vB Easy Archive - Dumb-*** MT question

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Dumb-*** MT question
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Posted by: AM Radio

like the header said.

um ... what is "matching RPMs"?

i've been reading up on engine braking / down-shifting, and i've read this term a few times. what does it mean? like say i'm doing 50km in 3rd, right turn coming up. do i clutch, downshift to 2nd -- and REV UP?!? during the turn? if i downshift, and then let the clutch up, wouldn't my RPMs shoot up anyway?

and in that scenario, using brakes instead: why wouldn't i brake from 50km, clutch and drop to 2nd, do the turn, rev up, clutch, hit 3rd again and go?

sorry if this is a dumb question. i'm not an expert stick driver by any means ...

Posted by: TheOne

To answer your question...

Yes, if you downshift doing say 50 clicks from 3rd to 2nd, your rpm's will shoot up. You'll also feel a nice (rather harsh...) jerking forward as your engine catches up with the driveline speed.

Matching revs means anticipating the correct engine speed for the gear you're shifting into. So... when you downshift, tap the throttle just before you let out the clutch and that forward jerk becomes a nice gentle push, or you won't even feel it if you match your rpms correctly.

At the very least, your engine will be "on the up" as you let the clutch out, so its not so harsh on your driveline.

THink of this real life scenario. You're standing still, and you're buddy comes up from behind you on rollerblades and pushes you. You'll probably fall over. But... if you were already running forward, and he hits you, the impact will not be as severe.

Posted by: BrokeMyWallet

Well put. Rev-matching basically saves you unnecessary wear on the synchros and also embarassment if you have any passengers with you

Posted by: Stock R

Yup. Like the others said. Matching revs will give a smoother ride/less wear on the parts. Also you don't have complaining passengers saying "it's soo jerky".

As for your turning question, i don't really get what you're asking.
try reading www.turnfast.com

they have really good articles.

As for how much blipping of the throttle you'll need, that depends on the speed/gear you're going into so just experiment till you get a hang of it.

Posted by: AM Radio

lemme see if i got this right. (it would be better if i was in my car, of course.)

1. cruising at 50 in 3rd. right turn coming up.
2. clutch, drop to 2nd, brake as necessary, enter the turn
** brake first or clutch first or at the same time?
3. let up the clutch just before the friction point, give it a blip
4. get just past the curve, let up clutch completely, gas and go.
5. get up to rpm/speed, clutch for 3rd.

do i got it?

two more related questions:

what about this: say i come out of 50 in 3rd; clutch, drop to 2nd -- can i just ease up on the clutch and use that to avoid high revs, then finish the turn and hit the gas? i.e. don't use the brakes at all?

or this: coming out of 50 in 3rd; clutch, drop to 2nd; then brake somewhat "more" than normal to get make sure i drop to a speed for the lower gear through the turn (i guess i'd be slowing down quite a bit, then, right?); finish the curve, clutch out, hit the gas? i.e. don't blip?

pardon my ignorance ...

Posted by: Stock R

well, first of all. don't use the tranny to slow the car down. use the brakes. they were put there for a reason. less wear and tear on the entire system and cheaper to fix. not to mention they do the job better.

personally this is how i would do it.

1)coming towards turn at 50 in 3rd.
2)step on brake. slow down until i'm almost at turning speed.
3)while i'm on the brake press clutch in. blip throttle with heel while gear goes into 2nd and foot comes off the clutch.
4)foot off brake. turn.

things i don't do. 1) use the engine/tranny to slow the car down
2)slowdown/turn without being in gear.
3)slow down without my foot on the brake.

hope it helps a bit.

Posted by: BrokeMyWallet

This is what I usually do:

1)Approaching a turn, start braking
2)Almost ready to accelerate out of the curve, clutch in & downshift to 2nd
3)Blip the gas to rev-match and go (chirping the tires is optional

)

>what about this: say i come out of 50 in 3rd; clutch, drop to >2nd -- can i just ease up on the clutch and use that to avoid >high revs, then finish the turn and hit the gas? i.e. don't use the >brakes at all?

It probably wouldn't slow down the car quickly enough before the turn. Just use the brake and a little gas as you clutch out slowly until you get the hang of it.

Posted by: TheOne

Just a word of advice..

Downshift before getting into the turn. Even if your heel toeing skills are mario andretti smooth, you risk shocking your chassis. What I mean by shocking, your car will shake, or shimmy, jerk or something as a result of the gear change and if you're cornering at maximum grip, that shimmy, shake or jerk will serve to push your car into oversteer, understeer etc..

This piece of advice also holds for wintertime driving...
LOL

To summarize, brake (hard), downshift etc.. while you are going in a straight line, and when it comes time to turn, do just that. Turn. Braking and turning is ok, but at maximum grip, you have to be extra smooth as to not upset the car's balance.

Posted by: AM Radio

thanks everyone!

brake to a turning speed; clutch and downshift before the turn; blipping as necessary and let the clutch up, gas and go.

so in a way, the "blip" is part of my acceleration out of the turn, yes?

Posted by: Sfkn2

Posted by: Stock R

Quote:

Originally posted by AM Radio

so in a way, the "blip" is part of my acceleration out of the turn, yes?

not really, since the blip is done while the clutch is in.

Posted by: Becks7

is there any damage if you over rev on your double clutch?

On my dad's stock 02' Civic LX, I can't heel-toe unless i'm wearing skate shoes hahha, damn stock pedals

Also, if your driving and you depress the clutch and leave it depressed, what happens?

Posted by: BrokeMyWallet

Quote:

Originally posted by Becks7
is there any damage if you over rev on your double clutch?

On my dad's stock 02' Civic LX, I can't heel-toe unless i'm wearing skate shoes hahha, damn stock pedals

Also, if your driving and you depress the clutch and leave it depressed, what happens?

There's no need to double clutch in modern manual cars, but if you over-rev when you are trying to rev-match, it causes wear on the synchros as well.

If you are leaving the clutch depressed all the way for a long period of time, it will cause excessive wear on the throwout bearing. If you are riding the clutch, well then you should expect your clutch to start slipping pretty soon.

Posted by: Becks7

Quote:

Originally posted by BrokeMyWallet
There's no need to double clutch in modern manual cars, but if you over-rev when you are trying to rev-match, it causes wear on the synchros as well.

prefect rev-match = no wear on synchro's right?

Posted by: BrokeMyWallet

Theoretically none, but it's pretty much impossible for human to do this "perfectly". You'll always be off by a few hundred RPMs (or 10s if you are pro) no matter how good you are at shifting. The synchros should last as long as the life of the car as long as you don't abuse the transmission. I wouldn't worry about it...

Posted by: TheOne

3 words...

Sequential Manual Gearbox!

LOL

In all seriousness though, double clutching is wholely un-necessary in a car... The only time I ever do it, is if i'm driving a truck (tractor trailer) and thats rare cause you don't even have to use a clutch in some trucks as its a dog-gear (direct engagement). In that case, its throttle, WHAM!, throttle, WHAM!

Posted by: Becks7

wat about for passing?

Posted by: BrokeMyWallet

Nah bro, You don't need to double-clutch in normal shifting conditions. Have you been brainwashed by the fast and the furious? Only time to use double clutch I can think of is when there's a problem in the transmission and gears are difficult to engage...sometimes it helps, or you can try putting the gear in second and then pop the shifter into the gear you are having trouble with, which will line up the gear teeth correctly...or something

Posted by: AM Radio

um ... what's double-clutching?

(i must be the lower-mainland's dumbest MT driver, i'm thinking.)

Posted by: TheOne

Its exactly what it sounds like... pushing and releasing the clutch in twice.

Can be done on upshifts and downshifts.

The only differences between doing it on the up and down...

On the up:
push clutch
put gear in neutral
let out clutch
push in clutch
put into desired higher gear (eg. 3rd to 4th)
let out clutch

On the down:
push clutch
put in neutral
let out clutch
tap throttle
push in clutch
put into desired lower gear (rev matching while doing so)
let out clutch

You don't need to do this on ANY new car...

thats what the synchro's are for. Unless you're having trouble with your synchro's, or if by some off chance, your car (gotta be real old...) does not have them.

Posted by: SharpST77

buy auto.

Posted by: Stock R

as the others said, double clutching is essentially a thing of the past now. the syncros do the job. some cars even put in more for some cars (2nd) just because they know that's where more stress is going to be. they're designed to last the life of the car if drivenly normally. some ppl complain their gears start grinding after a few years, but it's usually nothing a fluid change doesn't fix.

double clutching is still required on some trucks though. at the ministry of transpo here, i was reading a sign on the wall. Ppl who are going for their A license (truck drivers) need to provide a test vechicle with no syncros and a minimum of 12 gears. So obviously this is a case where you'd need it. On addition to what TheOne said. On the upshift, there's still a possibility to need to rev the gas a little.

Some ppl in auto-x and racing forums insist that double clutching is required on the downshift. beats me why, but oh well.

All this double clutching, heel toe granny style shifting is all blown out of proportion and confusion with F&F.

Posted by: TheOne

Quote:

Originally posted by Stock R
as the others said, double clutching is essentially a thing of the past now. the syncros do the job. some cars even put in more for some cars (2nd) just because they know that's where more stress is going to be. they're designed to last the life of the car if drivenly normally. some ppl complain their gears start grinding after a few years, but it's usually nothing a fluid change doesn't fix.

double clutching is still required on some trucks though. at the ministry of transpo here, i was reading a sign on the wall. Ppl who are going for their A license (truck drivers) need to provide a test vechicle with no syncros and a minimum of 12 gears. So obviously this is a case where you'd need it. On addition to what TheOne said. On the upshift, there's still a possibility to need to rev the gas a little.

Some ppl in auto-x and racing forums insist that double clutching is required on the downshift. beats me why, but oh well.

All this double clutching, heel toe granny style shifting is all blown out of proportion and confusion with F&F.

Yeah, I have my A license, except over here we call it class 1. I took my tests in a company provided truck and it had 21 forward gears! I never drive the trucks though... I did it because at work, there is sometimes a need for a backup driver for some of the cargo containers that go in and out of site. Production is 24/7 and a sick driver would cause major problems...

I disagree however with your statement that a tap of the throttle is needed on an upshift when double clutching. The purpose of this double clutching is to synchrnoize the components in a transmission as well as the engine. If you apply throttle on an upshift, and then shift, you will be out of range for the gear you're in... causing among other things, mismatched revs. Of course, if you apply throttle, and allow things to synchronize again, this won't happen, but by that time, you may as well shift back into the gear you were in. A good shift in a tractor trailor should take less than a second, waiting for synchronization takes longer. Whenever i'm in a truck, i've gotten to the point where I can shift without using the clutch at all... the transmissions in those vehicles are of a heavy duty type so they can take the grinding (if any), etc.. without problems.

Posted by: Sfkn2

Quote:

The reason why drivers in autox competition needs to double clutch is because there's no way you can get into 1st without double clutching. You wouldn't want to be at 3k RPM in 2nd gear struggling through the sharp turns, would ya?

I think double clutching, if mastered, reduces wear on syncros. More importantly, it allows the car to be driven smoothly. It also allows the driver to have better control of the car.

Posted by: Sfkn2

Quote:

Originally posted by TheOne
I took my tests in a company provided truck and it had 21 forward gears! I

LOL, I knew there was a reason why trucks shift so early.. They gas for half a second, then they shift. Bleh, 21 gears.. what the hell does the gearbox look like?

Posted by: TheOne

Quote:

Originally posted by PreFknLude_SiR
LOL, I knew there was a reason why trucks shift so early.. They gas for half a second, then they shift. Bleh, 21 gears.. what the hell does the gearbox look like?

Depends on the truck! but for the most part it looks just like a standard gearbox. Many have a "split axle" transmission... its a button that you push while shifting to get into the next gear... If you're transmission has for instance 6 gears, a split axle will have 12.

The reason why you hear gas (half sec) shift, gas (half sec) shift etc.. is because the driver is trying to save fuel.. instead of shifting at the redline, he's just shifting when the engine has reached a "good enough" speed for the next gear. Its called progressive shifting!

Posted by: Stock R

Quote:

Originally posted by TheOne
I disagree however with your statement that a tap of the throttle is needed on an upshift when double clutching.

I wasn't referring to trucks, that's probably why. the truck revs between what/ 750-1500rpm? obviously the throttle would upset it like you said.

but if we talk back in the day cars...

Posted by: AM Radio

okay, i admit it. i MUST be the dumbest MT driver in the lower mainland.

Quote:

Originally posted by TheOne
Its exactly what it sounds like... pushing and releasing the clutch in twice.

On the up:
push clutch
put gear in neutral
let out clutch
push in clutch
put into desired higher gear (eg. 3rd to 4th)
let out clutch

next dumb question: i know this doesn't apply to newer cars (by this, i'm assuming anything from 1980's onward), but if you had already pushed the clutch in: why put it in neutral, then let it out again, only to push it in again? like, why not just:

push in clutch
put into desired higher gear
let out clutch

Quote:

On the down:
push clutch
put in neutral
let out clutch
tap throttle
push in clutch
put into desired lower gear (rev matching while doing so)
let out clutch

ditto with this. why not just clutch / de-clutch once? again i apologize for my ignorance. how the heck did all of you get to be so knowledgeable about MT driving? i'm trying to be a better driver, but it seems like i missed out on a LOT of stuff.

Posted by: TheOne

Its done to "drag" the components inside the transmission into a synchronous, or near synchronous rotation with the engine. SEe when you let ou the clutch in neutral, the transaxle is not engaged but the clutch is still "clutched" to the engine, the clutch is connected to an internal part of the transmission called the layshaft. This important little piece must be synchronized to the rpm (thus everything else in the transmission will be) otherwise, you'll get a grinding sound. If you don't double clutch on a car without synchro's... your layshaft will not be synchrnized in its rotation with engine, ie. your gears will grind.

Basically:

The engine is connected to the clutch (sing this in your head, to the tune of... the thigh bone is connected to the, knee bone.. lol), which is connected to the layshaft. The gears ride the layshaft and your gear selector selects which gear you want. This is grossly simplified.. .lol

Engine > Clutch <> layshaft > Gears

It is the layshaft which must be synchronized.

The only reason i'm fairly knowledgeable... I've regularily driven almost every type of manual transmission there is... from motorcycles to semi's