Skipping gear?

[Rupe]

A couple of weeks ago I took my bike out for a ride and after a while when I changed up into 3rd it made some horrible clunking feelings. And it felt like it was skipping between 2nd, 3rd, and 4th when putting power on in 3rd. So I limped back and didn't use 3rd. When I got back, cheese had a quick go and he said it felt like it could be the chain slipping, and this was what it felt like. But after tightening the chain it made no difference. I had a little play on some small hill climbs and 2nd and 3rd was all good, but I didn't want to use third incase I did more damage than done needs be.

The engine is now completly stripped and I was expecting to see some obvious damage to 3rd, but it all looked fine to me and barty5 who help strip it done. Except maybe the shift fork has a mark on it, but it's not on a surface that makes contact.

I took the gearset into a bike shop and they guy in the shop had a look and said the fork with the mark needs replacing, and the forks have wear marks on the top and bottom surface showing that something was not right. He also said that the dogs on third were damaged so third needs replacing and the gear the dogs conect to (expensive). But I could get the gears machined by an engineer to get the sharp edge back.

Would machining be a good option, or get new gears.


Tonight I took all the gears off to clean and make sure no other dogs were dameged. And to me they all looked like the same, with the sharp edge slightly worn like a rear tyre, but not to bad.

When I took all the gears off the needle bearings on secondary pinion III fell apart. 6 needles are not in the bearing case, and I only have 4 which have shattered. So it this why it was skipping, or a result of it skipping????
Oh and Barty5 if you remember the shinny bits of metal we found taking it apart, I'm guessing it was the needles.

So do I buy news gears, get them machined, or just replace the bearings and see what happens?

[rudolph]

you can do that with a angle grinder, undercut the dogs abit, I have done this to my BSA, don't make them too radical or it won't come out of gear

[rudolph]

is it Skipping gear like over shooting into the next? your indexer might be bugged

[mattwood]

dunno man, ive got a problem with random false neutrals between 2nd,3rd and 4th sometimes... could be the same thing??

someone said something about gear selector forks might b fucked? could be worth a look for u anyway

[pete376403]

How hard is it to get the motor apart? If its pretty easy, you could try just replacing the bearing(s) and see how that goes. If stripping the motor is a major pain in the arse and costs a fortune in gaskets and stuff, you only want to do it once, so do all the work in one hit.
I'd try the bearing first, if the needle bearing that supports the gear is stuffed and the gear's wobbling all around the shaft, gear engagement will be erratic.

[barty5]

When I took all the gears off the needle bearings on secondary pinion III fell apart. 6 needles are not in the bearing case, and I only have 4 which have shattered. So it this why it was skipping, or a result of it skipping????
Oh and Barty5 if you remember the shinny bits of metal we found taking it apart, I'm guessing it was the needles.

part of the reason i sujested wshing all the gear set out this added to the fucked big end bearing may be all it is and could be the result of the bent/damaged shift forks up to you but i would most likely try putting back together with new bearings and shift forks an go from there cant be ant worse

[Danger]

Heck I hate these kind of fix ups. Its worth doing right and replacing any worn parts in my opinion. Save a lot of problems down the line.

[cheese]

yeah when I rode it it felt like it was shuddering, And I felt the rear wheel and the bearings where pretty shot and I thought that may have been a contributing factor.

Those bits of metal in your gearbox from the bearings sound like they could have been a major cause of your problems. One of those bits of metal in the gears would have made the bit feel really shitty. A shot bottom end wouldn't have helped. Maybe talk to Tjebbe Bruin about fixing the gears. I'm not sure if he does gears though, he does do a bit with suspension these days. Post up some photos.

[scott411]

Heck I hate these kind of fix ups. Its worth doing right and replacing any worn parts in my opinion. Save a lot of problems down the line.


exactly,
thier is a saying around here 'cheap man pays twice'
meaning if you do it on the cheap, you will have to do it properly sooner or later,

i know some people that have undercut gears to get them to fix issues, noramlly only works for a little while before having been done properly

[crazyxr250rider]

Under cutting should onl be used if replacement gears arent avaliable,replace all bearings too.

[B0000M]

sorry to not be overly helpful, but a CR might be a nice solution :first:

another thing to look at tho is what the parts / time are going to cost vs replacing the bike and selling it as is

[Taz]

I agree replace all the bits that are worn beyond their limit. Worn dogs increase the side loading on the gears which increases wear on the shafts and washers and o'rings etc. Do it once do it right IMO.

[F5 Dave]

Hard to say which came first, the bearing I'd guess & this could have caused the further damage. It would also be a good idea to see how far the gears engage. Perhaps a thinner shim may help if only just touching. Have undercut gears before without troubles, but would be best to leave to someone who has done it before & check that the gears don't pull in too close & rub.

Perhaps that fork was wearing as the shimming wasn't correct. Or perhaps it got damaged as the gear was rubbing because the extra play in the bearing falling apart?

[Rupe]

Thanks for everyones help.

I'm going to put it back together with new forks, bearings, and seals. As it happened all of a sudden I'm guessing it's probably the bearings that caused it.

So if it still does it I'll have to get new gears as I'll prob keep the bike for a while and machining is not 100%. And no booom I don't want to down grade to a honda, they're a clit's bike:bleh::bleh:

[F5 Dave]

I would still check how far the gears engage.

If the answer is 'only just' then the tiny amount of rounding off that may have occurred recently could be enough to cause a problem still. A shim change may sidestep that if tolerances had made it a bit marginal from the factory. ie you bring the gear closer to the other to start with. Have to test all positions but not too hard.

You need to reassemble it in one case & check to see the engagement. It can be hard to do this with one side unsupported though. The best way is with a sacrificial case which is sectioned so you can get into it. This is really a tuner only option if they had a dead spare.

Maybe make a 'sidecover' out of a sheet of ply to hold the other shafts at least the same relative to each other.

[Rupe]

I would still check how far the gears engage.

If the answer is 'only just' then the tiny amount of rounding off that may have occurred recently could be enough to cause a problem still. A shim change may sidestep that if tolerances had made it a bit marginal from the factory. ie you bring the gear closer to the other to start with. Have to test all positions but not too hard.

You need to reassemble it in one case & check to see the engagement. It can be hard to do this with one side unsupported though. The best way is with a sacrificial case which is sectioned so you can get into it. This is really a tuner only option if they had a dead spare.

Maybe make a 'sidecover' out of a sheet of ply to hold the other shafts at least the same relative to each other.


Thats good advice mate, I'll do that this week.

Thanks

[Rupe]

here's some pic's which might help. If you notice the dog at the back of the third gear, you can see the difference between the wear (right edge as you look) to the manufactured edge (left and front).

Bearings don't look good either!

And shows the wear on the fork

[cheese]

What are teh parts going to cost you? I'd get another opinion on those gears.

[Rupe]

What are teh parts going to cost you? I'd get another opinion on those gears.


Linton doesn't have gears, but he can get them, but not sure on price.

Or it's US$110 from the states plus shipping per gear.



Why, what do you make from the pics?

[barty5]

Linton doesn't have gears, but he can get them, but not sure on price.

Or it's US$110 from the states plus shipping per gear.



Why, what do you make from the pics?

from memory all the gears had small step cut in to them (the dogs) i didnt think they looked that bad and have seen a lot worse which dtill worked fine i would put the slipping and not engauging gear down to the trashed bearing and bent fork.

[4stroke]

dude the wear on the gear looks minimal, but the bearings and the shift fork id replace, if you cant get a fork i can get one made thro one of my suplyers who make gears and splines n stuff for me, by the look of the bearings if they are all like that, id say that thats mostly the problem but hard to say.
how do the thrust washers look?

[cheese]

Whats a fork going to cost you + the bearings?

[F5 Dave]

Gee I'm having trouble seeing the pictures in any clarity. Phones aren't cameras.

There appears to be a bevel on the RHS of the rear dog. That would be enough to cause issues if the gears aren't meshing enough as they would get spat out as they try to slide in. Further use would make the wear worse quite quickly. Obviously the bearing failure could have had quite an effect on the whole proceedings.

What does the shafts the bearings ran on look like? Chances are they are ok as hardened. The bearings rollers have been skidding so they wear a flat & destruct instantly as can no longer roll. Just wondering if there was a reason why they failed.