clutchless shifting

[karthik]

how does clutchless shifting work?? for example in a racing sequential gearbox, if the driver doesnt use the clutch, how does he match the revs?? i mean its a tight situation where he s left with no time to think??

 

[John]

The sequential box in my seven is linked via a load sensor on the shift lever to the computer, when i go to change up the load sensor reads at a preset weight 8kg and sends a signal to ECU which then cuts fuel and ign for an also predetirmind time, ie 1st -2nd change is 80ms, 2nd -3rd is 70ms, 3rd to 4th is 60ms 4th to 5th is 50ms and 40ms 5th to 6th, the reason is as the ratios get closer the shorter the cut, and the changes are almost imposible to feel, you just hear the engine note change,
downshifting is heel and toe or left foot brake with a blip
the one of many beifits is i can change up under WOT mid cnr with out upsetting the car in anyway, ie upset traction.
box in question is a Quaiffe 6 speed sequential dog box.
hope that helps
cheers John

 

[colin artus]

You need a gearbox with dog engagement rather than synchromesh; slight lift of the throttle on the way up and heel'n'toe with throttle blip on the way down, to match the revs and prevent wheel lock up. Modern boxes with ecu control and solenoid actuation can do all of this for you.

 

[karthik]

thanks for that folks.....colin you live in the uk right? can u tell me whether uk has institutions where i can pursue a masters in automobile engineering?? i personally like the united kingdom so want to study there

 

[colin artus]

My cousin did a phd (valvetrain vibration analysis) at Cranfield Institute of Technology (they may have changed their name since then) and I should think Imperial College (London) would have related courses. There are probably many others.

 

[Troy]

I too have a sequential 6 speed transaxle which I am currently fitting to my GT40. It runs straight cut gears and dog engagement. The shifter is set up exactly as John has described above. The change mechanism inside the trasmission runs a barrel with machined pathways for the forks to follow. This is the main difference inside the gearcase.

Also, try Brooklands College in Weybridge (UK). They have specific Motorsport Engineering courses.

 

[Frank Catt]

Besides the upshift similar to described above, we use a downshift that is very simple and works extermely well ( on a motorcycle engined single seater ) which can be adapted to heavier sequencial boxes. Pressure on the gearlever towards downchange operates a solenoid that breifly opens a vacuum line to a vacuum operated lever that blips the throttle. Downchanging is as fast as you can move your hand, and the only pedal you need is the brake ! no clutch or throttle.

 

[Darin S]

Firstly I would like to say I love this website. Focusing our use of maximum RPMs of the engine at usable power, but in order to shift, the load on the transmission has to be reduced in order to shift. Not taking into consideration, passing, braking, raceline, acceleration, etc. But the clutch is still used in first gear while starting off.