Author Topic: Crankcases assembled but can't select gears  (Read 2327 times)

Offline ebmbiker

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Crankcases assembled but can't select gears
« on: May 26, 2022, 11:44:04 AM »
Hello again folks,

I've got my crankcases assembled, no top end on. When I rotate the input shaft by hand and use the gear shift lever, it won't shift through the gears. The selector drum only rotates a small amount. The shafts rotate easily and the output shaft is engaged and rotating.

Any ideas?
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Offline Oddjob

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Re: Crankcases assembled but can't select gears
« Reply #1 on: May 26, 2022, 12:06:49 PM »
Did you assemble in the top case or bottom case?

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Offline ebmbiker

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Re: Crankcases assembled but can't select gears
« Reply #2 on: May 26, 2022, 12:18:31 PM »
Did you assemble in the top case or bottom case?

I assembled in the top case. I'm using the Haynes manual.
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Online McCabe-Thiele (Ted)

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Re: Crankcases assembled but can't select gears
« Reply #3 on: May 26, 2022, 12:58:57 PM »
Is your engine on the bench or in your bike?
If it's on the bike is the lever unimpeded?
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Offline ebmbiker

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Re: Crankcases assembled but can't select gears
« Reply #4 on: May 26, 2022, 01:14:06 PM »
Is your engine on the bench or in your bike?
If it's on the bike is the lever unimpeded?

Engine is on the bench Ted.
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Offline ebmbiker

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Re: Crankcases assembled but can't select gears
« Reply #5 on: May 26, 2022, 01:24:07 PM »
These are the limits of movement of the selector drum
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Offline ebmbiker

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Re: Crankcases assembled but can't select gears
« Reply #6 on: May 26, 2022, 01:24:56 PM »
Second position
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Online McCabe-Thiele (Ted)

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Re: Crankcases assembled but can't select gears
« Reply #7 on: May 26, 2022, 01:46:20 PM »
Sorry I do not think I can help you as it's outside my limited knowledge.

Only question I would ask is was the gear selector drum/selector forks  in the neutral position when you assembled the gearbox internals ?
Honda CB500 K1 (new pit dug out ready)
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html

Offline ebmbiker

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Re: Crankcases assembled but can't select gears
« Reply #8 on: May 26, 2022, 01:55:01 PM »
Sorry I do not think I can help you as it's outside my limited knowledge.

Only question I would ask is was the gear selector drum/selector forks  in the neutral position when you assembled the gearbox internals ?

I can't be sure if it was in neutral. The shift drum guide screw [the part that screws in from the top of the crankcase] that I have is the later version without the ball and spring. So there's nothing to fit into the detent on the drum.
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Offline Sesman

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Re: Crankcases assembled but can't select gears
« Reply #9 on: May 26, 2022, 02:28:58 PM »
I’m no expert and the photo is upside down. But that drum appears to be 180deg out of position. In the neutral position the wheel should be nestled in the neutral drum recess. So you might be correct Ted. The gearbox my not have been assembled in the neutral position.

Offline ebmbiker

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Re: Crankcases assembled but can't select gears
« Reply #10 on: May 26, 2022, 02:34:03 PM »
Makes sense. I'll start dismantling it! Everyday is a school day!
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Offline Sesman

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Re: Crankcases assembled but can't select gears
« Reply #11 on: May 26, 2022, 02:35:22 PM »
Like this

Offline Sesman

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Re: Crankcases assembled but can't select gears
« Reply #12 on: May 26, 2022, 02:44:01 PM »
Is the cam plate correctly assembled. It’s difficult to get wrong as only one locating pin is ‘raised’ relative to the others. If not the drum is in the wrong orientation, which is equally difficult to get wrong! Good luck.

Offline Oddjob

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Re: Crankcases assembled but can't select gears
« Reply #13 on: May 26, 2022, 02:51:28 PM »
I'd say you are right Phil, the top roller goes into the indent in the pin plate when it's in neutral, it's so you get a positive selection of neutral when you need it.
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline ebmbiker

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Re: Crankcases assembled but can't select gears
« Reply #14 on: May 26, 2022, 03:02:56 PM »
Cheers guys for the continued advice and wisdom. I need to get an M12 X 1.25 metric fine bolt so I can draw the primary shaft off. My car mechanic mate might have an actual slide hammer.
"Fast Beat The Feet!"

 

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