SOHC.co.uk Forums > CB500/550
500 ride again project
K2-K6:
It's worth checking the hardness of the fork first Matt.
Just run a metal file across non toleranced surface of a knackered fork to see if it'll cut it. It's usually the gear's that are heat treated material for obvious reason, fork's in many gearbox applications are only bronze.
A healthy gearbox would not routinely "run" the forks under load generally. The gear is not side loaded when driven on these straight cut boxes.
If they wear as discussed above, touching diagonally opposite faces on the pads, gear component making a mark further up, then it would suggest the fork is bent such that it's not presented to the gear slot perpendicular/true.
If that's the case, then if the dogs aren't engaged fully they can try to spit themselves back out of gear. This is usually obvious as the damage on the dog's noses gives evidence.
The original gears in this thread look like that's happened, you can see it starts to round off the leading/driven edge of the dog as well, making it even harder to stay in gear when loaded.
matthewmosse:
On the ones I have closely examined the gear has been a bit rough on the corresponding faces. Really need to look again though as it has been a few years. It might be interesting to make a rig to test the dogs ability to stay in engagement under load without the forks. Might only need to be a spring balance on the output, maybe on a bar welded to a worn sprocket, compare the jump out force on a problem box and good one - I would expect the good one not to but a bad one to be still quite hard to get jumping unless awfully. I have 2 cb500 engines that stuck in 2st and second gear particularly. Rather the opposite of the jumping out issue. I never did investigate further. Ax I clear my shed of BMW boxer bits I'm thinking ahead to get back onto my cb500 project. For now it's getting a cb550 mill, because that was close to hand and looked good to go, but cb500 is looking more tempting as times have moved on, it's going to be a fun bike, not the mile munching commuter it always was when last running. Mot no longer relevant, being stock for insurance might help. Being as it was when I did most of my miles would be nice. A sorted cb500/4 is just so very good.
Safo:
Yes I will oddjob, as I don't want to strip the engine again
Got a full oil seal kit and new wiring loom from the Honda guy at Newark at the weekend, also bought 2 sets of c/cases from the auto jumble, wi part g/box
Right and centre selector forks no good on both sets but one countershaft gear OK, and one full pushrod
Safo:
After paying £17 import tax the forks are finally in my hands, the L and R are like new but as oddjob said the centre one is just showing first signs of wear but as I said before, it's ten times better than whats in there, a big thankyou to trigger for the bolts
Safo:
Hi all, I know it's been a while since last post so here is a update on the progress.
After fitting the selectors that I bought from the US I began the search for the formentioned gears, I soon found out that this was going to to be a long search as all the gearboxes that I found, 3 in total had all suffered the same bar one and that had been robbed of the c/shaft 3rd but the 4th was OK so I bought it just for the one gear, finally just 2 weeks ago I got a gearbox in great condition from somone has built probably the best 500 classic racer I have seen, anyway as it stands the bottom end is now rebuilt and back in the frame, now awaiting std piston rings from silvers, about 3 weeks, will post updates and some pics soon
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