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09-07-2015, 08:26 PM | #1 |
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Non-M Differential with 3.64 Final Drive
Asking $400 plus shipping. Fits all 2003-2008 non-M's. Low mileage, ~30k miles. 3.64 is the final drive ratio Turner chose when building their Championship Motorsport Edition E46 330i ZHP. Turner charges $1535 + $140 core charge for the diff: http://www.turnermotorsport.com/p-10...ginal-bmw.aspx No noises or issues. The only reason I'm selling is because I recently came across a deal I can't pass up on another differential with a Quaife limited slip unit already installed. This diff was one of my favorite mods. Compared to the stock 3.07, torque to the ground increases by 18.6% in each gear at the expense of engine speeds being 18.6% higher. Speedometer is unaffected. This mod will provide the greatest increase in acceleration of any mod other than forced induction ($4k+). At low-mid rpm, it will increase acceleration more than a centrifugal supercharger. Only an ESS TS can produce comparable gains at low rpm. Unless your car has significant power modifications, top speed is unchanged. A stock car with a 3.07 final drive is electronically limited to 155 mph. With the governor removed, it's drag limited to 160-165 mph. With a 3.64 final drive, the car is redline limited to 164 mph. The 3.64 final drive is on the mildly aggressive side of the spectrum. 18.6% is a huge jump in torque, but an extra few hundred rpm on the highway won't dramatically change the car's manners. With the 3.64 the driver has the option of shifting right into the heart of the powerband at nearly any road speed. With a peaky engine, this is perhaps a greater advantage than the straight torque multiplication. I am fortunate enough to have a centrifugal supercharger installed, and the shorter final drive allows the car to stay "in boost" at virtually any road speed. The 3.64 pairs very well with both naturally aspirated and centrifugally supercharged cars. ***Technical Explanation*** At 30 mph with a stock 3.07 final drive (03-05 Z4 3.0i manual), the engine will be at 3000 rpm in 2nd gear. With a 3.64 final drive, the car will now be at 3550 rpm where the engine generates more horsepower. That same Z4 with a VF Engineering supercharger will generate 200 whp @5000 rpm. If the final drive is swapped to a 3.64, at the same road speed the car will be at nearly 6000 rpm where it generates 260 whp. With the torque multiplication added in, the car will accelerate at that road speed like it now has 308 whp. *********************** The downside of a 3.64 is that it requires the driver to shift sooner, briefly losing the mechanical advantage of the lower transmission gear. However, the moments are very brief (typically <1 sec), and 5th gear with a 3.07 is virtually identical to 6th gear with a 3.64 (within 1 mph). As compared with the 3.07, the 3.64 generates (approximate numbers): 20% more torque 80% of the time. 20% less torque 20% of the time. A shorter final drive is the best bang for the buck mod you can do to wake up the car. The car will behave exactly as it does now, except with more power to the ground and mildly higher rpm at the same road speed. There's no added noise or emissions to deal with. To see what final drive your car has now, visit: http://www.bokchoys.com/differential/GearRatios.htm To estimate speed in each gear, visit: http://www.bokchoys.com/differential...calculator.htm Z4 6-speed manual ratios: 1st - 4.35 2nd - 2.5 3rd - 1.66 4th - 1.23 5th - 1.00 6th - 0.85 Max speed in each gear (3.07 final drive): 1st - 38 mph 2nd - 66 mph 3rd - 99 mph 4th - 134 mph 5th - 165 mph 6th - 194 mph Max speed in each gear (3.64 final drive): 1st - 32 mph 2nd - 56 mph 3rd - 84 mph 4th - 113 mph 5th - 139 mph 6th - 164 mph I'm more than happy to answer any questions!
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Last edited by pokeybritches; 09-10-2015 at 11:07 AM.. |
09-10-2015, 10:35 AM | #2 |
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09-10-2015, 11:31 AM | #3 |
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Can this be used on any 03-05 Z4 with 5-spd auto, 5-spd manual, or 6-spd manual? Can I also use it on a E83 X3 that uses the same M54B30 engine? When you say it gives the car more power to the ground, does that imply lower 0-60 and 1/4 mile times?
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09-10-2015, 01:15 PM | #4 | |
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(03-05 Model) / (Torque to the ground increase) 2.5i manual (3.46 stock) / 5.2% 2.5i auto (3.64 stock) / no change 3.0i manual (3.07 stock) / 18.6% 3.0i auto (3.46 stock) / 5.2% If your model has a 3.46 now, moving to a 3.64 will feel like you've gained 12 horsepower. The difference in top speed in each gear is almost negligible. You should notice a difference in quarter mile times and power in daily driving. 0-60 mph depends on your current ratio. 0-60 mph isn't really the standard any more. 0-60 mph was useful when times were in the 10 sec range, but cars have gotten so powerful that traction has become a bigger factor in 0-60 mph times. 0-60 mph measures the time it takes to achieve a certain speed (60 mph) rather than a certain distance, and races are all about distance. With a 3.64, you may have to make an extra shift to hit 60, but you will cover more distance over time in nearly all races.
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09-10-2015, 03:14 PM | #5 |
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Since your car has a 3.07, it would perform like it has 267 horsepower but redlines sooner.
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09-10-2015, 03:51 PM | #6 | |
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I was asking about the X3 to see if one could just use a stock diff off a totaled X3 since they are for sale all over ebay. Ebay might be a little cheaper, but like you said the flanges might not line up and they will have way more miles on it. From what you've explained it sounds like going from 3.07 --> 3.64 will produce lower 1/4 ET times, but the trap speed will be the same. From 0 to 32mph the 3.64 will have MORE torque, but from 32 to 38mph it will have LESS torque. From 38 to 56mph it will have MORE torque, from 56 to 66mph it will have LESS torque, and so forth. The biggest improvement of the 3.64 will be felt in 1st gear from a stop. Once you hit 2nd gear, the advantage flip flops depending on your speed and gear, so the advantage won't be as dramatic from 32mph and up. Can someone do this mod and use tuning software to increase the redline to stretch out each gear to produce an even greater effect? |
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09-10-2015, 05:59 PM | #7 |
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This seems like a pretty good deal, GLWS! Still need to do final drive, myself.
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09-10-2015, 10:05 PM | #8 | ||
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No, the trap speed will change with quarter mile. It will be higher with a 3.64 versus a 3.07, reflecting the faster time. The biggest advantage is the ability to keep the car in the powerband at virtually any road speed. There will be moments of time when running through the gears that a 3.07 will have brief advantages, but as soon as the shift happens, the 3.64 will be in the sweet spot of the powerband plus have the torque multiplication advantage. A drag or roll race wouldn't be close. There are videos out there of M3's with stock, 3.91, and 4.10 ratios lining up and running from a roll, with the 4.10 geared car walking the others, but I'd rather not post a video of people doing stupid stuff on the street. However, the videos do show how much of an advantage hotter gearing provides, and how the race is not a back and forth but rather a clear victory for the shorter gearing. The best way to understand this mod is to think about how you drive the car now, and consider what a different gearset would do for you. As a personal rule of thumb, I never use first gear for anything other than a standing start. The wear and tear isn't worth it, and there isn't much difference between a clean run in second gear versus 1 sec of WOT in first plus a half second shift. From 20 mph or so in second gear, the 3.64 has a huge advantage over the 3.07. Same goes for low speed starts in any other gear (such as what's encountered during normal daily driving). The 3.64 will always have the advantage. Could you shift into second gear at 60 mph with a 3.07 for a brief moment of extra power? Yes, but why would you want to? It's very hard on the car, and in less than a second you would be shifting again. If you shifted into third at 60 mph, the 3.07 would be at just over 4k rpm (4120) while the 3.64 would be at just under 5k rpm (4860). The engine naturally generates more power at 5k rpm than 4k rpm, and the 3.64 applies the torque multiplication advantage (18.6%) on top of it.
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09-10-2015, 10:08 PM | #9 |
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Also, tuning pairs well with this mod. In my build thread I recommended a Shark Injector for a naturally aspirated car.
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09-10-2015, 10:08 PM | #10 | |
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09-11-2015, 03:02 PM | #11 |
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How many hours will an experienced shop charge for the installation? I'm checking the DIY online and people are claiming anywhere from 1 to 6 hours which is quite a big variance. This sounds temping, but can someone else please buy this? The wife says I'm done spending money on the car until next year, so I'm going to try my best to listen for once.
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09-11-2015, 06:28 PM | #12 | |
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I believe I was charged 3 hours labor when I had it done, but it's been a while. I put together a gearing calculator today. It's still in draft form, but I've attached some results of a 3.64 vs 3.07 final drive. - I analyzed a stock M54B30 dyno, pulling wheel horsepower in 200 rpm increments from 3000 rpm to redline. - Wheel speed is calculated in 200 rpm increments from 3000 rpm to redline, using tire size. - I multiplied wheel horsepower by transmission ratio, then by final drive ratio for each 200 rpm increment in each gear. If the car could be in multiple gears at a certain speed, I included a function to filter all but the lowest gear available (most power to the ground). Higher gear results were given null values. - I graphed horsepower per gear versus speed; the difference in power to ground in 10 mph increments for a 3.64 and 3.07 final drive (averaged); and the cumulative total of the average power for each 10 mph increment. - The second graph shows where each ratio is strongest. The third graph shows the total power, and demonstrates the effect of torque multiplication. - Only torque multiplication was analyzed. The ability to shift into the powerband at various speeds was not demonstrated. Time spent shifting gears, drag, and time to achieve a certain speed will be built in the future. - I'm aware there are gaps in the graph where shifting takes place. This is due to taking a speed value at a redline shift in one gear (example 56 mph), and then moving to the next speed for which I had data (which might be 58 mph due to the 200 rpm increments used). - I built in functions to adjust for various redlines, transmission ratios, final dive ratios, tire sizes, and power mods.
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12-20-2015, 02:08 PM | #13 |
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12-30-2015, 02:40 PM | #14 |
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I just wanted to thank you for all the great info on this thread.
I want this but shipping will kill me. I have a 3.0si 6-speed with 3.23Final, I really want to do the diff swap. I have found a few 3.64's locally. I just need to do it, but I'm trying to find a 3.73 from the automatics. Do you know what the actual work that needs to be done in order to use the 3.91 or 4.44 from the X3's? I do not know if I want to use any of these, but I like to keep my options open! |
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12-30-2015, 04:05 PM | #15 |
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As far as I know the X3 diff should bolt right in with zero mods.
See here http://www.bokchoys.com/differential/GearRatios_E46.htm The 3.64 is the perfect ratio for city and hiway driving IMO.
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12-31-2015, 08:16 AM | #16 | ||
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Shipping would be cost-prohibitive, if you can get a reasonable quote for a 70 lb item shipped from 37343, I would have no problem shipping. Quote:
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01-02-2016, 04:35 PM | #17 |
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01-24-2016, 09:38 PM | #18 |
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I'm interested in this differential but have a question. I was always under the impression that the Z4 manuals had at biggest a 3.07 rear end. Turner also says this on their site. But on that other link you put in your first post it says 3.46 . Do you know who is right?
The reason why I ask is because I would swap it out from a 3.07 but don't think it will be worth the hassle with a 3.46. If my car wasn't in storage them I'd probably try to use a mirror to see the tag to know for sure. |
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01-25-2016, 08:52 AM | #19 | |
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This ratio is about 5% higher than a 3.46, so the car would feel like it has 268 bhp instead of 255 bhp.
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03-01-2017, 10:24 AM | #20 |
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Revive-
Im picking up a 3.64 from a Wrecked E46 on Friday! |
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