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09-09-2014, 10:42 AM | #23 |
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09-09-2014, 10:52 AM | #24 |
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I guess I am not sure that I see the concern... you have your choice of final drives... choose the one that works best for you. Somewhat pointless to discuss since people will have different needs / concerns.
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09-09-2014, 11:05 AM | #25 |
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There are both positives and negatives, of which I've listed both, as well as addressed some common concerns and "myths"
At the end of the day, you should choose what is right for your setup, and also the capabilities of your tuner. I (we) are here to help with anything gear related, so please don't hesitate to ask or pm any questions |
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09-09-2014, 05:22 PM | #26 | |
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take a log in 2nd gear vs 3rd with the same load tables/no boost by gear.. 3rd will hit a higher peak boost. you're right, the 3.46 car will hit 100km/h even on a kill tune stock frame RB/stock.. because in 1st/2nd already, the torque multiplication is such that shifting at redline is optimum however, highway, road course, drag strip.. because you shift at ~6000 with the power band peaky and narrow, 3.46 gets less acceleration above 80-100mph.. yes you get more torque through the higher rev range still, but you have to shift to the next gear that provides less torque, sooner, due to the torque dropping off too rapidly.. you're increasing how much torque you get for a shorter period of time.. and again, the time spent shifting (even .1 second per shift) has to be taken into account. i'm having trouble finding the good calculators to show this though haha (one that does full 1/4 mile and time spent accelerating count) for cars with a midrange power band... longer gears = better high speed acceleration, 1/4 miles etc. for a car where you shift at redline for peak acceleration (ST N54's etc.)... shorter gearing is better. I remember another thread that had it all properly calculated, and a 2.56fd with all factors considered (launch/60ft/shift time) 2.56 came out a fair bit quicker in the 1/4. Last edited by flinchy; 09-09-2014 at 05:28 PM.. |
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09-09-2014, 07:59 PM | #27 |
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Again, you've based your assumptions on distance (i.e 400m), not net acceleration.
If you have to do calculations on distance, then yes, you need to calculate which ratios are most suitable, as well as have the correct tune/setup. But for acceleration on a general road car, or even one which does road course/auto-x, where distance is not a set factor like it is in the 1/4 mile, shorter gears (with the correct tune/setup)would prevail. Torque is torque, and it is increased throughout the entire rev range, not just at high rpm |
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09-10-2014, 02:13 PM | #28 | |
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Any Toyota supra MK4 with 400rwhp or so just spins tires in gears 1/2/3 its Getrag V160/161 is very close in ratios to the ZF 37GZ family units in the 135/335; you need to fit DRAG SLICKS to put down the power; a 135/335 does not have Supra size rubber in the rear stock (17x9.5JJ and 275mm rubber) changing ratios may be more "exciting" for the street; but in reality there will be TRACTION issues. I do support a local 1,200rwhp drag BMW (9.0@159mph) ~ 1.4 sec 60 foot. - just real world data........ when the ratio is TOO SHORT; the car cannot hook up. when the final drive ratio is TOO LONG; the car will bog on launch |
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09-10-2014, 03:36 PM | #29 |
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Hence why setup (i.e traction/chassis/tune) plays a very important role. If a 400whp Supra is spinning in 1/2/3, they need to find a better tuner.
You also need to remember, those who have installed the 3.46 so far have also installed our LSD which helps with traction immensely.
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04-20-2017, 03:39 PM | #32 |
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Anyone else have this in a 2011-2013 car?
I have a stock 2013 135i Msport 6MT with a Dinan Stage 2 flash as the only mod. Is there any ECU trickery that needs to happen to get the cars speedo to play nice with the 3.46 ratio diff? |
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05-01-2017, 01:21 PM | #33 |
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Thread necroed, but with my 09, I didn't touch the computer. Speed is measured by your wheel sensors for ABS/TC iirc.
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08-21-2019, 02:35 PM | #34 |
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Hi. I've been debating on whether to go 3.08 or 3.46, so I ran some rough numbers for those interested (estimated tire size.)
First off, we have the 135i with a 3.46 final drive vs. the M2, which also happens to have a 3.46 final drive. Second, we have the 135i at 3.08, 3.46 and the m2 at 3.46 to compare (only speeds listed.) Third, we have a 2015 Suburu WRX, which I thought was an interesting comparison, because my friend has one, and it has the same wheelbase as a 135i. The Suburu redlines at 6600, so I showed both at 6600 and at a virtual 7000. The Suburu has the shortest gearing of the cars in this comparison. Finally, we have a 2019 Porsche 718 Cayman S, which redlines at a higher 7500. I'm leaning towards 3.46, because the majority of my driving is fun mountain road driving, I like to shift, and it shouldn't hurt too much at my local track. Last edited by duder13; 08-21-2019 at 03:01 PM.. |
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09-25-2023, 01:26 PM | #35 |
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Bumping an old thread but I recently installed the MFactory helical LSD with 3.46 final drive ratio on my 2011 manual. I'm liking it very much. The shorter final drive makes the car feel lighter and more eager. The increased wheel torque and higher revs are good for my small local autocross venues. And of course, the LSD (combined with coding off the e-diff) finally makes the car feel like a proper RWD sports car. The rear wheels now push me out of a corner and I don't feel the brakes holding me back any more.
Sure, first gear is now hilariously short and highway cruising revs are higher (~125km/h at 3,000rpm) but that trade off is very worth transforming the car into the "ultimate driving machine" it claims to be. Some might find the shorter gearing too aggressive but it's perfectly fine for me. Also no noticeable difference in fuel economy. I bought through ECS Tuning and the process was very smooth. The core return was challenging and costly due to size and weight of the full pumpkin and due to me being in Canada. All things considered, this is an excellent upgrade for the E82 platform. |
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10-13-2023, 02:09 PM | #36 | |
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