Jolley

Do you lift off the accelerator, or just leave it floored?

SiPie

My limited knowledge and experience of this is that you have to be spot on (almost to the correct rpm) with your gearchange to get this to work, otherwise your box is going to be spitting teeth ...

PS My fecking old my99 classic wouldn't change into 5th even with a clutch on a good day far-less without

PPS Cost of sourced gearbox fitted at subaru dealers for me last year was around £1600

chaos.

"You wont need 5th or 6th"

Yeh, thats cause the gear coggs will be churned up pieces of sharp metal on the 'kin road!

TonyBurns

iTrader: (3)

No they wont, if you think about what gears actually do..... then you will know they are designed to go up as they go from slower to quicker, this has no effect, what does have an effect is going from a faster to slower gear, this will loose you gear teeth (thus why your gearbox crunches on down shifts if you dont use your clutch properly).
Simple mechanics.

Tony

TonyBurns

iTrader: (3)

Thats for going down gears, and normally on a straight cut box, though you can do it but you have to let the rev's drop so that you dont have too much resistance.

Tony

TonyBurns

iTrader: (3)

An STi clutch is pretty resiliant, 5k for the 265ps car will keep it from bogging down (and yes you get plenty of traction )

As for all those who dont think you can go up a gearbox without a clutch, have you tried it? (probably not ) and remember, your going with the flow (no resistance) and not going against it (going down, feeling resistance).
Also have you ever crunched a gearbox going up gears? (i really doubt it, its virtually impossible to do), you only crunch gears going down (which is when you cause damage).

Tony

greasemonkey

Does Tony drive a Spec C then?

Yes, you can, but changing gear quickly/aggressively without the clutch and without waiting for the revs to match on a synchromesh gearbox will dramatically accelerate wear, and possibly even f**k it in reasonably short order. The synchros aren't intended to take drive loads. It might not be spitting teeth, but it could be spitting bits of brass, steel, aluminium and nylon off the synchro cones, baulk rings, synchro hubs, coupler sleeves and selector forks.

It's irresponsible suggesting someone attempt this technique simply in an attempt to blow BMW 316's and Golfs off. It is not desirable for the long term health of the car, nor should it be necessary.

Bollocks, in a word.


Was that supposed to be ironic Tony? Seems as though you don't really know what is going on in the gearbox at all. As has been stated above, this is, if nothing else, akin to putting a big "Do not buy this car, it's been driven by a clueless lumphead and is fooked" sticker on your windscreen when you come to sell it.

richie,7,RA,spec C

if the timing is not right e.g revs +a smidge of lift off of the gas (to be kind to the engine and box) then yes i'd 2nd that but i think that mr burns knows how to drive considering his choise of motor
richie

greasemonkey

Lol. The ability to pay for a given car in no way implies the ability to drive it properly/sympathetically, as this thread ably proves! 'Sides, just look at the number of football players who crash Ferraris and Porsches!

NACRO

Used to drive my company car (Vectra-spit on floor)without using the clutch for laughs sometimes. I handed the car to a collegue at 13K miles ish and the gearbox failed at 15K miles. Not my fault- honest.

richie,7,RA,spec C

true
and i use my clutch all the time ,even to start the car

TonyBurns

iTrader: (3)

Well you dont design gearboxes do you?
My mate does
You get the same resistance going up a gear on any form of gearbox, no matter if its mated to a car or a machine, your resistance up will always be virtually zero, down will always be 100%

Now sit back and think about what you have said....
The syncromesh only needs this to work on downward shifts, not upward ones (thus the reason to double clutch!)
You are correct about the quick/aggressive gear changes though, even using a clutch these will kill your gearbox, but then again thats abuse.
Is it recommended... possably not, but engineers will have thought about this and taken this into consideration when building gearboxes, but then again, slamming in your gears going up the box using the clutch will wear the syncros and other parts a damn sight faster.

Tony
PS, no i dont do this on the Spec C as ive no reason to do it (though i have used this tecnique on an old r19 i use to have when the clutch cable snapped to get home).

mik

Synchro works on both up and downshifts.

With clutchless upshifts you are using the synchro rings to simultaneously
1/ Accelerate the car
2/ Force the engine rpm down to the point where full gear meshing can occur. This whilst applying full throttle....

Your rings will last no time.

I should point out that I don't design gearboxes either, but I understand how they work. Similarly I didn't design the F15, but I know that applying full flaps and dropping the undercarriage at vmax isn't a great idea.

greasemonkey

Lol, eejut. You don't have a clue what I do for a living, do you? Unless you think that "monkeying around" is meant literally?

PMSL, are you making this up as you go along?

The "resistance" you're talking about is the pressure being applied through the synchro hub to match the shaft and gear rotation speeds prior to engagement.

It is relatively easier on upshift because, once you disengage the clutch (or lift the throttle), the drive side of the synchro will obviously decelerate naturally due to friction and inertial dissipation, helping the speeds to match.

It is relatively harder on the downshift because the synchro has to work against said frictional and inertial forces, speeding the drive side of the 'box back up prior to engagement.

Wrong. The synchro hub works on both sides of the shift, although it's true to say it does more work on the downshift. The reason why double declutching helps here is that you use the engine to spin the input shaft back up, rather than relying on the synchro to do all the work.

If you try and downchange without using the clutch (or blipping the throttle to match speeds), the synchro also has to work against the deceleration of the engine and flywheel, which is why clutchless upchanges are (relatively) easier than clutchless downchanges.

The clutchless technique you previously advocated (but now seem to be backing away from) will lead to more stress/wear than using the clutch in an otherwise similarly aggressive gearchange.

Using the clutch on a synchro box will result in quicker, more sympathetic gearchange for most people, most of the time, as the synchros will be free to do their job without carrying transmission loads, and there's much less propensity to baulk the change.

Lol, yeah, that's why the same engineers thoughtfully provide a foot operated clutch, and why they'll tell you to use it when making a gearchange.

PMSL! Pull the other one Tony! You wholeheartedly advocate this technique to another Impreza owner while claiming that "your mate who designs gearboxes reckons they're designed to do it", and then say that you don't do the same on your own (virtually identical to Melina's) gearbox?

This either makes you a liar (for suggesting the boxes are designed to do it) or a hypocrite (for suggesting a technique which you wouldn't try on your own car). Which one is it?

Let's just hope this thread is long forgotten before you come to sell your car eh?

TonyBurns

iTrader: (3)

You lot just dont give engineers any credit do you?
Those rings will last alot longer than you think, they would be designed to work without a clutch, engineers will always design something to work in the worst possible conditions.
Ever see the one about the engine with no oil?
That ran for over 50 miles before it failed, and that was without any oil!

The worst abuse you will ever give a gearbox is slamming it into gear, this puts more pressure on it than anything else you care to name, and if you want to do traffic light gp's then your going to have to abuse your car, simple fact (i dont need to really, i personally prefer to just use the excellent midrange grunt my car has to show other cars up )
Mike Wood said it in the WR1 thread, this sums it up perfectly:-
You would never want to abuse your car the way this was to achieve the times stated.
Anyone for an ex demo car?

Tony

mik

So this means they are designed to run without oil then?


I don't do this either, but it's a lot less stressful than a clutchless change. You are forcing the synchro rings to rapidly slow the box shaft to allow the next gear to mesh. You're not adding in any load from the engine or drivetrain.

greasemonkey

Lol! So just what do you think I do then Tony?

Did your "mate" tell you that? If they're designed to work without a clutch, why provide a clutch?

No, they will try and design some ability to tolerate a worst-case scenario for a certain length of time, but working is a totally different kettle of fish.

Wow, it ran for all of 50 miles? Then it failed? I thought you said that engineers designed things to work in the worst possible conditions? This example obviously proves that they don't/can't, doesn't it?

Well, nobody's going to want to buy yours now, so the saleability of Prodrive's test hacks has probably just improved to some degree or other.

TonyBurns

iTrader: (3)

Ive already stated that i have used this technique (for around 40 miles whilst taking a car home when the clutch cable snapped), you can take from that what you will, it was for both up and down gearing also

Like i have also stated, if your doing traffic light GP's then you are going to abuse your car, simple fact, so you can either slam the gears in with a clutch change or be slightly less abusive and change without slamming in and not use a clutch, as i point out, possably not recommended but the car will do it, you could also do full bore launches, i only stated 5k ones due to the turbo bogging down on the STi's below 4k, either way, it was an option that was asked for and given, personally i wouldnt bother with golf gti's or bmw 316's but its a free world and advice no matter what type can be given freely (unless of course its not a country with free speech and ill have some people in black overcoats come round later on tonight )
You want to do it, you have to abuse it.

Tony

TonyBurns

iTrader: (3)

Are you really?
Look it up to see exactly what it means
If you do all that then yes you are an engineer, if not then no your not

Tony

greasemonkey

You can backpedal as far as your like, your comments are there in black and white for all to see. You advocated a specific gearchange technique without any form of caution or suggestion that it might be bad for the car, yet now, when your advice and the reasoning behind it is called into question, you claim you don't, in actual fact, use it yourself, and, furthermore, claim the only time you did use it was when driving your broken Renault home.

There is a load of difference between driving a car with a broken clutch in this manner, and suggesting someone use it to make their performance in the traffic light grand prix better.

Your advice was ill-considered and irresponsible, as was all this crap about "my mate who designs gearboxes" telling you it's fine and that the cars are designed to do it.

I can only wonder whether you'd be prepared to pay the repair costs of anyone who followed your technique and screwed their gearbox in the process...?

Melina

Greaseymonkey - Thanks. Note that my original question was seeking an alternative to slipping the clutch. However, as far as I can gather many of the responses advocated exactly that. A mate of mine whom I just lunched with with a WRX says that any hinting of burning of clutch is money of ouf the window and advises me to wait until I am in second gear and then burn them off.

TonyBurns

iTrader: (3)

And honestly, ill give the other method....
Go into 1st gear, sit at 5k rpm, lights change, go for gearchange using clutch, slam into 2nd gear to get the best time, then go for 3rd, 4th and beyond.... now tell me that this method is much better?
Like i have stated, i stand by that method i gave before, it works, it is less abusive as you put less pressure on the gearbox, the above method will kill your gearbox quicker.
Take your pick as either way your going to have to abuse your car, then you could also add that you may damage your clutch and running gear....

Take your pick.

Tony

Madjay2

dont u just love "by lesser cars" what do u think u drive a Ferrari, check the badge on ur car its a SUBARU ffs jap can with a turbo strapped on to it.

SiPie

Well said Madjay2

Some people on here eh

PS I'm with greasemonkey on the gearbox debate Sorry Tony

TonyBurns

iTrader: (3)

Thats fine , everyone has their opinion, ive given mine but i bet those 2? gearboxes you went though were because you were slamming the gears in

Tony

greasemonkey

Ah, now it's just your opinion. No problems with people expressing opinions. Bit of a shame you tried all this "my mate who designs gearboxes reckons it's fine" rubbish to begin with. If you'd initially said "You could try this, but be warned, it might not do your box any favours" (etc.), you wouldn't have come off looking like a mechanically ignorant and irresponsible eejut, especially since it now transpires you wouldn't drive your own Impreza the same way.

If you want to make a genuinely quick getaway, you'll need to slip it a little to keep the car on boost as you pull away. Even so, you should be able to minimise this with practice.

This is largely correct. You'll get more boost in second anyway, so provided you're going quick enough to keep it on boost when you get into second, change up and then let it rip.