Downshifting

[scooby dooby doo]

when you think you're getting somewhere - try double declutching ❗

 

takes a while to get your head round it but it IS useful for getting into 1st for hairpins etc.

 

damn difficult to get right though ❗

 

HOOPY

R706KGU Hoopylight R

[Myles]

Erm,

 

I thought DD was really just to help out with non-synchro and recalcitrant gearboxes etc. - what other advantages does it have (ignoring mechanical sympathy etc.)

 

Regds,

Myles

[Meldrew]

It's easier on your synchromesh (if you get it right 😬) than banging it into lower gears at high speeds ands so encourages longer life and smoother shifting.

 

Many people consider it unnecessary in modern cars, but I once used to own a battered Fiat and therefore got into the habit as the synchros all went ker-twang.

[scooby dooby doo]

you have 3 things spinning around.

1) engine, flywheel, cover plate

2) clutch, gearbox input shaft

3) gearbox output, propshaft, wheels, the car itself

 

when you change gear you need to adjust the speed of 1 and 2. a blip takes care of 1. if the change in rpm is small then 2 doesn't matter as the syncros can do it for you. they are effectivly like a small clutch inside the gearbox to help the gears engage.

 

however, when going into first, even with a blip, you'll hear a sort of whirring sound (easier to hear on a tintop) as the syncros spin up 2. this takes a bit of time so to change quickly you either need to be a bit brutal to them (which will wear them out faster) or DD. race boxes don't have them so avoid the problem.

 

so - we need to help them by DD. First we change from 2nd to neutral and let out the clutch. 1 and 2 are now connected, but 3 isn't. blip the throttle and 1 and 2 are both up to speed.

 

now clutch in again and change to 1st. since 2 is now up to speed it'll snick into gear nicely.

 

in practice you need a blip when going from neutral to 1st as well (ie two blips in total). can't see why though....

 

HOOPY

R706KGU Hoopylight R

[Meldrew]

in practice you need a blip when going from neutral to 1st as well (ie two blips in total). can't see why though....

 

To re-synchronise the engine speed with the roadspeed transmitted through the now nicely snicked-in drivetrain. The engine speed usually drops off enough to make it necessary.

 

[scooby dooby doo]

thanks ❗

 

Knew it was a mental block of sometype ❗

 

Did my explanation make sense then 🤔

 

HOOPY

R706KGU Hoopylight R

[Meldrew]

Looked good to me.

 

When I was about 13, John Lyon, the HPC guru did a whole series of articles about the techniques of fast, safe driving in "Motor" magazine. My Mum chucked them all away while I was at university. Your explanation tallies pretty well with what I dimly remember from that. Consider yourself a guru, therefore. 😬

 

 

Never get stuff like that in car mags these days - except LF, of course.

[scooby dooby doo]

😬

 

HOOPY

R706KGU Hoopylight R

[not a Postman Pat]

it IS useful for getting into 1st for hairpins etc

 

There is no hairpin so slow that you need to drop down into 1st 😳

 

You need to drive it, mate

 

Pat and his not quite black and white cat

[Peter Carmichael]

Have you got a five speed box, not-a-Postman? In the six-speeder you can certainly flirt with 1st for certain hairpins, especially if you want to come out sideways with an armful of lock.

[not a Postman Pat]

Sadly, yes ☹️

 

Just trying to get my good friend Hoopy to bite

 

Pat and his not quite black and white cat

[scooby dooby doo]

Peter - I don't remember you being with me on the Euro2001 tour 😬 That's exactly what i did the whole time. No wonder the yokos when from brand new to illegal in two weeks....

 

😬 😬

 

HOOPY

R706KGU Hoopylight R