clutchless gear shifting ...

[niky]

Originally Posted by Miller88

It's hard to do in an electronic throttle vehicle. The revs hang way too long.

That's only because they don't want the throttle to close, for better emissions. Some manufacturers actually implement rev matching on their manual models to facilitate smooth shifts. The rev-match feature on the Nissan Z should theoretically make it possible to shift on the fly without clutching or blipping the throttle yourself.

That said, I've done it on E-throttle cars. It's just a bit slower on some of the worse throttle-hangers. And it's easy to do it going down through the gears with a little heel-toe when slowing down...

[user removed]

All I can say after reading this thread is this. If you think you can shift gears clutchless then go drive and old 39 Ford farm truck with a granny geared 4 speed, with no synchros whatsoever.

I used to shift clutchless in my 959 Corvette with a M22 transmission. Only used the clutch to get going in first. That was close to 40 years ago.

Just becasue you accomplish a shift without a clutch does not mean you are not stressing and wearing the synchros as well as the rest of the transmission. Drive one of those ancient non synchro vehicles, like a 39 Ford farm truck with no synchros, where any small miscalculation is immediatly apparent when you hear the grinding of gear teeth.

The only time I would do clutchless shifting is when the clutch was broke. It's just advice, I dont need a bunch of nasty remarks about your or my skills. I occasionally shift my bikes without the clutch, but it is a mistake, not intentional. I have rebuilt hundreds of transmissions in case you want to call me ignorant.

regards
Mech

[razor02097]

Originally Posted by Old Mechanic

All I can say after reading this thread is this. If you think you can shift gears clutchless then go drive and old 39 Ford farm truck with a granny geared 4 speed, with no synchros whatsoever.

I used to shift clutchless in my 959 Corvette with a M22 transmission. Only used the clutch to get going in first. That was close to 40 years ago.

Just becasue you accomplish a shift without a clutch does not mean you are not stressing and wearing the synchros as well as the rest of the transmission. Drive one of those ancient non synchro vehicles, like a 39 Ford farm truck with no synchros, where any small miscalculation is immediatly apparent when you hear the grinding of gear teeth.

The only time I would do clutchless shifting is when the clutch was broke. It's just advice, I dont need a bunch of nasty remarks about your or my skills. I occasionally shift my bikes without the clutch, but it is a mistake, not intentional. I have rebuilt hundreds of transmissions in case you want to call me ignorant.

regards
Mech

I was about to mention the clutch broken thing.... when the clutch cable broke on my bike I did clutchless shifting to get home... but I felt guilty as hell the whole time. I am very sympathetic to machines.

I do a variant of the OP's procedure... but I use the clutch when selecting the next gear. When I shift the clutch goes in and next gear is selected then the clutch is let out the moment the RPMs drop to the appropriate speed at which point the clutch is out all the way and power is applied. It makes for a much smoother acceleration.

[Cobb]

Nuthin like having the gear selector thrown out of your hand or it trying to snap your wrist.

Yeah, knowing what I know I do what my dad calls double clutching it. Pausing in nutral, but not reworking the clutch to double clutch it.

Ive seen guys jam the shifter in any gear they want when they want and countless videos on youtube of power shifting, speed shifting, etc. I just picture their tranny fluid turning into kero syrup.

[Miller88]

Originally Posted by niky

That's only because they don't want the throttle to close, for better emissions. Some manufacturers actually implement rev matching on their manual models to facilitate smooth shifts. The rev-match feature on the Nissan Z should theoretically make it possible to shift on the fly without clutching or blipping the throttle yourself.

That said, I've done it on E-throttle cars. It's just a bit slower on some of the worse throttle-hangers. And it's easy to do it going down through the gears with a little heel-toe when slowing down...

Exactly. My focus hangs the revs FOREVER when shifting. And if the engine isn't up to temperature, it won't even consider idling below 2000RPM if the clutch is pressed.

Makes trying to take off on those cold mornings very hard when I'm trying to shift!

[Cobb]

In that case you need to take it out further in a gear so you can enter the next at 2 grand.

Or just clutch it through the gears and let it idle along til the engine warms up.

[niky]

Definitely agree with Old Mech's rant, though I'm guilty of doing this a bit too often... but just for the practice. Figure it's a good skill to learn in the event of a clutch failure.

But hardly ever on new cars or test units. Not my gearbox. So I be gentle.

[Blue Angel]

Originally Posted by Cobb

I think the chevy hhr has a no lift shift on the manual models that allow clutchless shifting once you start off.

No. Certain turbocharged GM vehicles have what's called "No Lift Shift", which basically means they are designed to be powershifted. Powershifting is taking the car to redline at WOT, pushing in the clutch, selecting the next gear, and then letting out the clutch again, all while holding the throttle wide open.

This can be done in ANY vehicle with a manual transmission, but the GM system cuts engine power during the shift to minimise drivetrain shock when letting the clutch out while keeping the throttle open. This helps to keep the turbocharged engines "on boost" during the gear change. Closing the throttle on a turbocharged engine mid-shift causes the blow off valve to de-pressurize the intake tract and slow the turbocharger down, which takes some time to overcome once in the next gear.

This thread has gone severely OFF TOPIC. The OP was interested in intelligent feedback circuits to the motor controller in an EV that would allow the motor to synchronize its speed with the next gear to be selected.

The new Corvette Stingray has a rev-matching system that does something similar, but forget about the fact that it has a gasoline engine and a clutch that still requires disengaging.

The specific technology I'm refering to here is the sensor system they developed for the shifter. It's a sensor that monitors the shift lever movement so the ECU knows which gear you are about to select, whether you are up or down shifting.

anderwgray, I believe this is what your idea would require... some sort of method to tell the controller which gear you are going into, and some smarts in the controller that would compare the desired gear to the current vehicle speed and match them up. THIS would make perfectly smooth clutchless shifting a reality with an EV.

It would also work with a gas engine as long as the RPM could be accurately controlled, BUT THAT'S NOT WHAT THIS THREAD IS ABOUT!

[ConnClark]

Of course It should be noted that clutchless shifting will do nothing to improve your mileage

[justme1969]

I had the 28 mile joy of clutchless shifting this very morning.
The KIA slave cylinder went out last evening, on return trip no biggie as I had a backroad with one stopper in middle to house.
Today was another thing!!! to get here to work required pushing vehicle out of driveway.
Then starting it in 1st. gear.
Then no stops and a hundred grinding power shifts to be here at work 25 minutes early.
This car does not enjoy power shifting situations.
Im a pro and would be inclined to believe that the shift plated are the root cause since there are no detents.
Hitting the detent location to 3rd. and 5th. with a clutch sometimes misses soo...
Sorta like trying to find mr happy after swimming in a cold lake.
Ya know its there and know where to look but are still amazed at how it could possibly be so small after ya find it.