[skier219]

I picked up my M2C today and love it except for the rev match feature on the 6MT. Normally if I wanted to rev match, I'd heel-toe the pedals myself. I can learn to let the car do that for me, no big deal. But I really don't want want rev match when downshifting purely to decelerate -- it's been my habit for decades to downshift for engine braking when slowing down or coming to a stop during normal road driving (ie, when I won't be accelerating out of a corner). Of course if the car is trying to match revs by blipping the throttle, I lose that deceleration and end up with awkward downshifts. I can feel the driveline clunk when this happens, as the engine is fighting my intentions.

I am curious what other folks are doing when they simply want to decelerate under normal driving conditions. Are you just not downshifting? Are you dropping into neutral and braking? Auto rev match is really only helpful in situations where you want to accelerate after a downshift, but if you want to be slowing down it's the wrong thing to do.

Maybe I need to break my habit of downshifting for engine braking, but I've been doing it for ~35 years so that is going to be a tough habit to break.

I plan to take a drive tomorrow with DSC off, which I understand will disable rev match. I wouldn't want to drive around this way all the time, but I feel like I need to try driving the car without rev match to get a feel for traditional downshift behavior. Then maybe see if I can train myself to live with the auto rev match.

[ContactPatch]

[QUOTE=skier219;25074656]



Maybe I need to break my habit of downshifting for engine braking, but I've been doing it for ~35 years so that is going to be a tough habit to break.

Indeed, brakes are a lot cheaper than transmissions.

[skier219]

Originally Posted by ContactPatch

Indeed, brakes are a lot cheaper than transmissions.

You know, funny thing, in the old days downshifting to engine brake was taught as a way to save the wheel brakes since they are a frequent wear item. Of course the clutch is too but I think the brakes still take more wear. There was another rule of thumb to always shift into neutral at a light and let the clutch out to avoid compressing the clutch pressure plate (a cantilever spring in disk arrangement) but I suspect that is minor in the grand scheme of things. Some other rules of thumb regarding wear on the throwout bearing and clutch fork that I can't even remember now. I wonder how many of these are even true or important. Occasionally I'd hear these topics come up on CarTalk, and of course they'd have a grand time discussing/ridiculing them.

[M Fifty]

Would now be a good time to mention the braking performance of my father's 1964 Ford Fairlane? Apparently, if you tried to slow from freeway speeds to a stop using just the brakes the pedal would go to the floor while the car was still doing the best part of 30 mph. So, the technique was to slow the car using the preselector to downshift until you'd got the speed down to about 40 mph and then brake to a stop...

3 speed torque converter transmission obviously.

[BroDoze]

I brake with the engine all the time on my MTs - that’s how I learned and how I’ll continue to drive MTs.
Still waiting to test drive the M2C.
When I do, I’ll pay particular attention to this! Thanks OP. Hope it’s not a show-stopper.

[silverds]

You have 35 years of experience driving a manual with sufficient practice to develop your own heel/toe technique and after driving your new car on day one, your first question to the internet is...

How do y'all drive a manual?

I have a spidey sense for being put on this feels like being put on.

In case you're not putting us on, please take some time to get used to your car, driving it as recommended during your break-in is strongly suggested.

This manual is the same as ALL other manuals except engine speed is matched for you (better than you, in most cases). Engine braking still works the way engine braking has always worked. This car's gearing might be different than your last manual so of course, this is going to change the way you drive it, but of course with 35 years of experience, you already know this.

I'm not trying to start an argument with anyone, if this car feels wrong or intolerable to anyone in any way, they have my sympathy and I hope they find something they enjoy.

[nioh_lbbm2]

Originally Posted by silverds

You have 35 years of experience driving a manual with sufficient practice to develop your own heel/toe technique and after driving your new car on day one, your first question to the internet is...

How do y'all drive a manual?

I have a spidey sense for being put on this feels like being put on.

In case you're not putting us on, please take some time to get used to your car, driving it as recommended during your break-in is strongly suggested.

This manual is the same as ALL other manuals except engine speed is matched for you (better than you, in most cases). Engine braking still works the way engine braking has always worked. This car's gearing might be different than your last manual so of course, this is going to change the way you drive it, but of course with 35 years of experience, you already know this.

I'm not trying to start an argument with anyone, if this car feels wrong or intolerable to anyone in any way, they have my sympathy and I hope they find something they enjoy.

100% agree. This guy does not know how to drive a manual car if he thinks the car isn't supposed to match revs upon downshifting.

Sounds to me like he thinks decelerating with engine braking means shifting into lower gear without blipping throttle and slipping the clutch as it tries to catch up.

News flash bud. The engine braking part is when the drivetrain is completely matched and mated and the engine is not receiving any throttle and "brakes" on its own due to physics of the engine working against itself to turn itself.

Rev match has nothing to do with the actual braking part. It is a precursor. To shift to a lower gear means higher rpm. The car has to match the rpm ratio of the gear you're in either you slip the clutch while downshifting (this is the WRONG way to drive a manual. Usually done by beginners first learning to drive a manual) or by blipping the throttle (be it auto rev match or manually blipping the pedal)

[Mosely]

Originally Posted by skier219

I picked up my M2C today and love it except for the rev match feature on the 6MT. Normally if I wanted to rev match, I'd heel-toe the pedals myself. I can learn to let the car do that for me, no big deal. But I really don't want want rev match when downshifting purely to decelerate -- it's been my habit for decades to downshift for engine braking when slowing down or coming to a stop during normal road driving (ie, when I won't be accelerating out of a corner). Of course if the car is trying to match revs by blipping the throttle, I lose that deceleration and end up with awkward downshifts. I can feel the driveline clunk when this happens, as the engine is fighting my intentions.

I am curious what other folks are doing when they simply want to decelerate under normal driving conditions. Are you just not downshifting? Are you dropping into neutral and braking? Auto rev match is really only helpful in situations where you want to accelerate after a downshift, but if you want to be slowing down it's the wrong thing to do.

Maybe I need to break my habit of downshifting for engine braking, but I've been doing it for ~35 years so that is going to be a tough habit to break.

I plan to take a drive tomorrow with DSC off, which I understand will disable rev match. I wouldn't want to drive around this way all the time, but I feel like I need to try driving the car without rev match to get a feel for traditional downshift behavior. Then maybe see if I can train myself to live with the auto rev match.

When I first got the car I had to get used to the downshifting timing. If you release too slowly, you'll get a clunk. I find that the car likes you to be very quick with the clutch on downshifts, especially in sport/sport+

[AlpsRider]

I downshift using the engine for deceleration when having fun in the twisties but in town it is a lot of work and wear and tear on the car to do it before every stoplight. The car has fantastic brakes.

[andrettifan]

I'm 65 and have been doing my own rev matching for almost 50 years. It becomes so ingrained in how you drive that it's hard to change, regardless of how well the computer does it for you. I drove my 2017 M2 for two years always in Sports + with all nannies off because I hated the auto rev matching, but as soon as I got my 2020 M2C one of the first things I did was (get someone else because I didn't know how) to code off the rev matching. I can now drive in any mode with the rev matching off.

My recommendation to anyone who doesn't want the auto rev matching and still wants the computer to save you from overdoing it, code the damn thing off.

[doughboy]

I'm confused by the OPs statement..

Engine braking still works exactly as normal with or without rev match. Changing down a gear and therefore raising revs increases braking as the lower ratio needs more torque to turn the engine.

Unless the OP is trying to slip the clutch against a slow engine speed, which is really not how to do a car any favours.

In town I tend to brake anyway in say 4th, then drop to 1st as I stop, no need to go down 4,3,2,1 every time.

[natmad]

I’ve been heel and toe rev-match down shifting several different performance cars for many years...

This is my first performance car with auto rev-match.

For me, it works like magic!

I operate the brake pedal and the gear shifter exactly as if I were heel and toe rev matching myself.

I just don’t have to roll my right foot onto the gas pedal anymore.

I’ve found it’s easy to get perfect rev-match downshifts every time.

Works great when I’m easing up to a stop, or when I’m braking hard and late for a corner.

Best invention since lager beer.

[CP911]

Yeah, this makes no sense. Engine braking is optimal when rev-matching occurs as the RPMs rise and give you more braking as the RPMs then begin to drop. If you don't want any engine braking at all, pop it into neutral and coast. I'm not sure what OP is struggling with here...

[skier219]

So I did a couple things this morning, first was to turn DSC off so that rev match was disabled. Everything about the car felt normal and like most other cars I have owned with some minor exceptions. I could heel-toe if I wanted to, or not. On deceleration with or without a blip, I got a very minor amount of engine braking on downshifts -- clearly the airflow of the engine doesn't result in a whole lot of back pressure, so it was actually very minimal and brief engine braking (sure, if I dropped into lower gears sooner it would engine brake, but I tend to be very well timed and spaced with my downshifts and compared to other cars I have owned, the engine braking is minimal in this scenario). The engine picks up RPMs very quickly after a well spaced downshift, whether rev-matched or not. This is perhaps the fundamental root of what I was noticing and not liking yesterday, and the minor amount of engine braking will be made to seem even less usable and more awkward during deceleration with rev match on.

I also realized the M2C had been doing rev match on upshifts as well. Without that kicking in, there are some nice burbles and cracks from the exhaust during upshifts (which again seems normal to me).

After getting reacquainted with the car and reestablishing my baseline, I turned DSC back on and played with rev matching again. Having it on upshifts is great -- it makes every upshift seamless if somewhat sterile and lacking in character. On downshifts, the trick (also mentioned by someone else) is to be quick, so that you're engaging the clutch in the lower gear within the timeframe of the rev match whether you want to be quick or not. Since this is not controlled by the driver's heel-toe motion(s), nor does it compensate for the pace of the driving or the shift, lazy downshifts are awkward and result in a driveline jolt (and since this driveline doesn't have much slack, there is a clank, which I am told is normal for the car).

Fast downshifts are seamless. No problem if driving lickety-split or deliberately, but for the way I was driving yesterday when babying the new car on the trip home from the dealer, rev match was getting in the way during gentle decelerating downshifts. For casual driving it's just plain awkward. I would not normally be blipping the throttle manually in those conditions, and having the car do it automatically was counterproductive to me. Combined with the lack of engine braking discussed above, throttle blips make decelerating downshifts feel transparent (best way I can describe it) and it's like there is no engine braking at all.

From what I learned this morning, when I want to decelerate, the trick is to use a lot more wheel brake than I would normally, downshift quickly, and just let the engine and gears "keep pace" with my deceleration via quick smooth downshifts that offer no significant engine braking. This will be a big change for me but I feel like I made a lot of progress in just 15-20 minutes of driving and experimenting. I actually like the idea of learning something new and having to grow into the car a bit.

Note: I tried dropping gears more aggressively and did get much more engine braking, but these were not properly spaced downshifts and it's not the way I would drive the car. My fundamental downshift habit is to chase down the gear ranges smoothly and evenly and see +hundreds of rpm during downshifts, not +thousands.

[chris719]

I’m pretty sure you’ve been “clutch braking” your whole life, not engine braking. If you don’t blip and just let the clutch out, this is what happens.

If you’re talking about lack of engine braking after you’re already in gear, this is how cars are now due to emissions and fuel economy.

[skier219]

I've always thought clutch braking involved intentional slippage and that is most definitely not the case when I do it -- clutch engages and hooks up so what happens at that point is engine braking, assuming the engine has back pressure to generate it.

[silverds]

Originally Posted by skier219

I've always thought clutch braking involved intentional slippage and that is most definitely not the case when I do it -- clutch engages and hooks up so what happens at that point is engine braking, assuming the engine has back pressure to generate it.

skier219 - You asked for advice, but you are engaging in debate. If it was advice you were seeking, the only appropriate reply to the advice offered is "Thank you". Any caveat you post with the intent of "correcting" the advice provided is the start of a debate. (hint: It's kind of a nasty trick to play on folks trying to help you by giving you what you asked for...and I am in no way insinuating that I am completely inocent of said behavior)

It is apparent to a majority of contributers to your thread that if you are having trouble figuring out how to engine brake in this car, that your 35 years of experience may have consisted of bad habits and a fundamerntal misunderstanding of the intent and appropriate method of engine braking.


That said...

Engine braking - The deceleration of a car when the engine and transmission are fully locked and synchronized and 0 throttle is applied.

How engine braking works - Since there is no (or greatly reduced) fuel for combustion in the cylinders, the combustion stroke (or "BANG" stroke) creates a vaccum in the cylinder that adds resistance instead of power to the stroke. The vaccum in the cylinders combined with the mechanical resistance of the moving parts of the engine and transmission will cause the car to decelerate.
Note: The lack of aerosolized fuel to cool the cylinder walls and reliance on the engines inherent frictional resistance results in additional heat buildup in the engine block.

How to engine brake:
1. Leave transmission in gear
2. Release the throttle
Congratulations, you have successfully achieved engine braking.

How to down shift: (before engine braking)
1. Press the clutch pedal
2. Select a gear (Note: Operator skill is measured by the ability to do steps 2 and 3 simultaneously and in a very VERY short amount of time)
3. Synchronize engine speed and transmission speed (This is called a "BLIP")
Option1. Do this manually by pressing the throttle pedal to achieve the desired RPM
Option2. Allow the ECU to rasie the engine RPM automatically
4. Release the clutch pedal

The cost of every imperfectly executed downshift (and upshift to a lesser degree) is the longevity of synchronizers and clutch...

... aswell as any credibility you might have had regarding your expertise in operating a manual transmission

[F87_LCI]

Originally Posted by silverds

skier219 - You asked for advice, but you are engaging in debate. If it was advice you were seeking, the only appropriate reply to advice is "Thank you". Any caveat you post with the intent of "correcting" the advice provided is the start of a debate. (hint: It's kind of a nasty trick to play on folks trying to help you by giving you what you asked for)

It is apparent to a majority of contributers to your thread that if you are having trouble figuring out how to engine brake in this car, that your 35 years of experience may have consisted of bad habits and a fundamerntal misunderstanding of the intent and appropriate method of engine braking.


That said...

Engine braking - The deceleration of a car when the engine and transmission are fully locked and synchronized and 0 throttle is applied.

How engine braking works - Since there is no (or greatly reduced) combustion in the cylinders, the combustion stroke creates a vaccum in the cylinder that adds resistance instead of power to the stroke. The vaccum in the cylinders combined with the mechanical resistance of the moving parts of the engine will cause the car to decelerate.

How to engine brake:
1. Leave transmission in gear
2. Release the throttle
Congratulations, you have successfully achieved engine braking.

How to down shift: (before engine braking)
1. Press the clutch pedal
2. Synchronize engine speed and transmission speed
Option1. Do this manually by pressing the throttle pedal to achieve the desired RPM
Option2. Allow the ECU to rasie the engine RPM automatically
3. Select a gear
4. Release the clutch pedal

Lol.
What? No "To start car, get in car with key in pocket. Depress clutch. Press red button labeled 'START'..??

[silverds]

Originally Posted by F87_LCI

Lol.
What? No "To start car, get in car with key in pocket. Depress clutch. Press red button labeled 'START'..??

Technology doesn't prove Darwin was wrong, it just proves he was a little optimistic.

[natmad]

OP, after driving around yesterday, paying close attention to the drivetrain during auto rev-match downshifting, I found that the Clutch Delay Valve (CDV) is likely the reason some down shifts may exhibit an unexpected slight clunk.

The CDV does take away some of the fine control the driver would otherwise have over the clutch action.

[BroDoze]

^^ CDV needs to be yanked on everyone’s 6MT!

[CTSean]

Originally Posted by skier219

I've always thought clutch braking involved intentional slippage and that is most definitely not the case when I do it -- clutch engages and hooks up so what happens at that point is engine braking, assuming the engine has back pressure to generate it.

If you are engaging the clutch on downshift without blipping the throttle to rev match, then you are using clutch slippage to decelerate the car, intentional or otherwise.