Smooth gear changes with a powerful car??

[LandingSpot]

Pondering going for the IAM Special Assessment and realising that among other things needing improvement, I really need to smooth my gearchanges.

A few months in to owning the Celica, I am no longer nailing it everywhere and need to blend the changes better, particularly 2nd-to-3rd and 3rd-to-4th. Now I've read of examiners asking for the neutral gate to be acknowledged when passing through it, which I have no problem with doing, but I find that if I make an effort to take time over the change, the revs drop too much requiring either a match for the new gear or for the clutch to take the strain produce a small lurch.

Rev matching on upchanges will need a whole lot more practice which I am happy to do. I just wondered how others handled it and where the line is between "acknowledging the neutral gate when passing through" and too quick a shift.

Thoughs appreciated!

[ScoobyChris]

I think if you're slowing down the gear change such that the revs are dropping too much, then it makes sense that to keep it smooth you need to lift the revs. One option might be to use a sustained change so that you don't come completely off the throttle during the upchange, but just relax the pressure a little to hold at the target revs.

Chris

[davepoth]

You need to double clutch...

[Vaux]

Maybe you're slowing it down too much?
How about saying "one and two" as you change gear, the and bit being the time passing through neutral?
It's not "onentwo" though.

[Tyre Smoke]

davepoth said:

You need to double declutch...

This.

EFA.

[cbcbcb]

I can't believe it makes sense to slow down gear changes so much that you need to blip the throttle to rev match. The 2nd to 3rd change ought to be: Push gear stick forward. Release gear stick. (gear stick centres itself). Push gear stick forward. So no sideways movement is imparted by the driver. This can be done quite quickly while still retaining the two separate movements. It can be easier to do this if you don't hold the gear stick, and simply push it; forwards with the palm of your hand, and backwards with your fingers flat against it.

Third to 4th is the same pull-relax-pull motion. Practise 3rd->neutral, and see just how little force is required to do it. Then 3rd->4th is the same action twice.

Disclaimer: not done IAM, don't know what they're looking for. It is quite interesting writing this, makes me think about my driving.

[Peng]

The trickier types of gear change would be a foth or fifth to second or first.

[LandingSpot]

Believe it or not, I actually find downchanges MUCH easier to manage when each phase is separated - in 5th, light brakes in to firm brakes, off brakes gear is two with a rev match.

It's making it smooth but keeping good firm acceleration that I'm having difficulty perfecting.

Edited by LandingSpot on Tuesday 29th June 13:48

[GravelBen]

I find a similar thing with my MX5, which has a very light flywheel and race clutch - the gearbox doesn't like to be rushed when cold, but the flywheel is so light that the revs drop off very quickly, necessitating either a blip on the upshift or holding some throttle on for a smooth shift.

Does take a bit more thought to drive smoothly at low speed but you get used to it after a while. Unless your Celica also has a light flywheel it shouldn't be that sensitive though.

Edited by GravelBen on Tuesday 29th June 11:46

[RobM77]

Racing flywheels are really designed to be used in conjunction with a straight cut dog ring box, where the most mechanically sympathetic and best way to change gear is to not use the clutch, so the gearchange is over in the blink of an eye and the rev drop is not a concern. In fact, in such situations a lightweight flywheel actually helps. If you put a lightened flywheel with a standard synchro road car box and use the clutch then the rev drop will make your life quite hard!

In a standard road car though, it should be possibly to make a smooth gearchange at a steady pace that looks unrushed. One consideration for the OP is whether his car has a clutch delay valve. My BMW is fitted with such a device and smooth upshifts are extremely difficult, if not impossible.

In my own humble opinion, if your passenger or assessor can close his eyes and think it's a smooth gearchange, who cares who you're doing it, provided it's mechanically sympathetic.

[A - W]

It is all about timing and getting it right.

If you have time you can do anything.

[Eggman]

What's all this talk about double declutching? On most vehicles you only need to do that if your synchromesh is a bit knackered, when you're doing a big downchange (e.g. 5th to 2nd) or selecting 1st on the move.

Rev matching isn't exactly difficult, it just takes a little bit of practice which will be well worth it. Once you've got the knack your driving will be much smoother and your entire drivetrain will thank you for not passing shock loads through it all the time.

(I suspect a lot of DMF failures would be avoided if everybody still learned to drive in worn out rwd cars with dud tyres! That combo soon teaches you why it's a good idea - especially when it rains )

[philoldsmobile]

LandingSpot said:

Now I've read of examiners asking for the neutral gate to be acknowledged when passing through it, which I have no problem with doing,

this is why i hold reservations about the IAM - this is a completely outdated practice harking back to the days of long ratio gearboxes and heavy flywheels.

modern performance cars SHOULD be snicked from gear to gear, i.e. 3rd to 4th in one operation for an upshift when pressing on. at lower paces its ok to make it a 2 part operation, its all about matching the speed of the change to the speed of the engine and road speed.

on a downshift, a blip of the throttle (heel and toe) and a slower shift helps enormously, as again you match the engine and gearbox speeds.

Edited by philoldsmobile on Saturday 10th July 17:57

[Eggman]

philoldsmobile said:

completely outdated practice harking back to the days of long ratio gearboxes and heavy flywheels.

Did you mean 'wide' rather than 'long'?

Anyway, outdated or not, slowing the change right down can be fairly revealing of your technique and I suspect this is why they want you to do it. It's not something you would do all the time and I think it would be a poor practice if you did, but if you stick the car in neutral, set the revs and then select your new gear it's easy to hear whether you are doing it properly or relying on the clutch to drag the engine revs up or down.

I have devised a similar little game (best played on straight empty roads at about 30-40mph), which is to change from 5th to 2nd to 4th to 3rd a couple of times. If you can feel any of the changes then you may say 'fiddlesticks!', 'bother!', or a strong swear word of your choice.

[RobM77]

Eggman said:

I have devised a similar little game (best played on straight empty roads at about 30-40mph), which is to change from 5th to 2nd to 4th to 3rd a couple of times. If you can feel any of the changes then you may say 'fiddlesticks!', 'bother!', or a strong swear word of your choice.

Try that in a BMW with a clutch delay valve :-) I'd like to sit next to you with a swear box if possible :-)

[alock]

RobM77 said:

Eggman said:

I have devised a similar little game (best played on straight empty roads at about 30-40mph), which is to change from 5th to 2nd to 4th to 3rd a couple of times. If you can feel any of the changes then you may say 'fiddlesticks!', 'bother!', or a strong swear word of your choice.

Try that in a BMW with a clutch delay valve :-) I'd like to sit next to you with a swear box if possible :-)

My version of this involes a stack of 4 chinese takeaway containers on the passenger footwell. If they fall over, you're not smooth enough.

Edited by alock on Sunday 11th July 14:14

[RobM77]

alock said:

RobM77 said:

Eggman said:

I have devised a similar little game (best played on straight empty roads at about 30-40mph), which is to change from 5th to 2nd to 4th to 3rd a couple of times. If you can feel any of the changes then you may say 'fiddlesticks!', 'bother!', or a strong swear word of your choice.

Try that in a BMW with a clutch delay valve :-) I'd like to sit next to you with a swear box if possible :-)

My version of this involes a stack of 4 chinese takeaway containers on the passenger footwell. If they fall over, you're not smooth enough.

Edited by alock on Sunday 11th July 14:14

A bit like Jackie Stewart's salad bill and squash ball game :-)

There's no way I could do that in my BMW, shame. The Lotus or my race car would be fine though. Another example of meddling technology making things worse, not better.

[Orillion]

RobM77 said:

Eggman said:

I have devised a similar little game (best played on straight empty roads at about 30-40mph), which is to change from 5th to 2nd to 4th to 3rd a couple of times. If you can feel any of the changes then you may say 'fiddlesticks!', 'bother!', or a strong swear word of your choice.

Try that in a BMW with a clutch delay valve :-) I'd like to sit next to you with a swear box if possible :-)

I've never heard of a clutch delay valve. What does it do? And why?

[jaf01uk]

You could try easing off the gas prior to changing gear so the car is just maintaining speed rather than change from acceleration, then as you change gear slowly you just keep your right foot steady and the revs will be there ready regardless of how long you choose to take to change, then get the clutch back up then re accelerate, most people try to apply gas as the clutch is coming up and it's harder to get right, do 1 thing at a time and it will be so much more smooth,
Gary

[Trif]

Orillion said:

RobM77 said:

Eggman said:

I have devised a similar little game (best played on straight empty roads at about 30-40mph), which is to change from 5th to 2nd to 4th to 3rd a couple of times. If you can feel any of the changes then you may say 'fiddlesticks!', 'bother!', or a strong swear word of your choice.

Try that in a BMW with a clutch delay valve :-) I'd like to sit next to you with a swear box if possible :-)

I've never heard of a clutch delay valve. What does it do? And why?

It stops you dumping the clutch and doing burnouts to save the drive train and tyres at the expense of destroying your clutch. When you dump the clutch it will release the clutch.