Do you need to rev match everytime you downshift?

[Kadarin]

I never bothered to rev-match.. I just worked the clutch with that same smooth magic the ladies always seem to like. Alas, I no longer have that car and now drive an automatic.

 

[spidey07]

Do you need to? well no I guess. I always do - makes for a smooth shift, little wear on the clutch/flywheel and less wear on the engine.

Gotten to the point now where I can downshift and not even feel it.

 

[boyRacer]

Originally posted by: Ferocious
I'd like to see that video.

Text

 

[boyRacer]

Originally posted by: Vic
Rev matching in the common use of the phrase (blipping the throttle prior to gear selection to match expected revs for the next selected gear) on upshifts is completely unnecessary. The proper way to get a smooth shift on an upshift is with proper shift timing. Remember that when upshifting the revs come down to meet the next gear, not up. If you have to blip the throttle prior to shifting into the next gear up, then you are shifting too slowly. If the car jerks forward when you engage the next gear up, then you are shifting too quickly. Watch your tach if you need to. If you're still having trouble, try to remember that every gear should end on a high note when upshifting, meaning that the clutch should go in a millisecond before the gas comes off.

In regular braking downshifts during normal driving, rev matching is also unnecessary. First, modern cars have synchros and downshifting into the 2-4k range (depending on the vehicle) should not harm them at all. Just pause briefly before the synchro gate using light but steady pressure on the shifter and it will engage itself. Second, your foot should be on the brake at that time, not the gas. I don't want 18 year-old newbie manual trans drivers thinking they're cool doing unnecessary and possibly dangerous heel-and-toe maneuvers just because someone on the intarweb told them that they should... especially little 15-20 mph downshifts into 2nd that almost rev match at idle.

And yeah, M4H, we are thinking of 2 different videos. I recall the other one now... in an early 90s Accord IIRC. The driver was an idiot and they whined like little bitches.

^ Listen to this guy :beer:... he's know what he's talking about.

...rev matching is unnecessary in casual driving.

 

[Tetsuo]

Originally posted by: MercenaryForHire

Originally posted by: Heisenberg
I think the synchro's in modern tranny's make most rev-matching unneccessary. However, it's still probably not a good idea to drop it into 2nd gear at 80mph.

Where's that video of the guy in the Accord who did the 5th-2nd misshift and owned his whole ride?

- M4H

That's an integra buddy

 

[conjur]

heh heh

that's still funny!

 

Rev matching in the common use of the phrase (blipping the throttle prior to gear selection to match expected revs for the next selected gear) on upshifts is completely unnecessary. The proper way to get a smooth shift on an upshift is with proper shift timing. Remember that when upshifting the revs come down to meet the next gear, not up. If you have to blip the throttle prior to shifting into the next gear up, then you are shifting too slowly. If the car jerks forward when you engage the next gear up, then you are shifting too quickly. Watch your tach if you need to. If you're still having trouble, try to remember that every gear should end on a high note when upshifting, meaning that the clutch should go in a millisecond before the gas comes off.

In regular braking downshifts during normal driving, rev matching is also unnecessary. First, modern cars have synchros and downshifting into the 2-4k range (depending on the vehicle) should not harm them at all. Just pause briefly before the synchro gate using light but steady pressure on the shifter and it will engage itself. Second, your foot should be on the brake at that time, not the gas. I don't want 18 year-old newbie manual trans drivers thinking they're cool doing unnecessary and possibly dangerous heel-and-toe maneuvers just because someone on the intarweb told them that they should... especially little 15-20 mph downshifts into 2nd that almost rev match at idle.

Exactly.

I don't know where you guys get the idea that when you rev match, the ride is smoother. If anything, it makes it less smooth, because the driver usually isn't smoother than their synchros in the tranny.

 

[lupohki]

Clutch pedal in, blip the throttle, change to lower gear, clutch pedal out.

 

[Jzero]

I don't know where you guys get the idea that when you rev match, the ride is smoother. If anything, it makes it less smooth, because the driver usually isn't smoother than their synchros in the tranny.

I get it from driving. If I downshift using only the clutch, the car will lurch, no matter how much I slip the clutch. As soon as the clutch grabs and the RPM starts to rise, the car lurches. You have to get the RPM up to an appropriate speed before you engage it, whether you double-clutch or not.

 

[thomsbrain]

you don't HAVE to rev-match, you could simply be easier on the clutch like your dad says. the problem there though is you're relying solely on the friction from the clutch to rev the engine back up to speed, which is hard on the clutch. if you're downshifting for the purpose of accelerating out of a corner, i would ask why you're bothering to let the clutch out until you actually need some power. just coast with it in until you're ready to get on the gas, then hit the gas and let the clutch out, which essentially is an easy rev-match, performed after you've done your braking.

but if you insist on not coasting and/or want to always be ready to apply power at any time, you should be rev-matching as you downshift through the gears in the approach to a corner. you have to brake while you're doing this, which is called heel-and-toe. you're on the clutch with one foot, the brake with your toe, and the gas with your heel to match the revs. it's a useful technique even if you never use it in daily driving because if you drive a car that stalls out at idle, you can keep the revs up while you stop, so it doesn't die out on you.

 

[Lithium381]

I really only revmatch on the way up, when i think about it i do it on the way down, but generally not

 

[The Dancing Peacock]

I revmatch on most downshifts.

 

[SammyBoy]

if I'm downshifting to lay the power on in a corner or to pass/accelerate hard, then yes, I do it every time.

When i'm downshifting to slow down, like I'm cruising at 50 in 4th, and i see a red light way ahead, i'll just release the clutch realllly slowly into 3rd, then 2nd, and usually by the time I get there it's green so I don't gotta worry about 1st.

 

[WinkOsmosis]

You don't need much throttle to rev match.

 

[Whisper]

The only time I'll rev match/blip the throttle on a downshift is when I'm planning on using the gas immediately afterwards...which, like someone already mentioned, usually only happens when you're trying to downshift in order to pass someone. If you don't use any gas in a situation like that, your car will definitely jerk.

But if I'm downshifting in order to engine brake, then I just keep my foot off the gas and/or on the brake pedal, downshift, and let the clutch out slowly. I'll press the brake if I'm stopping for something like a red light, and I'll just use the engine itself if I'm only moderately slowing down. The same procedure is necessary on a motorcycle unless you wanna fry your brakes every couple thousand miles. I'll generally throttle blip more on my bike than in a car, though...a bit easier to control, and seeing as how I'm usually downshifting into a higher RPM range, it makes me feel a bit better about what I'm doing to the engine, heh.

And I don't think there's such thing as rev matching/blipping the throttle during an upshift...that's called bad shifting technique.

 

[m2kewl]

i do it all the time, it doesn't hurt the engine and there's no jerk.

 

[LS20]

Originally posted by: Vic
Rev matching in the common use of the phrase (blipping the throttle prior to gear selection to match expected revs for the next selected gear) on upshifts is completely unnecessary. The proper way to get a smooth shift on an upshift is with proper shift timing. Remember that when upshifting the revs come down to meet the next gear, not up. If you have to blip the throttle prior to shifting into the next gear up, then you are shifting too slowly. If the car jerks forward when you engage the next gear up, then you are shifting too quickly. Watch your tach if you need to. If you're still having trouble, try to remember that every gear should end on a high note when upshifting, meaning that the clutch should go in a millisecond before the gas comes off.

In regular braking downshifts during normal driving, rev matching is also unnecessary. First, modern cars have synchros and downshifting into the 2-4k range (depending on the vehicle) should not harm them at all. Just pause briefly before the synchro gate using light but steady pressure on the shifter and it will engage itself. Second, your foot should be on the brake at that time, not the gas. I don't want 18 year-old newbie manual trans drivers thinking they're cool doing unnecessary and possibly dangerous heel-and-toe maneuvers just because someone on the intarweb told them that they should... especially little 15-20 mph downshifts into 2nd that almost rev match at idle.

And yeah, M4H, we are thinking of 2 different videos. I recall the other one now... in an early 90s Accord IIRC. The driver was an idiot and they whined like little bitches.

true, rev matching, by means of hitting the gas, on an upshift is unnecessary... because technically you do "match" the revolution but since the rpms are dropping you match by timing the clutch engagement rather than by manually raising the rpm.

however, you are wrong in your second paragraph. synchros are there to aid in the actual gear change. rev matching is done to smoothen the clutch engagement. DOUBLE-CLUTCHING is done to alleviate wear on the synchros. unless the car idle's fubar'ed, or the car is a tall-geared lambo, 15mph is usually 2000rpm at 2nd gear.

there should be a faq on this.

 

[LS20]

ok ppl, lets set this straight

to downshift with the following methods...
double clutch: clutch in, stick in neutral, hit throttle (to match would-be speed), clutch in, shift, clutch out
rev-match: clutch in, shift, hit throttle, clutch out

in a nutshell, the clutch connects the engine to the drivetrain... when disconnected, the engine spins freely and controlled by the gas. so when they are connected and the speeds differ, either the drivetrain 'pulls' the motor to spin faster or 'drags' the motor to spin slower... causing the jerk. thusly, revmatching makes the clutch engagement feel smoother

when you are moving the shift lever around, a dog collar moves around and engages with different gears in your tranny. a synchro facilitates this actuation/engagement by slowly getting the dog gear spinning at the same rate as the gear. by double clutching you control the dog gear and facilitate this action