T56 Shift Mods

[k31th]

Bloody hell, we have well and truly established how the load is taken off the box keif...

No load = easier time on the gearset (and any other intermediaries) for shifting.

In a dog arrangment the revs come down as the dogs engage and the revs just get pulled down pretty much. Its a brutal process.

That's correct.

Take your foot off the accelerator at the right rev-matched-point for the next gear (remove the load) and it'll slot straight into the next gear. The "brutality" of the shift depends on the alignment of gear ratio's and revolution speed.

In a syncromesh box a cone shaped clutch arangment allows the shafts to spin up to the same speed which is somewhat aided by pushing the clutch in and the revs naturally fall. It just simply takes fkn longer than 2 dog rings smashing into each other and engaging when they line up which happens very quickly.

So how the fark is this overcome with sycros. that's all I want to know lol. I belive its possible.

That's correct. The remaining load is transferred through the sychro. Lessening the load is ideal (spark-cut or throttle closing). Removing the "intermediary" (e.g. dog-engagement) is the most ideal situation as the load is transferred to the drive gears and gear shafts (much stronger).

If you shift at the right point (gear ratio and revolution speed alignment) it'll slot straight in as fast as you can move the selector.

[Mrs Jeturbo]

[Ralph Wiggum]

Will the gear stick take off?

Barnz, the synchro is designed to brake the driven element to match speed. Removing the engine load reduces the requirement to brake and if the duration of the spark cut is the same/slightly longer than the time it takes for the synchro to align BEFORE the braking portion of it function occurs it's possible to shift without a clutch

Not point discussing dog/straight cut gears as a dog clutch is designed to shift under load (basically has larger "windows" of alignment hence can be forced through under load) and a straight cut gear can also be using in synchronised applications

the simple fact is cut spark slightly before and during and after the shift to given the synchro time to align and engage and you can shift without reducing throttle input/engine RPM and thus retaining boost on the shift.

"Under Load" probably isn't the best way to describe it, also im not suggesting it will do wonder for the longevity of the box but it is doable.

[Ralph Wiggum]

My Opt 5 clutch can't handle a shift that falls back into the peak torque area. Here's a vid of short shifting with the clutch remaining engaged on all shifts and the foot pinned to the firewall. Stock T56. Ralphy's genius ideas at play again :-)

Mate I just handed you the ball, you're the one that kicked it.

Fuck that vid makes me miss the blue meanie and the wot box.

[BenDoCo]

Sooooooooooooooooooo

Straight shift you say --- awesome

I remember (yes you guessed it) back in my day there was a shifter for the 3 speed boxes called an Impala shifter.

Worked by using a spring to press down the shifter to simulate going across the gate.

T'was awesome fun

[IH8TOADS]

That was a 125ms ignition cut activated via the top clutch switch. So you can keep your foot pinned and pull/push on the lever...which won't budge under full power. If you're shifting into 2nd for example, you pull on the lever and as soon as you just gently tap the clutch pedal to activate the ignition cut, the lever slides into the 2nd with ease. Best way to describe it is like shifting with the car off....that's how it feels. The ignition cut allows the input shaft to slow and the sychro's to mesh. As Raphly mentioned, the clutch need to be beefy as when ignition comes back on and the revs fall back to peak torque with bulk boost, all hell breaks loose.

[k31th]

when ignition comes back on and the revs fall back to peak torque with bulk boost, all hell breaks loose.

This is the BEST part

[turboknapp]

I have a blue car

[camo86T]

Great reading, guessing this sort of setup would be sell-your-mother type pricey?

And wouldn't necessarily fit a tr-6060...

I bet impellor would be excited.

[Ralph Wiggum]

This is what Toads is using (complemented by his high level tuning skills)

http://www.npcompleteperformance.com/wotbox