Flat Changing In A Manual

[BlueXR6Turbo]

that includes reverse at 100kmh.

I bet that made a bit of a crunch!

[Turbo6man]

Flat changes are about fast gear changes (something the T5 isnt well known for!) and maintaining momentum within the engine and with the flywheel (and exhuast output in turbos). You can do them with or without the clutch, and you can do them in cars with helical or straight cut gears or with or without synchro. It all comes down to how hard you want to work your 'box.

(Ive never yet found a car I couldnt force into ANY gear at ANY speed under ANY conditions, and that includes reverse at 100kmh. Dont ever say Volvos arent indestructible!).

They are not necessarily a bad change. Under the right circumstances they can be a damn good change - unbeatable.

Personally, I've seen two people who reckoned they could flat change a syncro box without using the clutch. Both times when asked to demonstrate the result was the same - gear lever came off in their hand.

One was a BW single rail in an XB 351 and the other was a Celica rally car.

If you would like to demonstrate in YOUR car for me I'd be a very interested observer. :lol:

PS wish I'd been there when you destroyed the Volvo's gearbox - bit of a bang was there?

[NT TURBO]

Yup I agree Turbo6man, what are you saying mickq youre yet to find a gearbox you cant smash?

[Lumpen]

Both times when asked to demonstrate the result was the same - gear lever came off in their hand.

One was a BW single rail in an XB 351 and the other was a Celica rally car.

I've pulled the gearstick off of a Single Rail before as well, but it was only an XF 4.1! (I cant imagine a 351 having less torue than one of them)All I was doing then was changing down into second (blip and crunch) when I heard a ping-Problem- Main selector shaft from stick to box go kersnap!

[mickq]

Personally, I've seen two people who reckoned they could flat change a syncro box without using the clutch. Both times when asked to demonstrate the result was the same - gear lever came off in their hand.

One was a BW single rail in an XB 351 and the other was a Celica rally car.

If you would like to demonstrate in YOUR car for me I'd be a very interested observer. :lol:

PS wish I'd been there when you destroyed the Volvo's gearbox - bit of a bang was there?

Well if your gear lever is coming off in your hand, then it isnt a decent gearbox.

I could understand it if the car had 800+hp which would eat anything, but if it didnt, then they need a new gearbox manufacturer if a single flat chat change chewed their gear stick off.

With a quick gearbox, the rev change whilst kept flat-chat isnt that bad (Im assuming its not a snail driving it, and they can do quick changes). Its similar to a really badly stuffed up double-clutch or rev-match.

Think about it: in many cars you can side-step the clutch at redline from a standstill in 1st and the gearbox will cope (for a limited number of times, for sure!). Doing a flat chat change isnt nearly as bad on the gearbox or driveline as that.

When you do a flat-chat it will wear your synchros, and many other parts of your box, but there is certainly no reason why any car with a half decent gearbox and a non-top-fuel-dragster engine would be expected to chew a box over it except after extended use.

And yes, the Volvo made a fantastic noise. It was an auto (240 series), not a manual. The amazing thing was, after we stopped cringing at the noise it made and the car stopped spinning, the car was ok to he point where my friends mum continued to use it as her car for another year or two, despite the interesting transmission noises!

The things you do when you are 18-20 years of age!

Like I said, indestructable!

Edited 13/02/04 02:42 PM by mickq

[Turbo6man]

mickq> It has nothing to do with engine torque or gearbox strength. By your comments regarding this I venture to suggest that you haven't in fact ever achieved a flat change in a manual syncro box without using the clutch. The effect is nothing like side-stepping the clutch in a first gear take-off. To do this you already have the gear selected don't you? Quite a different thing when you are doing max revs in one gear and try to disengage the gears and then engage the next ratio which is going to be out of rev sync by maybe 2000 - 2500 rpm or more. The load on the shifter is enormous - this is why they break. If the shifter didn't break then the end result would most likely be mashed gears at best or a smashed housing at worst.

Like I said, if you'd care to demonstrate to me in YOUR car ... :lol:

[mickq]

mickq> It has nothing to do with engine torque or gearbox strength. By your comments regarding this I venture to suggest that you haven't in fact ever achieved a flat change in a manual syncro box without using the clutch. The effect is nothing like side-stepping the clutch in a first gear take-off. To do this you already have the gear selected don't you? Quite a different thing when you are doing max revs in one gear and try to disengage the gears and then engage the next ratio which is going to be out of rev sync by maybe 2000 - 2500 rpm or more. The load on the shifter is enormous - this is why they break. If the shifter didn't break then the end result would most likely be mashed gears at best or a smashed housing at worst.

Like I said, if you'd care to demonstrate to me in YOUR car ... :lol:

Sorry buddy but you are wrong.

Ive done it many times in various cars.

You get a nice cringe-worthy clunk for sure, but certainly Ive never broken anything as a direct result.

I was referring to the forces on the gearbox when I mentioned a 1st geear dump. And again, it is much more brutal than a clutchless flat-chat change.

You think 2000 revs hitting instantly is a lot? Try 5500 and a clutch dump. It involves forces going from 0 to 450Nm with close to 240kw instantly. (Actually near instantly- the clutch will usually bounce for a fraction of a second). Makes a flat change seem very, very tame. Not only hard on the gearbox, but the diff and driveline as a whole.

And torque is a VERY large contributor to the effects of any mal-formed gear change, especially on an XR6T where the gearbox stength isnt as perhaps it should be.

Being off by just 2000-2500 revs isnt a big deal. You can have similar fun by double clutching down without the clutch pedal being used, but not increasing the revs the appropriate amount. Result? Instant 2000rev+ discrepancy between road speed and engine speed. The gearbox cops it big time, but it usually wont disintegrate any part of a healthy gearbox.

At least not in any car Ive done it or flat changing in. (In general tending to be European and Jap cars).

And dont try to tell me you cant do a 2500 rev variance double clutch without using the clutch pedal either. You can. Up or down.

As I said, I havent yet found a gearbox that cant be forced into any gear at any speed. The result depends on the strength of the gearbox and how much the gear and speed varies from the chosen gear. Of course if you are pussyfooting around with your gear changes, you wont be able to get it into gear. It requires a little more forceful gearchange than normal.

[NT TURBO]

Remind me not to buy a car of you!