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Thread: What e36 diff ratio are you running?

  1. #1
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    What e36 diff ratio are you running?

    Long story short. 3.91 lsd turned my 2.5l into a torque monster.
    Ive since changed to a 3l and not sure if it would be helping or losing performance with the 3.91.
    Car is certainly faster and pulls dramatically faster with the 3l, but it also seems the acceleration is literally as fast as the engine can rev so maybe a longer geared diff would result in faster acceleration. So.. What have you guys found to he the best for overall "get it"? Top speed is not my concern as I will never be going 150mph.
    People get so judgmental at other judgmental people and act superior?.... Yes, its called ignorance.

  2. #2
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    3.73 works well in my car. It means highway I cruise @ 70mph to keep the RPMs under 4k lol

  3. #3
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    I have run 3.15, 3.23, 3.38 and 3.64. The 3.64 was a lot of fun anywhere but on the highway unless the highway trip was short like half an hour. Never tried 3.73. 3.91 seemed like it made the gears too short based on my study of gearing charts, but maybe with a 7200 rpm limiter and cams that make high rpm power it works.

  4. #4
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    no. Get the shortest diff you can and still get to full speed at the tracks you visit. We run a 4.44 with a 6 speed, before that ran a 3.91 with 5 speed. Both awesome, but the 4.44 is faster at shorter tracks. Longer tracks, not much difference.
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  5. #5
    MauiM3Mania's Avatar
    MauiM3Mania is offline Observer/Master Skeptic Moderator
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    3.91 is a lot of fun on the road but would be an issue if you drove much interstate w/o a six speed.

    Project | 88M3 AW 43k miles OEM Shift Knob
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  6. #6
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    I dont highway the car much. The farthest ill probably ever go would be within 40 minutes. From the sounds of it im already where I need to be for what I want. Thanks guys.

  7. #7
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    For A strictly track only car 3.64. For mixed use, 3.38 is the magic one.

  8. #8
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    3.64 has to be built. You can buy used 3.15, 3.23, 3.38 and 3.91 that are direct fit. I like the 3.64, though, if building is in the budget.
    Last edited by pbonsalb; 12-10-2019 at 08:19 AM.

  9. #9
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    Building isnt in the budget. But a 3.64 does sound enticing. I got a 94 325ic parts car. So the 3.15 stock gearing seems enticing. Maybe a 3.15lsd would be good. I think my clutches are going anyway as the break away seemed easier than before when changing wheels.

  10. #10
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    I went from a 3.23 to 3.46 a couple of years ago and I should have gotten a 3.64. 3.46 still leaves RPM unused in 5th gear on the longest straights. A 3.15 will make your car feel like it's way down on power.

    1999 BMW M3
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  11. #11
    MINIz guy's Avatar
    MINIz guy is offline #buttstuff2k14 BMW CCA Member
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    I run a 2.93 so I don't even know where the 5th gear gate is on my car. But class rules are class rules, if you have something besides lapping in mind.

  12. #12
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    I have a 3.91 in my M3 with S50 3L and a 5-speed. It's awesome for track use where the straightaways aren't super long. Like ScotcH says, use a ratio that gets you to top speed at the tracks you run. 3.91 worked well at west coast tracks like Laguna Seca, Thunderhill, Buttonwillow, Sonoma where I maxed out at 120mph or so. Now I live near tracks like VIR and Road Atlanta that have longer straightaways. At VIR I found myself bouncing off the rev limiter at 130mph well before the braking zone on the back straight. Time to build a 3.64...

    3.91 with a 5spd would suck massively for street/highway use.

  13. #13
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    Highway is Kinda annoying high revs.. City.. Its not so bad. Start off in 1st and little jerky. I just skip to 3rd to get to speed. Then skip to 5th to ride at 30 around. The massive amount of torque is alittle much when taking right on red while a cop is sitting at the red light as well. Lmfao

  14. #14
    NeilM is offline Member BMW E36 M3 Expert
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    It all depends on how you’re using your car. ScotcH is doubtless right for his purpose (straight up race car), but that wouldn’t work at all for me (drive to/from the track DE car, sometimes long distances). Also with an S54 the higher redline gives some headroom for shorter ratios that don’t work for my S52.

    My 96 M3 started life with the stock 3.23 and 5-speed, then went to a 3.73. That ratio is cheap and readily available from an E30, and I paired it with a 6-spd (not so cheap). Works fairly well on track, but there’s a somehow a tendency for corners to fall between 3rd and 4th, resulting in upshifts in odd places. Highway speeds are a bit buzzier than I’d like, even with the 6-spd. 1st gear is only good for, well, not much really. A 3.64 would be only somewhat better, and anyway, that ratio is neither cheap nor plentiful.

    I like my present 3.46 (also a cheap and plentiful ratio) better. 3rd gear is now more usable on track than with the 3.73, and 80 mph at 3250 rpm in 6th is wonderfully relaxed on the highway. 1st is even potentially useful.

    But this is for my usage. Truly, never was YMMV a more apt term.

    Neil
    Last edited by NeilM; 12-13-2019 at 09:50 AM.

  15. #15
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    My mileage got better going to a 3.91... In the city it took less to get to speed and pretty much coasts in 5th fown the street. Highway, still gets btwn 25 to 32 up and down the same Short length of road i take going 55. However... I certainly do burn more fuel when im slammin gears and double clutching. (That last one is for giggles).

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