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  1. #1
    Fellow Frogger! choiboi's Avatar
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    Default downshifting

    I was just wondering does downshifting shorten the lifespan of a manual transmission?

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    1000+ Posts CHRI'S16's Avatar
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    ...what exactly do you mean?
    If by down shifting you mean using the gears to slow the car dow (which is common practice)?, Then you won't accelerate the wear any more than up shifting.....
    If you mean harsh flat changing up and down the gear box then you are obviously adding to the aging process.
    I understand down shifting as going from 5th to 4th and using engine compression to slow down the car. When I did my license this was mandatory in a manual car, because it "showed control of clutch and gear box up and down the range"....
    perhaps im missing something? Cheers-Chris
    ... ptui!

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    Fellow Frogger! choiboi's Avatar
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    Quote Originally Posted by CHRI'S16
    ...what exactly do you mean?
    If by down shifting you mean using the gears to slow the car dow (which is common practice)?, Then you won't accelerate the wear any more than up shifting.....
    Yeap thats what I meant shifting down to slow the car down, yeah witht he license thing, thats what you're expected to do? thats why I'm wonderin' if this will wear out your gearbox prematurely or clutch.. cos when you down shift your clutch has to catch the revs or the higher gear. I don't downshift thats why I didn't do my p's test with a manual car. So I've always put it in neutral when I'm slowing down.

    I just don't see the benefit of keeping your car in gear at all times? is there any? apart from slowing your car down with downshifting, but I would've thought that prolonging your clutch life would be cheaper than replacing brakepads

    unless there is some sort of advantage to downshifting apart from the sound? it's not worth doin' issit?

  4. #4
    Fellow Frogger! matt205's Avatar
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    Quote Originally Posted by choiboi
    I was just wondering does downshifting shorten the lifespan of a manual transmission?
    Well the short answer is yes, just as starting your engine and running it occaisonally will wear that out too .

    But I assume you mean downshifting coming into a corner or slowing for traffic lights etc?

    If done incorrectly it will definetly cause stress on the drivetrain AND engine. Alot of people think "performance" driving includes using the gearbox to slow the car, this is known as compression braking or engine braking. They call it engine braking because it brakes engines! We get a lot of students at Eastern Creek for the first time come barrelling into turn 2 and start to downshift BEFORE they get on the brakes. Brake pads and discs are relatively cheap, engines and gearboxes aren't, the idea of downshifting is to have the car in the correct gear for the upcoming corner, but the downshifting should be done at the END of the braking zone, not before or at the begining of it.

    What many don't realise is that while you can't exceed a manufactures set rev limit while changing up through the gears it is possible to exceed it downshifting. Basically if you are in third gear at say 6000rpm and you slam it into second suddenly the engine has to rev at 8000rpm or more to keep up this is a mechanical thing and no electronic rev llimit or fuel cut can do anything about it. This will often end in a compression lock up of the engine and drivetrain, causing the driven wheels to lock as well. It doesn't take a rocket scientist to realise the amount of stress this can put on a car.

    All of this is the extreme though, generally downshifting at low engine RPM around town will not harm the gearbox.

    There are circumstances when enging braking is OK, coming down a steep windy incline, you will be in a lower gear and using the engines compression to help control speed (not brake the car) but again this is done at low engine rpm so no major problem.

    Tomorrows lesson - Heal Toe downshifting!
    Regards,
    Matt
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    2000+ Brad's Avatar
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    Agreed. using the engine to slow the car down is just as bad on the clutch as riding it, it's just that it's happening in the opposite direction. This is one of the reasons people blip the throttle to match the revs of the engine flywheel to the clutch plate of the gear box in the lower gear. The greater the difference in speed, the more wear as a result.

    I'm a great fan of double de-clutching (letting the clutch out while in neutral while coming back down the gears and blipping the throttle) as not only does this match the revs of the engine to the clutch, it also spins up the gear box internals taking the pressure away from the synchros. It also makes it MUCH easier to get into 1st gear while on the move. Takes practice to do it quick enough when driving hard though.
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    1000+ Posts CHRI'S16's Avatar
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    Mat, i think Choi ment in regular road use.... I agree with that for track use though. If you can't heel toe and revmatch properly on the track.... then go a get tought or learn carefully.

    Choi, honestly the main reason I use engine to slow down is to save my brakes, for when I need to use them.... the cooler I keep the pads/fluid the longer and better they work....
    But fact is anytime any of those 3 pedals are pressed something, somewere is wearing out.... just how you do this will vary what wears out and when. I do recommend that if you do use the gears to slow down, do try to blip the throttle and atleast try to match the revs.. but if rolling in neutral is what you are comfortable with then so be it.
    -Chris

    ps. I don't know of a PERFECT driving technique on the road, but anything that keeps your concentration/feel/attention were it should be is probably the safest technique.
    ... ptui!

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    Interesting.

    I've always been raised with the idea that engine braking is pretty critical to driving a manual car.

    Sure, if you are going to be silly about it, you are going to do damage to your gearbox/clutch but I was under the impression that as long as you're not stupid, engine braking is a core part of driving.

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    1000+ Posts edgedweller's Avatar
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    Default down shifting

    they dont call neutral "angel gear" for nothing.

    if you are not positively engaged in the appropriate gear you cannot access one of your cars primary functions ie. driving the car forward. You therefore have very limited ability to position yourself on the road, to avoid impact for instance. Why you would give up this option to save wear on one of the strongest components in you vehicle is dubious. As to clutch wear, you are far more likely to be doing damage on the way up than down if you can learn to competently down shift, saving pad and rotor wear and keeping the vehicle in the correct gear and rev range to fully utilize your cars ability.
    All drivers should be strongly encouraged to abandon this "angle gear" sic technique.

    cheers edgedweller.

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    1000+ Posts dino's Avatar
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    they dont call neutral "angel gear" for nothing.

    if you are not positively engaged in the appropriate gear you cannot access one of your cars primary functions ie. driving the car forward. You therefore have very limited ability to position yourself on the road, to avoid impact for instance. Why you would give up this option to save wear on one of the strongest components in you vehicle is dubious. As to clutch wear, you are far more likely to be doing damage on the way up than down if you can learn to competently down shift, saving pad and rotor wear and keeping the vehicle in the correct gear and rev range to fully utilize your cars ability.
    All drivers should be strongly encouraged to abandon this "angle gear" sic technique.

    cheers edgedweller.



    well said......I agree totally,......you really want to be engaged or in the process of being engaged at any time during braking except for the sub 10kmh speeds....,where you can safelly roll to a stop under brakes......
    The reason I say this is that engaged breaking is much more effective and you really don t want to get yourself in a situation where you are fumbling for gears to aid max braking or acceleration....If you r unsure, pick an empty parking lot and do a couple of practice runs (braking) with and without gear engagement.....If ABS this can be even more critical as it allows for re-acceleration during sudden turns......
    Obviously one needs to be carefull when it comes to high rev situations (I blew a gasket on an old merc when I accidentally put it in 2nd at around 80-90km/h"AUTO")...so listen to your engine and watch your speed and if correct gears are used when breaking at right rpm I really dont see you doing much more damage then you would while accelerating at anywhere the similar speed...



    cheeeeeers


    dino
    Last edited by dino; 25th August 2004 at 03:28 PM.

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    I think that the wear on the clutch is being exagerated somewhat.

    The clutch is designed to transfer the engine's torque to the gearbox and get 1.5 (or whatever) tonnes of vehicle moving from standstill.

    The entire rotating mass of the engine, would be 1/100 the weight of the car.

    As an example (rather crude admittedly) Imagine applying the brakes on your vehicle whilst the car was on a hoist with the drive wheel spinning at an equivilent of 100kph in 5 gear...the amount of brake pressure required to stop the rotating mass of the wheel would be 1/1000th of that required to stop the wheel rotating when braking normally on a road..

    I use my gears more than anyone else I know, and often heel-toe downchange whilst braking into corners (more to keep in practice than for any other reason) and the clutch in my car has done 230K and shows no sign of slippage and the gearbox does not crunch or show signs of weak syncros (a Fuego problem).

    By not down-changing correctly (heel toeing, or bliping the throttle to assist the syncros) you are actually placing more strain on the syncro rings (quite expensive to replace as it requires a gearbox rebuild)

    If the clutch died tomorrow, it has still given a longer than expected life.

    As has been mentioned, for safety's sake, it is vitally important to be in the right gear at all times. Cornering under neutral or negative acceleration is the easiest way to loose control of a car.

    As long as you are downchanging correctly, not over reving the engine, and are not having to devote excessive amounts of concentration to the actual function of downchanging, I can't see it being anything but a positive.
    Last edited by mistareno; 25th August 2004 at 03:52 PM.

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    i've been trying to teach this technique of leaving the gears meched at all times to my girlfreind for a few years now, but to date still unsuccessful.

    i reckon everybody should learn to drive in a B-Model Mack like i did. it'll sure as hell teach you how to rev match, otherwise crunch, and a truck box is much more expensive than a car box.

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    Driving around in neutral is NOT an option and is basically plain lazy. My previous post was based around "performance" driving not just tootling around town. However alot of the concepts are common to both.

    Neutral is not a gear! Along with the early downshifters we also see alot of people using the clutch as a footrest through corners, basically come up to a corner throw the clutch in, coast through the corner and let it out at the exit. This is actually quite a scary experience, particularly when there's some speed on board.

    High speed cornering is all about balance, to acheive this balance there needs to be throttle input and hence the car needs to be in gear. Turn 1 at Eastern Creek and Phillip Island are classic examples, anyone who is half serious is on the throttle as soon as braking is done, balancing the car with constant throttle pressure up to the apex then feeding the power on to the exit. If the car was in netral there is no way you could acheive the same cornering speed.

    One of the most common problems I see as an Advanced Driving Instructor is poor gear changing, even from people I consider to be above average, there seems to be a desire to change gear as fast as possible. In the immortal words of Sir Jackie Stewart "You should never feel a gear change" think about this next time you are driving, you need alot of practice to acheive this but it is possible. If you can do this on both up and down shifts it will be kinder to both the car and the occupants.
    Regards,
    Matt
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    "Imagine watching the entire French Air-Force crash into a fireworks factory. That's how much fun this car is."

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    Engine braking (downshifting) is an essential part of driving on WA gravel, you have to be able to do this and brake, if you want to go HARD on this type of surface. ABS certainly won't help you !!! Just remember .. "find em, don't grind em' ".

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    Coasting in neutral is poor driving. A truckie would consider it worse.

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    Can we delve deeper into the art of downshifting? Since owning my 2nd car (1963 Beetle) i've been downshifting, using a blip of the throttle to match revs, all the time. However I sometimes find myself blipping the throttle 2 times during a downchange; one when (while the clutch pedal is in) I move the gearstick into the lower gear from neutral, ie. 4th down to 3rd, and then again just prior to letting out the clutch pedal, to match the engine revs. Is it clear what I mean here? Is this overkill?
    According to the above posts, am I right in saying that that blip on the throttle should occur just before the clutch is let out in the lower gear?
    Very interesting thread.
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    Quote Originally Posted by Clandestino
    Can we delve deeper into the art of downshifting? Since owning my 2nd car (1963 Beetle) i've been downshifting, using a blip of the throttle to match revs, all the time. However I sometimes find myself blipping the throttle 2 times during a downchange; one when (while the clutch pedal is in) I move the gearstick into the lower gear from neutral, ie. 4th down to 3rd, and then again just prior to letting out the clutch pedal, to match the engine revs. Is it clear what I mean here? Is this overkill?
    According to the above posts, am I right in saying that that blip on the throttle should occur just before the clutch is let out in the lower gear?
    Very interesting thread.
    I guess we've kinda gotten off topic but what the hell.

    What you are describing is almost double de-clutching. Brad covered proper double-declutching in a previous post. This is basically blipping the the throttle with the clutch out and the the car in neutral just prior to clutching and engaging the required gear. ie clutch in, gear stick to neutral, clutch out, blip the throttle, clutch in, selct gear, clutch out. This is overkill in a full syncro gear-box but certainly does no harm. Also takes a little practice to master.

    The most common and accepted method is straight out heel-toe down changing. This process involves the left foot operating the clucth and the right foot operating the brake and throttle simultaneously. Braking, braking, braking, clutch in, toes of right foot still on brake pedal, heel moves over to throttle, blips throttle to increase revs to required level for next gear, clutch out.

    Probably not a great explanation but you should get the idea.

    Heel-toe downshifting (or double-declutching) is the only way to acheive really smooth down-changes. Again the goal here is to not feel the downshift, ie the car should not jerk when the clutch is released. I once heard a story about a well known race driver back in the early 80's who couldn't heel-toe. Apparently one year at Bathurst in practice the lack of this abilty caused the extinguisher to break free of it's mounting following a downshift leading to it going off in the cabin!

    It's easy to be fast, but to be fast and smooth takes alot of practice!
    Regards,
    Matt
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    "Imagine watching the entire French Air-Force crash into a fireworks factory. That's how much fun this car is."

    Jeremy Clarkson - talking about the V6 Clio
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    Budding Architect ???? pugrambo's Avatar
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    either it's because i'm a lefty but i find it easier to keep my heel on the brake and blip with my toes and i have always done it that way

    warren luff said to me at one of the advanced driving courses i went to "i don't know how you do it but it works so if you are happy doing it that way go for it"

    he did try and teach me the other way around but gave up after he learned i was a lefty
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    2000+ Brad's Avatar
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    On all of my cars, 85 Alfa Sprint, S16 and now the MX5, the pedels are closs enough to use either side of the foot to brake and blip the throttle. I must say the MX5 is mush easier to do it in than the S16 as you are more stretched out, therefore don't have to twist your foot up to the outside to grab the throttle as much given your right leg is on less of an angle.
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    Interesting reading - I'll have to try and practise more of it sometime. I tried it a little in an Opel Vectra I rented whilst on the continent and it wasn't too hard to get smooth and swift downshifts for acceleration (like an auto downshifting when you floor it), but I haven't quite mastered it for deceleration (eg into a corner).

    Have to say, out of all the AFers I've driven with, Peter/rek definately has the best downshifts - quick and smooth

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    nJm
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    Double-declutching is essential in my 505 for smooth shifts. The gearbox is quite a sloppy one and the clutch heavy and lacking in feel, but you get used to it. If anything I find making smooth upshifts hard at times. I never have that problem in modern manuals though. I think it is because my clutch pedal is so heavy and it is hard to 'feel' the bite point.
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    1000+ Posts U Turn's Avatar
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    Excellent thread.

    Matt, if you're accelerating down a straight hard in 5th, then begin braking for a 3rd gear corner, is it ok to brake and when setup for the corner, heel/toe shift straight from 5th to 3rd or do you change down to 4th and then 3rd?
    Take the long way home....

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    1000+ Posts CHRI'S16's Avatar
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    Quote Originally Posted by jastanis
    Excellent thread.

    Matt, if you're accelerating down a straight hard in 5th, then begin braking for a 3rd gear corner, is it ok to brake and when setup for the corner, heel/toe shift straight from 5th to 3rd or do you change down to 4th and then 3rd?
    .... depends on your level of experiance,
    and knowing that X-Kph= Yrpm x Zgear... I do this at several turns on tracks I know well and know/hear/feel my car into the corners.-Chris
    ... ptui!

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    1000+ Posts Luca's Avatar
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    Is this the Peugeot forum??

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    True, rather irrelevant to Pugs but a good enough thread to be in General Chat, so there it goes..........
    B to the R to the A from the D
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    Fellow Frogger! matt205's Avatar
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    Quote Originally Posted by jastanis
    Excellent thread.

    Matt, if you're accelerating down a straight hard in 5th, then begin braking for a 3rd gear corner, is it ok to brake and when setup for the corner, heel/toe shift straight from 5th to 3rd or do you change down to 4th and then 3rd?
    5th to 3rd or even 2nd is fine as long as you get the timing right. This is how I drive, at EC for instance turn 2 is 2nd or 3rd gear depending on the car. I'll go from 5th or 6th to 3rd or 2nd in one movement. Quite a number of the V8 guys do it this way too, Skaife and Murph in particular. This certainly proves the theory of not engine braking on a race track.

    Like Chris said it depends on your level of competence and lots of practice.
    Regards,
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