Re-engineering the Shift Spring

[Chuck]

"I didn't miss any shifts... "

 

Alrighty, now..

[Scud]

Can I still jump in for 2 pieces?

 

No need to "reserve" springs. I'll probably buy at least 100 of them to get a good unit price. 

[Scud]

"I didn't miss any shifts... "

 

Alrighty, now..

 

A few mores miles (to pick up a chain tool so I could install a new chain on the Ducati). It might be my imagination, or wishful thinking, but maybe, just maybe, the shifting has improved a bit and neutral can be found more easily and consistently.

[Chuck]

I "liked" the way the preselector worked with the new spring, but didn't want to say anything.

[swooshdave]

 

Turns out the Scura had a 16mm boss on the arm - but my spare pre-selector had a boss with 15mm. So I swapped them.

 

I'll take one of the springs, but I suspect I'll never need one.

[docc]

Oh, this is a *must-have* for any tried-and-true V11-er. Even if it only hangs on the tool box. by the hammers.

[LowRyter]

need one for the tankbag  

[nobleswood]

Scud,

 

Rather than have you carry the full cost of this R & D and then the expense of the limited run of springs, I for one am quite happy to order a few springs, whether I need more than one or not.

 

Which would be all I can offer as my 'testing grounds' are not available at the moment.

[Scud]

Scud,

 

Rather than have you carry the full cost of this R & D and then the expense of the limited run of springs, I for one am quite happy to order a few springs, whether I need more than one or not.

 

Which would be all I can offer as my 'testing grounds' are not available at the moment.

 

You snowed in? Bummer.

 

Chuck's also spent some money, and has invested the most time. I appreciate the offer, but I think the next expense will be under $500 and I can absorb it in my "PlayPal" account. I'll try to figure out a price that will allow me to send some $$ to Chuck, the forum, and have a little beer money left over. Ideally, one person in each of a few countries could buy a few and supply them to others via local post. But it's going to be at least a month till we need to worry about distribution. Meanwhile, I get to feel special - having the only V11 in the world with the new spring.

[nobleswood]

Good. Just didn't want this community spirited improvement to leave a sour taste in your mouth or Chuck's.

 

To quote Mr Hagan; 'Proud member of Moto Guzzi's envy-of-the industry post-sale R&D program!'

 

Happy New Year all !

 

Snowed in ? Yeah. Spent 5 hours snowblowing the drive & elderly retired neighbors drives. My Christmas good deed to compensate for them putting up with my Hillbilly ways

[Chuck]

No need to send me any money, Scud. I was just doing this as a partial payback for all I've learned here. Some of it useful.. :) Actually, its been fun..the sort of thing I used to do back in another lifetime as an engineering modelmaker.

[Steve S]

It's a shame this thread has wandered away from the original idea of changing the spring for a pull spring, my mate has just bought a Cafe Sport that has had no less than 3 spring failures in it's life, as he intends doing some European trips this year I suggested that I convert it to a pull spring so I''ll let you know how I get on, I've replaced a few stock springs over the years but not done the conversion yet, as far as I'm concerned the only permanent fix is a pull spring

[Scud]

I originally thought the pull spring would be the best too - but I am now convinced that there was a design flaw in the original spring. This thread got pretty long, but the essence is that the original spring fails because of two problems:

1. the short arm has a hook/tab bent at a sharp 90-degrees, and should have a more gentle radius (so the short arm snaps where it was bent)
2. the whole spring is forced to travel more than its safe limit - so it breaks on the coil (this problem is even worse with the 2002 bikes that have a too-big boss for the coil, which causes it to bind on downshifts)

Chuck's design addresses both of the above flaws, plus it extends the short arm a bit to further reduce the risk of over-travel. It uses a thinner wire with an extra coil - so it will bend, not break. Plus it provides more even pressure on upshifts and downshifts (compared to the original spring, which has very little pressure on upshifts).

 

I'll go test the spring a little more today - I think the Scura knows her way to some steep and twisty roads.

[Chuck]

It's a shame this thread has wandered away from the original idea of changing the spring for a pull spring, my mate has just bought a Cafe Sport that has had no less than 3 spring failures in it's life, as he intends doing some European trips this year I suggested that I convert it to a pull spring so I''ll let you know how I get on, I've replaced a few stock springs over the years but not done the conversion yet, as far as I'm concerned the only permanent fix is a pull spring

You can bleme me for going away from the extension spring. The original idea was to build a "kit" that could be installed by the average home mechanic. That would have included a custom made pedestal, the spring, a drill, tap, counterbore, o ring, a very accurate template to drill the preselector, and hardware to put it all together. By this time, it is getting expensive.. and.. not all home mechanics have a drill press, much less a milling machine which would have been preferable.

 

When it became obvious that the original spring was poorly designed, a proper spring design is the simple and viable IMHO solution.

Of course, you can do your own extension spring mod.. Footgoose has done one, and there are pictures of his in this thread.

[luhbo]

As a funny matter of fact this so poorly designed spring does not break if used in any short frame V11.

On the other hand, in some later bikes it tends to brake on a nearly daily basis. Poorly designed, does that mean a certain lack of flexibility then?

 

As mentioned earlier I fetched a bike from Italy on which one of the former owners did the 'Japanese Coil Spring Mod', alas the Italian way you could say. He just bore a hole through the cover resp. the lever, counter locked a bolt to the cover and hung in an equaly simple spring. He didn't even cut flush the bolt from the outside, being behind the starter anyway.