with the 3.46. For reference, with the 2.93 gears, I was seeing 77mph at 8300 in 2nd gear and about 110mph at redline in 3rd. When I ran my buddy's tuned non-Z06 with the 2.93s, I stayed neck and neck with him from 25-120!

With a 6 speed, I'd say a 3.38 or 3.46 is perfect gearing. In a light E30, you don't need to over-gear the car. A 3.73 with a 6 speed would be a bit much IMO, unless it was for a track car. I prefer to actually use my 1st and 2nd gear on the streets. I will be swapping an s54 into my Ti beginning of next year, and my 6 speed is going in next week. With my S52 I will be running a 3.25 and the 6 speed (currently have 2.93s and the ZF 5 speed). I ran the 3.25s before, but I commute 22 miles each way to work on the freeway, and cruising 3800 at 80mphs, vs. 3300 with the 2.93s was annoying. With the 6 speed I will have the best of both worlds, as my gearing will be the same 1st - 5th as the ZF 5 speed, but I will cruise even lower in 6th on the freeway than I did with the 2.93s. When I swap the S54 in, I will either be going with the 3.64 I just picked up or a 3.46 again. Since I will be running 17x10s with 255/40s, it should be close to stock E46 m3 gearing if I run the 3.64, which is a great balance for a light car that I use as a daily driver like my Ti.

[Staszek]

The ZF 5 speed has pretty much identical gearing 1st through 5th when compared to the 6 speed 420 Getrag out of the M3.

I ran a 3.46 with the ZF on my s54 e30 m3, with a 245/40/17 on 17x9.5s out back and it was a BEAST! Even in 5th gear on the freeway, it felt almost as torquey as my old s52 e30 with the 3.46 in 3rd!

All that being said, I switched to a 2.93 with the ZF and still LOVED the way the car drove. To anyone saying the s54 hates long gears, it really depends on your set-up and tune. My car made 317whp/264wtq and the car felt very similar to my friend's tuned C6 non-Z06 with the 2.93 gears, and felt like a C6 Z06 with the 3.46. For reference, with the 2.93 gears, I was seeing 77mph at 8300 in 2nd gear and about 110mph at redline in 3rd. When I ran my buddy's tuned non-Z06 with the 2.93s, I stayed neck and neck with him from 25-120!

With a 6 speed, I'd say a 3.38 or 3.46 is perfect gearing. In a light E30, you don't need to over-gear the car. A 3.73 with a 6 speed would be a bit much IMO, unless it was for a track car. I prefer to actually use my 1st and 2nd gear on the streets. I will be swapping an s54 into my Ti beginning of next year, and my 6 speed is going in next week. With my S52 I will be running a 3.25 and the 6 speed (currently have 2.93s and the ZF 5 speed). I ran the 3.25s before, but I commute 22 miles each way to work on the freeway, and cruising 3800 at 80mphs, vs. 3300 with the 2.93s was annoying. With the 6 speed I will have the best of both worlds, as my gearing will be the same 1st - 5th as the ZF 5 speed, but I will cruise even lower in 6th on the freeway than I did with the 2.93s. When I swap the S54 in, I will either be going with the 3.64 I just picked up or a 3.46 again. Since I will be running 17x10s with 255/40s, it should be close to stock E46 m3 gearing if I run the 3.64, which is a great balance for a light car that I use as a daily driver like my Ti.

I hear you, I wont be using this as a DD, it wont exactly be a full on track car, but it will probably see more track/autocross time then I would drive it regularly.

[grk325]

Well my heart is torn between a 3.46 and 3.73 for the 6 speed. Is the 3.73 going to be that much different from the 4.10?!? Wouldn't one run through the gears just as fast?!?

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[nando]

The M3 stock comes with a 3.64. I'd probably go with a 3.73. lots of those guys swap to 4.10s.