After reassembly following gearbox refurbishment, I cannot change down from 3rd to 2nd without an embarrassing and painful grinding of gears....finding it better to stop completely. Changing up through gears is fine, and I think I have followed all handbook instructions for adjustment of cable, pushrod etc. I wonder if I should continue to slacken the single spring and stops in order to allow the plates to separate more.
Any suggestions?
I think it would be worth adjusting the stops slightly to give a little more movement but if you adjust the main spring too much it will end up slipping. Also because they are not constant mesh gearboxes you do have to match the speed but I find that is easier said than done.
As an aside to this as my latest bike is an AJS K8, the instruction book recommends not to change down if your speed is above 15mph.
I have heard of a Register member ( hope it's true) who does clutchless changes using his left hand on the gearlever, I would guess that if you can do that then you would be able to match gearbox and engine speed for noiseless changes, not sure you could reach the lever on saddle tank bikes though.
Clutchless changes are possible without any drama on both my AJS G8 and my 1916 Model H Triumph. The Triumph instructions recommend it instead of using the clutch by using the decompressor to reduce engine speed instead of throttling back. Id agree with holding on to top gear - Im always impressed with how these engines will pull away at revs that you know would stall a lesser machine :)
Steve
I'd agree, speed is the issue. If your clutch isn't noticeably dragging -ie if you push the bike in gear, clutch withdrawn, it rolls freely - I don't think there's much to be gained by increasing lift and certainly as already said, slackening the spring won't help and may lead to slip.
I think the clutch stops should be set only to make contact when you pull the lever all the way to the handlebar, otherwise they will be rubbing away pointlessly at every gearchange. If you think about it, they only have any effect when changing into gear from neutral, because they bear on the clutch pressure plate which rotates with the gearbox mainshaft and so, in any gear, the pressure plate rotates with the wheel whether the clutch is in or out and the stops can't stop that!
Someone told me to think of Sunbeam's three speeds as 'pulling away, town and country' and if you look at it that way it makes more sense. The big flywheels and a bit of ignition retard should see you through most road situations without needing to change down and at junctions, you pull up in top and change into first when stationary, like a car.
On hand change bikes I set the friction on the twistgrip or throttle lever so it doesn't return by itself; that way on a down-change you can leave it a tiny bit open so that when you pull the clutch lever, the revs rise giving you an automatic throttle blip while your throttle hand is busy with the gear lever. But it doesn't work on Sunbeams, because, I think, the heavy flywheels are too slow to react. So instead whenever I have to change down when rolling, I pull the clutch, wait for the revs to drop to tickover and change then. That seems to work on my BT box but I guess it's easier with a close ratio CT and harder with a wide AT.
Cheers Rick
Many thanks to Rick, Greybeard, Shorrog and singleminded for your very helpful suggestions! The more I think about it, the more I realise the answer may be "operator error"! Too much time riding other bikes which don't have the idiosyncracies of my lovely 'beam......but they do have others! When it stops raining, I'll try again! M Thanks, Frank.
Hi Frank,
I ride a '28 Model 8 with no clutch stops but incorporating a dare I say it Norton "mushroom" to push out the presser plate. As a result the clutch clears completely, stationary or moving. With this condition and with the bike fitted with throttle levers as opposed to a twist grip I as Rick as eluded to double de-clutch; leaving a little throttle open pull in the lever as the rev's rise quickly move the gear lever into the natural position between the gears, re-engage the clutch quickly to spin up the gears and pull in the lever again and shift down. It sounds complicated but it's the same procedure as driving a car, van or truck with no syncromesh, it does need practice and after a while getting down shifts to 2nd and 1st can be made silently and with no damage to the gears.
Best regards,
Tom.