Dear friends.
on my Jawa engine the bearing of the secondary chain sprocket is bad and I would like to pull it out without haveing to dismantle the whole block and first pull out the shaft.
I know there is a kind of extractor where you drill up the ball case > slip in 2 or 3 fingers > connect an extractor and pull out (resting on the shaft's tip) the whole bearing. But that kind of white elefant tool isn't available locally and would be used only once in the whole life.
I have a machine shop, so if somebody has a good Idea it will be highly appreciated.
Regards
Sven Peter Pan
from Costa Rica
Would a slide hammer work with more than one drilled hole?
It's a thought.
Lonnie
Lonnie,
I I have the bearing in its nest and the shaft inside the gear box.
To pull would be hard but for sure the shaft would come out too and then we are in big trouble. But your Idea gives me a good hint 🙂
Drill and tap the ball case and make an extractor out of square bar stock. with a center thread for the extractor bolt and 2 holes for simple grade 10.9 (US grade 8) allan screws. Anyhow drilling is needed, so to tap shouldn't be too difficult. Some grease catches the chips so that they cannot fall into the gear box.
Thank you very much for the intuition.
That is the good thing about
the internet forums. Somebody will lead you onto a good track without selfishness.
God bless you.
Sven Peter Pan
Originally written by Peter Pan on 11/19/2007 6:30 AM
Lonnie,
I I have the bearing in its nest and the shaft inside the gear box.
To pull would be hard but for sure the shaft would come out too and then we are in big trouble. But your Idea gives me a good hint 🙂Drill and tap the ball case and make an extractor out of square bar stock. with a center thread for the extractor bolt and 2 holes for simple grade 10.9 (US grade 8) allan screws. Anyhow drilling is needed, so to tap shouldn't be too difficult. Some grease catches the chips so that they cannot fall into the gear box.
Thank you very much for the intuition.
That is the good thing about
the internet forums. Somebody will lead you onto a good track without selfishness.God bless you.
Sven Peter Pan
Hello!
The only thing I am afraid of with regard to your plan is that the bearing parts are extremely hard. They have to be to hold up in the usage that they are designed for. Drilling the holes really isn't going to be possible without disassembling the engine and using specialized machinery. I agree that if you could drill the holes, you could probably tap them but I've worked with bearings a lot and they are always hardened metal.
If it were my bike, I'd have to go the extra mile and disassemble the case to get the shaft out and then press the old bearing out.
I'm sorry to sound so negative but drillng a ball bearing race is not possible by ordinary means, at least as I understand what you are considering doing. With motorcycles and other mechanical things it's not uncommon to find that that what looks like the hard way is often the only way.
Best wishes.
GNM109
P.S. After WWII, CZ, Jawa and Ogar (two stroke twin) touring bikes were very popular. There was a dealer in Chicago where I lived and I had both a CZ 125 and a Jawa 250 at one time. They were great bikes. The little CZ 125 broke the shifter return spring. My Dad and I split the cases, installed a new spring and re-assembled the engine in about four hours ony sunny afternoon.
A fond memory of many yeas ago!
Well I stepped into the shop yesterday after work:
Sidecar and both sides of the engine covers are stripped down now, The bearing I thougt would be bad is in better shape then the first visible one.
No space to drill and tap. Bearing is fully packed with balls (secondary chain side, respectively the ball case is way too tiny to get hold of it(primary chain side).
I'll leave it to them how to remove the bearing. and if a minimum error or damage ocurres. Fernando will kick the whole engine appart and go the long way.
And he definetely agreed He would have been ready quite a while ago if he would have gone the long way from the biginning.
Sad how small a dismantled 350 Jawa and its pulled of sidecar lookes beside a 1600ccm special Harley.
...
Some day .. one of "those" dreams,... I'd love to put into its frame a Jawa-speedway 4 stroke engine.
For now just be patient
Regards Sven
Originally written by Peter Pan on 11/22/2007 9:49 AM
Well I stepped into the shop yesterday after work:
Sidecar and both sides of the engine covers are stripped down now, The bearing I thougt would be bad is in better shape then the first visible one.
No space to drill and tap. Bearing is fully packed with balls (secondary chain side, respectively the ball case is way too tiny to get hold of it(primary chain side).
I'll leave it to them how to remove the bearing. and if a minimum error or damage ocurres. Fernando will kick the whole engine appart and go the long way.
And he definetely agreed He would have been ready quite a while ago if he would have gone the long way from the biginning.Sad how small a dismantled 350 Jawa and its pulled of sidecar lookes beside a 1600ccm special Harley.
...
Some day .. one of "those" dreams,... I'd love to put into its frame a Jawa-speedway 4 stroke engine.For now just be patient
Regards Sven
I almost forgot how popular the Jawa engines are in Speedway racing. They have speedway in the US all of the time. There was a revival in California in the late 1950's thanks to the late, great Bud Ekins and others.
