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Flatshifting

joeyjoejoejuniorshabadoo
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joeyjoejoejuniorshabadoo Grand Master

joeyjoejoejuniorshabadoo

Posted
Posted

ok so i have a gtst with 265rwkw, all the usual supporting mods, an unknown clutch (wont know till i blow it i spose) and a nismo 1.5way diff.

how risky is it for me to be flatshifting on:

a) street tyres (245/40/18 RE001's) on the street ( theoretically of course :) )

b) semi's

c) the strip

thanx :D

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The Bogan Grand Master

The Bogan

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Flatshifting from 1st-2nd and 3rd-4th no problem. Hard part is across the gate like 2nd-3rd.

If you get this wrong on a car with good power, say bye bye to your box.

I have to pause between 2nd and 3rd for a second or a ,orrible sound of syncro,s griding is what i get, ive tryed double clutching which only works sometime, and ive got a newish excedy single plate.

Read in HPI somewhere you can grind of every second syncro for a smoother shift but that sounds a bit bush mechanics for me.

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The Bogan Grand Master

The Bogan

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Double clutch=Example-if im in 2nd and want to go to third I, 1. depress clutch and select neutral, 2. release clutch, 3. depress clutch and select 3rd, 5. release clutch.(it sounds tricky but is easy as with a bit of practice)

Flat shift= Example-if your in second when you change to third you dont release the accelerator you just punch the clutch in throw it in third and release the clutch (and hold on because your about to loose traction)

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joeyjoejoejuniorshabadoo Grand Master

joeyjoejoejuniorshabadoo

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Hmm....

The only times i would flat shift is if i know i'm going to spin the wheels. ie 1st to 2nd.

i think your car would spin 2nd to 3rd.

dont flat shift if its going to grip, thats asking for trouble.

i change pretty quickly when i'm giving it some... and even without flatshifting i tend to chirp 2nd 3rd and 4th

the car will spin 1st to 4th no worries if i flatshift....

so maybe on the strip with warm tyres its not a great idea?

just curious as the nismo diff is going in very soon and the car will be seein the strip for the first time and i dont wanna be trailoring it home

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blind_elk Grand Master

blind_elk

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mlr, double-clutch is used for down changes, not up changes. It is designed to match the speed of the engine to the speed of the gearbox. Between steps 2 and 3 (while clutch is engaged, but gearbox in neutral), you would also give a blip on the throttle to bring the engine revs up over what they were when you commenced the down change, so the the engine is revving fast enough to match the road speed. In most modern cars with healthy synchromeshes, it is not actually necessary to release and re-engage the clutch in the middle part (steps 2 & 3 - what happened to 4?), but simply "blip" the throttle. This is commonly referred to as "heel-toe".

Hamish, if you enjoy bouncing the engine on the rev limiter on every (up) gear change, then by all means go ahead and flat shift. Unless you have the supporting electronics, I would strongly advise against the practice.

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The Bogan Grand Master

The Bogan

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Step 4 was me swearing at the car.

Double clutching helps me between 2nd and 3rd, this i know for a fact. If i dont double when im up it it grids, if i double it generaly doesnt.

My box has about 170k on it so the syncros are sure to be worn.

You dont need to blip it going up gears only down, to match engine speed to road speed.

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Tezzah Experienced

Tezzah

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i change pretty quickly when i'm giving it some... and even without flatshifting i tend to chirp 2nd 3rd and 4th

the car will spin 1st to 4th no worries if i flatshift....

so maybe on the strip with warm tyres its not a great idea?

just curious as the nismo diff is going in very soon and the car will be seein the strip for the first time and i dont wanna be trailoring it home

The point I was trying to make is that you have to do a judgement call on LOAD.

When you drop the clutch and spin the wheels, there is significantly less load on the flywheel>clutch>gearbox>drveshaft>diff>half shafts...... then there would be if you did the same thing, but the wheels GRIPPED.

When you chirp gears, thats different to flat shifting. You're typically not transferring 100% torque through the driveline. (50% throttle or so)

heck, even some high HP cars will always chirp no matter how soft you shift =D

and of course, all of these techniques transfer more load then smoothe shifting.

judgement call at the time, get a better understanding of what your actually doing with these shifts, and you wont need to rely on forum opinions to tell you if what you are doing is safe.

Personally, at the 1/4mile, when your going for a good time, you want to chirp as many gears as you can, without spinning the wheels. But just know you are stressing the driveline. But you cant get a good time without doing so. it is a test of your car's capabilities after all...

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Tezzah Experienced

Tezzah

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you mean from just smashing the limiter?

Ignition cut rev limiters are baaaaaaaaaaaaaaad.

Step 4 was me swearing at the car.

Double clutching helps me between 2nd and 3rd, this i know for a fact. If i dont double when im up it it grids, if i double it generaly doesnt.

My box has about 170k on it so the syncros are sure to be worn.

You dont need to blip it going up gears only down, to match engine speed to road speed.

Perhaps your pressure plate is knackered?

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The Bogan Grand Master

The Bogan

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Posted

Na pressure plate was replaced w/ clutch and was doing it before they were replaced.

Back on topic, ive broken axles, driveshafts and a shifter once when i got a bit carried away once but that was in my old LJ torana.

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