07-03-2013, 08:42 AM | #23 | |
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07-04-2013, 01:34 AM | #24 | |
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AWD puts more stress on the drivetrain for that exact reason. It'll find the weakest link and break that part... then the next weakest, and the next, etc. Can't wait for the "Destroyed my drivetrain, will the dealership know I've been dumping my clutch?" thread. This may be the reason he's had 10 MT's... because they keep breaking |
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07-04-2013, 09:15 AM | #25 | |
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07-05-2013, 03:02 AM | #26 | ||
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As mentioned above, I want to learn, so objective and logical reasoning is key here. Let's use a 335i and 335ix as an example. Lets say both cars have 300 ft/lbs of torque, use the same drivetrain pieces (similar transmissions but same gear sizes/lands, same halfshafts, same driveshaft, same bearings, same differentials, etc etc). Now the awd version will have additional halfshafts at the front, but lets say they are the same pieces as the rear halfshafts in material and tensile strength. For the sake of simplicity, let's ignore drivetrain loss. As each car launches, the 335i's torque splits into 2 (150 ft/lbs per rear wheel), and the 335ix's torque splits into 4 (75 ft/lbs per wheel). Now assuming that all drivetrain parts have similar tensile strength/torque threshold, I don't see why and how 75 ft/lbs per wheel puts forth more stress than 150 ft/lbs per rear wheel? If the car is tuned to, say.... 600 ft/lbs, the 335i splits 300 ft/lbs per wheel, while the 335ix splits 150 ft/lbs per wheel. How is launching the car with 150 ft/lbs per wheel worse than 300 ft/lbs per wheel? Lastly, as a stress test for the 600 ft/lbs monster, if each halfshaft has a tensile strength/torque threshold to withstand 300 ft/lbs, wouldn't the 335i's drivetrain be in worse condition (from torque stress) than the 335ix? BTW... are you dinonz uncle? And happy 4th (shit... too late), oh well. |
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07-05-2013, 08:54 AM | #27 | |
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If you do the same in a 4WD/AWD the torque might not be enough to overcome the stiction of the tyres, so all that torque is transmitted to the ground as forward motion. The problem is that at the moment of dropping the clutch, you have an engine at 6000 RPM and wheels at 0 RPM and neither one wants to change that rapidly, so somewhere in the middle something has to give. Severe stress will be placed on all parts of the drivetrain as it gets twisted, and 99% chance the part that "gives" will be the clutch which will probably slip a bit to take up the strain, but only once the transmission and every CV/Universal joint have been wound up as tight as they can take without breaking. Until one day they do break. As they say, a chain is only as good as it's weakest link, and the weakest link in a 2WD is the tyre contact with the road. On a 4WD/AWD though, that's not the case, thus something else somewhere in the chain will eventually give up. That better Andy? It's difficult to explain on a forum - be easier with a white-board, but that's the general idea. |
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07-05-2013, 11:05 AM | #28 | ||
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07-05-2013, 11:13 AM | #29 |
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I would suggest doing this to your dealers Loaner car when you get your car into service :P
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07-05-2013, 10:13 PM | #30 |
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Dinonz......that's exactly what I was looking for. Very well explained sir and it makes sense. I was also under the impression that since the torque was dispersed over 4 wheels instead of just 2 there would be less strain on drivetrain.
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07-05-2013, 10:38 PM | #31 | |
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07-05-2013, 11:05 PM | #32 | |
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07-20-2013, 06:54 PM | #36 | |
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07-20-2013, 07:32 PM | #37 | |
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