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Flat shifting at drags?

JH32

By JH32,
in Engines & Forced Induction

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gtrken Grand Master

gtrken

Posted
Posted
Originally posted by JiMiH

Does it hurt the engine/gearbox/clutch/anything?

Cheers! :(

Yes, yes , yes and yes unless you are running a sequential boxed, fullshift rev cut Motec or Autronic then don't try it.

Ken

GTS-t VSPEC Grand Master

GTS-t VSPEC

Posted
Posted

It is possible to do, by matching revs, but the likelyhood of getting it right is slim. You can do this with a dogbox arrangement as there are no synchros.

The other option is to have your foot flat to the boards, clutch in, change gear, clutch out. If you keep your foot hard on the accelerator then you won't loose as much revs as normal shifting. This has the negative effect of loading up the clutch and gearbox.

In general you won't make sufficient time gains to make this worthwhile, as the risk of damaging some part increases.

See'ya :burnout:

JH32 Grand Master

JH32

Posted
  • Author
Posted
Originally posted by GTS-t VSPEC

The other option is to have your foot flat to the boards, clutch in, change gear, clutch out. If you keep your foot hard on the accelerator then you won't loose as much revs as normal shifting. This has the negative effect of loading up the clutch and gearbox.

ahh right this is actually what I was reffering to :D

i thought this was called flat shifting!

my bad!

so does this damage the clutch and gearbox when you load it up?

fatz Grand Master

fatz

Posted
Posted

most comps have a setting

you keep your foot burried it cuts ignition timming but not the fuel

pop the clutch and boom lots of zorst flame but a very quick spool of turbo casu of excess fuel

still very harsh on you clutch and box

worth it for the flames if you have a shtter of a car

pete

GTS-t VSPEC Grand Master

GTS-t VSPEC

Posted
Posted

JiMiH,

I think flat shifting is not using the clutch, and power shifting is not lifing your foot from the accelerator. But it could be the other way round.

I use power shifting while at the drags, it provides more punch between gears and keeps the revs higher in the power band. I do have a twin-plate clutch, so I think both it and the box can handle it fine.

It's worth giving a go, might improve times slightly.

See'ya:burnout:

slip Mentor

slip

Posted
Posted

jimih i wouldnt do it unless .1 of a second is important enough to you to justify the cost. It is not good for the box or clutch. Superbikes/GP Bikes have a special button to do this, but a bikes gearbox is different. V8 Supercars have a gearbox that can cop it. If you can afford to go through gearboxes then go crazy.

Revhead Grand Master

Revhead

Posted
Posted

Agreed - it's not worth it. One thing I do occasionally is to blip the throttle while the clutch is on the floor. Keeps the revs up without the sudden shock through the driveline.

I've always referred to flat shifting as holding your foot flat to the boards (hence the term 'flat') and changing gears as normal. The other method you refer to I've always called 'clutchless shifting'. This may or may not be the correct terminology but it's the terminology I've always used.

I would NOT bother with clutchless shifting either, unless you have a constant mesh/sequential gearbox in your car, or you're on a bike.

If your car is primarily a road car, treat it as such... just drive it like a much faster version of how you drive on the streets.

  • 2 weeks later...
Cubes Grand Master

Cubes

Posted
Posted

I've always flat changed but the rev's don't go higher as they don't have time. :)

I learnt in a Mild TE 250 Cortina 4 speed.

I soon learnt how to pull out the gearbox and replace syncro's and especially select forks.

VL 5 speed 3ltr.. Started crunching second after only a few quick changes.

The V8 T5 Commodore gearbox didn't like it, she started to pop out of gears and crunch second and third.

Skyline well so far so good. No crunches, just an input shaft bearing whine that was there from the start but is now getting worse.

b2barker Enthusiast

b2barker

Posted
Posted
Originally posted by gtrken

unless you are running a sequential boxed, fullshift rev cut Motec or Autronic then don't try it.

Or a T-SPORT Flat-Shift can do the full shift rev cut what ECU you have. $280. Can someone please try one of these, so I can find out if they are worth the free plugs I keep giving them?

JH32 Grand Master

JH32

Posted
  • Author
Posted
Originally posted by Revhead

I've always referred to flat shifting as holding your foot flat to the boards (hence the term 'flat') and changing gears as normal.  The other method you refer to I've always called 'clutchless shifting'.  This may or may not be the correct terminology but it's the terminology I've always used.

Yeah I was referring to the bit that you reffered to as flat shifting.

Or as GTS-t VPSEC says, Power shifting.

Cheers guys.

51jay Mentor

51jay

Posted
Posted

On the web page they suggest setting it about 2000revs below redline......that maybe ok for gearchanging ....but I don't fancy dropping the clutch at 5700 on the start line!!! especially with around 17psi boost

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