Author Topic: Gearbox  (Read 5962 times)

Offline cb550k-aaron

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Gearbox
« on: March 27, 2018, 12:27:09 PM »
Hi guys, i'm having bother trying to engage 3rd gear, its only this gear, any suggestions? It was selecting it last year but it would slip out of gear


Offline hairygit

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Re: Gearbox
« Reply #1 on: March 27, 2018, 02:58:49 PM »
Sadly I have seen this a few times over the years, normal cause is a worm or vent selector fork. The 500/4 was well known for it, and the selectors were modified for the 550's but do still fail occasionally. Someone else may have a different view on it, but my money is on the selector fork.

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Offline Bryanj

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Re: Gearbox
« Reply #2 on: March 27, 2018, 03:51:29 PM »
If its been slipping out you will need to change the gears as well as the dogs will have rounded edges. One pair of gears was modified but and must be changed as pairs as the tooth profile altered but cant remember which ones

Offline Bryanj

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Re: Gearbox
« Reply #3 on: March 27, 2018, 05:50:56 PM »
The 550's all use the later setup mate

Offline Tomb

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Re: Gearbox
« Reply #4 on: March 27, 2018, 06:40:33 PM »
Why you're struggling to engage 3rd? when the motor is running?

To stop slipping out of gear it is possible to undercut the gears, an angle of about 3o and ground back a little to sharpen the corners again does it. Careful not to undercut too much of an angle otherwise quick shifting and clutchless shifting is compromised.
Tom
'73 CB550 with CB500 engine café racer
'62 CB77 Sprinter
'70 CD175
'78 CB550 with sidecar
'80 Z50R
And a load of old Yamaha 1100's

Offline cb550k-aaron

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Re: Gearbox
« Reply #5 on: March 27, 2018, 10:15:43 PM »
 :'(

Great sounds like a lot of fun.

Someone has suggested changing the oil from 15w40 to 10w40 as well. It wouldn't be clutch adjustment related no?

Gutted if it's gearbox as I've only just got the bike built up again after the winter

Offline cb550k-aaron

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Re: Gearbox
« Reply #6 on: March 28, 2018, 08:18:17 AM »
Sadly I have seen this a few times over the years, normal cause is a worm or vent selector fork. The 500/4 was well known for it, and the selectors were modified for the 550's but do still fail occasionally. Someone else may have a different view on it, but my money is on the selector fork.

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A worm or vent fork???? your spell checker not working Hairy  :) :) :)

I did wonder lol!!

Probably a stupid question but I'll ask anyway.

Is this a case of a full engine strip down again? Or can I go bottom half down?

Offline hairygit

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Re: Gearbox
« Reply #7 on: March 28, 2018, 08:26:34 AM »
It's engine out, and work on it upside down (The engine, not you! ;D ;D ;D) and yes, you can split the cases without disturbing the top end.
If it's got tits or wheels, it's hassle, if it's got both, RUN!!!

Offline cb550k-aaron

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Re: Gearbox
« Reply #8 on: March 28, 2018, 08:36:51 AM »
It's engine out, and work on it upside down (The engine, not you! ;D ;D ;D) and yes, you can split the cases without disturbing the top end.

 :'(

I might need worked on lol (heartbreaking)

Can't be done with engine in the bike then? lol (reason i ask is it been in and out 3 times because of paint lol)

Offline hairygit

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Re: Gearbox
« Reply #9 on: March 28, 2018, 08:50:02 AM »
Afraid not. Silly question, but if it was jumping out of gear last summer,  did it not cross your mind to investigate it while the engine was out, would have saved you all this heartbreak.

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Offline cb550k-aaron

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Re: Gearbox
« Reply #10 on: March 28, 2018, 09:00:37 AM »
Afraid not. Silly question, but if it was jumping out of gear last summer,  did it not cross your mind to investigate it while the engine was out, would have saved you all this heartbreak.

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I know your totally right, but tbh i thought it was more Clutch related and maybe needed time to bed in or something :( (first time building anything like this)

Only other thing i can think of is the Rear Sets i Have Fitted, that gear change side has some movement in it that might not be helping getting a proper purchase to go into gear properly.

I'll try the old Gear lever on for a run and report back first.

The Forks you guys are talking about, is it normally the two on the upper shaft and not on the drum? ie 1&3 on the below link
https://www.cmsnl.com/honda-cb550k3-four-england_model14671/partslist/E16.html#results

Offline AshimotoK0

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Re: Gearbox
« Reply #11 on: March 28, 2018, 01:03:56 PM »
These pics I did a year or two back highlighting the -286- CB250/350K parts in the early 500 gearbox.
Parts books for 250k/350k & Cb500K0/K1 are on this forum in Dropbox links

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“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline deltarider

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Re: Gearbox
« Reply #12 on: March 28, 2018, 02:21:45 PM »
Ashimoto, just in case you're interested, you may have a look at the concerning pages of the CB500K2 (ED, F, G) a model that was assembled in 1976. Maybe you (or somebody else more technical than I am) can detect modifications that could explain why my gearbox after 130.000 kms is still functioning OK. Also I never had any clutch problems like broken pushrods. Maybe I am just lucky, maybe Honda improved something.
http://www.honda4fun.com/pdf_parts_list/pdf_spac500/CB500-76/CB500-76_1.pdf and
http://www.honda4fun.com/pdf_parts_list/pdf_spac500/CB500-76/CB500-76_2.pdf
For instance: on page 28 number 13, GEAR, COUNTERSHAFT TOP (27T) is a -374- part.
« Last Edit: March 28, 2018, 04:12:08 PM by deltarider »

Offline AshimotoK0

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Re: Gearbox
« Reply #13 on: March 28, 2018, 06:57:26 PM »
I know that the later gearbox had a little trochoidal oil pump fitted to the counter-shaft needle roller bearing.
If you look in my Dropbox links there is this SB.

https://www.dropbox.com/s/lits1e6t83gkhud/SB500_04.pdf?dl=0

Bryan/Oddjob/Triggers are the gurus on this on here
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline deltarider

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Re: Gearbox
« Reply #14 on: March 28, 2018, 07:42:03 PM »
Thanks. Can't remember I had seen that SB before, so thanks again. My enginenumber begins with 217... so I guess I'm safe. BTW, that little trochoidal oil pump fitted to the counter-shaft needle roller bearing was exclusively in the CB550 and CB500K3.
« Last Edit: March 28, 2018, 07:44:48 PM by deltarider »

 

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