Duratec Throttle Return Spring

[O.G.]

I find the standard throttle return spring strength a bit light on my Duratec 360R. I would like to increase the foot pressure required a bit when opening the throttle. 

Preferably I would like the modification to be at the butterfly end rather than the throttle box. It has been suggested this may assist in reducing a bit of kangarooing I have at the moment.

Are there any proprietary replacement springs available or has anybody got any other bright ideas.

O.G.

[John Vine]

You haven't received a reply yet so I thought I'd chip in.

I'm not aware of any stronger springs, but I was wondering if your roo-ing symptoms might be down to poor mapping rather than throttle return?

Certainly, my R400D was very ill-mannered in traffic until I visited the Two Steves for a thorough mapping session.

JV
 

[Jim 123]

For your spring question speak with Associated Springs Raymond in Evesham.  They should be able to match the dimensions of your existing spring but with a range of alternatives for compression rates.

Do you get the "Kangaroos" only when applying very small throttle inputs at low speed? If so that could be down to low levels of stiction in either direction somewhere in the linkages, or a small amount of free play in the cable, neither of which you might feel through your right shoe.  

[Jim 123]

Duplicate

 

[ScottR400D]

My R400D is easily led to kangarooing as I get close to home on the bumpy lanes I have to negotiate. The throttle is very light. 

My solution was to stick a small piece of emery cloth onto the panel where my foot rests. When I’m on the lanes I press the side of my foot against it as it’s on the throttle. 

Foot doesn’t move on the bumps, no kangarooing. 

Sounds silly but it works.......... 

[Jonathan Kay]

Is there a solution from the competition world, where two independent closure mechanisms are often mandated?

Jonathan

[Jonathan Kay]

My solution was to stick a small piece of emery cloth onto the panel where my foot rests. When I’m on the lanes I press the side of my foot against it as it’s on the throttle. 

Foot doesn’t move on the bumps, no kangarooing. 

Sounds silly but it works.......... 

Sounds to be totally in accordance with good practice in systems control. Damping is often the solution to instability in control loops.

More on this RSN.

Jonathan

[O.G.]

Thanks guys for all the great ideas.

This version of Kangarooing started after it was mapped by The Two Steves and it’s their suggestion about the stronger spring although I am planning to take it back. The previous rooing happened on overrun in low gears at low speed.

Sandpaper, I had thought about mounting a bar on the floor to give your heel something to push forward on. I’m not so sure it is bumpy road related as we were even getting it when entering the track at our recent Brilliant Cadwell Park Track Day.

I will be following up on the competition double spring idea and Associated Spring leads.

Thanks Guys.

O.G.

 

[Jonathan Kay]

The control loop is very complicated: brain to nerves to muscles to joints to pedal to cable to engine to engine speed to brain via ears, accompanied by muscle spindles, stretch receptors, pressure receptors and occasional glances at the rev counter. And then add the time lags.

And increasing the damping can often reduce instability in the loop. So the emery paper is fascinating and I've often suggested pressing the knee against a side panel. Increasing the force of the throttle spring could make it either better or worse.

It's one of those skills that you chunk down to not needing conscious effort once you've mastered it. Which makes it fascinating when you try and learn a new version: low speed manoeuvring of my Vespa, steering a motor boat (have a look back at your wake!), holding altitude in an aircraft, or trying to hover a helicopter, where any movement of one control seems to need correction with two others. 

And often infuriating for an unskilled teacher who can't understand why the student just can't do it. Offspring's clutch control, anyone?

Jonathan