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Thread: E46 Drifting Diffs

  1. #1
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    E46 Drifting Diffs

    Hey everyone,

    Noob to the forums.

    Picked up a 2003 325i last year and have been overhauling everything to get it ready for 2018's season.
    I know the E36 platform has seen a lot of diff ratio swaps for drift setups, and after searching I couldn't find much on E46's.

    Many on here have swapped a 3.46 out of an automatic, welded it up and it seems to work well but my question is has anyone done BOTH a 3.46 and 3.64 out of an E83 X3?

    Curious to see if a 3.64 is worth it vs a 3.46
    I read on a different site the diff bolts right up. (1 guy did it in a 330 but changed the flanges) Lots of guys with E36's like the 3.9's so I was curious going from a bone stock and doing it right the first time which one would be the better pick?

    Thanks!

  2. #2
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    Yea that sounds like you have read almost nothing.

    Status: Someone put glitter in my oil. Wait. Why's all my oil outside the engine? What's that knocking?

  3. #3
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    So here is what I know:

    you can swap a full m3 rear end in for like 600 bucks and have a good ratio and lsd and bigger axles and brakes.
    Also there are some LSD options out there out are upwards of 1200 bucks, which isn't bad for a 1.5 way lsd but that's about the price of most e46 these days. Also weldeds work great but I'm not a fan because it takes its tolls on axles and makes cars understeer.

    My ideas:
    I think an e36 sub frame will bolt up to and e46, you'd then have many ratio options, factory LSD options and have steel upper arms that wont crack with stiff spring rates like e46 aluminum arms. I'm unsure about Driveshaft compatibility. Ideally you're going to drop the subframe anyway because you NEEDDDD to do the reinforcements. so no extra work with either subframe swap option.

    I think your best bet is e46M rear subframe swap. but I think if e36 M3 subframe bolts up, has an LSD, better axles, and better brakes with the ability for bolt on dual caliper set up id do that.


    *Disclaimer* I'm not positive the subframes are interchangeable e36/e46


    IG: dimitriantoniou

  4. #4
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    I've never tried the 3.46, but I have the 3.64 diff in my E46 and its meh. I would much rather have a 3.9 or even a 4.10

  5. #5
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    But you have an Ls. that trans/power/etc makes a HUGE diff. None of this is even apples to apples. I wouldn't go to a 3.64 if the car is ever street driven.

    Status: Someone put glitter in my oil. Wait. Why's all my oil outside the engine? What's that knocking?

  6. #6
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    Wouldn't having more power/torque make a higher ratio diff more usable? I know all the NA S chassis kids want 4:10 or lower to make up for the lack of power, there was even people swapping in like pathfinder gearsets or something that were in the 5s.

    - - - Updated - - -

    My missile car is a 2.93 and it sucks balls. Think a 3.46 would be a noticeable difference and worth the effort? I have one in my garage.

  7. #7
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    well what trans do you have? i think t56 are super long compared to most bmw transmissions. So 3.64 wouldn't be very drastic for ls/t56 that's probably about stock gto/Camaro rear ratio. where as a stock 2.93 to a 3.64 for bmw would be a pretty noticeable difference.


    IG: dimitriantoniou

  8. #8
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    Quote Originally Posted by e30 394 View Post
    well what trans do you have? i think t56 are super long compared to most bmw transmissions. So 3.64 wouldn't be very drastic for ls/t56 that's probably about stock gto/Camaro rear ratio. where as a stock 2.93 to a 3.64 for bmw would be a pretty noticeable difference.
    Yeah, I never realized how short bmws trans are geared. 5th is 1:1 and only the 6 speeds got an OD gear?

  9. #9
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    Super short ratios are for cars with low power. So I see a ton of sub 300whp S chassis with 4.6 or 4.9 diffs.

    But if OP drives on the street, highway driving will be 3500+. If it's track only, I can definitely see a 3.64 or higher.

    And yea, trans/wheel size/etc all make giving diff ratio advice very difficult over the internet. Hence my original snarky statement to OP about not having read anything.

    Status: Someone put glitter in my oil. Wait. Why's all my oil outside the engine? What's that knocking?

  10. #10
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    Quote Originally Posted by protomor View Post
    Super short ratios are for cars with low power. So I see a ton of sub 300whp S chassis with 4.6 or 4.9 diffs.

    But if OP drives on the street, highway driving will be 3500+. If it's track only, I can definitely see a 3.64 or higher.

    And yea, trans/wheel size/etc all make giving diff ratio advice very difficult over the internet. Hence my original snarky statement to OP about not having read anything.
    Should have noted, its a track car. Stock engine with upgraded cooling system. Straight exhaust. Nothing major... gutted, cage, seats, welded stock diff right now. It doesn't leave the house unless its for testing.

  11. #11
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    Find the highest ratio you can ( like numerically high ) and weld it. cheap easy and if you don't like it you wont be 1200 dollars into a aftermarket LSD.


    IG: dimitriantoniou

  12. #12
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    Quote Originally Posted by e30 394 View Post
    Find the highest ratio you can ( like numerically high ) and weld it. cheap easy and if you don't like it you wont be 1200 dollars into a aftermarket LSD.
    Fair enough. I know a 3.91 is unrealistic for street driving, but I didn't know if going too high made 2nd gear less use-able forcing 3rd gear bogging down on power

  13. #13
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    it might at some tracks, while it might put you in the better rpm ranges at others. That's why the pros use quick changes

  14. #14
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    Quote Originally Posted by Novablue454 View Post
    it might at some tracks, while it might put you in the better rpm ranges at others. That's why the pros use quick changes
    this.

  15. #15
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    Quote Originally Posted by Novablue454 View Post
    it might at some tracks, while it might put you in the better rpm ranges at others. That's why the pros use quick changes
    A guy on Facebook says he has a 3.46 now and needs a 3.38 for the sweet spot at the track he goes to. Couldn't agree more now

  16. #16
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    At the local track where i host events I had a guy let me drive his E36 325is. Had a 3.91 and pretty much every bolt on for his M50 and I gotta be honest the car would have been better served with a 3.15 since with the 3.91 2nd gear on our oval was useless but 3rd was still a struggle for the car to really keep the tires lit around the bank. On a bigger track you have the extra mph to really keep 3rd going but it was a struggle making it work here. My stock non vanos car e36 with a 3.15 was much better since 2nd gear was right in the sweet spot.

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