adjusting the six speed

[docc]

I knew the throw of the pawl is adjustable under the acorn nut. But, with the side cover off I see there is an eccentric that, apparently, limits to travel of the pawl away from the shift assembly. Mine has a gap of 0.039" . MAybe less would take some strain off the springs that break??

[BrianG]

How much is absolutely required for positive shifting?

[dlaing]

I knew the throw of the pawl is adjustable under the acorn nut. But, with the side cover off I see there is an eccentric that, apparently, limits to travel of the pawl away from the shift assembly. Mine has a gap of 0.039" . MAybe less would take some strain off the springs that break??

Maybe I am not following correctly.

When I took the cover off I thought that the purpose of the eccentric cam was to limit travel, but then I realized that it was to balance the spring force.

Position of the cam is essential to good shifting.

If one blows downshifts but not upshifts, or blows upshifts but not downshifts, it is an indication that the screw is out of adjustment.

If you adjust it so much that the travel is limited, I think you will find that you will be blowing a lot of shifts.

I could be wrong, but I doubt it.

[docc]

Right. That would be the eccentric whose adjustment is under the acorn nut and adjustable from outside. It is on the left of this photo:

 

The other (hidden) eccentric is visible on the right of the photo, middle of the plate. It is nutted on the outside and adjustable from the inside by a screw slot. It appears to limit the lift of the pawl off of the shifting plate.

[docc]

OK, I see it now. The adjustment maintains contact of the pawl in the upshift where there is no play at all between the pawl and the stop.

[BrianG]

OK, I see it now. The adjustment maintains contact of the pawl in the upshift where there is no play at all between the pawl and the stop.

 

Still.... how is the proper positioning determined?

 

What is the result of improper setting?

[Dan M]

docc,

 

It doesn't look like adjusting that eccentric will change the spring's working range. The spring is most tensioned on the downshift when it is wound the tightest. If you bend the spring slightly to relieve some of the tension against the arm, the spring will not wind tight enough to grab the boss and cause the fatigue that snaps it. I've done this to mine and it also slightly reduces shift effort.

 

On my '02 there is simply a post pressed into the cover at that spot offering no adjustment. It appears that stop comes onto play is when you have released your foot from the shifter, and the arm ramps over the cam on the return to center so the spring is no longer in it's tightest position. I wish I had the cover off so I could study the action. If you operate the lever, does it contact the adjuster in question on both the up and down shifting? Does it limit the throw to keep from shifting past the next gear? The only way I can see that it would help save the spring is if it could be adjusted to limit the throw of the arm on the downshift action.

More info please!

[dlaing]

docc,

 

It doesn't look like adjusting that eccentric will change the spring's working range. The spring is most tensioned on the downshift when it is wound the tightest. If you bend the spring slightly to relieve some of the tension against the arm, the spring will not wind tight enough to grab the boss and cause the fatigue that snaps it. I've done this to mine and it also slightly reduces shift effort.

 

On my '02 there is simply a post pressed into the cover at that spot offering no adjustment. It appears that stop comes onto play is when you have released your foot from the shifter, and the arm ramps over the cam on the return to center so the spring is no longer in it's tightest position. I wish I had the cover off so I could study the action. If you operate the lever, does it contact the adjuster in question on both the up and down shifting? Does it limit the throw to keep from shifting past the next gear? The only way I can see that it would help save the spring is if it could be adjusted to limit the throw of the arm on the downshift action.

More info please!

Good points!

It looks to me as if spring will be tightest and most likely to bind when the arm approaches the cam.

Although the spring looks like it may loosen on upshifts and tighten on downshifts, assuming that it follows the same line. On downshifts the lever may move away from the eccentric adjuster and so that the adjuster has no effect on the binding issue. But if it is limited by the adjuster on downshifts, you might be able to prevent binding by adjusting it.

But what do I know, I had no idea that adjuster even existed!?!

I am surprised nobody has brought this up before.

So, what happens on the downshifts?

[richard100t]

I'll have to remember this thread when it warms up enough to play with the bike in the garage again. Merry Christmas everyone

[docc]

The post is an apparent stop that presses the pawl firmly to the to toothed gear as the shift is made, either up or down.

 

It is an eccentric as you can see in the photo of Post#1.

 

You can also see lobes on the back of the pawl for both the up and downshifts.

 

The travel and return of the pawl are not controlled by this spring and stop, but by the symmetrical spring and the eccentric adjustment covered by the acorn nut.

 

Apparently the spring which breaks applies tension to the pawl as it begins to roll the toothed gear shifting either up or down and the stop provides direct pressure to the back of the pawl as the toothed gear comes into engagement.

 

It certainly doesn't look like this could be contributing to spring failures. It is not mentioned in the shop manual and I wouldn't know if there have been service bulletins since. The boss for my spring does measure 15mm, but is gualed where the spring has been binding. I'll clean that up with some wet-dry paper on reassembly when th spring arrives (maybe this week!).

[Dan M]

It is an eccentric as you can see in the photo of Post#1.

 

The travel and return of the pawl are not controlled by this spring and stop, but by the symmetrical spring and the eccentric adjustment covered by the acorn nut.

 

Apparently the spring which breaks applies tension to the pawl as it begins to roll the toothed gear shifting either up or down and the stop provides direct pressure to the back of the pawl as the toothed gear comes into engagement.

 

It's been more than a year since I had mine apart but in a photo it looks like there is just a post where your eccentric is. So at some point they decided no adjustment was necessary.

You're right about the spring that breaks. It merely locates the arm against the pins and keeps it from falling away as it does when the spring breaks. There is no need for heavy tension against it. That's why I reshaped my spring slightly so it wouldn't bind when it winds up on the downshift.

 

Before I removed my cover I was having trouble with the shifter not returning to center after an upshift. It turned out to be a lot of metal paste in the box and after a clean out and a fill with Redline Heavy the problem was solved. While I had the cover off, operating the mechanism by hand, I noticed really rough action as the pawl returned to the center position. The ramp surfaces that slide on the pins when you release the shifter were a rather poor machined finish. This, coupled with the heavy spring pressure contributed to the rough feel. I smoothed them with some emery cloth and polished the edges. It made the action much slicker.

[Dan M]

Good points!

It looks to me as if spring will be tightest and most likely to bind when the arm approaches the cam.

Although the spring looks like it may loosen on upshifts and tighten on downshifts, assuming that it follows the same line. On downshifts the lever may move away from the eccentric adjuster and so that the adjuster has no effect on the binding issue. But if it is limited by the adjuster on downshifts, you might be able to prevent binding by adjusting it.

But what do I know, I had no idea that adjuster even existed!?!

I am surprised nobody has brought this up before.

So, what happens on the downshifts?

 

It doesn't have anything to do with the eccentric. The angle of the arm to the lever at rest is roughly 90 degrees.(like an "L") On the downshift the angle tightens to maybe 50 or so degrees putting more tension on the spring. (like a "V") On the upshift the angle opens, relieving tension.

[dlaing]

The travel and return of the pawl are not controlled by this spring and stop, but by the symmetrical spring and the eccentric adjustment covered by the acorn nut.

The eccentric adjustment should be used to balance the return home of the pawl, and not be used to limit the travel of the pawl.

But what could be happening is that it is limiting the travel of the pawl on either the up or down shifts, and then in the opposite direction to the one that is limited it is allowing the travel to be limited by the binding of the spring around the boss.

This probably occurs because the symmetrical springs are not perfectly balanced, throwing the pawl's home position off center so that the eccentric under the acorn nut must be used to balance the forces. Because it is not centered well enough, the spring binds before being limited on either the up or down shifts.

That is my theory and I am sticking to it! But yah, I could be wrong.

Apparently the spring which breaks applies tension to the pawl as it begins to roll the toothed gear shifting either up or down and the stop provides direct pressure to the back of the pawl as the toothed gear comes into engagement.

 

It certainly doesn't look like this could be contributing to spring failures. It is not mentioned in the shop manual and I wouldn't know if there have been service bulletins since. The boss for my spring does measure 15mm, but is gualed where the spring has been binding. I'll clean that up with some wet-dry paper on reassembly when th spring arrives (maybe this week!).

It is a little hard to believe that it would limit it enough to make a difference, but you never know.

[dlaing]

It doesn't have anything to do with the eccentric. The angle of the arm to the lever at rest is roughly 90 degrees.(like an "L") On the downshift the angle tightens to maybe 50 or so degrees putting more tension on the spring. (like a "V") On the upshift the angle opens, relieving tension.

I disagree, but yah it has been a long time since I opened the box, and I never noticed this eccentric adjuster, so maybe I am wrong and it does not limit the travel, but DOCC says it touching on both the up and down shifts.

Since it is touching on the down shift where the angle is greatest, it is limiting the angle from getting any greater, right?

The only other limiting factor is in the channel effected by the eccentric under the acorn nut.

[Dan M]

I disagree, but yah it has been a long time since I opened the box, and I never noticed this eccentric adjuster, so maybe I am wrong and it does not limit the travel, but DOCC says it touching on both the up and down shifts.

Since it is touching on the down shift where the angle is greatest, it is limiting the angle from getting any greater, right?

The only other limiting factor is in the channel effected by the eccentric under the acorn nut.

 

Yes, like I said in my first post. But, like the adjuster under the acorn nut, it must be adjusted to a position of balance so both up & down shifts are possible. I'm thinking if you try to limit the downshift throw to save the spring, you may have difficulty actually achieving the downshift or you will have too much throw on the upshift, possibly going past the gear you are attempting to select.

Moving the adjuster under the acorn nut can effect how far the mechanism has to move on the downshift, but only in theory. If you position it to bias toward the downshift, you will have difficulty obtaining an upshift.

If you have the acorn nut adjuster set properly to get balanced action on both up and down shift, and if your trans has one, adjust the limiting eccentric to get full throw in both directions. The pawl will still wind up the spring tight enough to fatigue it on the downshift. So, as I've said before, if you bend that springs arm some to lessen the tension against the pawl, the problem is solved.