Gear ratio

[trpremote]

So I'm making my mid life crisis daily driver e36 328i. I'm coming up on thre manual swap and want to be sure I'm able to cruise with easy. In a perfect world I'd be getting a donor manual 328 and just swap out the whole back driveline,but it's lookin like I might have to settle for a getrag for the time being. Rn my car has a 3.91 ratio and that it's not good for a manual configuration cuz first is pretty much useless and 5th ill be rolling at like 4500rpm at 70(which is where the car will tip out speed wise). What is the best set up for a daily driving 328i,not looking for a track application

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[bluptgm3]

Here is a list of chassis, models, and final drive ratios

The ZF S5D 310Z/320Z 5-speed came in a wide range of vehicles should be easy to find

The latest part number 23001434485

[TheJordanWhitte]

3.15 or 3.23 is probably the best option.

[pbonsalb]

If you don’t care about LSD, the stock manual rear works fine. I think it is 2.93 in the 328i. Relaxed highway cruising. Does not multiply torque as much, so if you want to orient towards performance, a 3.15 open from a 325i (there are also LSD 3.15 in winter package cars) or 3.15 or 3.23 LSD from an M3 are good choices. The LSD will cost more and the shorter gear means higher rpm and worse mpg. I think the shorter gear is more fun, though.

Holding out for a ZF320 would get you a better trans. Beware diffs have different input flanges and ZF and Getrag have different output flanges and slightly shift linkages so you will have to assemble your kit unless you can find a part out. The pedal box should be the same.

[Auto Parts Guy]

I had a 2.93 in my old 325i and it was fine, I would do it again. I have a 3.38 in my M3 6 speed and it's perfect IMO.
I would say anything you can find for a reasonable price in the 2.93 to 3.38 range would be ok. 3.91 not so much unfortunately unless you swap in an OD transmission.

[XnWarden]

I have both a 3.23 and a 3.91 that I swap between. The 3.91 REALLY wakes the car up and is a ton of fun. But as you said, highway driving is not so great. I turn 4k rpms doing like 75.

The 3.23 is a good balance between fun and efficiency

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[bluptgm3]

There is also a next step from the (1996+M3) 3.23:1, and that would be the 3.38:1 from the E36M3 automatic transmission cars.


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[Liquidity]

If it’s got 4 doors, it doesn’t classify as midlife crisis.

[66 6]

There is also a next step from the (1996+M3) 3.23:1, and that would be the 3.38:1 from the E36M3 automatic transmission cars.


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3.39 best option with ZF swap.

[importbanana]

I can't imagine living with anything shorter than the original 2.93. More than 3000rpm at 75mph? Wouldn't like that.

[pbonsalb]

You would have to be into performance to want shorter gearing. It can really make the car zing. I have run 3.15, 3.23, 3.38 and 3.64. With massive torque from a turbo, I don't need shorter gearing so I now run a 3.15.

If you just want relaxed highway cruising, a 6 speed conversion helps. The GS6-53 I put in my E36 does not have much OD at only 0.88 but a 420G has more and I am not sure what a GS6-37 offers.

[Nicolemen]

Hey man, yeah you're right — that 3.91 is way too short for a manual. First gear will be super quick and useless, and highway driving at 70 mph will be super loud and bad on gas. For daily use, a 3.15 or 3.23 diff would be a much better match. It'll cruise nicer and still feel fun to drive.

Oh, I'm so sorry, I didn't notice that the post was old...

[blckstrm]

Haha, not the worst necro we've ever seen.

For the record, a GS6-37BZ has a .85 6th gear. I believe a 420G is .82, so a GS6-37 splits the difference between a GS6-53 and a 420G. In any case, any of them are an improvement over a 5 speed in terms of highway revs.

[Spyke]

3.38 is my favorite, but if you don't do freeway much 3.46 is very nice for twisties as well.