Forum

[ogri]

May I ask why would anyone want to be sitting at the traffic lights with the bike in gear, even with/without a dragging clutch???

[jefrs]

Papasmurf, well aware how a sequential constant mesh box of tricks works. Raising revs to match speeds is so the clutch doesn't burn the plates.

Merely pointing out that a synchromesh has sprung dog teeth not friction plates, fyi an old school hydraulic/fluidic auto box does have friction plate clutches between gears, it's how it works.

Putting it into neutral is a well known method of making the lights turn green. At which point I jab the brake pedal into first and get a fistful of nothing.

Depending on how long the lights take, usual method is to sit on bike in first with clutch in, foot on brake, so there's no embarrassing wobble switching feet, grabbing the front brake whilst attempting to open the throttle and let the clutch out.

[Dennis C]

Told you so Papasmurf

[Thack]

There is one other cause of a dragging clutch, which is worth looking at if the usual adjustments don't work. It was common on older Brit bikes, but I've never found it on a modern Japanese bike.



The cause: wavy or distorted clutch plates. The friction plates were the most likely to distort. If they aren't completely flat, the clutch both drags AND slips (given enough torque).



On my 2002 Bullet I improved it a lot by testing each friction plate on a piece of plate glass. Hand pressure is all you need to bend them back into shape so they are as perfectly flat as you can get them.



I don't think any of this applies to the UCE bikes. The clutch on my 2014 model is brilliant.

[Thack]

Just a minute..... I've scanned jefrs's latest, and I have to say it doesn't sound like any synchromesh gearbox I've seen.



They DO have friction plates, except they are cones rather than plates. The friction from these cone clutches is what causes the synchro rings to block the gear engagement until the two elements are rotating at the same speed.



And what's all this guff about "sprung dog teeth"??? They aren't sprung!

Still, jefrs doesn't need to look inside one to be an expert on them.

[Scalyback]

"Sprung dog teeth"?


well, I had a dog spring out at me once, and it certainly had teeth.


However, blipping the throttle is good for a change down as Jefrs says. It helps match the clutch plate speeds, reduces wear and is quite pleasing when done well.

I think he meant to say that if done badly, it can turn into a synchro-mess?

[Beezabryan]

Jeffers advocates sitting at trafic lights holdin the clutch in and first gear engaged, that is abuse of the clutch & the box, bloody stupid.

[Leon Novello]

Anyone who has driven a pre-war truck /lorry will know most of the gearboxes had no synchromesh and they had to double declutch and give rev the engine to change down. Skilled drivers could gear-change without using the clutch at all by matching the engine speed to the speed of the gears driving the wheels.

[papasmurf]

The ancient Albion Clydesdale tractor unit I used to drive back in the 1970's had a six speed constant mesh gearbox.
A whole 56mph flat out downhill with a following hurricane.

[Beezabryan]

No crash boxes now Leon, no clutch pedal either, they are just a bigger version of the squirt & go scuttler