Electric Assist Clutch

[Jim]

Lets face it... we ain't gettin no younger. I don't know about you guys, but 15-20 minutes of stop and go traffic (which is common here in KC) and my forearms feel like I spent and hour in the gym.

So, here's an idea I been thinkin about for years but never pulled the trigger on: An electric clutch assist using a 12V pull solenoid like this...

This particular one has an inch and a half throw with 4lbs. of force. Only uses 10 Watts of power and costs about 25 bucks. It would take some measuring and a little trial and error to pin down exact figures but lets roll with this one for now...

My idea is to mount this solenoid in an "intermediate box" that could be hidden under the tank. The clutch cable would go from the lever to the box and another cable would go from the box to the engine (clutch). A brake light switch mounted to the clutch lever would energize the solenoid, helping pull the clutch cable through a lever, giving a slight mechanical advantage. When the clutch lever is released, spring pressure would (already does) unload the throw out bearing. Here's a quick drawing...


Lets say for shits and grins that it takes 10lbs. pull on the lever to disengage the clutch. As soon as you pull the lever, the solenoid energizes and it would be instantly reduced to 5lbs. Could even use a stronger solenoid for even more reduction. When you release the lever, solenoid would release and the full 10lbs would engage the clutch just as it does now.

The cool part is that this is scalable to any bike and could probably be made for under a hundred bucks.

I smell patent materiel here Like any good science project though, first ya gotta try and poke holes in it. So poke away guys! Lets talk this out and see if it will actually work.

I guess the first question is... has this been done before? Am I pissin in the wind re-inventing the wheel?

 

[Mailman]

I've seen hydraulic clutch mods, and 2M is currently working on a mousetrap mechanical linkage hidden under the left cover, but I've never seen an electrical assist. It's always fun to tinker and invent new things.

 

[Jim]

I've seen hydraulic clutch mods, and 2M is currently working on a mousetrap mechanical linkage hidden under the left cover

The advantage I see to this is that it would be a pretty simple "bolt on" mod. No extra machining or hydraulics required. That plus the force could easily be varied by adjusting the lever/solenoid pivot.

 

[Liftedzuki]

Aprilia slave, ducati master, and some hydraulic line from revival cycles (DIY, no special tools required, small high quality line).

Takes afew hours to do but I get double the throw from factory, takes 1 finger to pull the clutch and no wiring, or huge clutch cable!!

I can find neutral instantly every time too, it clicks into neutral very solid.

 

[Jim]

but I get double the throw from factory, takes 1 finger to pull the clutch

My plan is to NOT double the throw, keep it the same while reducing pull force. Was any machining involved for the master? And does it stick out the side of the case? Pics maybe?
Thanks for the input!

 

[Liftedzuki]

I mean double the throw at the clutch pack, not the lever**. Helps with disc separation.

No machining but drilling (and filing) required.

 

[Jim]

Looks good. Nice clean install.
What I'm (also) trying for is a setup that will fit any bike and not alter the stock appearance.

 

[Liftedzuki]

What about a hydraulic master, hydraulic ram that operates a pulley with the cable?

It would cost more but then you wouldn't need a clutch cable and wiring going to the bars?

 

[Jim]

What about a hydraulic master, hydraulic ram that operates a pulley with the cable? It would cost more but then you wouldn't need a clutch cable and wiring going to the bars?

One has a master cylinder on the bar and a hyd. line coming from it. The other has a cable (just like stock) and two wires (one if you gnd. the switch) that are easily hidden under the bars. If you have a classic and are a purist going for as stock a look as you can get and still reduce clutch pressure, which one would you go for?

Instead of looking for alternatives to my plan, lets explore the questions of "has it been done before" and "will it work?"
Thanks for the input.

 

[Liftedzuki]

I'm all for doing things different, I like to keep everything minimalist so that's always my thought process.

I don't see why it wouldn't work, just make sure you have a limit switch so the ram will stay at "clutch engaged" but not burn it up.

 

[TwoManyXS1Bs]

Jim, I like it. Would like to have some sort of strain gauge or pressure transducer monitoring the input clutch cable tension, and apply appropriate assistive force.

For ideas and some numbers to grind, piledrive thru my clutch threads.

Force is one thing, but I'm approaching this from an "energy" perspective. For example, and using rough numbers, the pressure plate force is about 400 lbs, traveling about 0.060". Energy is Force x Distance. Multiply those gets 24 in-lbs of energy. Our clutch cables demonstrate poor energy translation, requiring 100 lbs (or more) to travel about 0.45" (at best). That works out to 100 x 0.45 = 45 in-lbs of energy, about double the energy requirement at the clutch worm.

If the solenoid produces 4 lbs force over 1.5", that's 6 ft-lbs of energy, or about 6/45 = about 13% of assist.

To get 50% assist, at the cable's max travel of 0.6"-0.65" at an optimistic 80 lbs of cable tension, would require about 40 lbs, energy would be about 0.6 x 40 = 24 ft-lbs.

I wish Scotty would fix the transporter.
Would be great to come over there and hammer this out...

 

[Jim]

Your numbers look about what I expected... Didn't realize the energy loss in the cable was that bad though. The only problem with a stronger solenoid is the wattage. I guess I need to figure out how much power the electrical system can spare to figure the upper limit on solenoid size.

about double the energy requirement at the clutch worm.

OK then... what if we attached the solenoid directly to the worm lever? Wouldn't lose near as much energy in the cable. I think there's room inside the side cover for it.

I wish Scotty would fix the transporter.
Would be great to come over there and hammer this out...

Yeah. Two heads are better and all that...

 

[Jim]

We could even extend the worm lever to gain some mechanical advantage and use a solenoid with a longer throw.

 

[TwoManyXS1Bs]

Have a look thru these, especially the first and last threads:

http://www.xs650.com/threads/xs650-clutch-worm-actuator-experiment-tidbits.31554/

http://www.xs650.com/threads/xs650-clutch-pushrod-experiment-tidbits.32267/

http://www.xs650.com/threads/xs650-clutch-cable-experiments-and-tidbits.32945/

http://www.xs650.com/threads/xs650-clutch-worm-actuator-rotation-guage-degree-wheel.33545/

http://www.xs650.com/threads/yamaha-xs650-experimental-clutch.47498/

http://www.xs650.com/threads/finding-neutral-while-stopped-and-in-gear.47568/

http://www.xs650.com/threads/yamaha-xs650-experimental-clutch-version-2-0.50189/

http://www.xs650.com/threads/yamaha-xs650-experimental-clutch-booster-mousetrap-clutch.50625/

 

[Jim]

Just went through the first thread. You've put some serious thought and effort into this. Looks like I'm late to the party. Gimme a sec. to get caught up.

 

[Signal]

My first thought is that solenoids are either on or off, do you have a plan to address the starting off problem of it just dumping the clutch when you de energise the solenoid.
Some sort of slugging circuit could be built but then that would be a problem at other times when riding.

 

[gggGary]

IMHO read this; http://www.xs650.com/threads/short-...utch-cable-rerouting-ideas.41987/#post-419895
Get the best possible routing with a fresh, lubed cable then decide if reinventing the wheel, making a "simplicated" set up is justified.
gggGary who's spent a good portion of his life herding cats.

 

[CoconutPete]

Call me crazy, but I put the bike in Neutral at red lights.

 

[gggGary]

After many decades of oil bath clutch use I've got that light kick at the shifter DOWN into neutral from second as I come to a stop down pat.
Note; it's a light kick/tap not a (controlled foot already against the shifter) move. This works at a stop also. Try it, give it a chance, before you dis this technique.

 

[fredintoon]

Call me crazy, but I put the bike in Neutral at red lights.

Hi Pete,
of course you are crazy. We're all crazy, we ride 33+ year old bikes in today's traffic.
And while being in neutral at a red light is easier on the wrist (and on the clutch) than sitting there with the clutch pulled in first gear,
just sometimes one might need to get outa there real quick and the split-second it takes to shift into first may not be available.
And Jim,
I'm with Gary; check the cable's run and condition before you go all solenoidal on the clutch.
I reduced my XS11's cable pull ~50% by running it in a single free air swoop rather than deking it under the tank.
Only ~25% on my XS650 though as a completely free air re-route on that bike wasn't feasible.