1925 JD Cannonball Bike

[rwm]

jerry you can just pop in sealed bearings. i have heard guys say" when people rebuild jd trannys they over tighten the main shaft trying to make the copper disk seal in the oil. they claim this makes to much heat in the gear box.

[Tommo]

Robs right, use a 6208 2RS and a 6304 2RS bearing
On 26 and later gearboxes they go straight in.
I'm not sure about 1925 but 1924 and earlier boxes you have to grind some of the shoulder back on the output gear to get your required clearance.
There's a lot of kiwis using this mod and it is trouble free and doesn't leak any oil.
I don't remove any of the seals from the bearings and use grease in the outer cover to lube the kickstart.

[Jerry Wieland]

Rob and Tommo Thanks for the heads up. I had noticed that on 2 of the transmission I took apart that they had a different bearing on the right side of the main shaft. It had the same id/od as OEM but was approximately .060" wider.

Are these bearings sealed and do you leave the seals in ? I believe they ought to fit 1925 then also. The only difference I can see in a 25 tranny is that it still uses the old clutch release bearing and shifting lock - internals are the same.

Jerry

[Jerry Wieland]

I have been looking for the original seat T cross bar for awhile with no luck until a fellow JD enthusiast fronted me one that he had started on.



The stem is OEM and he made the cross shaft and sweated it in the stem. This is what the original one looked like and this is a seat that was loaned to me so I could copy it.





Today I made a fixture that put the bend in it. I haven't done a lot of this kind of work and it probably shows. The fixture was made to me a throw away because I do not have the time and no reason to make it reusable. I got to make it work the first time. I had about 4 hours in this whole situation.

Basically I turned a 1/2" hole in 2 spool shafts and welded them to a 4" x 4" steel tube and spaced it up with smaller square tube. The rest is just a plate that u bolted to the seat crossbar and held it at the exact angle I needed to replicate the original one. The rest of the steel is just a guide plate so that it stays firmly on track when I push on it.







The press is a 80 ton manual hydraulic press and this is child's play for it. I did have to use a little heat as I expected to get the bend how I wanted it. This is not ideal but I did not have one to practice on.








Jerry

[Jerry Wieland]

I was really happy with the way it turned out although it probably can be distinguished from an original if you lay them side by side. It does not have to be exact as I am using a later saddle and need to fabricate the angle plates on the end anyway.








Jerry

[Jerry Wieland]

I am also starting to think of chains, sprockets and gear ratios. Anybody have any experience with this. The bike needs to run comfortably at 55/60 mph but still have decent low end power.

I would appreciate any input on this - even negative because knowing what not to use is as important as what to use.

Jerry

[sswaney]

Jerry
Damned ingenious!
I'm really enjoying this thread.

As for gearing on the J Models. I can tell you what I'm running.
I am geared as tall as I believe is possible with these machines.
18 tooth motor sprocket
28 tooth countershaft sprocket
40 tooth wheel sprocket.
I experimented around originally with 44 and 48 tooth wheel sprockets and was running a 17 tooth motor sprocket on my 28 with good results. But I really like the use of the full 1-2-3 range of the trannsmission running as tall as possible. And I have no problems starting out in low despite being a 200 lb+ guy. The problems with trying to run 55-60 with a J model is your out of chassis/suspension and brakes around 40 mph!

Scott

[Jerry Wieland]

Scott Thanks for the information on the gearing. We're making progress but it is slow.

[Jerry Wieland]

Got my reproduction exhaust system from Tom Feeser of Replicant Metals at Oley. Anybody have any suggestions as to what finish to put on it? Willing to listen to all. Jerry

[MMasa]

I'd paint it with black high temp exhaust paint and cook it in a powdercoat oven to cure it.
Mark Masa

[c.o.]

This thread just keeps getting better and better!!! Great stuff Jerry!!

[petri]

I have had problems with my internet service provider and have not been able to follow this site for a year. Problems now resolved, I have read this thread from beginning to end this morning. Your dedicated effort to pass along this information is very educational and informative. I know it must take a lot of your time to take all of those pictures and write the comments. Having just finished a 10 year restoration of a 1932 Packard I am very interested in how restoration problems are solved. You're to be commended for passing along these problem solving solutions to the rest of us. I only wish I were as good at this as you are but hopefully one can learn. I'll be able to follow the rest of your work on a daily basis now.

thanks,
Howard

[duffeycycles]

If you don't have a powdercoat oven you can use heat gun in both ends and slowly bring it up to temp

[Jerry Wieland]

Tommo When you replace the bearings in the tranny with sealed units do you discard the brass shields used with the OEM units. I see no function for them now except to take up the space.

Thanks for the tips on the exhaust. Jerry

[Tommo]

Discard them if you leave both seals on each bearing but put them in if you remove the inner seal on the bearing.
I leave both seals on and discard the brass slingers.