Motorcycles with Synchromesh Gearbox?

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Gears mesh with other gears. Constant mesh gears are meshed with another gear all the time.
Ok, I'll let you call it what you want. But you need to understand the difference between the transmission in the Norton and the one in your car. They are not the same.
 
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Swooshdave said:
Ok, I'll let you call it what you want. But you need to understand the difference between the transmission in the Norton and the one in your car. They are not the same.
If you’re worried about my understanding, you can take comfort from the fact that I didn’t write this lot:

For cars there’s a host of reasons why constant mesh isn’t desirable. Sequential shifting and straight-cut (as opposed to helical gears) noise being just a couple.
 
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If you’re worried about my understanding, you can take comfort that I didn’t write this lot:
Also keep in mind I was describing the dogs not the gears. And also why synchro boxes aren't in motorcycles. But you keep misquoting me all you want.
 
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A NHT amc gearbox is constant mesh - dog engagement - sequential -
Plus "common shaft" unlike the other harley honda ducati where the power comes in one shaft but always exits another.
 

Tornado

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In this (straight cut toothed) example, you can see that the dogs’ rotational speed on the free-running gear and the “splined hub” are synchronised by the cones.

The hub is slid along the shaft. The gear is not.

So after watching the video linked by SwooshDave and from this diagram, is it the parts labelled in the above diagram "Dog teeth" & "Ring with internal dog teeth" that are making the grinding sound in my Mini when trying to downshift 4th to 3rd?
I did try a bit of double-declutching as recommended by some fellow local Mini enthusiasts...maybe improved a wee bit. I find if I'm really quick on the downshift, no clashing. If I hesistate, like happens when approaching a corner and braking with clutch pressed, before engaging again, then pretty nasty clashing.

Interestingly, the last time I was out on a mountain climb run, I performed about 4 total downshifts and absolutely no clashing happened. Beginning to wonder if it has something to do with oil temps and how the synchro cone friction is affected.
Need to do it's first oil change since purchasing a month ago as oil looks very clean but of unknown weight/type. Apparently Mini's like similar weight as our bikes, 20w50. For those that don't know the Mini's have engine/gearbox in a shared oil bath, much like most modern bikes. So you can't use specialty GB oils and the engine oil needs to be selected based on GB requirements. Valvoline VR1 with ZDDP is considered quite good (as it is for our Commando's), but that stuff is hard to find locally and typically costs $12-$15 a liter. I'm going to use Castrol GTX 20w50 and picked up some ZDDP additive to try with it. There is also a Lucas brand classic car/hot rod oil locally with specifically declares very high zinc content and at a good price. May try it one day.
 
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A NHT amc gearbox is constant mesh - dog engagement - sequential -
Plus "common shaft" unlike the other harley honda ducati where the power comes in one shaft but always exits another.
Yeah Brit factories used to sneer at foreign all-indirect gearboxes, because their Norton boxes and other sleeve gear designs had an efficient direct top gear.

They didn’t emphasise that the lower gears were doubly-indirect!
 
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olympus

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Gears mesh with other gears. Constant mesh gears are meshed with another gear all the time.
This takes me back to my City and guildes HGV apprentice days at tech college, Constant mesh gears are indeed meshed all the time, and there is way that helical cut gears could be anything other than
 
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One reason cars have a gate change is because it’s feasible: you can do things with your hand, that you can’t do with your toe.
 
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So after watching the video linked by SwooshDave and from this diagram, is it the parts labelled in the above diagram "Dog teeth" & "Ring with internal dog teeth" that are making the grinding sound in my Mini when trying to downshift 4th to 3rd?
I did try a bit of double-declutching as recommended by some fellow local Mini enthusiasts...maybe improved a wee bit. I find if I'm really quick on the downshift, no clashing. If I hesistate, like happens when approaching a corner and braking with clutch pressed, before engaging again, then pretty nasty clashing.

Interestingly, the last time I was out on a mountain climb run, I performed about 4 total downshifts and absolutely no clashing happened. Beginning to wonder if it has something to do with oil temps and how the synchro cone friction is affected.
Need to do it's first oil change since purchasing a month ago as oil looks very clean but of unknown weight/type. Apparently Mini's like similar weight as our bikes, 20w50. For those that don't know the Mini's have engine/gearbox in a shared oil bath, much like most modern bikes. So you can't use specialty GB oils and the engine oil needs to be selected based on GB requirements. Valvoline VR1 with ZDDP is considered quite good (as it is for our Commando's), but that stuff is hard to find locally and typically costs $12-$15 a liter. I'm going to use Castrol GTX 20w50 and picked up some ZDDP additive to try with it. There is also a Lucas brand classic car/hot rod oil locally with specifically declares very high zinc content and at a good price. May try it one day.
Apparently there are several models of the Mini gearbox. But I doubt (note: I only did cursory research) that they ever had dog gears (like the Norton). More likely is worn synchros. Why it might have worked on the mountain course is as you downshift while going up as you push in the clutch your wheel speed decreases faster than on flat ground, thus bringing the different gear speeds closer together. Try it again on flat ground and a well warmed up car and see if it still shifts cleanly.
 

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Apparently there are several models of the Mini gearbox. But I doubt (note: I only did cursory research) that they ever had dog gears (like the Norton). More likely is worn synchros. Why it might have worked on the mountain course is as you downshift while going up as you push in the clutch your wheel speed decreases faster than on flat ground, thus bringing the different gear speeds closer together. Try it again on flat ground and a well warmed up car and see if it still shifts cleanly.
Previous to that last outing, I had made a few "return to OEM" mods....one was to actually install a thermostat as the car had none and some kind of by-pass sleeve where the tstat normally lives. This would certainly get the engine up to proper temp better and keep it there. Another change I made...had discovered the clutch throw-out limiter was way out of adjustment, meaning the clutch pedal would push right to the floor. Now at spec adjustment (via adjuster & locking nut on the bell housing operating arm), I can feel pedal making a hard stop just before it contacts floor. Not sure what that change means for the clutch mechanism and potentially GB shafts.
 
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This takes me back to my City and guildes HGV apprentice days at tech college, Constant mesh gears are indeed meshed all the time, and there is way that helical cut gears could be anything other than
Helical gears run quieter and generally nicer, but they introduce end-thrust that has to be handled.
 

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