changing gear without the clutch

[Viney]

A bikes gearbox is what is called Sequential, in that to get from 5th to 2nd, say you have to go through each gear ins equence, where as a car, you can select any gear from the outset. For this to happen the gearbox is made up differently and the selector etc move in a different pattern.

Never having a gearbox apart, car or bike, i would assume that the bikes is a single gear shaft, and the cars, 2?? (Not sure on this)

As for changing, well, up for me is almost natural, down, well that take some doing, and can break the box and not advised!

Originally Posted by Viney

A bikes gearbox is what is called Sequential, in that to get from 5th to 2nd, say you have to go through each gear ins equence, where as a car, you can select any gear from the outset. For this to happen the gearbox is made up differently and the selector etc move in a different pattern.

Never having a gearbox apart, car or bike, i would assume that the bikes is a single gear shaft, and the cars, 2?? (Not sure on this)

As for changing, well, up for me is almost natural, down, well that take some doing, and can break the box and not advised!

Not sure about bikes... But I think that cars have 3. Input to lay to output - layout makes you thik there is only two as the input and output can be at the same height (IIRC it is on my Spitfire) on a RWD car. The lay shaft (I could be getting the terminology wrong here ) sits below the input / output shafts.

Stu

[Viney]

Originally Posted by MavUK

Not sure about bikes... But I think that cars have 3. Input to lay to output - layout makes you thik there is only two as the input and output can be at the same height (IIRC it is on my Spitfire) on a RWD car. The lay shaft (I could be getting the terminology wrong here ) sits below the input / output shafts.

Stu

Yeah something like that, where as a Sequexntial 'box moves in a liner fashion along the shaft?

Originally Posted by Viney

A bikes gearbox is what is called Sequential, in that to get from 5th to 2nd, say you have to go through each gear ins equence, where as a car, you can select any gear from the outset. For this to happen the gearbox is made up differently and the selector etc move in a different pattern.

Never having a gearbox apart, car or bike, i would assume that the bikes is a single gear shaft, and the cars, 2?? (Not sure on this)

As for changing, well, up for me is almost natural, down, well that take some doing, and can break the box and not advised!

it's not that the gearbox is sequential, its because it is constant mesh rather than syncronised mesh engagement

with a constant mesh, all the gears are engaged all the time, you just choose which gear you want, with syncro mesh, they are not, when you choose the gear you want , a syncronizing ring syncronises the gear then engages it .

you can start in any gear or select any gear you want on a bike, you just have to click thru the gears in order till you find the one you want,

The only time I use the clutch on an upshift is on the 1-2 shift simply because many times you will get a false neutral if you dont. Its a little embarrasing when
you rev to the moon and dont mean to. I learned this from the owners of a local bike shop here in Miami who are track racers and have been on sv's. I do however, use the clutch on the way down simply because i am a big fan of engine braking and rev matching. I dont know why the gearbox works this way but a friend said something about a wet clutch vs. a dry clutch and not to try this on a Harley!

Originally Posted by RandyO

with a constant mesh, all the gears are engaged all the time, you just choose which gear you want, with syncro mesh, they are not, when you choose the gear you want , a syncronizing ring syncronises the gear then engages it .

Not quite right. Both syncro mesh and constant mesh are very similar. All gears are meshed all the time. IIRC the gears on the input shaft spin freely on the shaft for both types. Between the gears on the input shaft are hubs that are locked to the shaft but can slide along it. In a synchro mesh gearbox these hubs have a clutch mechanism that synchronise the speed of the gear to the hub and also help align the dog teeth that locks the hub to the gear. In a constant mesh gearbox there are dog teeth but no mechanism to synchronise the speed. Looking at pictures I have seen on this forum the dog teeth on the SV are very large blocks on the side of the gear. On car gearboxes I have worked on they are very much finer/smaller in size and have leading edges to help them engage.

What I don't understand with constant mesh types like the SV gearbox is why you do not get any crunching of the dog teeth when changing gear.

IIRC the reason you have to go through the gears on a bike is the design of the gear selector mechanism not the gearbox itself. There should be no reason why you could not have a car style gear selection mechanism, but why would you want a gear lever on a bike!

Kind regards
Tim