What is "Rev Matching"?

[Lowrider]

Rev matching is when you blip the throttle on a downshift in order for the RPM's of the engine to match up close with the RPM's of the gear you are downshifting to.

Common when racing, this will prevent the rear end and overall balance of the car from getting upset by sudden compression braking caused when the engine RPM's are increased after the clutch is let out when you don't rev match.

If you like to downshift when slowing down, it also saves wear on your clutch.

Well said...And to compliment the explanation here is a video.

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[Double]

Sorry for the slight hijack here, but I think manual rev match has been explained very well here.

I still do not really understand the "Rev matching" for an automatic transmission. When you press the down shift on your auto how would it be different if it does or doesn't have "rev matching" ?

 

[GT Pony]

The point of a double clutch is to match the engine speed, input shaft speed with intermediate shaft speed. Rev matching matches engine speed and speeds up input shaft but doesn't match intermediate shaft speed. By letting out the clutch and blipping the gas you use the clutch's rotational inertia to spin up the intermediate shaft so that the synchros match the next gear closer. Simply picking a new gear and reving doesn't match all three. You match engine and Imput, but still used a slower moving intermediate shaft to select the gear (slow wear on synchros) If you properly double clutch the input/output shaft perfectly aligns with the intermediate shaft and there is almost 0 resistance when picking a new gear. The shifter almost falls into the next gear.

My mistake in not initially explaining the link between the engine/input shaft and intermediate. Intermediate and Input are always closely linked in my mind.

You double clutch guys haven't really talked about the fact that in order to do a double clutch shift correctly, the first throttle blip needs to be done with the clutch engaged and the transmission in neutral. See video below.

I try to rev-match when shifting and don't really worry about double clutching. I'm not down shifting at super high speeds anyway, and doubt the syncos are really going to care much. I do like to help keep the wear down on the clutch disk if possible, and rev-matching helps that out quite a bit.

On the same premise, if you don't want to "wear out your syncros" you should also be double clutching (without rev matching) on up shifts. How many people really double clutch when up shifting? I'd say not many or any. See 2nd video.

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[Infamous]

You double clutch guys haven't really talked about the fact that in order to do a double clutch shift correctly, the first throttle blip needs to be done with the clutch engaged and the transmission in neutral. See video below.

I try to rev-match when shifting and don't really worry about double clutching. I'm not down shifting at super high speeds anyway, and doubt the syncos are really going to care much. I do like to help keep the wear down on the clutch disk if possible, and rev-matching helps that out quite a bit.

On the same premise, if you don't want to "wear out your syncro" you should also be double clutching (withe rev matching) on up shifts. How many people really double clutch when up shifting? I'd say not many or any. See 2nd video.

Very informative, thanks for sharing!

 

[GT Pony]

Here's another good video explaining what's going on inside the transmission with and without double clutching.

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[Nazgul]

You double clutch guys haven't really talked about the fact that in order to do a double clutch shift correctly, the first throttle blip needs to be done with the clutch engaged and the transmission in neutral. See video below.

I try to rev-match when shifting and don't really worry about double clutching. I'm not down shifting at super high speeds anyway, and doubt the syncos are really going to care much. I do like to help keep the wear down on the clutch disk if possible, and rev-matching helps that out quite a bit.

On the same premise, if you don't want to "wear out your syncros" you should also be double clutching (without rev matching) on up shifts. How many people really double clutch when up shifting? I'd say not many or any. See 2nd video.

no you don't. When the clutch is in and it's disconnected from the input shaft, all you're doing is review the motor at that point.

 

[GT Pony]

no you don't.

No you don't what? ... you comment isn't too clear. So all the videos are wrong? What's your explanation on why you don't need to do it as the videos show?

 

[Nazgul]

No you don't what? ... you comment isn't too clear. So all the videos are wrong? What's your explanation on why you don't need to do it as the videos show?

You don't blip the throttle with the clutch in. It's clutch in pull outta gear, release clutch, Rev, clutch in pick new gear, release. There one blip.

 

[GT Pony]

You don't blip the throttle with the clutch in. It's clutch in pull outta gear, release clutch, Rev, clutch in pick new gear, release. There one blip.

Go back and read it again. I said with the clutch engaged ... which means the pedal is up. Pushing the clutch pedal down disengages the clutch.

 

[Horse]

You double clutch guys haven't really talked about the fact that in order to do a double clutch shift correctly, the first throttle blip needs to be done with the clutch engaged and the transmission in neutral. See video below.

I try to rev-match when shifting and don't really worry about double clutching. I'm not down shifting at super high speeds anyway, and doubt the syncos are really going to care much. I do like to help keep the wear down on the clutch disk if possible, and rev-matching helps that out quite a bit.

On the same premise, if you don't want to "wear out your syncros" you should also be double clutching (without rev matching) on up shifts. How many people really double clutch when up shifting? I'd say not many or any. See 2nd video.

Sure we double-clutch-ers haven't talked about that (blipping throttle at neutral with clutch up) yet in this thread. To me, that's how double clutch is done, from the textbook. There is just no other way to do it.

As for double clutch on up-shifts, I don't do it. My rational is that the clutch/counter-shaft is slowing down anyways, which (almost) matches the lower speed required for higher gear. (Yeah, one could double-clutch on up shifts, just saving the blipping part of course.)

 

[GT Pony]

Sure we double-clutch-ers haven't talked about that (blipping throttle at neutral with clutch up) yet in this thread. To me, that's how double clutch is done, from the textbook. There is just no other way to do it.

Most people who are not totally into double clutching would know about the rev in neutral and what it does. I thought it was a good piece of info associated with double clutching for the "non experts". ;)

 

[Nazgul]

Go back and read it again. I said with the clutch engaged ... which means the pedal is up. Pushing the clutch pedal down disengages the clutch.

Sorry I was interpreting it as you were pressing the clutch and blipping it while still holding the clutch pedal down.

 

[rio16]

heres my rev match down shift =)

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[GT Pony]

Thanks Nazgul - no problem.

 

[Double]

But but what are the benefits of having "rev matching" for the automatic transmission on the Mustang.

Does it make it quicker ? smoother ? what is the actual benefit for an automatic to have "rev matching" ?

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