adjusting the six speed

[dlaing]

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.

I agree with all of that except: "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."

Of course the only evidence I have is a little over 40,000 miles without a broken spring. It could be fatiguing but I can't tell and won't likely care till it breaks. But dang it, I am approaching the number of miles that docc has.

I thought most of the failures are related to the spring binding on the boss, but I could be wrong.

Maybe we need a poll to determine why most failed? I am sure the number that will fail for other reasons will increase as more people put miles on these bikes.

[leafman60]

Ive set up more than one of these shifters. That "second eccentric" controls the "up and down" motion of the ratchet shift arm that determines the engagement of its "hooks" on the shift drum/gear. Its complicated to explain if you are not looking at the mechanism. The under-acorn adjuster controls the motion of this internal shift arm one way while the "second" eccentric determines how far off the drum's ratchet teeth the arm's hooks are allowed to range. They both control the overall shift motion. If the second eccentric is too tight against the shift arm, it can cause it to bind or possible not even get its hooks over the ratchet teeth. If the second eccentric is too far away from the shift arm, it can delay the hooks going down into and engaging the ratchet teeth or possibly prevent them from engaging.

 

Ive tried the scientific way of setting both the eccentrics and things never work well that way. My best luck has been with setting them close to what the factory had and then fine tuning by trial and error. The clearance of the second eccentric is just above the shift arm. Normally, Id say 20 to 30 thousandths of an inch or so.

 

I dont think altering any of these adjustments is going to have any major effect on the springs' life. Also, Im not keen on bending the springs to make them less stressed. Once you smooth off the casting boss, if you transmission has it, as covered in other threads, I dont think youll have more spring problems.

[docc]

But dang it, I am approaching the number of miles that docc has.

While the Sport has 54,000 miles, this gearbox was replaced new and complete under the y2k 3 year warranty. It has 27,500 miles on it. The side cover casting has the date: 9 01.

 

I put the box together last night (Greg had the spring to me in four days counting Christmas! I told you guys he was really Santa! ) I'm waiting a couple more hours for the sealant to dry and the Redline to warm up.

 

I wish now I had taken time to smooth up the ramps on the pawl arm. I read that too late. I did smooth up the boss and the sharp edge where the spring hooks over.

 

Thanks for all the feedback.

[Dan M]

I agree with all of that except: "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."

Of course the only evidence I have is a little over 40,000 miles without a broken spring. It could be fatiguing but I can't tell and won't likely care till it breaks. But dang it, I am approaching the number of miles that docc has.

I thought most of the failures are related to the spring binding on the boss, but I could be wrong.

Maybe we need a poll to determine why most failed? I am sure the number that will fail for other reasons will increase as more people put miles on these bikes.

 

My overall point is, it is all about the spring. If the spring reaches it's binding point by winding up tight on the boss it will be fatigued. They all seem to break in the same spot, yet over a widely varying length of time. How tight it is determines how long it will last. Obviously the tolerances vary greatly from bike to bike. Not only boss size but how tight the spring is wound. I'd gamble that the bikes that have more loosely wound springs in combination with 15mm bosses will be the ones to maybe never have a failure. Those who make the change to their bikes, be it turning down the boss or relaxing the spring or both are likely never to have another issue with the spring. So far as the eccentrics go, if your bike shifted positively when new, they are most likely adjusted properly and need not be messed with. Those adjustments make up for differences in machining tolerances from unit to unit. Once set, no further adjustment should be necessary. It seems those who have played with it have then had to do the trial & error thing to get it right, probably back close to where it was to begin with.

[dlaing]

My overall point is, it is all about the spring. If the spring reaches it's binding point by winding up tight on the boss it will be fatigued. They all seem to break in the same spot, yet over a widely varying length of time. How tight it is determines how long it will last. Obviously the tolerances vary greatly from bike to bike. Not only boss size but how tight the spring is wound. I'd gamble that the bikes that have more loosely wound springs in combination with 15mm bosses will be the ones to maybe never have a failure. Those who make the change to their bikes, be it turning down the boss or relaxing the spring or both are likely never to have another issue with the spring. So far as the eccentrics go, if your bike shifted positively when new, they are most likely adjusted properly and need not be messed with. Those adjustments make up for differences in machining tolerances from unit to unit. Once set, no further adjustment should be necessary. It seems those who have played with it have then had to do the trial & error thing to get it right, probably back close to where it was to begin with.

An excellent overall point

[dlaing]

Ive set up more than one of these shifters. That "second eccentric" controls the "up and down" motion of the ratchet shift arm that determines the engagement of its "hooks" on the shift drum/gear. Its complicated to explain if you are not looking at the mechanism. The under-acorn adjuster controls the motion of this internal shift arm one way while the "second" eccentric determines how far off the drum's ratchet teeth the arm's hooks are allowed to range. They both control the overall shift motion. If the second eccentric is too tight against the shift arm, it can cause it to bind or possible not even get its hooks over the ratchet teeth. If the second eccentric is too far away from the shift arm, it can delay the hooks going down into and engaging the ratchet teeth or possibly prevent them from engaging.

 

Ive tried the scientific way of setting both the eccentrics and things never work well that way. My best luck has been with setting them close to what the factory had and then fine tuning by trial and error. The clearance of the second eccentric is just above the shift arm. Normally, Id say 20 to 30 thousandths of an inch or so.

 

I dont think altering any of these adjustments is going to have any major effect on the springs' life. Also, Im not keen on bending the springs to make them less stressed. Once you smooth off the casting boss, if you transmission has it, as covered in other threads, I dont think youll have more spring problems.

Another excellent post

My contention has been that if the spring is binding, an extra mm of play could make a major difference, (failure after 50,000 miles instead of 26,500 miles) but if you found that 20 to 30 thousandths of an inch is ideal because it shifts better, I'll go with that. But being the resident nitpicker I am curious as to what other settings you had tried and gotten error. If binding seemed to be an issue, I would be inclined to go with the largest (doh!) smallest setting that worked well.

Trial and error is a major pain, so I suspect you did not try many settings.

On my bike I saw no indication that it was even close to binding, so it does not effect me, but for others it can be an issue.

[andy york]

I think Guido had a little to much when it came to the trannys.

The second eccentric, which is "behind the pawl arm" is not present

on all trannys. Some just have the roll pin driven in the case. If this is

"your case", the back edge of the pawl arm never comes close to the

roll pin. So the pawl arm is attached to the pivot which attaches to the splined

shift rod. The spring that breaks keeps tension on the arm to keep it

engaged in the upper shift wheel. roll pin or eccentric, the arm is only

going to move away from the shift wheel enough to engage the next steel

pin on the upper shift wheel and since its always under tension why have the

eccetric?

Why have any eccentric. If you deviate form being adjusted in the middle, on the bottom

spring, you are going to screw up either the upshift or the downshift .

And lets not forget that there is not a lot of adjustment in this particular device.

Lets keep playing.

 

andy

[docc]

I'm just so glad to be on the road again. Frankly, the guys that I was riding with were a bit aghast that I would think I could diagnose the fault. But, with this forum I knew exactly what had happened. Five days later I am riding again! $10US with shipping. Too many BMW riders would have to add towing and shop labor!

 

Thanks again to all of you who regularly help keep my Sport on the tarmac!

[dlaing]

snip.... why have the

eccentric?

Excellent question!

Maybe it prevents the pawl from somehow getting flung into a bind.

Or maybe it was part of an alternative spring/pawl design that did not break, had sweeter shifts, but cost too much!!!!

[docc]

why have the eccentric?

 

andy

 

It may be for ease of assembly versus any real adjustment. The pawl and gear assembly would be easy to put together with the limiting post rotated away from the pawl.

[Dan M]

I'm just so glad to be on the road again. Frankly, the guys that I was riding with were a bit aghast that I would think I could diagnose the fault. But, with this forum I knew exactly what had happened. Five days later I am riding again! $10US with shipping. Too many BMW riders would have to add towing and shop labor!

 

Thanks again to all of you who regularly help keep my Sport on the tarmac!

 

 

Great to not only show your mates that you knew what was wrong but did the fix too.

And, when they break down you can fall back on "well, if it was a Guzzi I could probably help you..."

[Dan M]

Why have any eccentric. If you deviate form being adjusted in the middle, on the bottom

spring, you are going to screw up either the upshift or the downshift .

And lets not forget that there is not a lot of adjustment in this particular device.

Lets keep playing.

 

andy

 

Mine does not have one. I'm thinking the collective transmission engineers (Luigi, Guido & Aldo) realized that the eccentric under the acorn nut that centers the assembly was sufficient and eliminated the other one. The pawl arm is a fixed length so why would it need two adjustments for length of throw? I'm thinking the post that takes it's place limits the pawl from moving too far away when ramping over the pins as the shifter is released.

All pure speculation of course.

[leafman60]

The "teeth" on the shift drum/wheel to which I referred in my earlier post, was my trying to describe the "pins" on said wheel.

[belfastguzzi]

... 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.

There have been a number of threads on this post / pin in the past – particularly because at least one person has found the pin in the bottom of their box after it had somehow come out.

 

Bbennett:

"You are exactly correct in your last post. I finally took the bike into Moto Int. in Seattle and they confirmed the roll pin had fallen out. They said I was lucky that it had not damaged anything upon exit. The bike is shifting perfectly again and my thanks to the Forum and to my dealer.

If YOU are experiencing a large number (1 in 8 shifts) going both up and down, please consider the possiblity that this pin has fallen out (see above post)." http://www.v11lemans.com/forums/index.php?...st&p=102785

 

also thmpr: http://www.v11lemans.com/forums/index.php?...ost&p=62930

 

roll pin stop:

 

adjustable post stop:

from gallo_se who is another person who posted on this

 

The post is adjusted to the opposite side from Doc's, though I suppose that it's giving the same amount of adjustment.

[dlaing]

Thanks BFG!

That is good evidence that the pin does something!!!

Does it have a lock nut?

Maybe it needs thread locking compound??????