Author Topic: Gearbox  (Read 5965 times)

Offline Green1

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Re: Gearbox
« Reply #75 on: April 04, 2018, 09:40:01 PM »
you do as you want.
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Offline K2-K6

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Re: Gearbox
« Reply #76 on: April 04, 2018, 10:03:46 PM »
So for the curious, the gist of this damage is that gross misuse has stripped the teeth of 2nd and 3rd, locked up the free/splined cogs causing the shafts to rotate in their bearing housings and ramming the dowels down into the case where they have tried to exit. Subsequently the blind bearings are free(ish) to rotate as they want?

That's some achievement.

No,  it's the other way round. As Trigger says,  someone has put it together with the bearings not located on the positioning dowel pins,  then torqued up the cases forcing the pins through the casting and allowing the bearings to be something like free to position themselves.

If the gear shafts move in relation to the selector forks,  then it's possible to get two gears try to partly select at the same time. As you come out of second gear it should clear the engagement first and just before it drops the third gear dogs into place ( it's a fine line of synchronisation)  but if the third gear dogs just touch their target while second is still hooked up then the dogs are strong enough to take it. It just fires a couple of teeth off the cogs as they are more fragile / smaller than the dogs. Then the shrapnel goes through other stuff if chunky enough to do damage.

Ironically,  if it was bashed through quickly / brutally from second to third,  then you'd go faster than the conflict would occur so would get away with that situation. But you wouldn't know in the first place,  so moot point.

Offline tom400f

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Re: Gearbox
« Reply #77 on: April 04, 2018, 10:33:58 PM »
I would never imagine someone would not align the pins. Just goes to show, never underestimate the stupid.
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Offline K2-K6

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Re: Gearbox
« Reply #78 on: April 05, 2018, 10:43:59 AM »
I'm less familiar with the 500 but the 750 has always been built into the upside down top crankcase, I thought.
Different in that the gearbox secondary shaft is located in a hole within the bottom case with that bearing assembly put in after the gearshaft.

I haven't seen the pictures of this one,  the locator rings are there,  aren't they?  Something appears to have moved though during use as it's gone from being slightly difficult to failure.

I always feel that with any gearbox problems you've got to stop using them as soon as possible,  and then you may save it. Any conflict only ever gets worse if used.

Offline cb550k-aaron

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Re: Gearbox
« Reply #79 on: April 05, 2018, 11:29:23 AM »
As OddJob states.

Not Stupidity but a lack of experience. It's a learning experience for us atm. Never seen the inside of an engine until this one was originally taken apart.

Any tips for what Grease or oil or sealer or whatever we need would be greatly appreciated.

The only parts in the Sump and attached to the Magnetic Sump Nut was Gear parts. Nothing else.


Offline Seabeowner

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Re: Gearbox
« Reply #80 on: April 05, 2018, 12:11:43 PM »
Certainly the Honda manual I have states "install the crankshaft into the lower crankcase" but my 1975 vintage Haynes manual says " invert the upper crankcase and replace the crankshaft". As the shifter forks and the pins for the bearings are in this upper half it just seemed the natural way.
Phil
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1975  CB550F1   Shiny Orange
1978  CB550K     Excel Black

Offline Nurse Julie

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Re: Gearbox
« Reply #81 on: April 05, 2018, 12:22:56 PM »
I feel for you Aaron. I have recently just completed a complete rebuild on my CB400/4 engine. My plan was to use the Haynes manual and the Honda workshop manual as being a novice on engines and having  very limited mechanical knowledge, I hadn't a clue what I was doing. I was lucky having Graham (Trigger) to help and advise me when I got stuck, which was very often. My advice now would be to learn from the experience, get it sorted but most importantly, do it right and do it once. Any bodge will bite you in the arse big time.
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Offline Bryanj

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Re: Gearbox
« Reply #82 on: April 06, 2018, 08:49:59 AM »
I always build the 500 in the top case as its easier to locate those pins and the selectors and its easy to fit the primary shaft afterwards

Offline Seabeowner

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Re: Gearbox
« Reply #83 on: April 06, 2018, 10:01:16 AM »
Sorry Aaron, we've hacked your thread again, but it is good advice for putting the bits back in the cases:
Oddjob, Well Haynes book does show two pictures of the starter clutch assy with the primary chain round it lying loosely in the top half and and step 8 says "pass the pass the sprocket over the starter clutch sprocket". Steps 12 and 13 are bolting the halves together and step 14 is "re-install the primary shaft from the right hand side".
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The description earlier on gets a bit confusing as after putting the crankshaft in the top half, it describes uprighting the case, but it looks like it means just to get at the spring detent on the selector drum (not on the 550). Only bits for the kickstart it describes as being installed in the bottom half of the cases.

And I have sorted the few old Motorcyclye Mechanics mags from the 70s, so any referring to 500/550s are to hand and the March 74 edition 500 rebuild shows it being done as above, supposedly at the "Honda Service School" so they had all given up doing it by the Honda manual. The manual is littered with poor/incomplete advice and innacuracies.
« Last Edit: April 07, 2018, 09:36:13 AM by Seabeowner »
Phil
1971  CB500K0  Candy Jade Green or Candy Gold
1973  CB500K1  Candy Ruby Red
1975  CB550F1   Shiny Orange
1978  CB550K     Excel Black

Offline matthewmosse

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Re: Gearbox
« Reply #84 on: April 07, 2018, 08:25:43 AM »
If you are stuck for parts I have a few old cb550 engines that are either stripped down to bare cases and random boxes of old cogs ( how I bought my first cb550 ) or I may have engines that are complete that I could strip of the un needed bits. Unfortunately most of them are an un known quantity. There is 1 with a trashed top end that I know the gearbox was operating fine on but the cases are basically scrap since a valve punched through a piston then through the case. My old cb550 stuff is basically mothballed and I think I could let an engine go - I'd be ok with you popping up, opening the sump on a few and taking your pick as long as we got everything sealed up again. I also have a inspection camera to look inside the oil filler which might help check the locator pegs in the gearbox.
Got a 500/4 with rust and a sidecar and loadsa bits. nice and original and been round the clock

Offline cb550k-aaron

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Re: Gearbox
« Reply #85 on: April 10, 2018, 10:53:02 AM »
 So I got the Gearbox that OddJob posted it's like new! Well Happy.

Got the pins fixed and the Bearings now sit where they should without moving in my Casings and everything looks good thankfully.

Just wanted to say thanks for all the help so far and will keep you all updated. Fingers crossed for everything being ok.

Cheers
Aaron

Offline hairygit

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Re: Gearbox
« Reply #86 on: April 10, 2018, 12:03:13 PM »
So I got the Gearbox that OddJob posted it's like new! Well Happy.

Got the pins fixed and the Bearings now sit where they should without moving in my Casings and everything looks good thankfully.

Just wanted to say thanks for all the help so far and will keep you all updated. Fingers crossed for everything being ok.

Cheers
Aaron

I didn't post any gearbox Aaron, you sure your not giving me credit which should go to someone else, easy mistake to make but annoying if your that person and you don't at least get a thanks.
Glad to see it's working out, mistakes can sometimes really be expensive, lets hope yours is now rectified. Did you seal the holes in the castings where the pins poked through, the clutch one isn't a big problem, if it leaks it just leaks into somewhere there is already oil but the sprocket side wants sealing at the very least.
  I think he's referring to the link you posted about one a couple of pages back!
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 #87 on: April 10, 2018, 02:34:18 PM »
I'm not sure if a bottom end IS the way to go TBH, there is a lot of damage sure BUT the problem is the new bottom end isn't guaranteed to be any better unless it comes with one of course. TwoWheelSpares on E-Bay have some complete engines but no bottom ends, your never sure on what the crank shells are going to be like on another engine, his may be new but they don't transfer as we know unless your really really lucky.

Really blowing the pics up shows what I suspect has happened, just above the mainshaft 3rd gear where it is missing 2 teeth there is another tooth with just the leading edge missing, I suspect this came off, jammed between the gear teeth just below it when second was engaged, this would mean this gear cluster was sitting to the left, when the 2 teeth came off they were in close proximity to countershaft second and they jammed between the 2 gears, would explain why no teeth are missing from mainshaft second, which is puzzling as you'd expect them to be meshed but again I think maybe third was in the process of being selected. The selectors look fine, which again is puzzling as you'd expect them to be the cause of this but they clearly aren't. Maybe the PO was a bit clumsy and started the process by catching the 3rd gear tooth edge. Looking again at the pics you can see new damage just under the primary chain and again to the left of that, these were no doubt the result of all the debris getting flung out of the gearbox.

I'm not convinced the bearing spun in the casings, I've never seen them do that before even when the knock pins are squashed flat to the case as in this case, I'd like to see some pics of those bearings in detail to say for sure though, if they had I'd expect to see some damage to the knock pins and I can't see that.

I'd also think about just replacing the entire box,

 https://www.ebay.co.uk/itm/Honda-CB550-CB-550-K-F-Four-1974-1978-Gearbox-Gear-Box-Assembly/332536863177?hash=item4d6cbdd9c9:g:V5oAAOSwzRFabzr4

If you just buy a bottom end your going to need a complete set of gaskets as well, plus some time stripping both engines to see if there is any damage. However I'd also point out that the damage caused by crushing the 2 knock pins can sometimes be significant, I'd like to see pics of the sprocket area from the outside to see if the pin came through the casing and also of the clutch area for the same reason.

Oddjob this one!! Lol so thanks.

Yes both sealed and bearings sitting correctly too.

Yes but it's all a part of the learning process. I'll know all this for again and so will my Dad.

Dry run with the Gearbox in last night and it's engaging perfectly. I noticed a slight twist in the Gear Change rod, specifically on the end that has the fork where the clutch is so I ordered a new one of them.

Offline cb550k-aaron

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Re: Gearbox
« Reply #88 on: April 30, 2018, 07:07:39 PM »
Guy's stupid question but I'm asking it anyway.

Engine out being rebuilt atm

The Kickstarter shaft etc. We built it but when the chain drive is moving it clicks for want of a better explanation? Is this correct?

Offline hairygit

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Re: Gearbox
« Reply #89 on: April 30, 2018, 07:24:09 PM »
That sound will be the ratchet pawls inside the kickstarter gear, it's normal but with the casings on and the engine running you don't hear it.
If it's got tits or wheels, it's hassle, if it's got both, RUN!!!

 

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