Re-engineering the Shift Spring

[swooshdave]

During summer when I was in college a worked a temp job at a spring shop. Made everything from tiny little springs to car coil springs. It was too long ago for me to remember much about the details.

[Chuck]

I've really not been slackin on this job.. busy. Experimented with a different way of holding the wire. Used the other end of the bending tool lever. Made several springs using this guide in the tool post. It's faster, but  maybe not as repeatable.

2017-11-21_06-24-16 by Charles Stottlemyer, on Flickr

Supervised Austin making steel mill oiler nozzles..

2017-11-21_06-24-35 by Charles Stottlemyer, on Flickr

I think he's a keeper, btw..

Rewired the motor.. I'ma believer in using what you brung.. I'll be able to use it as a hanger door thingy after this project.

2017-11-21_06-27-20 by Charles Stottlemyer, on Flickr

Did *some* testing on various springs with my new scientific fish scale..

2017-11-21_06-37-03 by Charles Stottlemyer, on Flickr

Started on the design for the cam on the spring abuser ™.

2017-11-21_06-28-33 by Charles Stottlemyer, on Flickr

Let's see now, 46 rpm X 3 = 138 X 60=8280 shifts per hour. That's 198720 shifts per 24 hours.

I'll also make a couple of .080 springs with 2 1/2 active coils. My guess is they'll bind up, though.

Still have to make all this stuff and get it working reliably, of course.. but i think we're on the right track. Shouldn't be much longer.

[Scud]

That's 198720 shifts per 24 hours.

 

 

Same as one weekend in the Santa Monica Mountains, right? 

 

Seriously, that's a whole lot of shifting. Hopefully the rest of the pre-selector is up for the abuse - but I don't mind if you kill it. I'll just have a spare tranny with a dead pre-selector. All in the name of science. 

[Chuck]

 

That's 198720 shifts per 24 hours.

 

 

Same as one weekend in the Santa Monica Mountains, right? 

 

Seriously, that's a whole lot of shifting. Hopefully the rest of the pre-selector is up for the abuse - but I don't mind if you kill it. I'll just have a spare tranny with a dead pre-selector. All in the name of science. 

 

Oh, don't worry. I'll just be simulating what the preselector does. About the only wear yours is getting is taking it apart, trying a different spring, etc. I'm getting really good at that.

[Scud]

Oh - so you're just going to move the arm, not whole mechanism. Makes sense. I'll wait for pics.

[Chuck]

Oh - so you're just going to move the arm, not whole mechanism. Makes sense. I'll wait for pics.

 

I'm planning on using the bending fixture with a 15mm post and the cam driven by my low speed motor somehow. "Some sort of lever" also TBD in the picture of the cad drawing will pivot on the pin. The drawing shows the spring relaxed and at 39 degrees torsion.

No Guzzi parts (except the spring) will be harmed in this exercise..  

[luhbo]

No cam wheel. Too complicated in my eyes. Just place the lever plate near the electric motor and connect it with a piece of wire, then pull the lever. It's only one third of the speed though, but you'll win a week or two when you can start the test tomorrow, cutting out the 'somehow'.

[Chuck]

It's not complicated to my eyes, and we need to test several spring versions. 

[swooshdave]

The man has a machine shop, there's no such thing as too complicated. 

[Chuck]

Austin is finishing up his little production job, so I'll have access to the mill over the holidays. I did learn a little more this morning. A lot of spring pressure is not a good thing. It tends to over shift, and neutral is hard to find. Too little spring pressure is not a good thing, either. It makes shifting up a function of the adjustment of the eccentric. The sacked spring I took out of the Mighty Scura has *no* pressure at the end of the up shift.

Just for grins, I made an .080" spring with 2 1/2 active coils. I didn't think it would work, but it at least fits *this* particular shifter gizmo (technical term) and shifts beautifully, too. Should have plenty of travel, but I haven't run that through the spring calculator yet.

I'll be back.

Edit: Oh, yeah. Maximum safe travel is 56 degrees. (!) I'll look into it a little farther.

2017-11-22_11-33-07 by Charles Stottlemyer, on Flickr

[swooshdave]

Will the springs need any post-treatment?

[Chuck]

Will the springs need any post-treatment?

 

I doubt it will need stress relief. Most springs aren't. We'll find out after a few 10s of thousands shifts., *assuming* the gearbox of my little low speed motor holds up.

[bbolesaz]

It's not just a Guzzi problem.

 

[Jim in NZ]

"It's not just a Guzzi problem."

 

What kind of bike is that from, bbolesaz?

[bbolesaz]

BMW /5