Mechanical Insight Needed

[JenT]

Have a 1300GS. Not mechanically minded so don’t flame me.

When changing from 1st to 2nd (without the QS) most of the time it clicks in fine, a nice tight single click. Then every now and then it will have a real clattering feeling to the shift, feels what I imagine clutch plates spinning and locking kind of thing.

Anyone enlighten me on what’s going on here?

 

[SBD]

Sounds like the synchro isn’t working as well as it might, on occasions. Does it always happen when it’s cold, hot, hard acceleration, trundling round town, or is it random? Presume the oil is ok.

 

[leadfarmer]

You’re probably changing too slowly and letting the revs drop too much, just be positive with your gear changes

 

[Schtum]

Sounds like the synchro isn’t working as well as it might, on occasions. Does it always happen when it’s cold, hot, hard acceleration, trundling round town, or is it random? Presume the oil is ok.

I can't think of a single motorcycle that has ever had synchromesh cones in its gearbox.

 

[Santa-2512]

They all do that sir

 

[JenT]

Sounds like the synchro isn’t working as well as it might, on occasions. Does it always happen when it’s cold, hot, hard acceleration, trundling round town, or is it random? Presume the oil is ok.

Motorcycles don’t have synchros do they

I can't think of a single motorcycle that has ever had synchromesh cones in its gearbox.

This!

 

[JenT]

They all do that sir

So you know what I mean?

Do you know why it does it?

 

[Santa-2512]

So you know what I mean?

Do you know why it does it?

Sorry, supposedly its the stock response when asked

i have a a tractor TC, so silence would make me worried lol

 

[pbbanks]

Have a 1300GS. Not mechanically minded so don’t flame me.

When changing from 1st to 2nd (without the QS) most of the time it clicks in fine, a nice tight single click. Then every now and then it will have a real clattering feeling to the shift, feels what I imagine clutch plates spinning and locking kind of thing.

Anyone enlighten me on what’s going on here?

What sort of speed and revs are you trying to change into 2nd when you have problems.

 

[SBD]

Sounds like the synchro isn’t working as well as it might, on occasions. Does it always happen when it’s cold, hot, hard acceleration, trundling round town, or is it random? Presume the oil is ok.

Apparently not

“Most modern manual motorcycle gearboxes have "constant-mesh" gears which are always mated but may rotate freely on a shaft until locked by a toothed sliding collar, or "dog clutch". Since the gears are always rotating and can only be accessed sequentially, synchromesh is not generally needed. To save space, both shafts may contain a mixture of fixed and free-spinning gears, with some gears built into the sliding parts”

I haven’t had a bike gearbox to bits for 40 years, so please forgive the assumption.

I’m perplexed however. Typical manual car gearboxes are all constant mesh too, but the do have synchromesh cones. Perhaps synchro is not needed as the gears are sequentially selected and adjacent, but perhaps the much lower inertia of the bike & rider, and the rotating parts, means the cost and weight saving is possible.

Anybody in the know?

 

[leadfarmer]

Anyone enlighten me on what’s going on here?

What you hear clattering is the dog ring engaging into a gear, you’ve probably got too much difference in speed between the engine and transmission as said before

Here’s a good explanation of how a motorcycle gearbox works

 

[LOLGEOFF]

The obvious difference is you can change from any gear to any gear, block change, in a non sequential gear box, eg 1st to 6th without going through the gear range. With a sequential box you have to go up through the gears and back down again, you might dab down to first when coming to a stop without letting the clutch out but you've still selected all the gears in between.

 

[JenT]

What you hear clattering is the dog ring engaging into a gear, you’ve probably got too much difference in speed between the engine and transmission as said before

Here’s a good explanation of how a motorcycle gearbox works

Thx. The video is super helpful. Any harm or damage to the dog rings or just normal wear and tear?

 

[JenT]

What sort of speed and revs are you trying to change into 2nd when you have problems.

Prob between 3-4k

 

[pbbanks]

Prob between 3-4k

I found changing into 2nd just using the quick shifter as soon as you were moving and on a steady throttle work fine on my 1300gs.

 

[Troppo]

About 3000 RPM, relatively light load: 1-2 just snicks in.

 

[Pukmeister]

You might have a dragging clutch if the gear dogs are baulking on engagement?

I was told NOT to use the quick shifter between 1st and 2nd due to the large ‘gate’ action through the neutral position plus the large difference in ratios. As you go up the box the difference in ratios is progressively less so gears shift faster.

I always use a firm positive action between 1st and 2nd to effectively push the dog clutch pawls together.

I always downshift using the clutch, I don’t like the QS method at all.

 

[MotoRevive]

Are you using it correctly ? Most of the problems and complaints we get in a dealership from QS is incorrect usage or unrealistic expectations.

Read the manual. It's actually very specific.

You must have a constant throttle when using it. Not opening or closing.

It also won't let you do "bad changes". It can't over-ride huge differnces in engine speed and transmission speed. You have to change gear like you should. You can't slam into gear at the wrong engine speed and expect it to be smooth.

You'll find the QS will let you UP-change gear without the clutch easier at lower revs.

You need to firm and smooth with the lever. Not fast slam changes like a race bike.

The QS wont work if you try to down shift if your engine speed is too high to match the transmission speed. Engine speed needs to be pretty low for a downshift. Probably too low in my personal opinion.


I always get sent out to test ride bikes which have been brought in for "QS not operating correctly". I've not ridden one in a long long time which wasn't working exactly as intended.

 

[theop]

I can't think of a single motorcycle that has ever had synchromesh cones in its gearbox.

Indeed. In motorcycle gearboxes all gear are always "in mesh", thus no need to synchronise anything. I believe their "sequential" effective design is the reason for it.

I think the issue is that 1st to 2nd gear goes through the neutral gap and perhaps the OP is not using enough positive force on the shifter. I think an early 05 1200GS I used to run was need a heavy foot or it would often produce false neutrals changing up...

 

[GS TRV]

I think it's just called character