Thread: Clutch
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Old 05-29-2014, 12:15 PM   #7
extrashaky
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Quote:
Originally Posted by Lavalover View Post
The lurch sounds like engine compression/braking to me.
That's what it sounds like to me too.

ninedice, first gear in this car is geared pretty low, and the compression of this engine is high. When going down a hill with your foot off the accelerator, the weight of the car is going to pull it down the hill against the compression of the engine, and the engine is going to try to slow it down. Give it any gas at all, you're going to lurch forward. Let off the gas, you're going to be slammed against your seat belt.

If you are trying to ride that "in between" space by accelerating gently down the hill, the car will buck like you're describing because there is no in between at that gear ratio. It wants to either go or slow down, with no coasting in between. What's worse, if you try to react to the bucking, you will not be able to time it perfectly, and you will create a form of pilot-induced oscillation (or, I guess in this case it would be driver-induced oscillation). In fact, the bucking of the car can change the amount of pressure you're putting on the accelerator so that you enter a PIO condition without even trying.

It sounds like you're not shifting out of 1st soon enough. When I'm taking off downhill, I either start in 2nd or use 1st just long enough to get rolling, then immediately shift into 2nd. Use the gears you need and skip the others.
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