When you're on a motorcycle, it's possible to upshift without actually engaging the clutch. Is it possible on a car as well, or is there a difference between bike and car clutches that I don't know about?

 

Not the clutch, its the tranny. Racing trannys with no syncros are shifted without the clutch.

 

It is possible to upshift and downshift a normal car tranny without the clutch, but it's tricky to do and will destroy the syncros very fast unless you get it perfect. Only dog boxes or real sequential trannies should be shifted without the clutch.

 

yes its possible. took me a little bit to learn. its all about balancing the force of your engine to the tranny to the wheels. if the power is balanced, just ease the shift and it will be nice and smooth. first try cruising in gear but with just enough throttle to keep the car at a constant speed [lets say 4th gear]. then try to ease the stick into neutral. if you suceed then try doing the same but once you get it in neutral [from 4th] slowly increase your rpm and lightly push the shifter into 3rd. if you do it right it will slip into 3rd with no problem.
edit: my car is stock

 

^ I shift up and down without the clutch all the time in traffic, but it makes for a far slower shift than using the clutch would.

 

What DamonB said.

You can easily shift bikes no-clutch because they have dog rings instead of synchros, and they have very low inertia drivetrains and their clutches have some "give" to them. Road racing dog boxes are still somewhat required to use the clutch, it can be done without but it's rough on things.

Additionally, there are special no-lift drag transmissions that actually engage the next gear before the previous one is disengaged (two piece slider assemblies, LOTS of taper on the dogs) but they require clutches that slip a bit or they can and will frag.

If it sounds like it's a good idea to use the clutch no matter what, you'd be right.

 

I learned to drive a manual transmission in a '71 VW beetle. In that car I learned to up and down shift without the clutch, it just takes practice.

Most of the time I am shifting without the clutch in my FC, I usually start off with the cluch then use no clutch going into 2nd, 3rd, 4th then I use the clutch to go into 5th. In every FC I have tried it in I have found it nearly impossible to shift into 5th without the clutch. I am not sure if it is the design of the gear/syncros or what but no matter how hard I try to match the RPM's it just will not go into 5th without some grinding. I just don't even attempt 5th anymore.

Depending on the trafifc situation I will also downshift without using the clutch. If the situation is right I can even slide it into first without the clutch. (car MUST be rolling to do this) There is a stoplight near my house that puts me on a downhill slope. I release the brake and let the car start rolling then barley put pressure on the shifter towards 1st gear. Once the RPM's match the speed of the car it will slide into first like butter.

As long as you are not forcing the shift (ie: bending shift linkages) or grinding the gears there is no harm done to the transmission.

 

^ I wouldn't go so far as to say there is no harm done to the transmission when shifting a syncro box without the clutch

when you you pre load a syncro and wait for the rpm/speed to syncronize your just burning the blocker rings up.

to sum it up there is zero benifit to shifting a syncro box without the clutch but there are many negatives I do have to admit i am guilty of popping into n without it though...do to nothing more than pure lazyness.

 

I don't know the gear ratios of an FC but usually 5th has a larger spread than 1-4 so the timing of the shift is different. In my FD for instance I must run the RPM out farther and breathe the throttle a tad more while going for 5th before it will snick right in. A blip as you pass through neutral can help too.

 

merlin---this isnt a yahama keep the clutchless shifts to the bikes

i used to drive my bike and never use the clutch unless i was coming to a stop or starting off. my dad drives without a clutch. after he did this once in my old rx7, i wont let him drive my new one why? i know its bad. it may not cause instant damage, but thinka bout the long run. weight the good and bad side? i could easily be wrong, but im big on playing it safe. so i always use the clutch.

 

I don't think that's necessarily a good example, as weren't those later beetles equipped with a specially designed "clutchless" manual, that you only used the clutch when starting and stopping?

 

I am not familiar with any of the "clutchless" VW transmissions. I am sure this one that I learned to drive on was not one of these. It had the same transmission that my '68 VW (the one I bought at age 16). It took lots of practice to get that transmission to shift without the clutch, in the beginning it was "grind it until you find it".

 

must...resist...making...first...time...sex...joke ...

 

Ok, that answers all the questions I had on the matter. Clutchless shifting = bad. I guess that would also explain the much louder whine of a bike's transmission as well. Thanks for the answers everyone.

 

FB and SA transmissions have nice tight spacing 4-5, actually a lot closer than the 3-4 shift.

The FC and FD have stupidly tall 5th gears, which seems to be why they eat 5th synchros all of the time.

A proper rev-matched clutchless shift will not use the synchros at all. The slider just falls over the splines with no effort at all. Oddly enough this is MUCH easier to do once the synchros are dead and gone, since there is no chance of them getting in the way. With properly functional synchros, clutchless shifting is actually more difficult.

I rarely use the clutch in my RX-7 when driving around town. Take a second or two for each shift, but it's a lot easier than trying to push the clutch pedal.

 

LOL I never knew there were so many lazy *** rx7 drivers.

 

here is a video of what you are looking for ,this video is
a Rx4 with PPG straight cut gears .I used to have something
similar on my rx3 for the street and track a few years ago.

You have to download to watch video.Pretty cool demonstration.

http://www.ppgearbox.com.au/images/content/SCDOG.wmv