Throttle return spring removal, tweak & reinstall - re-done

[Nissbird]

Tobers' thread has inspired me to make a weaker throttle return spring, and I thought a good place to start would be a spring that requires half the force, using an online calculator I have found that if I make a new spring to the same dimensions as the original but with 1.3mm dia wire instead of the 1.6mm dia wire of the original spring it will meet this criteria.
I shall create a mandrel to bend the wire round and fit it to my lathe. If the springs tests ok I shall make a batch for anyone else who wants one.

 

[Dogdaze]

That's a nice thing to do Nissbird ::008::
On a slightly different thought, why would manufactures make the return spring with the tension it has? Am I wrong is assuming that it is to counter any dirt/ debris like grease accumulation in the cables, throttle housing that the extra tension is required to ensure full closure and return to closed position of the butterflies?

 

[Nissbird]

That's a nice thing to do Nissbird ::008::
On a slightly different thought, why would manufactures make the return spring with the tension it has? Am I wrong is assuming that it is to counter any dirt/ debris like grease accumulation in the cables, throttle housing that the extra tension is required to ensure full closure and return to closed position of the butterflies?

If it closes the throttle under all normal circumstances then it is good to go.
If resistance to throttle operation increases then maintenance is required, this is true for the standard spring also.

 

[Nissbird]

This is how the new spring would look compared to the standard one on the right

 

[twinrider]

^^ Great, looking forward to how it goes.

 

[estrasil]

I bought a 2013 Tenere a month ago. The stiff throttle bothered me.

First I took the original spring out and went to a spring making shop and asked if they could make a similar spring out of half the diameter. They said, yes they could, but it would cost $800. So um... NO.

I bought some .045" diameter stainless weld wire and formed my own spring using a mandrel in a vice and wrapping the wire around about 12 turns, then I wound the spring about 1.5 turns and installed it (This took Forever!). I was happy how the throttle returned, but by the time I put all the other stuff together, the throttle did not return anymore.

So I bought 3 different spools of stainless wire from McMaster Carr, .051", .055", .059". I also made a table using a spring calculator (http://www.tribology-abc.com/calculators/t14_4.htm) to figure out which force I would want to try.
https://www.mcmaster.com/#9495k91/=17gd008


I made a spring with 8.5 turns, copying the stock spring as close as possible, using the .055" diameter.

To make the spring, I pinched the wire in a vise against a shaft. Then I wound the wire clockwise around the shaft keeping the windings tight and spiraling immediately adjacent to the previous turn. (picture is of an early attempt where I had not done the tight winds yet). I picked a shaft and the final diameter once the spring is relaxed was too big. Picked a smaller shaft and it was too small... so I found a deep drive socket wrench between the two sizes and the final diameter was close enough.
I think I wound more than 8.5 turns, but then afterwards cut it at about 9 turns, and used the last .5 turns to make the doubled back bend.


the force of the stock spring ranges from 3.26 to 4.95 lbs. The new spring I made ranges in force from 1.93 to 2.89 lbs.
I figured out some tricks to assemble everything, using a looped piece of wire to wind both springs AFTER installing other parts, so I didn't have to hold tension in addition to holding the shaft out and all the other things you need 3 hands for.
I left out a part and forgot to put the last spring in the last square cutout of the last piece of metal, and the motor reved to max as I started it and scared the crap out of me, but in the end, I got it all back together.

Take a look at where the second spring ends up in the last metal part that goes on the shaft. I am glad I took "before" pictures because I missed this step initially.

And OMG! It feels AMAZING! I just did a 380 mile ride this weekend, lots of dirt riding where I didn't use the throttle lock, and I felt so much better afterwards.


Thanks again for all the posts, I really really really am glad everyone spent the time to document this.

 

[Commuter Boy]

Does anyone know what was the diameter of the stock wire is, and what was the OD of the deep drive socket you ended up using to wrap the spring was?

Cheers!

 

[estrasil]

The stock wire diameter is .063"
I can't remember what socket diameter I used... but I also didn't make a stock wire size spring.

 

[Toyamaha]

Latest on this. The lighter spring I installed had a smaller inside diameter han the stock one. Whilst lighter, as the throttle reached the end of its travel the spring tightened on the spindle resuling in the last 10% of travel being a bit heavy. Unable to find a supplier of thinner guage torsion springs with bit enough inside diameter, I decided to tweak the original spring again and reduce the initial load on it.

I did this by uncoiling one coil of the spring at the hook end and reforming the hook 90 degrees closer to the straight end. This means that there is a quarter turn less preload on the spring which makes a lot of difference to both the torque needed to turn it and the ease of reassembly.

Additionally I found that the backstop tang on the throttle cam itself was rubbing on the screw that holds the assembly to the throttle body. When the cam is bolted to the body this does make a bit more resistance and frankly shouldnt be happening at all. I bent the tang gently so it would miss the screw head.

End result - this is actually much better than the too small lighter torsion spring. Smooth and light throughout the travel range. If you were going to do some changes yourself I'd suggest that you use this approach. I'll keep a look out for correctly dimensioned torsion springs in the meantime as hacking your original is a bit of a one-way trip.

Im in the same situation. I would like a lighter spring for my super tenere 2012. But I am not comfortable to modify the original sping. Did you ever find a spring that did the job Tobers.

 

[Toyamaha]

This is how the new spring would look compared to the standard one on the right

Hello Nissbird. Do you still have some of those throttle springs made for some of us to get.