Help - 1971 R/50 Barnfind

[daz]

Everything went pretty well, and I'm ultimately glad I took it down this far. The only buggery part that didn't want to come off is that pin on the clutch lever. I think this one will require a wee bit of propane.

1971 R 50/5. Exact same bike. I just had mine apart and it was a cotter pin. Production: 08/69-07/73 parts fiche shows cotter pin. (split pin 3 x 28).

[Ken in Oklahoma]

That pin should have a circlip on it, to stop it migrated upwards and breaking off the ears on the gearbox rear cover. Check for this before getting too physical. Make sure you replace with new, or use suitable sized bolt with nylock nut.

Yeah - it is normal for the circlip (e-clip?) to be disguised and dirty grease.

It will also disappear forever when you remove it...

The best fix IMNSHO is a slightly modified bolt. I had just replaced the clutch on my R100/7 and was taking it for it's first excursion. After several minutes I suddenly had a LOT of play on the clutch lever. All too often I tend not to be prudent about things like this. But this time I was. I stopped the bike and looked things over. I was horrified to see that my circlip had come off and that only one of the two "ears" on the back of the transmission was taking the twisting load of the clutch spring pressure.

I pushed the pin back into place and rode home without using the clutch.

My fix was to replace the pin and circlip with a slightly modified bolt of the right diameter (8mm?) I selected a bolt long enough that the unthreaded part of the shank engaged both ears. Cutting off the excess threads and smoothing the cut I installed a nylock nut. I put no pressure on the side of the ears, the bolt "floating" like the original pin did.

I then took the pre-emptive step of applying that same mod to my other riders.

Ken

[audiowize]

Yeah, I have the cotter pin, but I don't see a circlip. The book also notes that it is just the pin on the older bikes.

I like the idea of the floating bolt,though I would imagine that the greased zerk fitting is intended to keep a layer of grease between that pin and the pivot, to confine the wear to those pieces.

I'll hit that whole thing with the soda blaster when it stops raining here to be sure there isn't some hiding hardware.

[melville]

I did the same mod as Ken, but used double nuts locked against each other rather than trust Nylock. I considered also a castellated second nut and drilling the bolt for a cotter pin or safety wire.

Belt, suspenders, duct tape, and baling wire. Maybe just enough to keep the pants up.

[Ken in Oklahoma]

. . . I like the idea of the floating bolt,though I would imagine that the greased zerk fitting is intended to keep a layer of grease between that pin and the pivot, to confine the wear to those pieces. . . .

I'm thinking that there was no such "intention". Those drilled pivot lugs on the back of the transmission are just drilled aluminum. I see no "defined" method for grease to get there, without migrating there. Of course that part of the bike can get kind of ugly with oily crud. Maybe that's enough.

Ken

[audiowize]

No, I'm thinking that the pin is supposed to bind on the forks on the transmission case, then the clutch lever is supposed to pivot on the pin. The zerk keeps grease in this space, so that wear is minimal.

[barryh]

Yeah, I have the cotter pin, but I don't see a circlip. The book also notes that it is just the pin on the older bikes.

Even if it has a circlip it will be hard to see as you rationally expect it to be on the end of the pin instead of which it is sandwiched between the inside of the top lug and the operating arm. Logical enough when you realise it stops the pin moving in either direction.


"It will also disappear forever when you remove it..."

Yes, mine did the leap in hyperspace first time I removed it. Leapt back again 6 months later after I'd bought several spares.

[Ken in Oklahoma]

No, I'm thinking that the pin is supposed to bind on the forks on the transmission case, then the clutch lever is supposed to pivot on the pin. The zerk keeps grease in this space, so that wear is minimal.

I see what you're saying.


Ken

[daz]

[quote="audiowize"]Yeah, I have the cotter pin, but I don't see a circlip. The book also notes that it is just the pin on the older bikes."

That's because there in NO CIRCLIP on your bike. You and I have a cotter pin. That's better than the circlip. Later years did away with the circlip as well. The job of the cotter pin is to keep the clutch lever pin from migrating out of the holes it rotates on. Really no big deal.

[audiowize]

Well,

I have a huge pile of new bits for the bike, and I'm likely going to do the rust encapsulating primer tonight.