Re-engineering the Shift Spring

[Scud]

I wish I had measured the spring on the Greenie's transmission when I had it apart. Perhaps they used thinner wire (with more flexibility) - then switched to thicker wire in 2002? Just idle speculation. If memory serves me, the Scura has broken 2 springs in about 15,000 miles. I have only put 2,000 on the Greenie, which is coming up on 7,000 total. I did not replace the springs when I had it apart to reseal the transmission, so it will be interesting to see how long it lasts.

 

But back to the Scura, our current "test platform." I believe it now shifts better than ever, having enjoyed a spirited romp today (although it was sad to see the damage caused by the recent "Lilac Fire"). But I have not isolated the variables; I made three changes at the same time: 1) the new spring 2) a used pawl arm with the smaller diameter boss, and 3) resurfaced an area to remove a groove and polished it where the short arm touches. The shifting just seems more crisp and neutral is very easy to find.

[Chuck]

"The shifting just seems more crisp and neutral is very easy to find."

 

Yay.

[Lucky Phil]

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

Well I hate to disagree, but I disagree. After Chuck identified the reason for the original spring breakages and modified the design to mitigate I think the Chuck spring is the way to go. The pull spring mod lacks the elegance, simplicity and economy of componentry of the original design and introduces another potential leak point.

No point reinventing the wheel in a more complicted fashion when a refinement, quality enhancement and product improvement of the original design works.

BTW chaps I need 3, whatever they cost:)

 

Ciao    

[Steve S]

Time will tell as neither spring has been tested for long yet, maybe both springs will last forever 

[Chuck]

Time will tell as neither spring has been tested for long yet, maybe both springs will last forever

 

I tested the new design with 10 degrees extra preload, and the hooked end barely on the lever for a quarter million shifts.. At any rate, I'm convinced it won't break in service. My concern was how it would work in a bike. So far, Scud thinks it might be better.

Footgoose mentioned a shifting problem with his coil spring mod. Again, so far.. the new spring has been without issue.

[nobleswood]

Time will tell as neither spring has been tested for long yet, maybe both springs will last forever

 

As the Chuck re-engineered spring was put on a test bed & run for thousands of cycles, I don't think you can compare the testing of the springs & lump them in the same category.

[Steve S]

When the new spring is in production I would be happy to have a few here in the UK and offer a fitting service for the few V11 owners here

[Ian]

Now I like the idea of the fitting service as well

[Lucky Phil]

When the new spring is in production I would be happy to have a few here in the UK and offer a fitting service for the few V11 owners here

You know if we can ship some here to Aus I can distribute and probably fit them as well if needed.

 

Ciao

[MartyNZ]

 

When the new spring is in production I would be happy to have a few here in the UK and offer a fitting service for the few V11 owners here

You know if we can ship some here to Aus I can distribute and probably fit them as well if needed.

 

Ciao

I'd be happy to act as NZ distributor. If Scud's field test proves ok, and anyone else in NZ is interested in a genuine Improved Spring designed by Chuck, you could send me a personal message. I can send on at cost.

[Scud]

Good stuff, guys. I ordered 100 springs - should take about 2 weeks. 

 

Spring installation party at my house.  

[68C]

So, all you Americans are going to spring along to Scud's for a Spring spring fitting party?

[Jim in NZ]

Well done, Chuck and Scud! Your efforts and ingenuity are really appreciated. Though I will miss those hours squatting in the gravel on the side of the road replacing the spring when it decides to surprise me (NOT!). I have PM'd Marty NZ to put my name down for one. Happy New Year to you both.

Cheers,  Jim.

[terje_m]

I have a 2001 red frame, which I understand is not so prone to spring trouble. Am I wrong? Still would be interested in one or two; better safe than sorry. As I have a annoying third gear I am going in for some fine tuning anyway as per recommendations elsewhere in this splendid forum (have the lucky-phil-extender-mod).

[LowRyter]

terje

 

As I understand it, the redframes aren't prone to breaking the shifter spring- only cracking the transmission case.  After tearing your bike and  tranny  apart and welding the crack in the case, you'll have a great opportunity to install a new shifter spring.  

 

 

I guess it's pick your poison.