...and you rely too much on wikipedia.

 

Yes. I suspect that the RPMs are not blipped up high enough.

 

Don't wanna argue, but did you NOT read what i said? rev-matching is pointless when you know and do double cluching, or simply said because the two thing are similar "BUT NOT THE SAME", one helps you transmission, the ather makes you feel like a better driver, because it makes the transition to another gear smoother. PLS do not misinterprit what i said, because i do know the difference, just because i do not you the same term as rev-matching. OK now as i said i am not argueing, just commenting.

 

Yeah, you seem to know what i was talking about, since you drove an old dodge, now think about this, you are on the high way driving with 60-65 mph, you need to down shift to 3rd (supose you are in 6th) if you just "Rev-match" you tranny basically has to sustain all that friction and pressure to synchronize itself with engine and drive train(ofcourse the synchros do it for you),but if you doublecluched it what would have happened? did it have to sustain anything?

 

I do a sixth to fourth shift but, I take it slow and make sure I hit it just right. It's not a perfect U if you know what I mean. If I have to shift quickly from 6th to 4th for power; step part way in 5th for a split second (enough for syncro alignment) with the clutch in and continue to 4th. Goes in smooth as glass. The syncros like that move a lot better just take a split second more. However, it much better and faster than actually engaging 5th. Bimping the gas twice along the way at the right time helps as well.

Timing is everything.....

 

Sorry for the misunderstanding. I did read what you said. But you might not be blipping as high as you need to. What RPM are you at at 6th gear, and what RPM do you blip to before entering 4th gear?
What you could also try is, get to a decent speed on 2nd gear, and use your shifting technique to downshift from 2nd to 1st. If you can't shift to 1st even if you double clutch, you are not matching the revs well enough.

 

well, 2nd to 1st -- ahhh, i dont do it much , i mainly use first to take off, or for a hard launch to gime me some good speed. 6th gear with 60 mph the car runs at 'bout 2100rpms. when i downshift i would rev it pretty high and just drop the cluch(after i double cluch it of course) when all vibrations on the gear **** and pedal lessen out, i dont know exactly to tell you can't do the same thing on two cars , you just feel it, my daily driver is a 92 bmw 318, and you know in the city you use 2nd gear alot, so i do double cluch it 99.9999% on the time, either way grinds like nuts, the Zed is different story, so i dont try to memorise certain RPMs, and what gear where, it has to feel good, just intuition i guess.

 

I'm not sure what RPM 4th gear will be at 60 mph. But that's what I would try. Take 4th gear up to 60 mph, and take note of the RPM. Then when you downshift from 6th to 4th at 60 mph, aim for that RPM. If you still feel something 'blocking' you, at least you've ruled out the rev-matching bit.

 

I would,, about you - have you ever tried to shift without depressing the cluch pedal. Now, see the rpms in 4th gear at 60mph, try to be on an even surface, so the car can retain 60mph, without pushing the cluch pedal, just give some gas and with a gental push the shift **** out without using the cluch at all, than as you try to match the rpm of 4th gear at 60mph , and push gearshifter back in 4th , it works well in situation where your clutch is completly GONE, pedal down to the flore,

 

Do you just let the clutch out or do you give it a bit of gas while letting it out to balance it.

 

Hey I only used wikipedia to use the correct term baulk, instead of just block


Ideally you give a bit of gas to balance it out. Basically you use the gas to hold the rpms, so they dont fall while shifting

If your fast and smooth enough you can throw up the rpms, and simply ease off the clutch, but theres the chance of a rough shift if you get it wrong.

 

here is a bit more gas for the fire...

If you match the revs correctly, the clutch is not required. Simply put all it does remove the load of the engine from the input side of the gear cluster.

If you take your foot of the gas, it should be very easy to move the shifter into neutral. Then if you match the revs to the gear you want to go to, the shifter should slide right in...

One caveat though, this isn't something I would learn on an expensive gearbox like in a new Z. Spike100's old dodge truck, or the old Ford Cortina that I learned on 20+ years ago would be great. It is actually a lot of fun to learn if you have an old beater to practice with.

 

You mentioned that depressing the clutch is equivalent to the transmission being in neutral, but I disagree. The two conditions are the same from the point of view that the engine speed can vary without affecting the wheel speed, but I think that's where the similarity ends. When the clutch pedal is depressed the transmission is disconnected from the flywheel, meanwhile when the transmission is in Neutral and the clutch pedal is not depressed the engine is spinning the transmission input shaft at engine speed, although no gear is selected. (To my knowledge the transmission input shaft is 'free-wheeling' at engine speed in this condition).

Therefore if you do not double clutch, meaning you clutch in - blip throttle -shift into new gear - clutch out, the throttle blip gets the engine speed to where it should be based on the drive shaft speed translated through the newly selected gear. The synchros have to do the work of synchronizing the newly selected gear speed with that of the drive shaft.

When double clutching, the throttle blip occurs when the transmission is in neutral meaning the clutch is engaged and the input end of the tranny is free-wheeling at engine speed. The throttle blip increases the tranny input shaft speed so that the synchros have to do very little work to allow the selector to mesh into the new gear.

Not intending to argue here, but I just wanted to create a discussion for the difference between Neutral and disengaged. I like these discussions, because I think a lot of people who know how to drive get a chance to learn what actually allows them to do it.

 

Sry110,

That is a great explanation of the differences. thanks for taking the time to write it up.

 

double clutching?

 

You are correct. Clutch pedal down while the transmission is in a selected gear is quite different than clutch pedal down while the transmission is in neutral. I mis-spoke and my statement confuses the discussion; thanks for pointing this (my error) out.

--Spike

 

I haven't watched that movie in a long while, but I seem to remember that during the race that precedes the infamous "double clutching" comment, I think the Paul Walker character downshifts about 3 times during that quarter mile....you know, all those times he drops a gear and pulls ahead? So in that fantasy world where within one quarter mile you manage to downshift 3 times, double-clutching might be 100% relevant.

EDIT: I just found out that all the smoke that pours out from under the hood wasn't from fried piston rings, it was actually melted synchros from all that high-speed downshifting without double clutching. Let that be a lesson...

 

I always knew there was a difference, but I wasn't quite sure exactly what it was until about a year ago I went to howstuffworks.com and looked it up. They have all sorts of pictures and animations to accompany their explanation...great website for finding out all sorts of actually useful stuff!

EDIT: Here is the link for anyone interested:
http://auto.howstuffworks.com/transmission.htm

 

Yup... That how I do it. I depress the clutch pedal, go from 6th to 5th (but not engaging the trasmission, i.e., the move to 5th is only to orientate a quick shift to 4th), blip the accelerator to rev-match the downshift and the clutch pedal is down the entire time, then pull the shift to 4th and engage the clutch. That haqppens very fast and avoids missing the "gate" when trying to go directly from 6th to 4th.

You make a good point.

--Spike

 

Yep I have done this too, but never knew why. The gears are close enough in ratio that the shift into 5th gets the speed close enough that a little throttle blip will do.