Downshifting whilst Braking
Discussion
waremark said:
BertBert said:
brakes are for slowing apart from all the circumstances where using the engine is more appropriate"!
Some of those circumstances are? I am not sure whether you are disagreeing with the general approach for road driving of slowing to an appropriate speed before changing gear, or only with trying to describe this approach using a simplistic form of words.I took my tablets this morning though!
Bert
BertBert said:
waremark said:
BertBert said:
brakes are for slowing apart from all the circumstances where using the engine is more appropriate"!
Some of those circumstances are? I am not sure whether you are disagreeing with the general approach for road driving of slowing to an appropriate speed before changing gear, or only with trying to describe this approach using a simplistic form of words.I took my tablets this morning though!
Bert
Best wishes all,
Gloria.
GuvGTI said:
If on a pursuit and need to brake hard for the hazard such a roundabout, blind corner etc is there any harm in applying consistent pressure on the brakes, after a few seconds as speed is down matching revs and pressing down on clutch downshifting ie from 4th to 3rd and whilst braking to brush of more speed lift up clutch on the biting point ( for further brake assist)pre hazard. Then engage gear with the clutch pedal fully up as it is clear to continue on with the hazard and accelerate away out of the exit point.
Just wanted to know your views on this approach and any pro's and con's with it?
The way I was taught to deal with "brake gear seperation" was to envisage the hazard being 10 metres closer towards you then it actually is. You then aim to lose all the speed to negotiate the hazard by this nearer point, and the extra distance then gives you the time to change to the appropriate gear before negotiating the hazard.Just wanted to know your views on this approach and any pro's and con's with it?
The Brakes will exert far more stopping force than the clutch and engine ever can, and if you're really braking hard (i.e. emergency stop) then lifting the clutch halfway through your braking will actually have an adverse effect on yur braking - the engine will most likely be turning too fast for the road speed and the brakes will have to work even harder to remove inertia from the drivetrain and engine. It may also destabilise the car.
The whole point of the "system of car control" is that it is a system. It remains the same regardless of conditions or hazard, giving the "advanced" driver a framework to plan and exectute their drive around. Losing speed via the brakes and then changing gear will always work, and maintain a safe drive. This is particularly important in police/pursuit driving, when you're also operating a radio, trying to second guess your quarry, shouting at your passengers for spilling their coffee, and suffering the effects of red mist.
Of course, in day to day driving, it's nice to have a little bit of flair. A good series of downshifts under light braking, with perfectly matched rev, well planned and exectued, is a pleasure to behold. C'etait un rondezvous anyone???
Edited by WeirdNeville on Thursday 14th February 21:57
at this threadp1esk said:
Are you sure they're the right tablets? Perhaps 'higher gear' should actually read 'lower gear' - or am I completely misunderstanding the situation?
Best wishes all,
Gloria.
Good point Gloria, just checking everyone was concentrating!Best wishes all,
Gloria.
Really have got the right ones this morning!
Bert
The Black Flash said:
Gromit37 said:
Sorry, but I disagree. Surely the amount of wear depends on the differential between the two clutch plates and how regularly it is done? Using the gearbox for *braking*, as the OP implied will wear out a gearbox far more quickly than using it correctly. Unless you know how to bend the laws of physics? 
Ian
It'll wear out more quickly I'm sure, but that isn't the same as "ruining it PDQ". I think that many (most) people drag the clutch on downshifts because they don't know any better...and modern clutches seem to cope ok.Ian
Mind you, it puts my teeth on edge when people do it.
Gromit's theory of ralativity at work here: I've read of people wearing clutches out in a 10-15K miles, whereas clutches should easily last 80K plus. I'd call that PDQ. Relatively speaking.
Gromit37 said:
Gromit's theory of ralativity at work here: I've read of people wearing clutches out in a 10-15K miles, whereas clutches should easily last 80K plus. I'd call that PDQ. Relatively speaking.
Yes I agree that it's all relative. Interested to see how you showed that the early failures were down to "engine braking" though. How big was your sample, or did you post-mortem the faileed clutches to determine mode of failure, interview the drivers to classify their driving style and correlate the two?Sorry, couldn't resist
Bert
I have passed my bike IAM test. In this you are positively encouraged to use the engine to slow you down. Smooth riding is often not using the brakes, properly timed down-shifts with a throttle blip are smooooth and a key pleasure of the ride.
I've never tried a car IAM (despite far more miles under the belt) because I know I would just get into an arguement. I like to double de-clutch with a throttle blip as I slow - and I for one, don't see its wrong.
I've never tried a car IAM (despite far more miles under the belt) because I know I would just get into an arguement. I like to double de-clutch with a throttle blip as I slow - and I for one, don't see its wrong.
waremark said:
p1esk said:
Best wishes all,
Gloria.
Is Gloria Dave's pseudonym or Mrs Dave?Gloria.
BertBert, not much disagreement with you.
Best wishes all,
Cynthia.
balls-out said:
I like to double de-clutch with a throttle blip as I slow - and I for one, don't see its wrong.
The main disadvantage I see is that the gear change takes longer, keeping your mind, hand and feet busier for longer at a time when you are likely to be approaching a hazard and need full control and attention for other things. I don't see any particular advantages to offset this disadvantage.GreenV8S said:
balls-out said:
I like to double de-clutch with a throttle blip as I slow - and I for one, don't see its wrong.
The main disadvantage I see is that the gear change takes longer, keeping your mind, hand and feet busier for longer at a time when you are likely to be approaching a hazard and need full control and attention for other things. I don't see any particular advantages to offset this disadvantage.I don't accept the 'keeping your mind busy' bit. Even with my limited mental capablity changing gear is an automatic action that requires no conscious thought.
GreenV8S said:
balls-out said:
I like to double de-clutch with a throttle blip as I slow - and I for one, don't see its wrong.
The main disadvantage I see is that the gear change takes longer, keeping your mind, hand and feet busier for longer at a time when you are likely to be approaching a hazard and need full control and attention for other things. I don't see any particular advantages to offset this disadvantage.Some people may prefer to do something a certain way for no other reason than that particular approach provides the most consistent high performance result 'for them'.
Edited by vonhosen on Friday 15th February 16:56
balls-out said:
I guess it does take longer, but it is occuring while you are braking not after, so when you have finished braking you are in the right gear, rather than still requiring to change.
I don't accept the 'keeping your mind busy' bit. Even with my limited mental capablity changing gear is an automatic action that requires no conscious thought.
Given that in this scenario you must be applying H&T as well as double declutching, I'd add to the list of disadvantages that it extends the time that you compromise your ability to control the brakes.I don't accept the 'keeping your mind busy' bit. Even with my limited mental capablity changing gear is an automatic action that requires no conscious thought.
Edited by GreenV8S on Friday 15th February 17:16
vonhosen said:
Some people may prefer to do something a certain way for no other reason than that particular approach provides the most consistent high performance result 'for them'.
I think there's a fundamental difference between using a technique yourself merely out of habit, and advising others to adopt it because you have decided that it is the optimal one for that set of circumstances. vonhosen said:
Some people may prefer to do something a certain way for no other reason than that particular approach provides the most consistent high performance result 'for them'.
You're talking my language there, although I'm not so sure about the 'high performance' bit, but that's a relative term anyhow.
BTW, have an early night and get yourself to Eaton Socon tomorrow for about 0900. I think at least one member of your fan club is expecting to be there, and if I can manage it from 190 miles away, I'm sure you can manage a short tootle up the road.
Best wishes all,
Prudence.
After many years as a club and professional racer and quite a few years as a paid instructor for two different high performance driving schools (Corvettes and Vipers), I can tell you that you will get no better performance than threshold braking in a straight line accompanied by H&T downshifting. Release the brake and roll on the throttle just a split-second before turn-in and go.
How much does your dealer charge for removal, repair and re-installation of the gearbox? How much does he charge for replacement of front brake pads?
How much does your dealer charge for removal, repair and re-installation of the gearbox? How much does he charge for replacement of front brake pads?
chili555 said:
After many years as a club and professional racer and quite a few years as a paid instructor for two different high performance driving schools (Corvettes and Vipers), I can tell you that you will get no better performance than threshold braking in a straight line accompanied by H&T downshifting. Release the brake and roll on the throttle just a split-second before turn-in and go.
How much does your dealer charge for removal, repair and re-installation of the gearbox? How much does he charge for replacement of front brake pads?
That's all very well for high-performance driving under racing or rally conditions, or when performed by a driver highly competent in heel-toe gear changes.How much does your dealer charge for removal, repair and re-installation of the gearbox? How much does he charge for replacement of front brake pads?
But I think we're talking about road driving with respect to maximising safety, not performance. In which case someone who is probably NOT experienced in driving a vehicle on the limit of mechanical performance (ie. most police drivers and ordinary motorists) would be better off concentrating on only one driving task at a time: braking to appropriate speed first, then changing to appropriate gear.
The general rule of thumb is to avoid brake-gear overlap unless pre-planned on the grounds of enhancing safety, or if overlap provides a benefit without compromising safety.
I think Chris Gilbert put it best in his post, found here:
http://www.advanced-driving.co.uk/bb/viewtopic.php...
Edited by Jungles on Sunday 17th February 10:39
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