Can the FR-S trasmission Rev-match?

[Huehuecoyotl]

just wow

[Dynotronics1]

Originally Posted by CSG Mike

This was never a track/race level discussion, which is why I'm confused as to why a high-wear (abusive for street use) technique would be brought in... (clutchless shifting)

I still don't see the speed benefit; you have to wait for the engine revs to drop, whereas using the clutch, you can force it to drop.

Now we are having a useful debate!

First your correct, I assumed he was talking about track use, so thats my fault. However you have to admit that rev matching on the street is only useful in a vehicle with a crashbox, such as a semi truck.

Please explain your last statement to me "whereas using the clutch, you can force it to drop" .

Second, you keep assuming that this is "high-wear", what makes you think it is? If we were to agree that there is only one place where the driven and drive ratio gears will mesh(rev wise), and we are both getting there before the gear change occurs( you with a clutched blip, and mine without), how does this translate to high wear? Your synco is doing the SAME EXACT work as mine, because the layshaft and mainshafts are still turning. If the change is done correctly there is no more or less wear one way or the other.

Third, think about this; when you apply the throw out to the clutch cover, where does the energy go?

Now the last thing I will say is this; is it worth the effort to learn this for the average track day driver, no. I do it because thats the way I learned, driving low output front wheel drive stock type race cars. and the fastest way to drive them is left foot trail braking. (I find the BRZ responds quite well to this same style, BTW.) But thats me.

[mad_sb]

@Dynotronics1,

I see you have been busy defending your method since i asked my question...

Anyway... with a clutchless downshift.. at what point do you slide out of gear? is it during the transition from wot to braking? That the only time i can imagine the gears are unloaded enough to allow for an easy exit from gear.

[Huehuecoyotl]

Originally Posted by Dynotronics1

Now we are having a useful debate!

First your correct, I assumed he was talking about track use, so thats my fault. However you have to admit that rev matching on the street is only useful in a vehicle with a crashbox, such as a semi truck.

Please explain your last statement to me "whereas using the clutch, you can force it to drop" .

Second, you keep assuming that this is "high-wear", what makes you think it is? If we were to agree that there is only one place where the driven and drive ratio gears will mesh(rev wise), and we are both getting there before the gear change occurs( you with a clutched blip, and mine without), how does this translate to high wear? Your synco is doing the SAME EXACT work as mine, because the layshaft and mainshafts are still turning. If the change is done correctly there is no more or less wear one way or the other.

Third, think about this; when you apply the throw out to the clutch cover, where does the energy go?

Now the last thing I will say is this; is it worth the effort to learn this for the average track day driver, no. I do it because thats the way I learned, driving low output front wheel drive stock type race cars. and the fastest way to drive them is left foot trail braking. (I find the BRZ responds quite well to this same style, BTW.) But thats me.

I'm late to the party, but if you're advocating clutchless shifting then there is no debate

[CSG Mike]

Originally Posted by Dynotronics1

Now we are having a useful debate!

First your correct, I assumed he was talking about track use, so thats my fault. However you have to admit that rev matching on the street is only useful in a vehicle with a crashbox, such as a semi truck.

Please explain your last statement to me "whereas using the clutch, you can force it to drop" .

Second, you keep assuming that this is "high-wear", what makes you think it is? If we were to agree that there is only one place where the driven and drive ratio gears will mesh(rev wise), and we are both getting there before the gear change occurs( you with a clutched blip, and mine without), how does this translate to high wear? Your synco is doing the SAME EXACT work as mine, because the layshaft and mainshafts are still turning. If the change is done correctly there is no more or less wear one way or the other.

Third, think about this; when you apply the throw out to the clutch cover, where does the energy go?

Now the last thing I will say is this; is it worth the effort to learn this for the average track day driver, no. I do it because thats the way I learned, driving low output front wheel drive stock type race cars. and the fastest way to drive them is left foot trail braking. (I find the BRZ responds quite well to this same style, BTW.) But thats me.

Letting the engine RPM drop on its own, so that you can get into the next gear up, versus clutch in, shift, clutch out. Lets say theoretically, engine RPM drops at a rate of 100RPM/s. The shift requires a 2000RPM drop. You'd need the RPM to drop for 20 seconds to match, and get into the next gear. Or, you can clutch in, shift, and clutch out, and the wheels will force the engine rpm to drop to the appropriate gear. Obviously much slower numbers than real life, but it's for illustration purposes.

Explain to me how quickly the change change can be done with a near perfect revmatch. I am perfectly able to execute a clutchless shift, but it's nowhere near as fast. Alternatively, I can do it quickly, but at the cost of putting a heavy load on the synchros. While the layshaft/midshaft are still turning, the RPMs are not matched, and matching the RPM is what causes synchro wear.

Not sure what you're asking with the 3rd question.

Left foot trail braking can be done just as effectively if your right foot pedal technique is good enough. As long as the end result is there... I know some very fast guys that don't blip downshifts.

[SloS14]

Originally Posted by Dynotronics1

yes your wrong!

*you're

[Dynotronics1]

"Or, you can clutch in, shift, and clutch out, and the wheels will force the engine rpm to drop to the appropriate gear."Say what? If your matching correctly there should be no difference in the engine speed before and after the downshift, in other words; you come down into a corner running 5000 revs in 5th, brake , then as the revs come down below the point of peak tq, downshift to get more engine brake. Lets say that this point is 3000 revs. We know( for this example) that a downshift at 3000 revs into 4th will bring the engine back up to 5000(your 2000, ok?). If done correctly the second the shift is complete(clutched or clutchless) when the engine and driveline are recoupled, the revs should fall to exactly the 5000rev mark, or the correct matchpoint.

From above, it would appear to me you are saying the clutch should be engaged and the driveline allowed to slow the engine? Isn't that the entire idea here, to match revs, and allow the car to SEAMLESSLY continue to decelerate? Am I mis reading your statement?

"Alternatively, I can do it quickly, but at the cost of putting a heavy load on the synchros. While the layshaft/midshaft are still turning, the RPMs are not matched, and matching the RPM is what causes synchro wear."

perhaps this is what you and I are not connecting on, the revs are matched when I shift down. If its done properly, and with practice, I assure you, there is no more or less load on the syncos.

You keep saying a clutchless shift is not as fast. Do you know this to be the case, or do you just think it to be so? In the final count, the results seem to speak for themselves, don't they?

[Dynotronics1]

Originally Posted by SloS14

*you're

I confess, I was a lousy english student. But then engineers don't have to spell well most of the time..............LOL

[LeeMaster]

<--------- *Reads 3 pages*

Now =

[BrianJC]

Originally Posted by Noob4Life

Never raced before but from what I know that would mean that you are braking while turning which your not suppose to do. You brake before the turn that way you can use all the tire grip for the turning not braking and turning.

Sent from my SAMSUNG-SGH-I317 using Tapatalk 2

Braking while turning is absolutely fine, in fact, many will say it is required. I have never personally tested data in race car, but there have been tons to data out there to support braking while turning will produce faster lap times. In fact, most professional drivers who say they do not brake during turning, when measured during driving, data shows otherwise! From what I remember, many of the greats, ie Schumacher, Senna, etc all shows braking while turning. Maybe super race car differs from low end stock cars, that I do not know.

[ft_sjo]

Originally Posted by Dynotronics1

What most folks seem to forget is that the gearbox has very very good syncos

You mean apart from 2nd gear synchro which is too small, too heavy, and is the biggest culprit for it not wanting to go into 2nd when cold. Oh and the huge gap between 1st and 2nd doesn't help either. I'd be surprised if anyone really knows the true reason for that big gap, though.

[Razor]

I am to deduce that by "blimp the gas pedal between shifts" is only a momentary depresion of the gas that rises the RPM's and through practice I will inuitively find how long the "blimp" to match the current speed on the FR-S?

[ATL BRZ]

[dc50818]

autoblip.com look it up