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If people knew how to drive efficiently they'd use gears to do this and only use brakes to stop. Just sayin'
by digitalWestie 14y ago
If people knew how to drive efficiently they'd use gears to do this and only use brakes to stop. Just sayin'
- __alexs 14y agoI'd like to see a gearbox that can get you from 120 mph to 0 in less than 3 seconds.
- Toucan 14y agoHow would that be efficient? Engine braking wears transmission components which are considerably more fragile and expensive than replacing brakes. Engine braking only stops you using the driven wheels, brake discs apply to all wheels.
- mpyne 14y agoEngine braking allows you to save fuel (by using stored energy of the drivetrain to handle compression of the air that normally would require work from combustion). And, as long as the car remains in gear there's not much extra wear on the transmission itself (certainly not compared to the torque from the acceleration the preceded it, at least).
- Toucan 14y agoI think we're talking about different things. digitalWestie's advice to use the gears to slow implied changing down through the gears to use the engine to brake, not simply leaving the car in gear while applying the brakes. For what it's worth, it does makes complete sense to leave the car in gear while braking and not to change to neutral.
- jamesjguthrie 14y agoI think he meant not waiting for the revs to match, just downshift. This will cause wear and increased fuel consumption while also slowing the car.
- mpyne 14y agoWell as someone from an engineering background I'd never recommend skipping rev matching (though I'm lazy and the car does it for me on my automatic).
- ferongr 14y ago>Engine braking wears transmission components No it doesn't. Synchronized, rev-matched downshifts put negligible load on the drivetrain. Coasting to a stop with the gear already selected, putting it in neutral just before stall does that even less. The stresses produced by acceleration are ballpark estimate around an order of magnitude greater. This can be inferred by the fact that usually the rate of deceleration by engine braking is smaller than the rate of acceleration for a given gear ratio, ergo, the drivetrain is strained less.
- Toucan 14y agoIt still wear components that are not as easily replacable as brakes. As for coasting to a stop whilst still in gear, I agree with that being a good idea but I don't think that's what digitalWestie was getting at.
- jamesjguthrie 14y agoUsing gears to slow your car uses more fuel vs just braking. Just saying / rant over / other clichéd sign off.
- jamesjguthrie 14y agoNote: perfectly matching revs while downshifting isn't using your gears to slow; it's just slowing.
- k00pa 14y agoFuel usage is 0 when you slow down without brakes... When you use brakes your engine needs fuel to idle. (Assuming you are using manual transmission, and on automatic you can force down the gear to do the same.)
- Toucan 14y agoWhen I use my brakes I don't put the car in neutral until I'm almost stopped. The fuel consumption is the same.
- RobotCaleb 14y agoSome cars even stop fuel flow if you're in gear but not applying gas. I think it's called Deceleration Fuel Cut-Off (DFCO).