csmeance

I was having a slight debate with a friend who drives a stick and he doesn't believe in downshifting when approaching a light or a stop.

For example if he's in 5th and he sees the light red ahead so he'll Clutch in, put the car in neutral, clutch out and then brake. If the light turns green then he'll clutch in, 3rd gear, clutch out and then accelerate.

It was my understanding that you cannot skip shift (if you do it can damage the synchros) and as well that you should always downshift when approaching a light in 5th gear by "clutch in-> 4th ->clutch out-> clutch in -> 3rd and so on.

Now is it appropriate to do clutch in -> 4th ->3rd-> 2nd ->Clutch out or is it the way my buddy does it or to do it by "clutch in-> 4th ->clutch out-> clutch in -> 3rd, clutch out -> clutch in-> 2nd ->clutch out-> clutch in -> 1st?


Would that cause additional wear on the clutch and bearings or what?

S A CHO

I've always done it the way your friend does it. Lights red, wait for RPM's to fall around 1500 while braking, clutch in just before I come to a stop.

There's no damage in doing so, much the same way a lot of people drive 1st to 3rd to 5th to save gas.

As long as you're not grinding gears and the shifter slides in smoothly, your not doing any damage to the transmission.

Sarlacc

Ive never heard you should skip gears while downshifting...I mean you shouldnt go from like 6th to 3rd gear while going 70mph, etc pending where you redline.

But I often do what your friend does...or I downshift...just depends on what I feel like doing.

Best thing on the freeway is to drop from 6th to 4th and gun it....so much fun.

oonowindoo

Your friend is right and i can't remember the last time I downshift from 2nd to 1st.

Also if you downshift 5-6 times at every light, then you also have to heal and toe 5-6 times because the car is not going to brake by itself. Assuming you don't just jam the gear in to downshift.

have you driven a stick car for more than 6 months?

I personally dont downshift when coming to a light, i would just leave in whatever gear i am in and brake then neutral before around 2000 rpm. EXCEPT:

- Light turn green before i come to a complete stop
- Hard braking
- turning
- up/down hills...

i am sure most of ppl who drive stick do the same thing...

Ken1997TL

For me its a matter of how much engine braking I need. I don't want to rev the piss out of the motor either. And of course, I try to anticipate what gear I reasonably should be in if the situation changes. Corners, light changing etc.

007Acura

It is fine to skip shift but he should try to leave it in gear while slowing down as it saves gas and reduces some wear on the brakes.

TommySalami

ok stupid question but while we're on the subject, how do you downshift without making the car jerk? Is heel toe/rev matching the only way? or do I let the clutch out too quickly or something? relevant because I'm buying a manual car soon

civicdrivr

iTrader: (9)

Unless my speed is very low (>10mph roll), my car is always in gear in case I need to get out of the way of something. Its also better for gas mileage if you leave it in gear and let the revs drop on their own as the fuel injectors are cutoff (you can go as low as ~1500rpms IIRC in Hondas before the injectors kick back in).

I also skip gears all the time. Be it for an upshift or a downshift, it just depends on the situation.

Tommy - rev matching is the best way to downshift, but it takes practice to make it seamless. In my previous cars, I would just downshift and let the clutch out slowly to bring the revs up - thats not good for the clutch. One thing I have noticed in newer vehicles with drive by wire is it is more difficult to rev match. In my brothers 08 Accord and my sisters 08 TL-S, I find that I have to double tap the throttle to get it recognize what I am trying to do.

NIGHTEHAWK

you want to bring the RPM's down to 1k or 2k for the car not to jerk, good luck on your buy.

alex2364

There are 3 ways.

1. Rev match
2. Double clutch
3. Let the clutch out slower but that causes more wear and tear on the clutch

Costco

Practice, really. I'm sure some of you have read southernboy's posts - they're great for reference or just for learning

I downshift just for the hell of it - rev matched of course. When I downshift more than one gear (nothing beats a smooth double clutched rev matched downshift from 5th to 2nd) I double clutch rev match it. When done properly, it goes in gear with little resistance. No bucking or jerking.

A good forum I used as a reference is standardshift.com. There's even professional race car drivers on there, such as Gary Sheehan. IIRC he had some vids of heel toe and double clutching in action. Once again... It's all practice. With time it becomes second nature. You'll be able to rip smooth downshifts one right after another like they do in those Best Motoring videos - another good reference

As far as if it's required... Absolutely not. I just love hearing my car scream as it engine brakes and IMO it's funner to downshift than upshift. Nothing wrong with braking as long as you don't bog your engine and you don't ride the clutch.

JERU

Man,I don't think I ever downshifted into a stop light. Out of gear, in neutral, coast to a stop...

phee

iTrader: (5)

i always downshift sequentially when stopping. you really shouldnt skip gears, but there is nothing wrong with going into nuetral. i just like to be able to have power on-tap if i need to perform any evasive maneuvers

would clutching in and going to a lower gear without blipping the throttle cause excessive clutch wear?

phee

iTrader: (5)

fixed

JS + XES

iTrader: (1)

I always just put it on neutral and brake when stopping for a light. I'm lazy like that.

Also, when I downshift on freeway, I always double clutch rev match downshift. If you get it right, it downshifts so smoothly without any bucking or jerking. It feels soooooo great.

I NEVER downshift without rev matching it in some sort of way, I just feel so bad for my car when that happens. You can literally feel that the car is being stressed out.

I don't heel and toe much because I don't really feel the need for it. Double clutching smoothly and slowly is all you need whenever you have to downshift.

phee

iTrader: (5)

know your gear ratios and what MPH=the redline on each gear.

begin braking
clutch in-nuetral
rev up to match
clutch in->lower gear
clutch out

S14 n Tsx

how about you just stick to AT?

neuronbob

I don't bother to downshift when coming to a light. I keep it in gear until almost time to stop, then clutch in/neutral/clutch out/brake.

If I do have to downshift, rev matching is the ONLY way for me. Double-clutching is good too, but I'm too clumsy for that. I just haven't practiced enough, and I've driven manuals for 21 years.

S14 n Tsx

I always skipped gears all the time on my tsx.

No need to down shift everytime....
Time to time, I would down shift to engine break.

speedemon90

Whats wrong with skipping gears when downshifting??

Say you're approaching a red light, you're going 50 and in fifth. You slow down to about 30 and downshift straight to third/w rev match then eventually come close to a hault and put it in neutral.

I also dont have a manual car but i plan on it for my next car so i read things occasionally about techniques used. So my thoughts may be totally wrong, but i like justification as to why you do things.

JS + XES

iTrader: (1)

Seriously, how can you guys downshift every time you stop at a light. I must be super lazy... lol

silver3.5

Slowing down to a red light or stop sign I just leave in gear, usually I'm always in 5th gear, and when RPM reaches 1400-1500 I step on the clutch and put it in neutral! I don't believe in going 5-4-3-2-1-neutral! Waste of energy and time!

phee

iTrader: (5)

well ive only build honda transmissions but by design, skipping gears isn't favorable for the synchros or the shift linkage longevity.

if you feel like going from 5-3 then just row through the 4th gate on your way to third while holding the clutch pedal down.
it doesn't actually take longer when you think about how cumbersome skipping gears actually is.

teranfon

Uh oh

There are a number of opinions about this. Even some manufacturers have different opinions on how or how not to drive a manual transmission. Most of my cars and trucks are manual, and I've rebuilt more than a few in regards to restorations, so if you like I can give you my personal opinion.

For the past few decades the vast majority of manual transmissions in cars and light trucks have been synchromesh. A synchromesh transmission does away with the need to double-clutch. What makes a synchromesh able to do this is that the gears are always in mesh, or rotating. All of them. To be very simple, a dog collar allows a gear to engage the shaft that carries it. A synchro ring prevents this engagement until gear and shaft speed are matched. Again, this is a very simplistic definition. The problem, according to some, is that skipping gears while driving is putting premature wear on the synchros as the shaft and gear speeds are not precisely matched. Shifting each gear generally allows proper engine and shaft speed. Ever try to put your car in first gear at 60 mph? It won't do it (well, not supposed to), as the gear and shaft speed are not equal. I suppose one can argue if one is proficient and precisely matches engine speed and shaft speed while skipping gears there is little wear to the synchro itself. Others say another reason to downshift each gear is that it ensures the car is always under load, or power. Some maintain, and I agree, a vehicle should always maintain power to it's driving wheels in all circumstances. This primarily for safety reasons.

Personally, I still choose to either double clutch or not use the clutch at all except to starting or disengaging a gear. Double clutching is somewhat of a lost art, while not using the clutch takes a tremendous amount of patience to learn.

However one drives a manual, it can be a very rewarding experience. Is there a right way or wrong way? Again, it depends on one's perspective and training.





Terry

Rockstar21

iTrader: (1)

i never downshift..

I keep my hand on the shift knob and left foot on the clutch, if I need to boogie it will be done in the blink of an eye.

Miiike

iTrader: (4)

With the price of gas here I'd rather not rev more than I have to, I just put it in neutral and brake.

SuperTrooper169

iTrader: (2)

What's that saying? Opinions are like something, everyone's got one?

Sometimes I downshift, sometimes I don't.

I skip shifted all the time in my Accord and well after 100,000 miles it still shifted like butter with the original clutch. Whether you skip shift, rev match, double clutch or always throw it in neutral, things over time wear and I personally don't think ones necessarily better than the other.

JS + XES

iTrader: (1)

A thought of doing a downshift without rev matching just hurts me for some reason....

Costco

When you can downshift from 2nd to 1st without any jerking, thsts when you know youve got it down. Still, theres nothing wrong with downshifting or not downshfting while coming to a stop

dallison

If on a flat surface i'll keep it in the same gear or neutral and brake. If on a decline, i might downshift to help braking.

Remember it is cheaper to replace brakes than it is a clutch.

SouthernBoy

Bad form. Don't do this. Keeping your hand on the shifter can impart pressure on the shifting forks and therefore the synchronizers. And resting your foot on the clutch can prematurely wear the release bearing.

SouthernBoy

Oh boy. Here we go again. Lots of valid questions on this thread and with them, lots of disinformation as well. I would first recommend you all to gain a functionally useful understanding of how a clutching system and a manual transmission work. With that said...

The manual transmission in our TL's are what's called "constant mesh" transmission. As Terry mentioned, this means that all of the gears are constantly in mesh with one another. When you shift gears, you are not really shifting gears at all but rather you are moving a collar into a mating hub. For a decent depiction of this concept, take a look at the links at the end of my post.

Synchronized transmissions have been around since 1929 (Cadillac) so they are not exactly new kids on the block. By the mid 1950's, most American manual transmissions were fully synchronized (this means all forward gears had synchronizers). There appears to be some confusion with terminology so I'll try to clear that up a bit.

Rev-matching. A technique whereby engine speed is increased sufficiently enough during a downshift while the clutch is disengaged in order that it matches wheel speed for the lower gear when the clutch is re-engaged. The purpose of this is to make a smoother downshift and to significantly reduce wear on the friction surfaces in the clutching components.

Double clutching. A technique whereby engine speed is increased sufficiently enough during a downshift while the clutch is disengaged in order that it matches wheel speed for the lower gear when the clutch is re-engaged PLUS the shaft speed for the selected lower gear.

Rev-matching does not reduce synchronizer wear... double clutching does. That is the difference between these two methods of downshifting.

When rev-matching as you enter the neutral gate, you pause and blip the throttle (rev the engine's speed) and then continue with the down shift. When double clutching, you do the same thing with one additional step. As you blip the throttle in the neutral gate, you simultaneously engage the clutch (some or all) in order to spin up the transmission input shaft. Essentially when you do this, you are doing a good deal (virtually all if done correctly) of the work that the synchronizers do.

Now a lot of folks will tell you that rev-matching, and in particular double clutching, is not necessary, and they would be correct in saying this. If you are not concerned with increasing the life of your clutch and your synchronizers then absolutely.... you certainly do not need to perform either of these downshifting techniques. However, if you would like to extend the life of these components well beyond what you may have heard to be their expected service life, then you have a choice to make. Your car, your money. Once again, rev-matching will significantly increase clutch component life. Double clutching will not only significantly increase clutch component life, but it will also significantly reduce synchronizer wear which in turn, increase the life of those components.

The OP's question dealt with whether or not downshifting when approaching a stop was desirable or simply a lame effort. More often than not when I am approaching a stop light, or stop sign, I wait until engine speed is close to idle (say around 1200+ RPM) and then just slip the transmission into neutral. Unless I see the light changing, see some sort of traffic pattern developing, or perceive a need to downshift, a simple stop is not generally a cause for me to downshift through several gears as I slow down. Now if I am approaching a red light up a ways and I am going around 60+ MPH in 6th gear, I will usually downshift to fifth and start slowing down since fifth offers better torque multiplication and engine braking than 6th, and by the time I get close enough to the light, it could change. Basically, I treat each situation somewhat uniquely. As has been already stated, it is not a good idea to be without power to the wheels for extended time and distance.

Skip shifting. Most people do not know how to do this correctly. I put skip shifting in the same bag with quick shifting, and by quick shifting, I'm not talking about speed shifting or racing. I'm talking about someone who, just by nature, quick shifts in their normal everyday driving. This is not good on the synchronizers because they are forced to do more work in matching gear set speeds. The same thing happens with skip shifting. Most people don't wait the extra second or two for engine speed to come down enough when skip shifting during upshifts. As for skip shifting on down shifts, this is where you really do want to double clutch because of the higher gear ratio spread and the increased load on the synchronizers to match the greater disparity in gear set speeds.


http://auto.howstuffworks.com/transmission.htm
http://www.youtube.com/watch?v=o-3SqMsgVdI
http://en.wikipedia.org/wiki/Manual_transmission

SouthernBoy

Rev-matched downshifts are the second best technique to employ. The best is double clutching for the reasons I stated in my above post.

SouthernBoy

Only if you let the clutch out. This is how most people downshift (example is a 4-to-3 downshift);

• Remove foot from throttle.
• Disengage (depress) the clutch.
• Move shifter into third gear.
• Slowly engage (release) clutch.

You can downshift in this manner but if you were to ask if this is the correct way to downshift, the answer would be a resounding, "No".

SouthernBoy

You first need to understand the disparity in gear ratios between fifth and third gears which is 0.98:1 vs 1.70:1 respectively. That is close to double the difference in the ratios of these two gear sets. This translates to a much wider disparity in shaft speeds. If you perform a successful double clutch on such a downshift, then there won't be any added wear. But just rev-matching will not do anything for synchronizer wear reduction and a skipped down shift like this is going to require quite a bit more work on their part to complete the shift.

SouthernBoy

Should have told them why this is so. It is so for the same reason that when sitting at a light that turns green, you should go into a higher gear first before going into first gear. Less first gear synchronizer wear when you do this.

oonowindoo

you should start doing that going uphills/downhills.

Brakes don't seems to work as good as when the car is in gear....

oonowindoo

Who said Heel and toe is not needed anymore?

how do you exit from the freeway at 70mph and the exit ramp has a 45 degree curve?

Rev-match is not enough because you also need to brake at the same time = heel & toe

and leaving in 6th turning at 20-30mph is just crazy, you might as well leave it in neutral.

I have seen ppl Brake then rev match downshift, then brake again, then rev match again then brake then rev match again..and sometimes, they don't do it fast enough and get stuck in neutral when turning...

and if you don't know how to heel n toe on the track, you will spin out at the very 1st corner...

JS + XES

iTrader: (1)

are you pushing your car to the limit every time you exit the freeway? :tomoto:

6th@70mph -> double clutch rev match downshift to 4th -> brake

you can totally live without doing heel and toe for sure at least for daily driving.

oonowindoo

well it depends on cars, considering 70mph in 6th in s2000 is close to 4k rpm...

you can imgaine how high it will be in 3rd or 4th.. you will literally have to rev match to the redline.. and you should be in 3rd, not 4th.

hearing cars scream to exit is pretty funny...