Rev matching on downshifts

[TiGeo]

Most modern cars have Rev hang

So you “may” get a blip if you rapidly depress the clutch as you let off the gas and shift and simulate a Rev match. If you didn’t do that the car would Rev to far and slowly float down making you have to wait take a nap, cook a lunch…

My Cobalt is that way, what sucked was to rev match the up shift you had to effectively let off the gas a second before clutching and shifting or you would burn up the tissue paper clutch from constantly dragging the engine down every upshift.

Doing up shifts correctly was slow because of the float

This. Doing this in our Focus is tough, you have to really stab it to get the RPMs up b/c of the rev hang. It's just not necessary and you can work around it by not slamming downshifts mid-corner etc. that cause huge RPM deltas.

 

[TiGeo]

Rev matching on down shift was a well known/used procedure, esp on sports cars.- its also known as "heel and toe". I still do it and down shifts are a lot smoother

2 different things - heel/toe is when you rev match simultaneously with braking, you can rev match without braking as well.

 

[TiGeo]

yes, but it is not nessessary is my point, in a big rig, it is nessessary to properly shift

34 years of driving with many manuals and nobody every showed/talked about rev-match downshifting for just driving around. I'd never head of it/seen it until more recently when I started performance driving. Thank goodness I have a dual-clutch auto that does this for me automatically

 

[wings&wheels]

Because not doing so is a crime against humanity......

It won't make a difference during normal driving and to a modern transmission at any reasonable mileage. It is the right way to shift though and fun to get right, especially when driving different vehicles. Heel and toe, or toe and toe depending on pedal placement is also an art.

Now let's talk double (de)clutching....

Great example of both rev matching and heel & toe from one of the best motorsport videos of all time:

 

[ARCOgraphite]

The synchros don't care if you rev match or not. If you blip the throttle while the clutch is in, the transmission doesn't know. The synchros are relieved if you double clutch, though. Rev matching can possibly save some clutch wear though, since you can let the clutch out faster without shock.

The tailshaft is connected to the driveshaft spinning at road speed x rear gear ratio You are trying to match layshaft speed to synchro hub assembly speed.

 

[Pew]

Tough in many cars without modifying the gas pedal. No way you can do it in our Focus. Cool technique for race/track drivers. Many modern sports cars auto rev match so no need. I had a ride around with my instructor in his C7 at VIR in 2021...7spd...I ask about it and he laughed..."We don't do that anymore."

Yea I couldn't do it in my focus either - the brake pedal was waaaay to high. The evo's was hard for those with larger feet because of the close proximity of the pedals but my feet are small so it worked out for me. The auto-blips on downshifting is a pretty cool feature too.

 

[weaponoffreedom]

34 years of driving with many manuals and nobody every showed/talked about rev-match downshifting for just driving around. I'd never head of it/seen it until more recently when I started performance driving. Thank goodness I have a dual-clutch auto that does this for me automatically

Have you ever drove a manual big rig? In order to downshift, you MUST match rpms with the next lower gear, or the tranny WILL NOT go into gear. Driving a truck is much different than a car. And by truck i dont mean a pickup. Double clutching is taught or at least was taught in driving schools as the proper way to shift, up or down.

 

[weaponoffreedom]

Because not doing so is a crime against humanity......

It won't make a difference during normal driving and to a modern transmission at any reasonable mileage. It is the right way to shift though and fun to get right, especially when driving different vehicles. Heel and toe, or toe and toe depending on pedal placement is also an art.

Now let's talk double (de)clutching....

Great example of both rev matching and heel & toe from one of the best motorsport videos of all time:

not sure if i could roll on the right ride like that, after driving on the left for so long.

 

[chris719]

The tailshaft is connected to the driveshaft spinning at road speed x rear gear ratio You are trying to match layshaft speed to synchro hub assembly speed.

If you just clutch-in and blip you are not changing the input shaft speed. Hence why double clutching is needed.

 

[willbur]

2 different things - heel/toe is when you rev match simultaneously with braking, you can rev match without braking as well.

We all know this...

 

[SHOZ]

Most OBDII cars don't really drop the throttle that much in neutral anyway. I never do and my last clutch on the Accent went bad but still half the OE disc at 187k miles. Grease on the input shaft dried up and TO bearing was sticking. It was probably worn to from the lack of grease.

 

[mr_boring]

I think using not your clutch at all (except on takeoff) is more of an art than heel/toe..... Just my personal opinion. Just ride up through the gears without ever touching the clutch, and coming down through them the same way is when you know you can drive a stick. I always just kick it out of gear down around 3rd though when I'm going to have to stop at a light.

 

[SHOZ]

I had a after market clutch in my Gen Coupe that was so bad you had to shut it off to shift into rev and 1st from neutral you had to shift to third then 1st whit the engine running.

The one I have now I don't even rev to get going unless uphill from a stop. Just let ti out. All shifts I go to neutral then the gear in a deliberate motion or I get grinding in third and fifth.

 

[Killer223]

dunnno if it's good bad or indifferent, but i usually only use the clutch to get moving. once moving I hardly ever use a clutch. on my 95 12V, my 01 996 C4, the 19 accord. not really needed once you learn where the RPM's should be.

 

[PontiacHO]

I’d rather wear brake pads than add unnecessary wear to my drivetrain/engine/accessories coming to a stop. No one I know is impressed with constant downshifting. That’s for a racecourse.

 

[TiGeo]

We all know this...

Yes but you made it sound in your post like they are the same thing which they are not....I can rev match down shift and not heel-toe.

Rev matching on down shift was a well known/used procedure, esp on sports cars.- its also known as "heel and toe". I still do it and down shifts are a lot smoother

 

[TiGeo]

I’d rather wear brake pads than add unnecessary wear to my drivetrain/engine/accessories coming to a stop. No one I know is impressed with constant downshifting. That’s for a racecourse.

Yep.

 

[TiGeo]

This post is ripe for it....who is double clutching a syncronized transmision in a modern vheicle?

 

[AmBeRnEcTaR]

I’d rather wear brake pads than add unnecessary wear to my drivetrain/engine/accessories coming to a stop. No one I know is impressed with constant downshifting. That’s for a racecourse.

Everyone knows double clutching and heel-toe'ing is for seriously spirited driving.
They're not techniques used driving a Tercel home from Taco Bell or the bowling alley...

 

[Rmay635703]

I’d rather wear brake pads than add unnecessary wear to my drivetrain/engine/accessories coming to a stop. No one I know is impressed with constant downshifting. That’s for a racecourse.

This Honda Insight never downshifted