rev matching...am i doing it right?

[cDUBB]

So I've my care for almost 6 weeks now and both my launches and upshifts have got a lot better (still working on a consistently smooth 1>2 shift). The one thing I might be having problems with is SC rev matched downshifts. I'll explain how I do it and if you guys can let me know if I'm doing it right that would be great. Pass along any tips and pointers also.

So i'll be going say 40-45 mph in 4th @2200 RPM and I'll want to downshift into 3rd. I'll take my foot of the gas and press in the clutch. Once the clutch is all the way down, I move the shifter to 3rd. I'll then blip the throttle to about 3000-3200 RPM (lately I've been getting pretty close to my target RPM) and let out the clutch as I ease back onto the gas.

Does it matter that I'm blipping the throttle after I am already in gear or should I be blipping as I pass the shifter through neutral?

[Draklen]

as long as the clutch is down, it doesn't matter. The transmission is disconnected from the engine.

[theholycow]

It doesn't matter.

If the result is smooth then you did well.

[FDSpirit]

Word. Even if you're off by a few hundred RPMs, it's better than not rev-matching at all.

[cDUBB]

Thanks guys. Ya that's what I was thinking. I'm practicing blipping as I shift to make for a quicker downshift, but good to know that the way I'm doing it now is good too.

If I know I'm right on with my throttle blip can I release the clutch quicker (controlled of course)? Right now I'm still letting it out a little slower because I'm not consistent with my blips. I don't want to let the clutch out too quick and be at either to high or too low RPMs for the gear I'm going into. Don't wanna hurt the tranny.

[theholycow]

A botched rev match with a quick clutch release won't hurt the tranny. I'd say the most likely thing to get hurt, if anything at all, is a CV joint, but really I don't recommend worrying about it.

[Reverence]

If you release clutch pedal slowly after a blib, chances are that your blip would have served no purpose and you would have relied mostly on being on the gas afterwards.

a) either you (controlled) release clutch pedal quickly and eventually adapt your blips according to the feedback you get every time,
or
b) you quickly release clutch pedal to friction point, and let the clutch smooth the over/under blips,
or
c) you do a blend of the above, aiming to shift your technique towards a) with practice.

I did SC rev-matched down-shifts for the first 2 years of driving, then moved on to DCRMDS and never went back to SCDS, unless....:

SCRMDS for fast acceleration, however I don't ease off the gas, I keep it static through the down-shift, that takes care of the rev-matching.

[Rope-Pusher]

A botched rev match with a quick clutch release won't hurt the tranny.

If you don't want to hurt your tranny, just tel him he's beautiful and don't let him know you saw his junk sticking out.

[theholycow]

don't let him know you saw his junk sticking out.

He's not really a tranny without the stick shift, is he?

Reverence, I'm lost in your alphabet soup. What is the 'DS' at the end of "DCRMDS" and "SCRMDS"?

[Reverence]

Reverence, I'm lost in your alphabet soup. What is the 'DS' at the end of "DCRMDS" and "SCRMDS"?

DS= Down-Shift or Down-Soup, you chose!

[six]

Thanks guys. Ya that's what I was thinking. I'm practicing blipping as I shift to make for a quicker downshift, but good to know that the way I'm doing it now is good too.

If I know I'm right on with my throttle blip can I release the clutch quicker (controlled of course)? Right now I'm still letting it out a little slower because I'm not consistent with my blips. I don't want to let the clutch out too quick and be at either to high or too low RPMs for the gear I'm going into. Don't wanna hurt the tranny.

The only way you can hurt your transmission during normal driving is by grinding a lot. A LOT. And even then, you are only hurting your synchros. Otherwise, your transmission will be fine. The transmission itself (the gearbox) should be the least of your worries as it is the most durable part of your car.

You should let out the clutch as quickly as possible during rev-matched downshifts. There are two reasons for this, as some have mentioned above...

1) It teaches you the correct timing (or more refined throttle control). A quick jolt that throws you back in your seat: you've revved too high. A quick jolt that throws you towards your steering wheel, you've revved too low. Correct for it the next time, and it will eventually be so smooth you wouldn't even feel the shift. If you release the clutch slowly every time, you rely on the clutch as opposed to a correctly-timed rev-match, which leads to...

2) Releasing the clutch slowly defeats the purpose of a rev-match. Rev-matching's purpose is to save clutch wear (also time, and handling balance, but that's a story for another time). If you smooth out your downshifts with the clutch, there really is no use for a rev-match. Granted, using the clutch to smooth out an over or under-rev match is better than not rev-matching at all...

[scionkid]

6 is right.

Also, I wouldn't take my foot off the gas when downshifting. It takes more gas to bring the rev up and it takes time. I would release just enough gas that my rev would stay constant when I push in the clutch. As I move the shifter, I would ease into the gas to smoothly raise the rev. By the time I'm done shifting, my rev is about where it should be. Release the clutch relatively quickly and the shift is completed.

Jump to 7:20 to see how it is done professionally. Notice that the driver did not let the rev drop until the clutch comes up at the completion of the shift.