2019 Mustang GT (Manual) auto rev matching

[Vlad Soare]

On my little test circuit I come into a 200 deg climbing banked corner at 80mph in 4th, brake to 45mph and shift to 3rd. At around 55mph I push in the clutch, select 3rd and gently feed the clutch back in as I'm also tapering off the brakes while entering the first 1/4 of the turn. By 1/3 into the turn I'm back on the gas. Since I'm not heal-toeing yes I am smoothly dragging the engine up to the revs needed to match road speed. But since I'm also still braking the gap is narrowing by the moment.

That's exactly what I do in a manual car without the auto rev match. But it does wear out the clutch more than it would if the revs were matched.
Now, if you don't have ARM, then you have no choice but to accept the increased clutch wear as a fact of life. Nothing wrong with that. But if you do have ARM, which works perfectly each and every time and reduces the friction to a bare minimum, then why not take advantage of it?
I get Norm's point, that the ARM is useless if you can do its job yourself. But so far I haven't been able to figure out how I could do its job myself (not without heel & toe, that is). Sure, I could live without it if I had to, but the point isn't whether one can find an acceptable workaround (like slipping the clutch more), but whether one can replicate it exactly, to the point that it becomes really useless.

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[shogun32]

but the point isn't whether one can find an acceptable workaround (like slipping the clutch more), but whether one can replicate it exactly, to the point that it becomes really useless.

the mechanics don't change. Back when I had ARM turned on I was still feeding in the clutch just as slowly and deliberately as before. Ok, maybe fractionally faster but the dance was the same.

The increased wear is so inconsequential it doesn't matter. People do FAR more damage to clutches starting from a stop or botching an upshift than they do smoothly dragging the motor up to speed.

 

[Mikepol2]

Wow, this got out of hand quick LOL!

Lotta strong opinions of why one way is good but not the other.

I think Ford as usual has it set up to work for almost everyone’s preference. If you like it, leave it on, works great. If not turn it off.

I’ve driven stick for about 35 yrs and first time experiencing it was test driving a 2020 PP2 last summer. Bugged the shit out of me, hated it.

But I’m a lazy shifter. 90% of the time approaching a stop from any speed I put it in neutral and coast. Yeah I know some folks think that’s not safe but whatever. I don’t track it and suck at heel and toe. Driving spirited on the road my right foot is the auto blip.

But based on some of the comments here, wonder if I’ll change my tune when (if?) my Mach 1 ever arrives.

 

[Norm Peterson]

Here's a situation I encounter every day. I'm doing 45 mph in fourth gear. Suddenly a car in front decides to brake for some reason, be it a speed limiter, pedestrian crossing, whatever. So everyone behind it, including me, must brake as well. I need to slow down from 45 mph to about 15 mph in perhaps 120 yards. That's a fair deceleration rate, during which I need to downshift twice (or once, if I skip third).

For 120 yards, that's only about 0.17g (hardly any braking). For 120 feet, it's 0.5g (now we're getting somewhere).

There's always going to be situations that end up being outside what your preferred downshifting technique can reasonably accommodate, and you simply have to make adjustments.

You're asking me to consciously run through a situation that I handle pretty much subconsciously, so this is what I think I'd be doing. In 0.5g stops such as you described, I think I'd be leaving the transmission in 4th and the clutch pedal out until somewhere above the point where the engine would start to lug (another matter of subconscious awareness). I'd finish the rest of a double-clutch downshift to 2nd as the speed of traffic ahead stabilized at 15 or whatever. Gotta roll with the punches sometimes.

If I didn't have the auto rev match I would have to release the clutch veeeeery very slowly, to make it swallow the difference in revs and avoid jerking the car.

Making the rpm differences go away is exactly the reason for double-clutching. Everything else is just different reasons for doing it.

I would love to be able to match the revs myself without any assistance, but in such situations I simply can't figure out how that would be possible short of using heel & toe. Which is why I'm so curious as to how you're doing it.

It's not rocket science, and you don't have to be mathematically perfect about it (like those who obsess over tachometer readings and gear ratios might have you believe). If you "over-kick" the revs up, the revs fall once you're off the throttle like you should be, and it ends up being about the same as lift-throttle upshifts. Nobody ever worries about screwing those up.


Norm

 

[Norm Peterson]

That's exactly what I do in a manual car without the auto rev match. But it does wear out the clutch more than it would if the revs were matched.
Now, if you don't have ARM, then you have no choice but to accept the increased clutch wear as a fact of life.

There's no need to gradually drag engine rpms up by slipping the clutch. I've got a clip taken from a track day session where the strength and briefness of the throttle kick is evident. In this case, I'd already burned off about 25 mph while still in 4th (clutch fully engaged). At 91 mph you can see where the throttle% spikes from 0 to 90+ (gotta look close, it only lasts for a small fraction of a second, probably no more than 3 frames @ 30 fps). I have this in slo-mo as well, just not uploaded to YT yet.




All I can offer is that this can and does come with practice and experience.


Norm

 

[Vlad Soare]

I think I'd be leaving the transmission in 4th and the clutch pedal out until somewhere above the point where the engine would start to lug (another matter of subconscious awareness). I'd finish the rest of a double-clutch downshift to 2nd as the speed of traffic ahead stabilized at 15 or whatever. Gotta roll with the punches sometimes.

I tried that, and it does work quite nicely. Thanks.

During the last few days I tried to double clutch on every downshift. It's really awesome. As long as I avoid shifting while braking, everything works great. I use the ARM to gauge how well I'm doing - meaning that I consider it done right if the ARM doesn't intervene at all. If I don't blip the throttle hard enough, then there's a second blip of the throttle done by the ARM - which I take as an indication that I didn't get it right. But this happens more and more rarely. Most of the times the ARM does nothing, and the gear lever goes into gear unbelievably smoothly.

At first I thought I would give it a try just out of curiosity, to see what the fuss is all about, then I would go back to my usual routine (i.e. downshift whenever I please and let the ARM do the rest). But surprinsingly, I find that I love it and don't want to go back.

 

[Norm Peterson]

Yeah, it's pretty satisfying when you get it right. Incentive to do better the next time when you don't.


Norm

 

[ice445]

the mechanics don't change. Back when I had ARM turned on I was still feeding in the clutch just as slowly and deliberately as before. Ok, maybe fractionally faster but the dance was the same.

The increased wear is so inconsequential it doesn't matter. People do FAR more damage to clutches starting from a stop or botching an upshift than they do smoothly dragging the motor up to speed.

I play a game called "minimum possible wear", it's a fun balancing act to use the clutch for exactly the minimum amount of time to still be (mostly) smooth. ARM helps with this. Of course, it's not really necessary, the stock clutch is a twin disc and I'm running factory power levels. I don't really disagree with your point that you can slip the clutch on downshifts and not really suffer much for it from a longevity angle.

The only time I've smelled clutch on this car was when I had a brain fart coming up to a yellow light, I had literally just shifted into third, then for some reason just mentally failed to understand what it was I was going to do next (caught between wanting to drive through it and wanting to push the clutch back down to downshift), so I didn't fully release the clutch and left it in the bite zone for about 2 seconds. So it really seems like the clutch is pretty robust, you have to do something stupid to hurt it.

 

[Vlad Soare]

I think I spoke too soon. I had no idea just how much the ARM was still helping both on upshifts and on downshifts. When I turned it off... disaster! The double clutch per se works fine, but everything else is a mess.

You'd think that all the ARM does is a short blip of the throttle immediately after a downshift. Not so. It's much more active, in more subtle ways. Not only does it rev the engine after a downshift, but it also holds it there for a short while, and the revs drop noticeably slower until you lift the clutch than they would without ARM. Also, the engine management seems to be different. With ARM you lift the clutch and the car continues to roll steadily, as if it were under light throttle. Whereas without ARM, even with matched revs, as soon as you lift the clutch you get a strong engine brake.
Also, the ARM works on upshifts as well. Obviously there's no throttle blip, because there's no need for that, but the revs drop more slowly than without ARM, and a very light throttle is maintained while (and a bit after) you release the clutch, so that overall it feels as smooth and seemless as an automatic gearbox. Turn the ARM off and you'll get either engine braking (if you don't accelerate at the same time), or a jolt (if you accelerate at the same time, but just a tiny bit too hard), or a nice and smooth transition when you finally get it right (which happens 2% of the time).

If you're a perfectly smooth driver with ARM on, that's exclusively thanks to the ARM.

So, It seems I have much more to learn than I thought. I thought mastering the double clutch was all there is to it, but that's just the tip of the iceberg. I've got so used to the ARM helping me on upshifts (without even realizing that it did), that now I'm not able to upshift smoothly without it, even though I never had this problem in any of my previous manual cars.
It's time to relearn how to drive properly.

 

[shogun32]

It's time to relearn how to drive properly.

yup.

 

[Sivi70980]

I think I spoke too soon. I had no idea just how much the ARM was still helping both on upshifts and on downshifts. When I turned it off... disaster! The double clutch per se works fine, but everything else is a mess.

You'd think that all the ARM does is a short blip of the throttle immediately after a downshift. Not so. It's much more active, in more subtle ways. Not only does it rev the engine after a downshift, but it also holds it there for a short while, and the revs drop noticeably slower until you lift the clutch than they would without ARM. Also, the engine management seems to be different. With ARM you lift the clutch and the car continues to roll steadily, as if it were under light throttle. Whereas without ARM, even with matched revs, as soon as you lift the clutch you get a strong engine brake.
Also, the ARM works on upshifts as well. Obviously there's no throttle blip, because there's no need for that, but the revs drop more slowly than without ARM, and a very light throttle is maintained while (and a bit after) you release the clutch, so that overall it feels as smooth and seemless as an automatic gearbox. Turn the ARM off and you'll get either engine braking (if you don't accelerate at the same time), or a jolt (if you accelerate at the same time, but just a tiny bit too hard), or a nice and smooth transition when you finally get it right (which happens 2% of the time).

If you're a perfectly smooth driver with ARM on, that's exclusively thanks to the ARM.

So, It seems I have much more to learn than I thought. I thought mastering the double clutch was all there is to it, but that's just the tip of the iceberg. I've got so used to the ARM helping me on upshifts (without even realizing that it did), that now I'm not able to upshift smoothly without it, even though I never had this problem in any of my previous manual cars.
It's time to relearn how to drive properly.

I can see this being similar for me too. It took a few weeks to calibrate myself to the way this car works with ARM and now that I am, recalibration would surely be needed if I turned it off. This just confirms my suspicions that a new manual driver learning in this car will still have trouble driving a 50 years old manual car.

Edit: Just for the hell of it, gonna drive home from work today with ARM disabled and see how laughable it goes.

 

[Norm Peterson]

You'd think that all the ARM does is a short blip of the throttle immediately after a downshift. Not so. It's much more active, in more subtle ways. Not only does it rev the engine after a downshift, but it also holds it there for a short while, and the revs drop noticeably slower until you lift the clutch than they would without ARM. Also, the engine management seems to be different. With ARM you lift the clutch and the car continues to roll steadily, as if it were under light throttle. Whereas without ARM, even with matched revs, as soon as you lift the clutch you get a strong engine brake.

When you're doing your own rev matching, you're not quite done when you let the clutch out. You do have to keep the engine from dropping still more revs. I suspect that takes timing - and perhaps a tiny bit of leading throttle as you're letting the clutch pedal come back up. I'm having to guess a bit here, because it's something I just did without ever paying conscious attention to.

Also, the ARM works on upshifts as well. Obviously there's no throttle blip, because there's no need for that, but the revs drop more slowly than without ARM, and a very light throttle is maintained while (and a bit after) you release the clutch, so that overall it feels as smooth and seemless as an automatic gearbox. Turn the ARM off and you'll get either engine braking (if you don't accelerate at the same time), or a jolt (if you accelerate at the same time, but just a tiny bit too hard), or a nice and smooth transition when you finally get it right (which happens 2% of the time).

Practice will turn that 2% into at least 92%. Use the Force, Luke.


Norm

 

[Vlad Soare]

When you're doing your own rev matching, you're not quite done when you let the clutch out. You do have to keep the engine from dropping still more revs. I suspect that takes timing - and perhaps a tiny bit of leading throttle as you're letting the clutch pedal come back up.

Exactly. The ARM takes care of that, too. It's unbelievable how much the ARM really does. You'd think it's just a flick of the throttle when the shifter goes through the gate, but actually it's so much more than that. I used to take pride in my smooth driving, but now I've come to realize it was all an illusion. A monkey could drive this car smoothly with the ARM on.

 

[boB]

" The lack of a synchromesh means that the engine electronics must synchronise the speed of the engine with the speed of the gearbox internals before engaging a gear. "

If it's good enough for F1... ;)

 

[Vlad Soare]

If it's good enough for F1... ;)

Yeah, but all F1 cares about is winning the race by any means necessary. Driving pleasure isn't one of its goals, not even by far.

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