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Decided to fit a M3 diff
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01-17-2013, 06:06 PM | #243 |
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I have the M3 rear on my FBO 135i and I am also 6AT. Going taller than stock sounds silly to me. I have the 3.85 of the manual M3 and it is perfect.
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01-17-2013, 06:46 PM | #244 |
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I just figured that with my setup launching from 2nd gear is better because i have the torque exchange in my transmission
therefore going taller would mean 1st gear is more usable for standing starts. once rolling 6AT's just adjust accordingly and wit all the torque of the N54 those taller gears would suit it better. what do you think? |
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01-18-2013, 03:27 AM | #245 | |
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Remember it is not just for the launch... |
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01-18-2013, 06:44 AM | #246 | |
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So I can presume that apart from the final drive gearing there is no difference between the DCT and MT diffs Maybe I need to learn how difficult is it to change final drive gears in the diff. |
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01-18-2013, 07:38 AM | #247 | |
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The only major negative I have is that at highway speeds the revs in 6th sit in the drone sweet spot of the AE Exhaust I had on. It was unbearable and I have put stock exhaust back on. At 120-130km/h the car cruising right in the droning spot. My consumption with the diff also sits lower than 10L/100km always.
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08 E90 335i AT RB Turbos -NX Wet Kit - Chiplogic Flash or Procede V5- M3 Diff - AE Exhaust- Forge Dv's - Helix Intercooler - AR DP's - P3 Boost Gauge - Vishnu Meth- Stett Chargepipe and CAI
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01-18-2013, 08:55 AM | #248 | |
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Is the M3 Manual diff shorter FD than our OEM diff? if it is then the dct is the best choice |
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01-18-2013, 11:40 AM | #249 |
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Hey George, didn't realise you were an auto 335i. Does that mean you went from 3.46 stock to 3.15? I'm kinda planning on going shorter rather than longer.
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01-19-2013, 02:17 AM | #251 |
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I went with the 3.85 M3 manual diff first which was a bit short for my liking then fitted the DCT 3.15. I have RB's and am always at the 440whp level so the longer 2nd allows for slightly better traction on road. With the 3.85 I would loose traction at the lower end of third with stock Michelin RFT.
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08 E90 335i AT RB Turbos -NX Wet Kit - Chiplogic Flash or Procede V5- M3 Diff - AE Exhaust- Forge Dv's - Helix Intercooler - AR DP's - P3 Boost Gauge - Vishnu Meth- Stett Chargepipe and CAI
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01-19-2013, 03:26 AM | #252 |
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From my head I think even the finned cover of diff has different part numbers so I'm not sure about are internals same. Though still I don't know what is your car MT DCT or AT but like I said for best performance stay close to OEM ratio.
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01-19-2013, 04:05 AM | #253 |
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The Manual diff is 3.85 .
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08 E90 335i AT RB Turbos -NX Wet Kit - Chiplogic Flash or Procede V5- M3 Diff - AE Exhaust- Forge Dv's - Helix Intercooler - AR DP's - P3 Boost Gauge - Vishnu Meth- Stett Chargepipe and CAI
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01-19-2013, 09:48 AM | #254 |
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So the 335i 6AT OEM diff is 3.46 FD
M3 Diffs M3 dct is 3.15 FD M3 mt is 3.85 FD So in fact they are both +/- 0.30 FD difference Based on the fact I'm running more power going longer must be the better option As for the 335i MT diff it's 3.08 FD therefore the M3 DCT diff is the clear choice because the M3 manual 3.85 FD thats going to shorten the gearing significantly. Imagine that with slick drag rear wheels |
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02-10-2013, 11:41 PM | #255 |
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George, were the 3.15 and 3.85 diffs different lengths? Did you have to modify the driveshaft again when you switched?
On my 6 mt the front half of the m3 shaft ended up being 673 mm from center bearing to guibo face. Put a couple hundred miles on it so far. Theres a slighy wobble but we're trying again. I'm actually wondering because the m3 manual shaft on realoem is only a couple mm from my final driveshaft length. Not that it matters because they had to re-tube it to switch the tri-flange, but just wondering if I'd have bought the m3 manual shaft if this would've been easier... |
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02-11-2013, 05:03 AM | #256 |
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Hey Skyguy, nice work. If you don't mind I'm going to use your measurements to get my Mt driveshaft made up.
Are you happy with the length, or would you change it at all? Is the guibo the rubber end piece that bolts on to the driveshaft? And was there a particular part of the centre bearing you measured from? :-) Thanks! |
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02-11-2013, 09:23 AM | #258 |
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Guibo or flex-disk, yeah same thing. If you're looking underneath at the two sets of center bearing mounting holes, they measured from the center-point of the rear set of holes to the face where the flex-disk bushings meet the tri-flange on the shaft. Like I said I'm still having some wobble accelerating through 20-25mph, I'll update when they tell me it's fixed and what the solution was. Hopefully it's not a length issue, so to speak...
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02-11-2013, 09:53 AM | #259 |
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I had the wobble at 25mph full throttle
this is because you have to use the 335i center shaft bearing on the M3 one. The M3 bearing will not align the shaft to the gearbox, it will hang the shaft too low!!!! |
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02-11-2013, 09:55 AM | #260 | |
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02-11-2013, 11:32 AM | #262 | |
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Must me a very slight difference I didn't even notice it, hope that will solve my problem. Thanks, Sky |
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02-11-2013, 11:39 AM | #263 |
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I had to refit the shaft 3 times and ask an expert friend to notice this difference, you simply can't see it below the car.
It was a nightmare to find out!!!!!!!!!!!! If I remember well it is 10mm difference, because the M3 gearbox sits lower, it is a V8... you can reuse the one of the 335i it fits the M3 mid shaft. My 677mm are from the middle of the hole in the bearing (where it bolts to the car) to the flange surface where it meets the guybo at the gearbox |
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02-11-2013, 11:47 AM | #264 |
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Thanks so much for the response Marconi. Really hoping it's really this easy of a fix, never had the center bearings next to each other separated from the shafts but now the difference looks obvious. Crossing my fingers they still have my bearing and don't charge me.
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