Topic: CB 500 transmission removal

[CB4EVER]

Has anybody out there ever removed a transmission out of a cb500/4 ?
I thought it was as easy as flipping the engine upside down,  removing the case bolts, separating the cases and volia !
I have been told it is a lot harder than it looks.

So, if you have an experience you would like to share, or a tip like, get drunk and look for another engine,  I would sure like to hear from you.
 
thanks,  Dave

[paulages]

i don't know the 500 transmission, but the 550 is that simple. i believe the 500 trans is almost identical, barring the clutch plate actuator shaft being on the left side and going through the main shaft.

[bryanj]

Depends on wether you want the primary shaft out or not.
You doo have to remove the clutch to get at the interlock mechanism that spans both cases and dont forget the bolts under the starter

[CB4EVER]

I really don't want anything out,  except the row of gears that mate with the row of gears on the chutch shaft. The needle bearing that support that shaft, has exploded all over the engine, hence, the manditory removal of that row of gears for replacement of that bearing.   I am trying to make this as painless as possible.
Clutch is already off,  shifting mech. off,  oil pan off, just need to know if this is an easy or hard proceedure.
Your thoughts ?   
thanks,  Dave

[turboguzzi]

you will have to split the cases to get to the parts you mention.

disassembly is quite easy, undo all the bolts on the top side, flip over and undo the bolts on the bottom. I am of course skipping on many details but if you download the manual it details everything you have to do.

The tricky/fun/painfull bit is assembling it all back. Have no idea what is your skill level, but definitely not a beginners job. You will also need another pair of hands or blocking the whole motor somehow when you torque back the main bearing 8mm bolts.  Absolute cleanliness is a must as well as using a really good sealant like threebond.

here's my race motor before closing the cases

TG

[CB4EVER]

My skill level is moderate to novice, but I have a really good friend who happens to be a good bike mechanic.  From what you said, and what the manual shows,  accessing the bad bearing should not be a problem after the case bolts are removed.  Top bolts first,  flip the motor and bottom bolts next.  I will find out next week when we attempt this.
Thank you for sending the picture of your race engine and the other members that contributed.
Dave

[turboguzzi]

one major thing

dont forget to pull out the primary shaft before taking the bottom case off.

TG

[hymodyne]

Its a good time to look at shift forks. one of the three for the 500K is available, the others are hit and miss on ebay.
hym

[paulages]

one major thing

dont forget to pull out the primary shaft before taking the bottom case off.

TG

is the 500 different from the 550 in that regard? on the 550 the primary shaft resides in the top case--if it's upside down, you can remove the bottom case without removing the primary.

[BSA_Mikael]

Good luck with the transmission! You have chosen a very good bike, take it from someone used to get deep into British bikes.. I had to tear my CB 500 down completely and it took a couple of hours (Would have been faster if I would have had access to an additional resource, for example when lifting the engine out of the frame.. It is a very good bike to try your mechanical skills on. Easy to work with in comparison to most other I experienced.

2 things to think of, although not unique to Honda:

1. Get a good manual and use it! (My own experience is Haynes are good and with plenty of explanatory pictures)

2. Aluminium threads all over.. Be careful, use the right torque settings (Check twice) and use a high quality torque wrench ONLY! (Take it from one that stripped a couple of threads with a cheap wrench..)

3. If something does not work out reasonably easy, leave it a while and maybe ask advise rather than be persistant and end up loosing your temper and a good engine

Best regards, Mikael

[turboguzzi]

Hei paul

you got me confused with what's top and what's bottom.....

When engine is in right way up position, the primary shaft is in the bottom case. see my pic. there motor is upside down, so to remove the bottom case you need to pull the primary shaft out. It's pretty much the only way to do it if you dont want to pull the top end off.

CB500 and 550 should be the same. the only difference tranny wise is that in the 550 they put two of the shift forks on a separate shaft + a tranny oil pump.


Cheers
TG

[paulages]

Hei paul

you got me confused with what's top and what's bottom.....

When engine is in right way up position, the primary shaft is in the bottom case. see my pic. there motor is upside down, so to remove the bottom case you need to pull the primary shaft out. It's pretty much the only way to do it if you don't want to pull the top end off.

CB500 and 550 should be the same. the only difference tranny wise is that in the 550 they put two of the shift forks on a separate shaft + a tranny oil pump.


Cheers
TG

i must be thinking dislexically here (spell check didn't like that one)... i've been playing with my trans and primary shaft so much lately trying to figure out what works and what doesn't, that i must be mixing up what's top and bottom. come to think of it, thinking of the orientation of the primary clutch gear you're right. the trans assembles easier in the upper half, as that's where the locating pins and half-rings for the bearings are, like here:


anyway, to further your advice to CB4ever: honda suggests using a puller to remove the shaft, i believe. you can use a drift (plastic, or something softer than the splined end of the shaft works best) on the end of the shaft opposite the clutch primary gear to knock the shaft out. the whole bearing on the gear side will come with it (unless you remove the circlip holding it in). there is a wedge of an opening on the side you're hitting, exposing the bearing and the end of the shaft, and is just big enough to get the drift into.

...i had to install and remove that shaft over a dozen times a few days ago trying a mish-mash of 650 and 550 parts. i've become an expert of sorts at removing it. 

[CB4EVER]

The primary shaft in my motor is in the bottom half of the case and  totally understand what is at stake after reading your replies.
How difficult is the primary shaft to remove ?
 I talked to a local mechanic that specializes in these old Hondas,  he would replace the bearing for 600.00 usd plus parts.  I would rather find a good manual and do it myself, with your help of course.
For the 1971 500, which manual would reccomend ?
And the seals,  replace all or leave them be ?
I am all ears and eyes,
thanks again,   Dave





   

[paulages]

The primary shaft in my motor is in the bottom half of the case and  totally understand what is at stake after reading your replies.
How difficult is the primary shaft to remove ?
 I talked to a local mechanic that specializes in these old Hondas,  he would replace the bearing for 600.00 usd plus parts.  I would rather find a good manual and do it myself, with your help of course.
For the 1971 500, which manual would recommend ?
And the seals,  replace all or leave them be ?
I am all ears and eyes,
thanks again,   Dave





   

we could help you step-by-step on here for...wait, let me check my paypal account... free. save the $600 and do it yourself. virtually no question is considered dumb on here, and there are plenty of people with nothing better to do than help you (okay, maybe that's not a flattering description...  ).

remove the primary shaft as i previously described, and the cases split easy. the offending bearing can then be replaced. wait, which bearing is it? ...

[CB4EVER]

It is the 20mm needle bearing that is sandwitched between the
case halfs, on the clutch side, that supports the shaft ths holds the countershaft gears (I think this bearing touches the 40t gear)
I show it as part number 91022-286-004.
Would a wooden dowel work to push the primary shaft out ?
thanks,  Dave

[paulages]

It is the 20mm needle bearing that is sandwitched between the
case halfs, on the clutch side, that supports the shaft ths holds the countershaft gears (I think this bearing touches the 40t gear)
I show it as part number 91022-286-004.
Would a wooden dowel work to push the primary shaft out ?
thanks,  Dave

don't know what to tell you about the bearing itself, as i've had a hard time finding the same bearing for my 550 trans. western hills honda had mine a few months ago, but i haven't tried them again yet. yours is a different part number then mine (91022-374-003).

a wooden dowel would probably work fine, you'll just have some splinters to clean up which could be a mess. i've used a metal drift and it didn't chew up the gears, i just wouldn't necessarily recommend it.

[CB4EVER]

Paul,  What side would you reccomend tapping the primary from,  the right or left? Also,  I found the 20 mm needle bearing we discussed at western hills honda,  so thanks for that lead.
Going camping w/ the kids for a week,  will dig into this when we get back.
thanks for all your help !
Dave

[paulages]

there's a little "window" in the case on the left end of the shaft, where you'll see the left side ball bearing and the tip of the shaft in the middle. if you tap it from this direction, the shaft and right side bearing will come out, leaving the primary chain gear and starter gear.

[bryanj]

Remove the oil pump and you can see the end of the shaft to tap, dont forget to remove the bearing retainer plate from the other end

[CB4EVER]

Finally removed the primary gear and shaft, as was a piece of cake thanks to your expert advise,  took the offending bearing out and noticed the new bearing would not mate to the shaft.  Further examanation showed excessive wear due to the failing of this bearing on the shaft,   so.......time to purchase a new shaft or find a used one.  There are two on ebay for a 72 and 73 which I assume are interchangable with my 71 ?  If so,  should be a straight drop in.
Your thoughts
thanks,  Dave

[lordmoonpie]

A wooden dowel could work but be careful of it splintering little bits everywhere that you than have to clean out of the cases - it's easy to do unless you have a collection of hardwood dowels at hand!

Go for the split though - it's the best way of learning and really isn't that difficult if you're methodical and use a good manual like Haynes. The only reservation I'd be concerned about is that if the bearing has disintegrated, what you'll find when you do open the cases - i.e. what have the little bits done floating about in your bottom end?

There's nothing to be lost by having a go and you'l learn loads in a short space of time. Good luck! 

[CB4EVER]

The cases are split, and all the bearing frags have been cleaned up.
the gears look great except the "modeled" surface at the end of the shaft where the offending gearing once was.  That once super smooth surface is now pretty chewed up, so time for a new shaft.
the manual used for this project is a recient ebay purchase, an actual factory honda mechanic overhaul manual (the 3 ring notebook style) now,  where to find that shaft......
thanks,  Dave

[bryanj]

www.davidsilverspares.co.uk did have stock at £35 ($70) plus shipping.

shaft clutch goes on 23210-323-000

shaft sprocket goes on  23220-323-000

If the last three numbers change its ok but one with a 374 middle number wont fit---thats 550 four