down shifting and not coasting

[wushumasterku]

Hi folks,
I have a question about driving manual. do you downshift all the time? or do you let you car coast to stop and use brakes when necessary?

i heard that the "modern" engines don't actually use any gas when you leave the car in gear. now is this same as downshifting (when they say leave it in gear?) but when you let your car coast in neutral, the engine actually uses some gas.


I'd like to hear your thoughts on this.

thanks

[DJ_SpaRky]

good question, I am interested to know too as this will be my first manual car.

[celica girl]

Personally I don't downshift unless I'm taking a corner. The way I see it brakes are cheaper to replace than a clutch. Unless you know how to rev-match properly when you downshift I say just pop it into newtral.

[echo_hrs]

Downshift all the way...If you downshift properly you're not going to wear out your clutch...

[Sp33dY]

I downshift 90% of the time ... Depends on what speed im slowing down from :) Sometimes go from 5th to 3rd to N, or 4th to 2nd to N, really dpeends on the road and conditions!

[Idjiit]

Heel-toe'ing is half the fun of owning a manual, so you bet I downshift/rev-match.

As for the technical question, I would be very surprised if downshifting consumed less fuel, but I suppose it's possible.

[celica girl]

Downshift all the way...If you downshift properly you're not going to wear out your clutch...


Exactly... that involves rev-matching. I'm not too good at that. :cry:

[SmellyTofu]

Yes all modern engines from the 90's to now run on no fuel when it's at a certain engine speed so yes, downshifting runs over (general rule of thumb is around 1500-1700rpm for petrol.. lower on diesel) will use less fuel than coasting down but you wouldn't use all that much at idle anyway. It also helps emissions in case anyone really cares.

[Idjiit]

Yes all modern engines from the 90's to now run on no fuel when it's at a certain engine speed so yes, downshifting runs over (general rule of thumb is around 1500-1700rpm for petrol.. lower on diesel) will use less fuel than coasting down but you wouldn't use all that much at idle anyway. It also helps emissions in case anyone really cares.

Err... But downshifting would mean higher revs if you're maintaining the same speed.

[why?]

I use my brakes as little as possible, but I don't make the engine brake any more either, as that uses fuel. I just disengage the clutch and coast to a stop.

[SmellyTofu]

Err... But downshifting would mean higher revs if you're maintaining the same speed.

Your wheels run the engine when you're going down a hill in a lower gear (rather the other way around when you're accelerating). Engine speed doesn't mean you're using more fuel.

Out of interest, drive a car with a instantaneous fuel consumption gauge. You'll find idling at say 80km/h down a hill, you'll be using <0.5L/100km but when you're using engine braking, you'll be using 0.0L/100km.

[TRD_Yaris]

This is an EXTREMELY interesting topic..i've been wondering about this for many years. I love rev-matching on both up and down shifts, and I pretty much coast to slow down for stop lights. but, it would be really cool to use a measuring device to check actual fuel consumption (like in many 90's BMWs)..

[boxerboy]

When the engine is running it is burning gas. I have yet to wear out a clutch in any car. My highest mileage was 108,000 on a toyota tercel mostly city in Dallas. I was a service rep. Any way I almost always downshift, so if the light changes or the traffic starts to move I will be in the right gear to keep moving. When I see that the light has just turn red or traffic is not moving I will just brake. Of course that depends on the speed. I will downshift a higher speeds and not at low speeds.

[sroberts]

I used to drive big rigs when I was in my early 20's and always used the engine/gears to slow down, although the yaris doesn't weigh anywhere near a semi so you can't compare the two :) But, its less wear on the brakes and like what boxerboy said you are ready to go if traffic starts moving. If I know that traffic isn't going to move then I would put it in neutral the last 100 ft and use the brakes to stop.


When the engine is running it is burning gas. I have yet to wear out a clutch in any car. My highest mileage was 108,000 on a toyota tercel mostly city in Dallas. I was a service rep. Any way I almost always downshift, so if the light changes or the traffic starts to move I will be in the right gear to keep moving. When I see that the light has just turn red or traffic is not moving I will just brake. Of course that depends on the speed. I will downshift a higher speeds and not at low speeds.

[Master2192]

When you are engine braking, the ECU turns off the injectors until the rpms get down to a certain value (~1500). This is very easy to see on a AFR Gauge or a scanner showing Injector duty cycle.

I rev-match downshift all the time, and it doesn't add anymore wear to my clutch and my brakes last 2x as long. I believe it is a skill that all manual drivers should learn. It is definitely an advantage to be already in gear if you need to start accelerating again.

[ricko]

This is a great thread. I had no idea that ECU technology was that "smart"! :clap:

Although the original question was in reference to coming to a complete stop, my comment relates to the car's behaviour while cornering. Downshifting and keeping the power on (even very moderately) has the advantage of keeping the suspension under load, which improves the car's ability to make the turn. It is safer to drive around a corner than it is to coast around. The process is: brake to reduce speed, downshift, and drive through the corner (the more skilled can do this all at once). This SEEMS to be especially true for front-wheel drive vehicles, although I have no concrete evidence to back this up. Maybe someone can explain the physics of cornering and braking in better terms for us. :help:

[plushDJ]

I'll downshift from 4th to 2nd but that's about it

[pennystocks]

Bad news, the yaris doesn't "en-lean" when engine breaking. All the GMs i'v owned you could really feel it kick the fuel flow down when engine breaking. My aurora you could see then MPG increase when engine breaking, it auctually got less MPG when in neutral vs drive for coasting.

My scan gauge shows 0.2 Gallons Per Hour when costing in neutral for the Yaris. I did some engine breaking in 2nd and it was around 0.5 GPH. Also when you feel that slight engine break when coasting (you can slightly feel it kick in and out on my auto) is putting the PCM into open loop for a couple of seconds and the GPH is the same as in neutral. Also coasting it reads about 200-250 MPG and when downshifting it drops to 60-100.

I dont think there's a need for the yaris to enlean tho. I just did a trouble code test on a chicks car at work and her 2000 or so neon 4 banger showed 0.6 GPH at idle. I cant imagine what my aurora was at at idle. So thats round 5 hours for the car to idle out a gallon of gas. and 2 days to idle out a tank, not too shabby :)

So coasting in neutral is the best way in the yaris for MPG. BTW full throttle is around 6-7 GPH and normal driving is 1-3 ish and idle w/ the AC on is 0.3 and auctually shutting the car off while long coasting can add 1 or 2 MPG as long as its done on a normal basis. I have an auto so it kinda sucks to crank the starter 50 times a day. Just think of them as free miles that dotn cost you $$$ :)

[stuffy]

i've been driving manual since i got my license about 16 years ago, and i have always downshifted when coming to a stop, and i have only replaced a clutch once,but what i would like to know...

...what the hell is rev-matching? i've never heard that term before (car illiterate to some degree),
does this mean that as you slow down you just continue to drop it into the appropriate gear so the engine rev doesn't increase?

[pennystocks]

rev matching w/o using the clutch Lets say in 2nd gear at 20 mpg your at 3k rpm. You can put it into 2nd gear w/o the clutch by reving the enigne to 3k rpm while in neutral and off the clutch. Dont try it at that speed or rpm, i dont knwo the rpm spots of the yaris stick but its less wear on the clutch if you can get used to double clutching. If you do it wrong it wont go in or it'll grind.

Double clutching is for less wear on teh syncros (the things that make it so the gears dont grind). Lets say your in 5th at 40 mph. If you stick it in 1st its gonna fight for a second to go in w/ the clutch down, those are the syncros spinning up the trans part of the clutch to match the required engine rpm. To double clutch, pop it in neutral off the clutch, rev the engine to 5-6k rpm, then real quick hit the clutch and pop it in 1st, should go in smoothly.

Basically you want to rev the engine to where you think it should be when putting it in a gear and you must be off the clutch and in neutral to spin up the trans.

[echo_hrs]

The whole reason synchromeshes were invented for manual transmissions was to eliminate the need to double clutch...However it can save wear on the synchros if you are driving in a manner (aggressive) that puts heavy wear on them...I have driven previous cars in my youth being hard on the clutch, and all I can say, is that I still got 200k kms out of those original clutches with 1st and 2nd gear tire spinning etc...

Cheers

[stuffy]

thanks for the info guys, i would like to try that sometime, maybe i should go to driving school to learn.....

[Fat Felixxx]

In my experience, the general rule of thumb is to use brakes as the primary way of slowing the car down. I heel-toe all the time, but I almost always have the brakes doing A LOT more work than the engine is.

The clutch will not experience any abnormal wear and tear when downshifting correctly(via rev-matching), but it is the tranny that is taking the load when engine braking.

Bottom line, what's more expensive to replace? Brake pads and rotors or a transmission?

[Leenis24]

I just put the clutch in and coast using brake to come to a complete stop. I see it being pointless to keep downshifting through every gear until you stop, its just not necessary, and wears your clutch more. I dont care how good you rev match, your still using your clutch more. And to me, more clutch usage means it wears faster.

[Fat Felixxx]

I just put the clutch in and coast using brake to come to a complete stop. I see it being pointless to keep downshifting through every gear until you stop, its just not necessary, and wears your clutch more. I dont care how good you rev match, your still using your clutch more. And to me, more clutch usage means it wears faster.

Keeping the clutch depressed for long periods of time also wears out the clutch quicker.

[boxerboy]

With proper driving you should not need worry about the trans. You will go threw many brake jobs first.

[Uglyboyed]

i usually downshift if im in a rush. most of the time i coast so i can give my car a lil break from the damage i do to its engine when i driving.

[pennystocks]

However it can save wear on the synchros if you are driving in a manner (aggressive) that puts heavy wear on them

Yea i'm speaking from experience with a '97 6-speed Trans Am 5.7 liter tho :burnrubber:

But if can get good at shifting w/o a clutch it puts less wear on the clutch which will need to be replaced in the future reguardless of how you drive it.

and i have only replaced a clutch once

I'v replaced on my TA, ahem:
clutch
throwout bearing (a 30 mile drive w/o a clutch really sucks :)
stock gears once
4.11 gears twice
transmission once

Fun but sometimes not worh the money
BTW she ran low 13's in the 1/4 mile (or 400 meter) and a top speed of 160 mph (or 260 kph), talk about a rush =D
http://clantnp.net/hosted/ass/images/transam/front_left_2.jpg

[ricko]

thanks for the info guys, i would like to try that sometime, maybe i should go to driving school to learn.....

If you want to have some real fun while learning, try the race driving school at Shannonville (aka Nelson International Speedway). They have different programs at different pricepoints, covering everything from defensive driving techniques, to actual learn to race days. I've done one of the motorcycle race days, and it was first class!!! :thumbup:

[hoahmaru]

I just started driving manaul again when I got my Yaris. I normally leave the gear in neutral and use my break to stop but some of my friends says that it is dangerous especially in the winter time because your wheel will slide easier if you don't have the car in gear. I just wanted to know if anybody knows if this is true or not. And also does the car stop faster if it is in gear or in neutral?

[stuffy]

thanks for the info ricko, i am definitely interested in taking a class or two!

[pennystocks]

If you have ABS then pop it in neutral, the ABS along side the EBD will work fine.

If you dont have ABS then keep it in gear. It will be alot harder to lock up the tires when its got resistance from the engine. If you engine does die tho make sure you quickly hit the clutch, cause the engine will keep the tires locked.

[60 Somethings]

Guess it's time for us older folks to chime in.

We have been driving mostly stick-shift cars for the last 45 yrs - including 3 ALFA's, 3 VW's, a Ford Fiesta, Datsun 510, Dodge PU, Ford Explorer and a Ford Ranger.

We have kept out cars for long periods, replaced very few clutches and required very few brake jobs. Our last two vehicles ('97 Explorer & '98 Ranger) had 114,000 and 90,000 miles respectively and both had the orginal brakes and clutches operating properly when sold. The '79 Fiesta was finally wrecked by our daughter at 180,000 miles and it was still pretty much all orginal. It was the most like our Yaris - very fun to drive.

We brake by downshifting and NEVER coast in neutral. My dad told me at a very young age that you have no control over a car running in neutral. (This was in the early 1950's, and I recently learned he had been an auto mechanic in San Diego around 1914, before he was an airplane mechanic in the Navy in WWl, which was before he was a minor star in silent movies in Hollywood - an interesting man.)

The secret is driving SMOOTHLY. As my wife says, when you are doing it right it's like a dance. As others have said, brake going in, rev up, back-shift and accelerate out. The Yaris is very quick thru tight turns.

I am currently experimenting with driving styles and gas mileage. Got 37MPG on last tank driving more spiritedly.

Must note thet we have had problems with two of our manual transmissions - both the result of towing, not normal driving. It's also the reason we now tow with a 2006 4Runner V8 - with an automatic transmission.

[boxerboy]

Thats the key smoothly. Well said.