Selector box

[Chuck]

I just purchased a 1966 Ducati Monza because i need something smaller to ride. I have many years of experience with British singles and twins and this is my first little Ducati. I read the helpful information about shifting technique and I have been doing a modified version of this for years with the British bikes, especially getting into 1st with my Velocette. My problem is that the shifting peddle does not return to a central (horizontal) position after I shift. To make the shifts I have to carefully move the peddle with my foot into the horizontal position so the claws will push the shifting pegs to the next gear. I bought a new spring and I think I installed it correctly, all the books I bought have no useful information or pictures, but it seems there is only one way to put all the pieces together and get the cover closed. The peddle moves easily but it has no spring tension to return it to a level position. Can anyone help me?

[DewCatTea-Bob]

" I read the helpful information about shifting technique and I have been doing a modified version of this for years with the British bikes, especially getting into 1st with my Velocette. My problem is that the shifting peddle does not return to a central (horizontal) position after I shift. To make the shifts I have to carefully move the peddle with my foot into the horizontal position so the claws will push the shifting pegs to the next gear. I bought a new spring and I think I installed it correctly, all the books I bought have no useful information or pictures, but it seems there is only one way to put all the pieces together and get the cover closed. The peddle moves easily but it has no spring tension to return it to a level position. "

____ I hope you were referring to MY (strongly)- suggested method of shifting (which works on all motorcycles I know of).
__ Concerning the pedal return issue, I've always thought that the stock return-spring was a bit too weak,, cuz although it's quite adequate when all the shifter-box internals are new, once they get worn, the spring (whether new or not) then no-longer seems to be able to bring the foot-lever all the way back for BOTH up-shifting AND down-shifting.
However with such worn internals, it's still always possible to adjust the return-mechanism so that either up-shifting OR down-shifting can be done with normal/expected pedal-return results.
For such cases, I always adjust the adjuster -(eccentric-head screw) for normal pedal-return for UP-shifting,, and then have to use my toe's bottom-side to lightly TAP the pedal so as to help the return-spring bring the shifter-pedal merely back to it's reload-location, so that the shifter is then ready for the next downshift.
__ That you thought it necessary to replace your original (unbroken) return-spring, leads me to suspect that you hadn't first tried to use the adjuster-screw to get your shifter-pedal to correctly (or merely better) reload (between each gear-shift).
And NOW (that you've attempted the installation of a new spring), your shifting-issue has gotten very-much worse, correct ? _ If so, it then seems that you have not installed your replacement spring correctly, as it is a more difficult task than just inserting the return-spring into it's location ! ...
The installation of the return-spring in the required manor so as to (pre)- LOAD the spring, is more easily accomplished with the shift-lever attached to it's shaft/spring-retainer, so that ya -(one person) can then more-successfully get the spring preloaded/assembled (within the 3-part assembly).
____ Hopefully something of my above wording helps get your mind's gears to mesh further and you next figure-out what exactly needs to be done. _ And/or also hopefully, on the other-hand,, some part of my wording has spawned related questions in some specific area which you now wish to further learn more about,, and if so, please ask ! _ As there are a number of different directions that this topic could possibly branch-off & migrate-onward to (which may not be in whatever direction that YOU particularly need to head for).
Here's an example (which may or may-not be of specific help to you) : viewtopic.php?f=3&t=929&hilit
.


Hopeful-Cheers,
-Bob

[vt450scr]

Chuck:

Sounds like the "pedal return spring", P/N 0400.13.130 (see parts book at MotoScrubs "Technical") is displaced or broken.

Cliff

Sorry, Chuck: Did you spread (squeeze, actually) the tangs on said spring before mounting to the "adjustment shim"? Not an easy
procedure, especially without an extra set of hands.

[Jordan]

A nice thing about old Ducatis and Hodakas is the selector box is able to be removed in toto, and worked upon at the bench.
If you carefully arrange for it to be clamped in a bench vise, you can test its action with the foot lever.
If installed correctly and nothing binding inside, then the 2 way selector ratchet can be adjusted with the external slotted screw and locknut.
Starting anywhere, loosen locknut and move screw slightly in either direction. If shift improves continue until it's good both ways. If it gets worse turn screw in the other direction and continue.
Note that it's possible to have the slotted shaft out the back of the box 180 degrees out, so make sure you've got it the correct way when assembling.

Jordan

[Chuck]

I have not touched the cam selector because my Mick Walker restoration book say not to mess with it. I just got the bike and am learning how to shift it, fortunately it is the same pattern as my British bikes. I can get all the gears to work just fine if I get the selector pedal to the horizontal position. The more I ride the bike the better my shifting becomes but is not easy to locate the selector peddle in the correct horizontal position between every shit. I put a new spring into the spring holder and it was a little difficult. I compressed the ears and got it to nest into the holder, I'm pretty sure I have it facing the right way-it looks like it can only go in one way. Then the operating spindle was more difficult because I had to spread the ears to get the spindle into the closed spring ears. After I did this it negated the spring because the ears were too far away from the holder's bent up piece of metal. It seems that these parts can only go together one way and I was carful to put the parts back in the way I got them. I also bought another selector box and I think it it from a wide case because it has a door hinge kind of operating fork. I got to work on the bike but was not as good and I decided since it seems to be the wrong part not to fool with it. Are these boxes better that the NC selector boxes.

[Chuck]

I think I had the spring in the wrong way. I put the ears in opposite directions and there is now lots of spring pressure to center the peddle. It works on the work bench as as soon as the temperate on the east cost drops below 90 I'll try it on the bike. Is there a difference in the NC & WC selector boxes in how they work, they have different parts.

[Jordan]

I only know widecase, but I did come across a WC that had an unhinged type ratchet plate - possibly the whole selector box was from a narrowcase?
On the face of it, the hinged type would seem to be better in that there would be less lost motion I think.
Otherwise, the 2 types are very similar.
Looking at parts lists, you can compare and see what is the same and what is different, as the numbers were carried over to more recent Ducati models, through the decades. Not lately though.
I'm not sure if you are saying that you aren't inclined to alter the threaded adjuster that centralises the ratchet plate. If you are, I'd urge you to reconsider!

Jordan

[amartina75]

hello,
I am trying to figure out a problem i am having with the shifting of my 450 Jupiter.
after a complete restoration i have been working out the last few bugs, the shifting problem is, I hope the last one to solve.
this is what has gone on so far;
I was having trouble getting the bike to downshift, it seemed to go up through the gears fine but would get stuck trying to downshift,
to the point where i would have to stop and pull the gear lever up with my hand.
i took the shifter box off and shifted it in my hand while holding it, i could tell that the lever was not returning while pulling up on the lever, as if downshifting.
i then adjusted the screw untill the shifter worked well in either direction. it makes all the right noises, doesn't get stuck, shifts and returns seemingly like it should.
BUT...when i put it back on the bike it is getting hung up or something between 3rd and 4th gear, shifting between those gears is slightly harder then any other gear.
i read through some old posts about shifting problems and didn't find anyone that this had happened to.
i found some info where Bob had suggested a way to shift where you hold down the shifter untill you start to engage the clutch. i tried this and it did make a difference,
for the better, smoother shifting and no missed gears. but there is still that problem between 3rd and 4th.
i tried the shifter box off of my 250 scrambler on my 450 and it seemed better at first but i still feel something between 3rd and 4th gear.
i put the 450 shifter on my 250 and had no problems at all, it shifted perfectly well.
is it possible for the shifter box to be so slightly out of adjustment that it would cause this to happen, harder shifting between only 2 gears?
Thanks, hope someone has some insight into this,
Aaron

[Jordan]

As the difficult shifting stays with the 450 bike even when the selector box is changed, and also your 250 works well with either selector box, it points to the problem being in the 450's gearbox.

[amartina75]

As the difficult shifting stays with the 450 bike even when the selector box is changed, and also your 250 works well with either selector box, it points to the problem being in the 450's gearbox.

I can see why you would say that but I am not ready to consider that an option at this point, for many reasons one being that it would totally suck! if that was true,
another being that the motor is a fresh build by my brother who is VERY meticulous when he builds things, every part of the gearbox was cleaned and inspected and the smallest burr removed before being reassembled.
I would like to consider all other options before considering a problem with the gearbox itself.

my 250 is older and dirtier and sloppier in every way, its probably never been rebuilt other then the work ive done to it.
isn't it possible it just shifts easier then the 450 does and that is why there is no problem with it