Techniques - Constant Throttle Downchange
Discussion
Your driving at a constant speed and need to drop down a gear - better control as you pass a juncton/other hazard etc.
Normally, you dip clutch/release throttle pedal/move gearlever.
Next time, try holding the throttle pedal where it currently is, then dip clutch/move lever. You might need to play around with the speed you move the lever, but once you get it right, apart from the change in engine noise, you won't be able to feel the change.
Benefits ? Well, none really apart from the challenge of getting the change as smooth as possible.
Normally, you dip clutch/release throttle pedal/move gearlever.
Next time, try holding the throttle pedal where it currently is, then dip clutch/move lever. You might need to play around with the speed you move the lever, but once you get it right, apart from the change in engine noise, you won't be able to feel the change.
Benefits ? Well, none really apart from the challenge of getting the change as smooth as possible.
Surely if you keep the RPM's the same and change down a gear then you will get an unsmooth change as when you engage the lower gear the RPM's will be too low for the new gear and the engine revs will be brought up by the road speed?
Surely while between gers you need to raise the revs to ensure a smooth change?
Or am I missing something?
Surely while between gers you need to raise the revs to ensure a smooth change?
Or am I missing something?
Joe, it's a constant throttle, not constant rpm change. As you move the stick thru' neutral, the rpm flares to cunningly match the lower gear.
Just try it......
CJ, I don't really understand your question. This is simply an easier way to blip the throttle on a downchange. If anything, there would be less clutch wear.
Just try it.....
>> Edited by bor on Sunday 4th September 14:01
Just try it......
CJ, I don't really understand your question. This is simply an easier way to blip the throttle on a downchange. If anything, there would be less clutch wear.
Just try it.....
>> Edited by bor on Sunday 4th September 14:01
This is also very satisfying when done right under firm acceleration, the more throttle you have on the faster the gear change needs to be completed to time the clutch engagement with the rising revs, the clutch also has to be brought up fairly quickly which gives little scope to smooth out any revs mismatch. It takes a bit of bottle and can go horribly wrong if you bring the clutch up to early or late. I might do this if I make a mistake that leaves me trying to accelerate in the wrong gear, but the rest of the time I rarely need to change down under acceleration. Obviously it is not a technique that works on a trailing throttle, where most downshifts occur.
It'd work in a very low inertia engine if you had a very fast gearchange. It's not at all mechanically unsympathetic if you get it right but as GreenV8S says there is very little margin for error. You need to be pretty well in tune with the car's responses to grok how fast the revs rise at no load and full throttle and time your clutch/gear movements precisely to correspond with that.
It's a lot easier to do it changing from an even to an odd gear, straight forward through the gate, than from an odd to an even gear, back through a dogleg...
It's also something that's not called for very often. The only times I've ever found it useful have involved going up steep hills. Where I live it's pretty flat
It's a lot easier to do it changing from an even to an odd gear, straight forward through the gate, than from an odd to an even gear, back through a dogleg...
It's also something that's not called for very often. The only times I've ever found it useful have involved going up steep hills. Where I live it's pretty flat
DanH said:If you already had 8000rpm on the clock, why would you be changing down?
Hmm not sure I'd want to do this at 8000 rpm.
I already do this and it's very useful (I think I learnt it from Tom Topper's "Very Advanced Driving" book). You're pootling along at 40mph and start to go up an incline. Leave the accelerator where it is, dip the clutch and with a bit of deft handywork use the gearlever to drop a cog, slotting it home at just the right time to coincide with the increase in revs. Very satisfying. If you apply just the right amount of pressure, it will only drop in when the synchro rings allow it, so perfect every time.
This works well in a low-inertia engine. My Gti-6 revells in blipping the throttle to match revs, did an awesome 80mph 4th to 3rd tonight, just perfect. A Ferrari SMG couldn't have done a better job 
But doing that keeping throttle down at same space and letting revs rise as you drop a gear works less well at low rpm as the engine response it pretty pants low down, and it takes too long and is weird.
I'm sure a v6 or v8 would happily do it at lower engine speeds though.
Hmmm
Dave
But doing that keeping throttle down at same space and letting revs rise as you drop a gear works less well at low rpm as the engine response it pretty pants low down, and it takes too long and is weird.
I'm sure a v6 or v8 would happily do it at lower engine speeds though.
Hmmm
Dave
Before I got into auto's I used this regularly as part of the 'heel and toe' technique - really ball of foot/big toe on the brake and outer edge of foot blipping the throttle.
The problem with the blip of throttle is that it might compromise the nice steady pressure on the brake pedal, makes the 'feel' of the brake pedal less interpretable and generaly is a bit iffy for the public roads, especially if the pedal spacing is not ideal. So that's most typical cars then!
Using the constant (or very near constant) throttle means that your right foot is primarily concerned with just braking and the throttle control is a by-product. Which in turn means that there should be a better chance of a smoother gear shift since the revs will, eventually, rise steadily to the ideal engagement point as the as the road speed falls to meet the revs. Blipping, on the other hand, could mean not quite getting the revs up to the the level required or over revving and having to wait for the revs to fall back, all the time playing catchup with the braking effect.
It is likely that result can offer greater stability under braking than a blipped throttle change - at least for all but the most expert of drivers. Or at least that is my opinion, but I am happy for it to be disproved by those with far more expertise than I have.
How easy it is to do some of this sort of stuff with modern engine management systems I am less certain.
>> Edited by LongQ on Tuesday 6th September 19:41
The problem with the blip of throttle is that it might compromise the nice steady pressure on the brake pedal, makes the 'feel' of the brake pedal less interpretable and generaly is a bit iffy for the public roads, especially if the pedal spacing is not ideal. So that's most typical cars then!
Using the constant (or very near constant) throttle means that your right foot is primarily concerned with just braking and the throttle control is a by-product. Which in turn means that there should be a better chance of a smoother gear shift since the revs will, eventually, rise steadily to the ideal engagement point as the as the road speed falls to meet the revs. Blipping, on the other hand, could mean not quite getting the revs up to the the level required or over revving and having to wait for the revs to fall back, all the time playing catchup with the braking effect.
It is likely that result can offer greater stability under braking than a blipped throttle change - at least for all but the most expert of drivers. Or at least that is my opinion, but I am happy for it to be disproved by those with far more expertise than I have.
How easy it is to do some of this sort of stuff with modern engine management systems I am less certain.
>> Edited by LongQ on Tuesday 6th September 19:41
I tried it on the way home and to be honest I did not really like it. Bearing in mind the car I was trying it in was a 1.6 Cavalier I found the main problem to be this:
Following my initsl ridedrive session I was advised to try and smooth out my driving style and in addition slow down the gear changes to compliment this. Because of the free and quick revving nature of the chavalier engine it meant you had to very quickly change gear to avoid over revving the engine and missing the correct engagement point. I did not like the rushed aspect of the change so gave up.
I will have a go in my other car, Audi S2 which is turbo charged and has a dual mass flywheel and behaves in an almost opposite fashion to the engine in the cav....
We will see.
Cheers,
Steve
Following my initsl ridedrive session I was advised to try and smooth out my driving style and in addition slow down the gear changes to compliment this. Because of the free and quick revving nature of the chavalier engine it meant you had to very quickly change gear to avoid over revving the engine and missing the correct engagement point. I did not like the rushed aspect of the change so gave up.
I will have a go in my other car, Audi S2 which is turbo charged and has a dual mass flywheel and behaves in an almost opposite fashion to the engine in the cav....
We will see.
Cheers,
Steve
Mr Whippy said:
This works well in a low-inertia engine. My Gti-6 revells in blipping the throttle to match revs, did an awesome 80mph 4th to 3rd tonight, just perfect. A Ferrari SMG couldn't have done a better job
How is a Gti-6 a low inertia engine?
My point was more about engines that rev so very quickly due to lightened internals (i.e. titanium pistons, light weight flywheel etc).
Dunno may give it a go, but scared of lunching something
Hey, why bother with the clutch 
It's a common technique and regularly taught/used by some police schools as it requires less effort (to teach) than double de-clutching or whatever other techniques you choose to try, and in these times of reduced training time that gives the instructors more time to try and stop them crashing into something large and immovable 
Obviously if you aren't quick enough with the gearlever than it's time to wear out the clutch and the speed of movement varies from car to car, so if you swap cars a lot it's not the smoothest of techniques. But if it works for you, whyh not.
Obviously if you aren't quick enough with the gearlever than it's time to wear out the clutch and the speed of movement varies from car to car, so if you swap cars a lot it's not the smoothest of techniques. But if it works for you, whyh not.
DanH said:
This works well in a low-inertia engine. My Gti-6 revells in blipping the throttle to match revs, did an awesome 80mph 4th to 3rd tonight, just perfect. A Ferrari SMG couldn't have done a better job
How is a Gti-6 a low inertia engine?
My point was more about engines that rev so very quickly due to lightened internals (i.e. titanium pistons, light weight flywheel etc).
Dunno may give it a go, but scared of lunching something
Well it's pretty low inertia over a "cooking" 2.0 4 pot, probably won't find a lower inertia 2.0 4 pot on the road in an normal ish car?!
Revs quickly enough for blipping anyway
Dave
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