Stress on the driveshaft

"The man in the iron mask" (Themanintheironmask) 09/26/2013 at 07:40 • Filed to: Mechanics

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what would be more stress on the driveshaft, launching a car with the gearbox on the rear, or the conventional gearbox-driveshaft- differential?

Z_Stig > The man in the iron mask 09/26/2013 at 07:43

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I don't think there will be a difference. Launching a car can be very hard on all the drive train components.

The man in the iron mask > Z_Stig 09/26/2013 at 07:49

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well yes in everything, but when you dump the clutch and you are in first the driveshaft doesnt rotate at the speed of the engine, and in the corvette with the gearbox on the rear, the driveshaft will rotate at whatever rpm you where holding on the launch

V8Demon - Prefers Autos for drag racing. Fite me! > The man in the iron mask 09/26/2013 at 07:54

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I've seen quite a few relatively stock Corvettes GRENADE their rears with LSx motors

Mattbob > The man in the iron mask 09/26/2013 at 08:00

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conventional has more stress. If the trans is in the back, the torque tube sees less torque on launch as it is on the other side of the gears.

the__man > The man in the iron mask 09/26/2013 at 08:23

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They call this the torque tube for a reason.

the__man > The man in the iron mask 09/26/2013 at 08:23

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oh and 2 stage exhaust flappers FTW.

UserNotFound > The man in the iron mask 09/26/2013 at 08:29

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Less torque, more inertial load. Same power.

You can tell a Finn but you can't tell him much > The man in the iron mask 09/26/2013 at 08:50

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Since a transmission is a torque multiplier the driveshaft in a box-shaft-diff setup will see much more torque loading than it would with a shaft-transaxle setup. But the inertial loading on the shaft-transaxle setup will be a lot higher than the conventional setup. It really depends on whether the torque loading or the inertial loading of a rear gearbox(transaxle) is higher and frankly I don't know.

In reality the driveshaft will probably see pretty similar stresses because they would design the driveshaft to the system. The manufacturer will put in the smallest driveshaft that will handle the design load as that will minimize weight and cost for them.

Chteelers > the__man 09/26/2013 at 09:05

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I hate these things. Primarily because after a while, two of the tips looks black and two look shiny.

deekster_caddy > The man in the iron mask 09/26/2013 at 09:10

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Technically the driveshaft is under more stress in 1st gear after the gearbox - full engine power multiplied by 3 or 4 depending on your 1st gear ratio. Putting the gearbox in the back means the driveshaft only sees raw engine power. Is the driveshaft always spinning at engine speed or is there a breakaway/clutch of some sort at the front?

04sneaky - Boxers. Blowers. Bikes. And bitches. > The man in the iron mask 09/26/2013 at 10:15

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All this talk about less torque forgets that these cars have huge problems with wheel hop due to the small axles and the flew in the rear drivetrain.

Torque isn't the only thing that causes stress, especially in a real world environment where everything can't be solid mounted and therefore has rubber bushings in and throughout the design.

oddhammer > The man in the iron mask 09/26/2013 at 14:17

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Anyone else think they were looking at an AWD 'vette? Just for a second?

The man in the iron mask > deekster_caddy 09/26/2013 at 14:23

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good question, i dont know where could the clutch be at, between the engine flywheel and the driveshaft or driveshaft and rear gearbox, maybe at the flywheel, because whe you start the engine you would have to crank the driveshaft as well

deekster_caddy > The man in the iron mask 09/26/2013 at 14:33

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I would assume there is a clutch right at the gearbox so you don't have the spinning mass of the driveshaft to contend with. But I wonder if there would be an additional clutch on the engine side, for example while it's in Neutral or the engine is off/starting. The more I think about it, though, the less I think it would be necessary.

Is there a flywheel in the back attached to the driveshaft? You could even put the starter motor under the back of the car!