LBMEFM
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| posted on 22/6/10 at 08:36 PM |
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Gear Changing
Out in my MK Indy-Blade at the weekend I tried some clutchless changes, I know on a car that this can damage the syncro/gears but I believe I heard
somewhere that it is acceptable on bike transmission. Any comments?
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Dangle_kt
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| posted on 22/6/10 at 09:01 PM |
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yeah it is fine, tecnically it can be done on the upchange and downchange, but I only do them on the upchange - and I don't do them if I'm
not caining it - they are a bit jerky if your just crusing but when in "attack mode"  its silky smooth.
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David Jenkins
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| posted on 22/6/10 at 09:20 PM |
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You might find this page useful - it's for a racing gearbox, but the principles are the same.
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bi22le
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| posted on 22/6/10 at 10:00 PM |
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should not be a problem. Bikers do it all day long. Not too sure on the downshift though, i would use the clutch.
It does increase wear but then again so does ragging it in the first place.
I use to always do it on my bec when showing off. Just do what you normally do but with out the clutch. If you dont let off the power it damages the
box more. If you let off alittle then the gear lever will move alot easier.
Now get out in this brilliant weather and annoy your neighbours!
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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JF
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| posted on 22/6/10 at 10:28 PM |
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Yep no probs on the upshift. But you don't want the engine pulling when you shift. As mentioned above slight lift off on the throttle can
already be enough. Personally I use the clutch most of the time combined with slight lift off on my bike. But especially when you rev it, it shifts up
quite easely without the clutch.
Same story with down shifting really. But much harder to get the revs right.
There are special electronic kits you can use to make life easier on both you and the tranny. Micro switches detect when you shift and the electronics
cut the ignition for a few milliseconds. Just enough to take the load of and shift.
[Edited on 22/6/10 by JF]
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nitram38
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| posted on 22/6/10 at 11:20 PM |
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I just use my flatshifter/auto blipper.
Lazy but seemless!
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bigpig
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| posted on 23/6/10 at 06:53 AM |
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As mentioned upshifts are fine if done right.
What I'd be concerned about is wear to the dogs and clutch. On the dogs, the teeth tend to round off at the edges causing the gearbox to drop
out of gear when under load. This would require a gearbox rebuild (of course easier if you have a cassette gearbox).
Common sign of gearbox wear on a bikes is falling out of 2nd gear as this is generally the one that gets the most abuse.
Checking for any fine slivers of metal during oil changes should give you an idea if the dogs are taking excessive wear.
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BenB
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| posted on 23/6/10 at 07:27 AM |
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Personally I use the clutch on both up shifts and down shifts. Mostly because to swap the box I'd have to take out the engine 
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David Jenkins
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| posted on 23/6/10 at 07:51 AM |
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quote:
Originally posted by bigpig
What I'd be concerned about is wear to the dogs and clutch. On the dogs, the teeth tend to round off at the edges causing the gearbox to drop
out of gear when under load.
The Hewland article I posted suggests that using the clutch INCREASES the wear on the dogs.
[Edited on 23/6/10 by David Jenkins]
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JF
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| posted on 23/6/10 at 08:25 AM |
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Yeah well it is all about the word "proper". When you lift of the throttle properly while shifting yes it probably is best. But listen by
the roadside to bikers coming by you'll hear that very few manage to this properly.
And yeah using the clutch probably will wear it down a bit more I'm sure. But I'd much rather service the clutch, witch is easy to get at
(in a bec maybe not that easy, but still...) and readily available. Changing damaged coggs is a lot more work, much more expensive, harder to get and
where do the filings and chips end up?
Anyway it is all about getting the transmission neutral, load free. Neither pulling or dragging. And then a quick shift. When you get that right there
is very little wear on any part of the transmission.
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