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Rev Matching

Discussion in 'Detailing' started by amoffat, Jun 23, 2003.

  1. amoffat
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    amoffat Member

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    Thought I would kick off with a proper driving technique post.

    Since getting the S2000 I have decided that I need to learn how to drive 'properly' now that I have a car that can be seriously provoked, especially on the limit. I have decided that I need to learn how to heel and toe. My first stage to this is to learn how 'rev match'.

    For anyone who doesn't know, reve matching is all about ensuring the revs and the engine stay equal when braking for a corner. As you approach a corner and you are braking and changing down you will feel a weight shift and a jerk as you use the engine to brake.

    As you are braking hard, dip the clutch and quickly blip the throttle to match the revs that you expect in the next gear that you are going to select. Complete this for each gearchange. When you do this successfully the car will not jerk back and forth when changing down, and the braking will be achieved much more smoothly without unsettling the car.

    I have been practising for about 1 week now, and its quite difficult. Usually I would not use engine braking, and just brake, then select the required gear before entering the corner, but it can still be used for this gear change. I tend to use engine braking more often when I am driving very hard.

    I would advise that you practise this at slower speeds, in a straight line without any traffic, just incase you screw up and smash into the back of somone or end up in a ditch.

    That is all in 'moff' langauge (novice!) and I am sure that some driving techie will be able to explain better. Has anyone else tried this or use it in their everyday driving?
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  2. audi_girl
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    audi_girl Active Member

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    Hi Moff - when I did the HPC course they told me to double-declutch. (i.e. when changing down, change down into neutral bring up the clutch and match the engine rev's, then redepress the clutch and select the lower gear).

    I have my reservations about it, and whether the newer cars benefit from it or can you just rev-match without double declutching, but it is another way of rev matching I guess.
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  3. graemedunn
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    graemedunn New Member

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    Hi Moff, Rev matching ,or sustain changes as most advanced training bodies call it , is a very useful skill.Not only will it lessen the wear on your car's drive train and gearbox but it will greatly improve your driving ability.If an engine at 2000 rpm produces 40 mph in 4th gear then it may produce the same road speed, i.e. 40 mph at 4000 rpm in 2nd gear.By knowin what terminal speed you need for a bend or corner then it is simply a case of slowing to that speed and then 'blipping' the throttle sufficiently during change down to lift the engine revs to the required engine speed.

    Sounds easy but can take a little practice. Another very useful skill is to learn to change up and down gears without using the clutch.If you drive a car with a cable clutch, this can break at any time - your clutch pedal hits the floor and you suddenly can't change gear.Most cars if driven properly do not need the clutch pedal except to move off and stop. Try changing gear without using the clutch by building up speed in each gear - 1st-2nd=10mph, 2nd-3rd=20mph, 3rd-4th=28mph.Don't force the gear lever through if it doesnt want to go.By building up to a constant speed it should be easy.

    There's also 'heel and toeing' which is another skill altogether.......

    Have fun!
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  4. audi_girl
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    audi_girl Active Member

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    But if you can match the engine speed when changing down, without double-declutching, what is the benefit to double-declutching??

    (Thanks Lyrac!!)
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  5. LYRAC
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    LYRAC Member

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    /ubbthreads/images/graemlins/angel.gifHarmony and unison = less stress on all. It also allows the syncronisation of all of the internal parts of the gear box to mesh better and cause less ware, allowing th baulk rings to do their job. As I said a real aid when heel and toeing!! Don't ask me to explain that with a tune though!! /ubbthreads/images/graemlins/smirk.gif
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  6. audi_girl
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    audi_girl Active Member

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    Thanks Lyrac - I will continue practising my double-declutching, and defend it from those disbelievers out there!!!

    I do find it helps, especially when changing from 3rd-2nd - makes the change a lot smoother, but it does take a lot of practise and I'm not there yet /ubbthreads/images/graemlins/frown.gif
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  7. amoffat
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    amoffat Member

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    I'm now getting a lot better at rev matching, but it will take some time to get it right.

    I don't do it to look after the transmission etc, its a company car /ubbthreads/images/graemlins/tongue.gif I am doing it to ensure that my already slippery backend has less chance of being provoked through weight shifting (no, not going to the toilet /ubbthreads/images/graemlins/grin.gif).

    The car feels much smoother when attacking corners, but at the moment I am braking much earlier to get used to the rev matching.

    Oh well, have to get some more practice in today. Just means I'll have to take the cross country route home again... thats if it stops raining /ubbthreads/images/graemlins/mad.gif
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  8. Drystone
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    Drystone Member

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    Ah I get it now, so to rev match you just dip the clutch, engage the lower gear then blip the throttle to get the revs up before lifting the clutch again.

    No need to lift the clutch before blipping the throttle then depress it again to engage the lower gear, the pedal can stay depressed during the entire process.

    I've been practicing on the motorway to quell boredom on the drive home /ubbthreads/images/graemlins/tongue.gif. It's quite satisfying to say drop it down to 3rd from 5th then rev match before lifting the clutch, the power comes back in very smoothly with no big jerk due to the effects of engine braking.

    Braking into corners is a different matter. It's impossible to rev match whilst braking without heel and toeing (unless you've got three feet /ubbthreads/images/graemlins/wink.gif). Heel and toeing is damn tricky. /ubbthreads/images/graemlins/confused.gif

    Christian
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  9. audi_girl
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    audi_girl Active Member

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    Yeah - as soon as you touch the brake pedal the throttle is disengaged. John tried it on mine when wearing the brakes in..
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  10. Drystone
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    Drystone Member

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    Moff,

    What I meant is you can't hold the clutch down, brake and blip the throttle without heeling and toeing (unless you're a triped!).

    As you say you could brake earlier before a bend then come off the brake and change down whilst blipping the throttle to match the revs, then turn into the bend.

    I'd imagine you'd be a lot slower round the bend doing this though, hence the need for heel and toe so you can brake and change down at the same time but still rev match.

    Christian
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