Topic: Question about shift linkage (CB350 twin)

[Raul CB750K1]

When I bought my CB350 twin it had a "direct" shift pedal, you know, just like the CB750, a pedal that bolts directly into the gearshift axle.

I saw by the parts manual and the pictures that it should have a "shift linkage", a pedal that bolted to a peg in the frame, and a linkage to actuate the gearshift axle. I bought a set from eBay, it was in very good shape, but one thing that I noticed as soon as I rode the bike was how much free play did the pedal have. It could move up and down to almost one inch, without changing gear. It was necessary a wide movement of the feet. Downshifting was easier, it almost had no free play, as soon as you pressed the pedal it downshifted.

With the bike on the stand, I could move the pedal up and down. That's when I noticed that the problem was in the linkage. Seemed that there was too much free play in the linkage, like if it was worn. The pedal weight put it in the rest position, "eating up" all the wear, thus it was easy to downshift, but in order to upshift, the first inch of the pedal was used to travel the wear in the linkage bushings, and then it was when the shifting started.

I removed the linkage, dismantled it, and could see there was too much free play indeed, but it doesn't seem there is some noticeable wear. That's when my question arises, whether it was such a loose fit, or it has indeed been worn out.

I can probably eliminate the wear using something as a shim, but still, I would like to know how was it suppoused to be.


Thanks in advance

[tbpmusic]

http://www.hondatwins.net/forum/viewtopic.php?f=17&t=1992&st=0&sk=t&sd=a

[Raul CB750K1]

Thanks for the link. I've read the three pages. Lots of interesting advice, specially that referred to the relative lenght of the linkage. Seems that it is wear on the pins/linkage.

I could also use a "direct" shifter but I would like to keep it as close to stock as possible. Probably I will shim the wear somehow. But it will be in a couple months time, first I have to rebuild the engine.... :-)

[tbpmusic]

I could also use a "direct" shifter but I would like to keep it as close to stock as possible.

Why??
You've already discovered that the stock setup is junk.
Use the other one, keep the stock part in a box and give it to the new owner if you ever sell the bike.
Unless the bike is a Trailer Queen, just goes from show to show.

[Raul CB750K1]

Well, that makes sense. I for one have a modern master cylinder in the CB750. I vouch for practicality when it comes to use, originality when it comes to show.

Tell you what, I'll try to shim the wear, and if it doesn't work, I'll use a regular shift pedal. What I can't understand is why Honda used such a setup. Linkages are usually used when the distance between the pedal and axle is long, or the axle is in an awkard position, or it is needed to reverse the operation, but I don't really see the point to use the linkage in the CB350.

[Green550F]

good question because the CL scrambler was direct and they are so similar. infact the CL frame has the piviot for the linkage!

[Raul CB750K1]

good question because the CL scrambler was direct and they are so similar. infact the CL frame has the piviot for the linkage!

Really?

Then, what seemed to be a simple question, has turned into what's the purpose of the linkage setup.

Any ideas?

[tbpmusic]

good question because the CL scrambler was direct and they are so similar. infact the CL frame has the piviot for the linkage!

Uhhhh, no......

Look at the fiche - CB/CL 350 used the same setup.

[chickenman_26]

I can probably eliminate the wear using something as a shim, but still, I would like to know how was it suppoused to be. Thanks in advance

Hi. New guy here. Just stumbled in here from the VJMOG forums and found your post. I had the same issue with my CL350 and solved it with two rod ends and a piece of threaded rod from Ace Hardware. Also, the bushing end of my shift lever was badly worn, so I got a brand new one from eBay. The pedal is tight enough now that it only has a couple of millimeters of up & down slop. That's caused by either the shift shaft or the case bushing being worn as well as the hole in the sprocket cover being enlarged. Can't do anything at this point about the shaft or case bushing, but I may have the hole in the sprocket cover sleeved to eliminate the side movement of the shaft. Here are 2 pics of the rod ends and threaded rod. This "fix" allows you to retain the height adjustability of the shift lever.

Stu

[Raul CB750K1]

Stu, thanks a lot for the feedback and specially for the pics!

First of all, because I don't feel alone anymore, there is more people who has suffered the "pedal wear syndrom".  :-)

I like your solution a lot, because it seems that the rod ends are tightly bolted to the shift and pedal -thus no wear no play- and they have some kind of "knee joint". Where did you get them from?

I could easily live with a 1-2 mm slop. I would not bother shimming the sprocket cover hole. And I really doubt there is much wear there because there is -in theory- no friction.

[Raul CB750K1]

One question: how do you actually adjust the rod lenght? Because the linkage rods have one of the ends reverse-threaded. Otherwise, regardless of which direction you turn the rod, what comes in in one side comes out on the other, so there is no difference in rod lenght...

[ohiocaferacer]

Have to adjust with the rod ends fixed so they dont move.......like when it is mounted on the bike. Then you just twist the rod clockwise or counter-clockwise to make the throw shorter or longer.

[Raul CB750K1]

Have to adjust with the rod ends fixed so they dont move.......like when it is mounted on the bike. Then you just twist the rod clockwise or counter-clockwise to make the throw shorter or longer.

That's what I mean. With a regular threaded rod, regardless of which direction you turn it, the lenght won't be affected. You need a rod that has reverse-thread in one of the ends.

[ohiocaferacer]

Yep.....exactly.

[Raul CB750K1]

I still don't understand how Stu adjust the rod lenght on his setup... :-(

[chickenman_26]

One question: how do you actually adjust the rod lenght? Because the linkage rods have one of the ends reverse-threaded. Otherwise, regardless of which direction you turn the rod, what comes in in one side comes out on the other, so there is no difference in rod lenght...

Raul,
Sorry if I misled you. You can't adjust it the same way as the factory setup. But it's not hard. Just loosen the jam nuts, remove the rod end from the brake pedal. Then screw either one or both ends a turn or two and reassemble. Once you get it where you want it, you won't ever need to mess with it again. I actually wanted to duplicate the action of the factory linkage, but I couldn't find a rod with both left and right threads that was long enough. So I settled for this.

To answer your question about where I bought the stuff, it came from a hardware store. These are pretty common items. I don't think I paid more than $15 for everything.


Stu

[Raul CB750K1]

Thanks again Stu, I'll try to find those parts.

[chickenman_26]

Thanks again Stu, I'll try to find those parts.

Well, let me know if you run into a dead end. I suppose I could get some here and send them to you, if it came to that. Just reimburse me for the parts and postage.

The rod was a 3' length of allthread - 5/16" X 24 thread pitch. I just measured it, and there's 3 3/8" missing from it, so that's apparently the length I used. I have no use for the rest, so you're welcome to a chunk. You'll also need a flat washer and a self-locking nut to attach each rod end to the levers, plus a 5/16" X 24 jam nut for each rod end. Set the pedal height where you like it, and attach both rod ends to the levers first. Then swivel both rod ends down as far as they'll go so they're aligned with each other, and snug the jam nuts.

Stu