Push pull throttle cable on Engine dyno

[Choripan]

Hey, New here, and I'm just a volunteer so I'm trying to learn as much as possible.

So I am in charge of creating the push pull throttle cable lever system and I have broken one cable thinking it acted as a normal throttle cable. Were getting a new one and to prevent breaking that one (and wasting what little money we have) I was wondering if anyone can give some advice on their lever set up. I'm thinking I have to take into consideration where the pivot point will be, how, if at all possible, to set up an adjustment screw for the throttle plate opening and some other things.

Thanks in advance.

[Choripan]

Hey, New here, and I'm just a volunteer so I'm trying to learn as much as possible.

So I am in charge of creating the push pull throttle cable lever system and I have broken one cable thinking it acted as a normal throttle cable. Were getting a new one and to prevent breaking that one (and wasting what little money we have) I was wondering if anyone can give some advice on their lever set up. I'm thinking I have to take into consideration where the pivot point will be, how, if at all possible, to set up an adjustment screw for the throttle plate opening and some other things.

Thanks in advance.

[kcapitano]

Prepare to Win by Carrol Smith has some good diagrams of how to install throttle cable and provide the necessary adjustment. A good quality push/pull cable will be your most reliable option for sure.

That said however, my team has used the brake cable from a tandem bicycle (tandem bike for the extra length) for quite few years and we have only had problems when we mounted it incorrectly. Taking a good look at how the brakes on your bicycle are installed should help you quite a bit and spending a bit of time at your local bike shop won't hurt either.

[Drew Price]

Piece of electrical wire?

How did you break it? It's a pretty simple thing. Taking a look at bicycle brakes like kcapitano is a good suggestion - you could also go look under the hood of any of the team member's older cars to see how theirs it attached.

It doesn't need to be complex, you just have to have a way for the throttle to snap back closed when you release the cable.

[Choripan]

Kcapitano: Thanks for the input, I have prepare to win, haven't read it yet but I will take a look at it, thanks!

Drew Price: our project manager wants us to go with a push pull cable this year. as far as breaking it, it was pretty much a mounting problem (used a lever without a rod end, put too much stress on the cable when pushing and pulling it.) As far as simplicity goes, that's the rule I live by lol

[Warpspeed]

Probably the safest way is a pull only cable, with one or more return springs at the engine.

There is an old saying "you cannot push on a string" and pushing on a cable to close the throttle sounds like tempting fate.

[Kirk Feldkamp]

Generally, the mounting geometry required for a push/pull cable are somewhat prohibitive for most FSAE throttle body systems. If you want any sort of normal throttle cam, it's a whole lot easier to use a standard pull cable for this. Generally, I like to use either kart-sourced off-the-shelf cable and housing... or just stock bicycle cable stuff. The bike stuff is readily available, can be bought in bulk, inexpensive, and can be teflon lined. If you're interested in building custom cables with special housing pieces or different end fittings, places like California Push/Pull (http://www.push-pull.com/) in Chico can build those for you quickly and cheaply. Alternatively, you could search on Google for swaging products (fittings and swaging machines) and figure out how to make your own.

In my experience, throttle cables will last for a LONG time as long as you make sure it doesn't carry any load (in any position) other than the return springs. Often, people setting up the throttle pedal stop won't ensure that the pedal travel is halted before the throttle valve itself hits any sort of open stop. In other words, the throttle valve itself needs to be able to move beyond where the throttle pedel will cause it to travel. If the valve hits the stop before the pedal does, the cable will be put into tension. If this is how the cable is set up, then eventually the cable will break.

-Kirk

[Choripan]

Thanks for the input, I've been looking this stuff up and I think I got all the "calcs" down just need to put it together.

[Warpspeed]

Production cars all use pull cables, and having two redundant throttle return springs right at the throttle is now a safety design rule requirement around the world.

You could do a lot worse than fit the same on your own car.