1950 WL won't downshift

[67sidecar]

Good morning folks! Looking for some advice regarding a shifting problem with a 1950 WL. With the bike NOT running, the trans shifts through all the gears, both going up and then back down. However, when the bike is running it's a different story. Foot clutch is working properly (bike easily goes into first from neutral), no gnashing gears when shifting. Bike shifts up to 3rd with no issues, however when it comes time to get it back into first, the tank shift lever is stiff as a wedding pecker. I've tried to finesse it back down but no luck, feels like you'd break something if you pulled any harder! The ONLY solution is to shut it off, put it in neutral, restart and drop it into first and take off. It seemed like clutch adjustment might be the culprit, maybe there was drag on the trans that wouldn't allow the shift forks / clutches to slide but it ONLY happens when you try to go from 2nd back to first, all other shifts are smooth. I should add that the trans was rebuilt using some aftermarket gears/parts. I'd appreciate any input from folks who may have dealt with a similar problem. Thanks in advance, Bill

[Rubone]

It sounds like the shifter cam may be timed a tooth off. That can make the angle between the rod and lever too narrow causing it to bind rather than move.

[67sidecar]

Robbie, Thank you for that! I never even considered something like that. I'll be tearing into it soon, that's number one on my list to check, I'll let you know what I find. I seem to remember I read somewhere, (maybe Palmers) about different length shift lever arm (the piece that protrudes from the trans that the shift rod connects to). I'm wondering if that too could be a contributing factor. The fact that this was a "basket case" originally, I guess it's possible the trans isn't even the correct one for a 1950 WL. Do you know what the correct arm length would be?

[67sidecar]

Just an update after pulling the transmission out of the bike. I found the shifter cam timing to be on the money, however with the top cover removed, I could simulate the down shift problem by simply "loading" the main shaft 2nd gear very slightly with my finger, the 2-3 shift clutch would not pull out of the gear. Worth mentioning here, for comparison, when I "loaded" the main shaft 1st gear with the same finger pressure, the 1st gear clutch would slide out of the gear with no issue. When you watched the 2-3 clutch closely, you could see the shift fork slide to one side of the shift clutch groove trying to pull it away but without success. After pulling the main shaft gear cluster, I hand lapped the 2-3 shift clutch on the main shaft multiple times with valve grinding compound to "improve" it's movement on the shaft. I also took a carbide dremel tool to the inner edges of the shift clutch, creating a slight chamfer where it mates with the main shaft. After re-assembly, the 2-3 clutch pulls out of 2nd gear much better than it did. The tranny goes back into the bike today, fingers crossed I've solved the problem!

[Rubone]

Keep in mind it is a "crashbox", no synchronization, so blipping the throttle to unload the gear faces is normal operating procedure.

[67sidecar]

Robbie,
Thanks again! You're exactly right. I got a chance to test ride the bike this morning. Most all of my experience is with big twin foot shift 4 speed bikes, so right out of the gate, I'm a little intimidated with the foot clutch / hand shift routine. That being said, it shifts 85-90% better than before I lapped the main shaft / shift clutch combo. No issues coming out of second, through neutral and back to first. Up shifts to second and third are much smoother also. The only bugger that's there now is it doesn't want to come out of third easily. Your comment about blipping the throttle is very timely as I found myself doing just that to help it release from third. Just wondering if I didn't spend enough lapping time on the 3rd gear end of the shaft. My other thought was possibly the shift surfaces on the third gear (also an aftermarket item) may need some attention. Your comment about the shift lever angle being too narrow if mis-timed is bouncing around in my head again. When the trans is in third gear, the lever is laying back at about 2 o clock, which makes for a tough pull for the shifter rod to rotate the drum. The shifter gear inside the tranny has an alignment line on it, not the a number "3" that's referred to in the manual. The shift drum has a chamfered tooth that mates to the line for timing the pair. Just mentioning those things in case it means anything. Worth mentioning here also is the rivets holding the clutch basket to the sprocket were not completely flush with the surface the fiber plate rides against (both inside the basket and outside on the back of the basket). A little ashamed of myself for not noticing it before. Corrected it, gained additional clutch plate clearance and better engagement. Appreciate any and all comments that might help the old girl shift a little better.