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View Poll Results: What Final Drive Gear Ratio Should I Select for my Limited-Slipp Diff? | |||
3.23: Stock Ratio | 3 | 10.00% | |
3.46: 130i-Spec | 16 | 53.33% | |
3.73: Ooomph! | 11 | 36.67% | |
Voters: 30. You may not vote on this poll |
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11-12-2015, 09:17 AM | #24 |
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Drives: 130i coupé ;)
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As much as I like the 3.46 (or 3.38 or maybe if possible the 330i/130i auto 3.64)...
I believe they are harder and more expensive to achieve because a 3.73 pumpkin is a direct swap and is a cheaper path. While the others need Flange swaps on each side and sometimes the input shaft flange.
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11-12-2015, 09:19 AM | #25 | |
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11-12-2015, 08:58 PM | #26 |
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2004 e60 525i & 530i M54 pre lci has a small pumkin and a fined dif. Only the input flange is odd. I think those have good ratios
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128i Sport 6MT converted to Euro 130i spec, 3.73 diff, tuned by evolve ~220 whp 207 wtq(ft-lb) SAE
In-progress: //M front arm, M3 rack, e36M lip Wishlist: Coils, n55 mnts, headers, LSD, e60 finn diff "The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is |
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11-13-2015, 06:08 AM | #27 | |
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It will be either BSP or DSP. I do not know the final answer. I, along with other wrote letters to reclass it. If/when that's the case, you will be only allowed to update/backdate within the 128 bloodline |
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11-13-2015, 06:14 AM | #28 | ||
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That would mean 3.23 or 3.73. And I had pretty much just decided on 3.46! Although it does make much sense to class the 128i in SP separate forgot the 135i & 1M. Any idea how long it takes for them to announce a decision? It seems like it would be a long time. I hate to keep my builder in limbo... Oh wait, I just saw that the decision is due on the 20th. That's not too bad.
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11-13-2015, 06:19 AM | #29 | |
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Which is good, because if they're going to decline a letter it'll be pretty much instant, however if it stays within the discussion board they feel the move is necessary and try to find the right spot for it. The 128 will be moved out (from the sources I've heard), just a matter of where. |
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11-13-2015, 11:27 AM | #30 | |
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I do think BSP is a better fit than ASP, for sure. A little annoying as I had convinced myself that a 3.46 final drive ratio was the way to go, and was on the cusp of ordering one. I do greatly appreciate the heads up, as it would've been extremely frustrating to get this news while the diff was being built! So now the only question is do I stick with stock or jump up to 3.73? Honestly, I'm leaning towards the latter. Highway driving will be fine, I'm just wondering if I'm going to be bouncing off the limiter all the time during AX? I think short, technical courses should be fine. The faster courses (like we have at Cherry Point) might be more problematic, but I'm moving this summer and so will be competing at a different site for the next 3 years or so don't know what the layout will be like there (Puget Sound area - anyone drive at Bremerton Motorsports Park?). |
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11-13-2015, 12:23 PM | #31 | |
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The Letter Number is 17104 The December Fastrack will be available here when updated: https://www.scca.com/pages/fastrack-news It doesn't go public until published there. |
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11-13-2015, 01:53 PM | #32 | |
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The one other area I did autocross in Washington is at Packwood, which I liked a lot more but it's much further from Seattle. The layout there is a big squarish parking lot. The time I went there the course was much tighter. There's also autocross at another airfield run by WWSCC but I have not tried going there before so no idea what that one's like. I have some videos on youtube here if you want to get a sense of what the courses were like (don't mind my terrible driving, I'm still learning!). This one was at Packwood: This one was at Bremerton:
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11-13-2015, 03:36 PM | #33 | |
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11-13-2015, 04:48 PM | #34 |
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If you're in Whidbey, Packwood might be even more annoying to get to unfortunately. It's near Mt Rainier, maybe on the south east side of it, still at a decent altitude. Although, the drive through the mountain to get there is a nice drive when there's no traffic.
Google map link to the town: https://maps.google.com/?q=Packwood%...hl=en-US&gl=us |
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11-13-2015, 05:53 PM | #35 |
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Thanks to everyone for your input.
I had all but decided on 3.46 gears as a good compromise between stock and aggressive gearing - I was only hours away from an order, in fact - and then this SCCA re-classing bombshell dropped. I think it's actually a sensible move (if it goes through), but it does affect my choice of gear ratio, at least if I want to compete in SP rather than SM. I'm not 100% sure that that's even important to me, but honestly, if I'm not building for autocross I almost have even more reason to go with 3.73 gears because then I don't care so much about a shorter 2nd gear, and it should be more fun just about all the time. So it's kind of a catch-22: probably the ideal AX ratio will negatively impact my classing, and the "who cares, I just wanna have fun" gearing nets me more favorable classing. Oh well, I'm just going to go for it. The fact that Quaife sells a 3.73 gearset for the 130i (which has slightly shorter 1st, 2nd, and 3rd gears) makes me think this will work. Here goes nothing, I guess. |
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11-14-2015, 06:40 AM | #36 |
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I think personally i'd go with 3.46, but that's only because my driving consists of a ton of highway. If that wasn't the case the 3.73 would be ideal. I've always felt that the gears are way too long and shortening the final would really wake the car up. I personally don't care if i have to shift more or if it slows my 0-60 time. As long as the car is fun to drive nothing else matters!
Can't wait to hear your feedback. An LSD is really one thing i've been wanting it just hasn't been in the cards.
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11-14-2015, 09:13 AM | #37 |
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The transmission's the problem...or rather BMW's choice of gears for the 6 speed. I'm getting ready to install the Wavetrac in mine and would love to put the 3.73 in there, IF I could change tranny gears...
Much taller 1st... 4th is now the "straight-thru" gear, not 5th... 5th is now the old 6th, and 6th is even taller for highway...
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11-14-2015, 09:33 AM | #38 |
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Time to change your cards! Even with the stock gear ratio, I think that it was worth it for me. I definitely have more traction and the traction control kicks in a lot less. If I had to do it over again, I'd spend a bit more to find someone who would put in a 3.46 final drive ratio.
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11-14-2015, 11:13 AM | #40 | |
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11-22-2015, 07:12 AM | #41 | ||
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Also, what does this mean, really? Are they just kicking the can down the road? How long is his comment period open until they make a decision? And then how long after that until classing is actually changed - 2017, maybe?
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11-25-2015, 11:32 AM | #42 | |
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Nothing proposed is going into act until 2017 |
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