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First question on the site, I hope this is appropriate.

I drive a 2013 Ford Fusion SE with manual transmission. I learned to drive a manual as a kid but picked up a lot of bad habits. In particular I tend to naturally ride the clutch. Now, of course in 1st or Reverse you have to let the clutch slip a little, but I'm having difficulty not letting any slipping from 1st to 2nd.

My question is: when shifting from 1st to 2nd, is it ok to give the car some gas as you release the clutch?

My feeling is that the answer should be no, I just need to practice and do: "clutch. switch gear. release clutch. gas." but at the apprioriate RPM.

I'm confused because many people on various fora say that it's ok to give gas while you're releasing the clutch, but I'm skeptical because this seems like it would wear on the clutch. I want to learn perfect form.

Thanks.

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If you don't, I wouldn't want to ride in the vehicle with you. Shifting without giving any gas as you release the clutch tends to jerk your passengers and/or cargo around quite a bit. –  R.. Aug 3 '13 at 21:15
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Not if you time the shifting right. I admit it's difficult, but it is possible. –  Lepidopterist Aug 3 '13 at 22:07
    
OK, that's true. I made a point of paying attention to my clutch usage today, since otherwise I have a hard time thinking about what I actually do. For the most part, I hit the gas right at the moment my left foot is coming off the clutch, and indeed acceleration is very smooth. –  R.. Aug 4 '13 at 17:45
    
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2 Answers 2

up vote 9 down vote accepted

Is it ok to give gas while releasing the clutch?

Yes, but your goal is to give exactly the right amount of gas.

The thing to remember is that the clutch is a consumable part (it's really a whole system of parts that can be consumed but let's pretend that it's a single unique piece for the sake of discussion). As such, it has a finite supply of work that it can do over its service life, useful or otherwise. To clarify, this is what it means to slip the clutch:

Between these extremes of engagement and disengagement the clutch slips to varying degrees. When slipping it still transmits torque despite the difference in speeds between the engine crankshaft and the transmission input. Because this torque is transmitted by means of friction rather than direct mechanical contact, considerable power is wasted as heat (which is dissipated by the clutch). Properly applied, slip allows the vehicle to be started from a standstill, and when it is already moving, allows the engine rotation to gradually adjust to a newly selected gear ratio.

As noted, the clutch is a friction-based part (rather than a direct gear). The above quote means that your goal as the driver is to attempt to ensure that the clutch is spending more time in a static friction mode (i.e., where the frictional surfaces of the clutch are turning at the same speed, pressed tightly together) rather than a kinetic friction mode (i.e., where the frictional surfaces are turning at different speeds and are slipping past each other).

This means that the answer to your original question is that it is ok to give exactly the right amount of gas when releasing the clutch pedal. Any more or less than the optimal amount will lead to some slippage of the clutch. Some slippage is to be expected, with wear increasing super-linearly as the difference between target and actual revs increases.

The better you are at rev matching, the longer your clutch will last (and the more comfortable your passengers will be).

tl;dr: You have to slip the clutch from a stop. In higher gears, your goal is to avoid slipping the clutch. You do this by matching engine speed to transmission speed before releasing the clutch pedal.

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Just think of the this way-

When you use a higher gear, the RPMs will be lower than a low gear at the same speed. However, while shifting to a higher gear, you let off the gas which will cause your RPM to drop low- most of the times I find it a little too low, even for a higher gear. So you want to add some gas, just as Bob wrote, so your engine can catch up to the clutch speed. But just enough so the engine can pick up from idle. You don't want the engine spinning slower or faster than your clutch at a higher gear. Just feel it out and try to match the clutch and RPM as best as you can.

Same thing with downshifting- you are going to have to add gas more aggresively when downshifting since lower gears need to spin at a faster RPM to match the clutch speed. If you don't add enough gas, the slow engine could catch your clutch and cause your wheels to suddenly lose speed and skid. You have to always be the computer that matches engine speed with clutch speed.

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