Gear ratio comparison...

[MR 325]

How does this compare for gearing, which one will end up shorter or longer? This is with a S50...

Getrag 260 w/3.73 diff
vs.
ZF E36 w/3.25 diff

Would an E36 trans be too short with a 3.46?

Oh, and how do gear ratios in the trannies compare between E36 250 and ZF trans?

[7pilot]

Depends on the primary use of the car.
With an S52 and ZF 320
3.25 is best for primary road use and economy.
3.46 is best for primary track use and acceleration. Top end may be compromised at a large track like Road America.

The 3.46 is rarer.
The 3.25 is probably the best FD for a dual duty car.

1. 4.20:1
2, 2.49:1
3, 1.66:1
4, 1.24:1
5, 1.00:1
Reverse 3.91:1

What revs you turn at highway speeds will also depend on the size of your tyres.
eg, 235 40 17 do 3100 @70mph with the 3.25

m (Looking for a 3.46)

[lennon]

those two combinations are very close on gears 1-3, gears 4 and 5 will be longer with the 260 and 3.73. whether or not 3.46 is too short is subjective

[etxxz]

ZF with 2.93 ~ g260 w/ 3.73
ZF with 3.25 ~ g260 w/ 4.10

gearing between trannies differs, but this is comparable.
s50/52 with a zf and a diff shorter than a 3.25 on a street car is stupid imo. too short.
fun on the track but depending on the track and your mods, you may gear limit your power.

[evil_twin]

i love my zf with my 3.25diff. I would go with the getrag just because those parts are easier to find than a 3.25diff

[Jason89i]

http://www.diffsonline.com/techinfo/GearingCalculator.xls

[hugh jass]

i've got a 250 with a 3.25 and would definitely not want to go shorter than that. a 3.46 would rev too high for a street driven car imo.

[FredK]

I have a 3.46, and though it revs a little high (around 4000 at 80 mph with 205/50 R15 tires), I don't really mind it. Running a 3.25 would drop the revs 250 rpm at the same speed, which isn't really noticeable.

[dude8383]

i've got a 250 with a 3.25 and would definitely not want to go shorter than that. a 3.46 would rev too high for a street driven car imo.

x2

perfect for daily use. best compromise would be to get yourself a 3.46 and swap it out whenever you hit up the track.

[z31maniac]

I have a 3.46, and though it revs a little high (around 4000 at 80 mph with 205/50 R15 tires), I don't really mind it. Running a 3.25 would drop the revs 250 rpm at the same speed, which isn't really noticeable.

What's your top speed in 2nd?

[e30polak]

I'll let you drive my car with the ZF and 3.46 if you let me drive your's Matt! It's honestly a little torque monster! First is pretty short, but a lot of fun! Every other gear pulls perfectly.

I had the 3.25 before, and it was better for gas milage, but the extra torque feel is definitely worth it! The 3.46 and ZF is torquier then the 4.10 and 260. The best part of the ZF is the 1:1 in 5th!

[FredK]

What's your top speed in 2nd?

Um, according to the calculator, 56 mph at 7k rpm, but I never shift that high.

[jrdeamicis]

I think a Zf with a 3.46 is money.

I am chilling with a 3.73 and a 6 speed for now.

[e30polak]

I think a Zf with a 3.46 is money.

I am chilling with a 3.73 and a 6 speed for now.

First is useless with that ratio! 2nd-6th on the other hand... :up:

[WADE30]

I have an M50 with all the upgrades and fix-ins, S50 cams, 24# injectors, chip, blah blah blah.... I'm matching that with a ZF transmission and stock IS diff, 3.73....is that going to be pretty short to non-existent first and 2nd gears?