Proper way to REV match?
Joined: Jun 2005
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From: NYSE
For downshifts, I double clutch. I'm pretty sure double clutching isn't necessary, but that's what I do.
http://www.waycoolinc.com/z3/essentials/fi...oe/shifting.htm
http://www.waycoolinc.com/z3/essentials/fi...oe/shifting.htm
DOUBLE CLUTCHING:
There are *three* separate spinning entities that need to be coordinated when shifting: The engine. The transmission input. (I'm going to refer to this as the intermediate shaft). The transmission output (which is directly related to the vehicle speed).
When the clutch is disengaged (pedal pushed down) and the transmission is in neutral (such as when shifting between two gears), the intermediate shaft is essentially free spinning. In normal shifting, we rely on the synchro's to control the speed of the intermediate shaft as it engages with the gears connecting it to the transmission output.
Decades ago, transmissions didn't have synchro-mesh. (Many large trucks still don't). On these transmissions, it is necessary for the driver to manually control the speed of the intermediate shaft so that it matches the speed of the gear to be engaged. This is done by the following process when shifting from one gear to the next:
1) Power is removed and clutch is disengaged (pedal down). 2) Transmission is shifted from original gear to neutral. 3) Clutch is re-engaged (pedal up). (Driver now has control of intermediate shaft speed by controlling engine speed). 4) Driver 'blips' throttle to match intermediate shaft speed to speed of new gear. (This takes practice to get the right match). 5) Clutch is disengaged (pedal down). 6) Transmission is shifted from neutral into new gear. 7) Clutch is re-engaged (pedal up) and power is applied.
Steps 1 - 3 can be done casually or quickly. Steps 4 - 6 *must* be done quickly so that the intermediate shaft doesn't slow down again before it's engaged. If step seven is also done quickly, the engine will also be 'rev-matched' to the rest of the driveline so that engagement will be smoother.
REV-MATCHING:
When taking off from a stop and then going up through the gears, steps 1,2,6,7 above are the normal shifting method for each gear change. The synchro-mesh are more than enough to control the intermediate shaft speed. The engine will passively rev-match itself because it slows down naturally and this is appropriate when shifting up.
When down shifting, the engine needs to spin faster as it engages the new gear. This can be achieved by 'blipping' the throttle as the transmission passes through neutral. If the engine isn't manually sped up by the driver, it will be sped up by the driveline when the clutch is re-engaged. This can be OK for normal street driving, but if the car is cornering near the limit this can upset the suspension and the tire adhesion.
The synchromesh are usually adequate intermediate shaft control when down shifting one or two gears. Aggressive downshifts (like a 5 - 2 shift from high speed) can benefit by using double-clutch shifting to assist the synchro's. Shifting into first gear in a hard corner is nearly impossible without double-clutching (this is useful for those really tight hairpins, especially if they exit uphill).
There are *three* separate spinning entities that need to be coordinated when shifting: The engine. The transmission input. (I'm going to refer to this as the intermediate shaft). The transmission output (which is directly related to the vehicle speed).
When the clutch is disengaged (pedal pushed down) and the transmission is in neutral (such as when shifting between two gears), the intermediate shaft is essentially free spinning. In normal shifting, we rely on the synchro's to control the speed of the intermediate shaft as it engages with the gears connecting it to the transmission output.
Decades ago, transmissions didn't have synchro-mesh. (Many large trucks still don't). On these transmissions, it is necessary for the driver to manually control the speed of the intermediate shaft so that it matches the speed of the gear to be engaged. This is done by the following process when shifting from one gear to the next:
1) Power is removed and clutch is disengaged (pedal down). 2) Transmission is shifted from original gear to neutral. 3) Clutch is re-engaged (pedal up). (Driver now has control of intermediate shaft speed by controlling engine speed). 4) Driver 'blips' throttle to match intermediate shaft speed to speed of new gear. (This takes practice to get the right match). 5) Clutch is disengaged (pedal down). 6) Transmission is shifted from neutral into new gear. 7) Clutch is re-engaged (pedal up) and power is applied.
Steps 1 - 3 can be done casually or quickly. Steps 4 - 6 *must* be done quickly so that the intermediate shaft doesn't slow down again before it's engaged. If step seven is also done quickly, the engine will also be 'rev-matched' to the rest of the driveline so that engagement will be smoother.
REV-MATCHING:
When taking off from a stop and then going up through the gears, steps 1,2,6,7 above are the normal shifting method for each gear change. The synchro-mesh are more than enough to control the intermediate shaft speed. The engine will passively rev-match itself because it slows down naturally and this is appropriate when shifting up.
When down shifting, the engine needs to spin faster as it engages the new gear. This can be achieved by 'blipping' the throttle as the transmission passes through neutral. If the engine isn't manually sped up by the driver, it will be sped up by the driveline when the clutch is re-engaged. This can be OK for normal street driving, but if the car is cornering near the limit this can upset the suspension and the tire adhesion.
The synchromesh are usually adequate intermediate shaft control when down shifting one or two gears. Aggressive downshifts (like a 5 - 2 shift from high speed) can benefit by using double-clutch shifting to assist the synchro's. Shifting into first gear in a hard corner is nearly impossible without double-clutching (this is useful for those really tight hairpins, especially if they exit uphill).
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Joined: Jul 2004
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From: Queen City, NC
I'm gonna be more simple - Upshifting occurs pretty naturally, just let the rpms drop as you change gears. Downshifting pretty much requires that you know where the rpms will be for a given gear at a given speed. Start paying attention to where the rpms need to be in a gear, like 2nd, for example, and next time you downshift from 3rd, blip the throttle to get it to the 2nd gear rpms (3000 to 4200 for example).
Registered User
Joined: Jul 2004
Posts: 8,796
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From: San Diego, Wess-Side!!
Clutch, blip, shift...
Watch your tach..
A proper downshift rev-match you will see the revs jump on the throttle blip and then after you shift and release the clutch the revs should "catch" at the blips highest point.
Your best bet is to ride with someone in your local group who can do it and show you how it's done.
Tim
Watch your tach..
A proper downshift rev-match you will see the revs jump on the throttle blip and then after you shift and release the clutch the revs should "catch" at the blips highest point.
Your best bet is to ride with someone in your local group who can do it and show you how it's done.
Tim
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Joined: Sep 2005
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learn to heel toe, double clutching takes to long for one, also rev matching, if not done corectly will lock the rears or make the car leap depending on your revs. search in the racing and competition on how to heel toe and get somebody to help you with it that knows how.
Joined: Mar 2001
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I've beaten this thing to death lately and you can go find those threads to see what already been written.
Just to recap briefly, rev-matching should be done in both upshifting and downshifting. Doing it for UPshifting is a fairly natural thing since you simply allow the rpm to DROP down to an appropriate speed. DOWNshifting requires giving gas to raise the rpm to meet with the fastest spinning part of the tranny once the clutch is re-engaged in the next lower gear. This takes a bit of practice.
Double Clutching is NOT necessary in a modern day car EXCEPT when trying to engage 1st gear at speed. D. Clutching is almost always accompanied by rev-matching. Leave DC alone if you are just getting used to driving stick.
Heel/toe is a technique for scrubbing off speed AND downshifting AND rev-matching. It is POINTLESS to do this on the street or in circumstances where you don't need to do heavy braking at the same time as needing to be in the next lower gear. This only becomes a distraction for those who are just getting good at driving stick.
For many people, they do not know what the differences are between all of the above and use the terms interchangeably and tell people do this or that when they themselves aren't really doing it at all.
Just to recap briefly, rev-matching should be done in both upshifting and downshifting. Doing it for UPshifting is a fairly natural thing since you simply allow the rpm to DROP down to an appropriate speed. DOWNshifting requires giving gas to raise the rpm to meet with the fastest spinning part of the tranny once the clutch is re-engaged in the next lower gear. This takes a bit of practice.
Double Clutching is NOT necessary in a modern day car EXCEPT when trying to engage 1st gear at speed. D. Clutching is almost always accompanied by rev-matching. Leave DC alone if you are just getting used to driving stick.
Heel/toe is a technique for scrubbing off speed AND downshifting AND rev-matching. It is POINTLESS to do this on the street or in circumstances where you don't need to do heavy braking at the same time as needing to be in the next lower gear. This only becomes a distraction for those who are just getting good at driving stick.
For many people, they do not know what the differences are between all of the above and use the terms interchangeably and tell people do this or that when they themselves aren't really doing it at all.
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Joined: Feb 2001
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From: West Henrietta UPSTATE NY
Originally Posted by xviper,Jan 5 2006, 08:42 AM
Double Clutching is NOT necessary in a modern day car EXCEPT when trying to engage 1st gear at speed.
Well not in all car with all drivers...
Bud!Happy New Year Dave
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Joined: Oct 2001
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From: San Diego, CA
i want to get a little education on this. would upshifting be like regular shifting then? i dont understand how to "blip" the throttle? i THINK it has something to do with tapping the throttle somewhere in between the shifts? i have no clue. im interested in learning how to rev match.
perhaps is there a video that shows the feet and when they switch gears? 
perhaps is there a video that shows the feet and when they switch gears?
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Joined: Feb 2001
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From: West Henrietta UPSTATE NY
Originally Posted by xviper,Jan 5 2006, 10:46 AM
Of course, we all know that you are an anomoly or icon in this area. 
It's good to live for speed...
And Dave, you would be so proud of me, if the big red Titan was not enough, now I'm shopping for a big red car hauler to drive the S around on for schools.