Technical throttle cable do's & don'ts

LOL I have always mounted my cables to the motor. It never even occurred to me to mount it to the firewall.

Any throttle mechanism can fail as can return springs. Mechanical throttle is susceptible to broken motor mounts where as a cable usually is not (when properly run). Cable became popular because of its ease of routing.

There is a cable that will push and pull, I can never remember the name of it but on cable applications in the NHRA it used to be required with a toe hook on the throttle peddle.

I do have a very old (and in excellent shape) like in circa 1954 old cable setup in the garage that actually has idlers for making tight corners. The housing is about as thick as your little finger and the cable is at least 1/8". Not purdy enough for a modern car but passable for what any of us would do. LOL

I really don't have anything to add to this that has not been said except that if one is using a modern cable setup it is best to spring for a Teflon lined cable housing. it is a good way to avoid a lot of the pit falls of cable wear and welding.

 

As mechanical rod linkage.

 

I see what you're saying, and I've done the same thing on my '57. I bent a piece of 3/8' stainless brake line into the shape, crimped the ends in a vise and drilled them for bolts. Been very effective for the past 14 years. But not everybody has or wants a bell crank or mechanical linkage sitting out, so the cable is the next best option. Honestly, the strength of the braided stainless cable is more than you may think, and certainly many times strong enough to handle the tension forces of opening the throttle blades against the return spring.

The way I see it, whether it is a cable or mechanical linkage, if the position of the engine changes drastically for whatever reason, be it a broken engine mount, chassis, or external forces, the throttle is going to hang open. The only difference is whether it's being tugged by a cable or mechanical rod, unless the entire throttle assembly, pedal and all, is attached to the engine itself. This is obviously not practical and presents a host of other safety issues, like having the entire engine in your fucking car. Bottom line is that proper safety precautions should be taken, like lubricating the cable, not routing it with sharp bends, using dual throttle return springs, etc. But shit still happens. Recognizing the issue quickly and taking appropriate steps like shifting to neutral or depressing the clutch, steady braking, and potentially NOT turning the ignition off (so as to lock the column or eliminate power assisted steering/braking) will be the difference between a minor scare and simple fix and a possible catastrophe.

 

I tried to Reply to your "same as mechanical linkage" post, but something is not working this morning.

Usually mechanical linkage will have a pivot point on the firewall, then an arm coming up to connection point to rod to carb. This change in geometry allows for engine movement without a direct pull on throttle like your firewall to carb cable.

 

my motor mounts bolt through with a grade eight bolt and a lock nut. so short of a structural failure i don't see any problems there. so i'm still leaning towards firewall mounting of the cable. seems like the cable would pull out until the gas pedal bottoms out before there would be any WOT issues. i don't think i would have enough space for a loop if i carb mounted the cable.

 

anybody else willing to post pics of their set up?

 

You don't carb mount the cable, your cable stand is mounted to the last two bolts of the intake manifold, or right at the firewall.

 

Beaner,
It all depends on the height of the carbs. On the 2x4 setups I fab a bracket that uses the carb hold down bolts. On most 4bbls setups I use either the coil mount holes or the intake manifold bolts that have a stud.
FYI, they switches to cables because of sudden uncontrolled acceleration issues brought on by the hard linkage binding.

 

LOL we had a '59 Chevy once that if you nailed it at the light the engine would stand up and bind the linkage it would rev until you threw it into neutral.

I should have clarified what I meant, they became popular with rodders because of ease of routing.

 

I've been running this setup for 7 plus years, as unusual as one would get. My pedal sits sideways in the car do to the tight confines, so the pull is at extreme left. You can see the S curve of the cable running to the bracket mounted on the rear carb.
I have broken a drivers side motor mount before without any throttle problems too. In fact the only way I knew the rubber mount broke was because the fan got into the radiator shell.
So as long as you mount it right a cable can be used in some weird positions and can be mounted off the carb.

 

Anybody got a sure-fire way of cutting those cables without strands unraveling? (you may not have to guess why I'm asking)

 

Cable cutters (also called wire rope cutters) cut from all sides toward the middle. Mine came from a bicycle shop. "Must have" tool.

 

Use tape around the cable first, electrical tape is nice, wrap it tight with a couple wraps, cut with a cut off wheel and leave the tape on, it should fit into the housing.

 

on my setup there are carb spacers and the rear carb is so close to rear of the intake it's the carb hold down bolts or the firewall.

 

I have always used electrical tape and a cold chisel. Of course I am still using cave man technology.

 

Good sharp cold chisel on an anvil works fine.

 

Its always worked for me and I been cutting cables for both cars and bikes for a very long time. Of course there is always the option that the only reason it works is because I don't know that it won't.

 

>>There is a cable that will push and pull

Bowden cable.

I've used mountain bike rear brake cables for years. They come in stainless, they're Teflon lined and engineered for a safety critical situation (no brakes - you're dead). I use proper cables though - not stuff from kids bikes.

 

Thanks
I can never remember the name when I want to and now I won't have to wake up in the middle of the night and say it out loud to whomever is listening.

 

Only if your engine moves from front to back instead of side to side' As far as the fire wall mount, it's no different than mounting it to the carb or intake manifold. The gas pedal is mounted to the firewall and where you put the cable guide between the two makes no difference. All the in between mount does is keep the cable pulling straight.

 

It may not be much, but any movement changes the distance from throttle arm to a point on firewall. Bracket on carb or manifold stays the same distance to throttle arm. (Kind of like bump steer in the throttle cable.) And it does keep cable pulling straight.

 

come on boys, somebody has have some pics of various examples.

 

its called a morse cable they are bulky but when hooked up right they make positive movement , we use them on throttle cables on Idle controls on trucks , Pto engagements , 2 speed axles if its mechanical not electric shift , and I have it on my OT's trans shifter ( makes it real smooth ) they are expensive .

I basically steal the pedal assys from modern O/T cars brackets, springs,pedal and all why should I spend my time enginerring a set up when the OEms spent $$$ to do it for me . as for cables I prefer cables over mechanical as a cable can flex with any movement , a rod can cock and stick in the pivot points when the lube drys out . only if it has a heim joint would I use a rod

 

scottyT,
I just did a google search on throttle cable mounts and I just scrolled through at least 40 different combinations.

 

i've done the same search, not a lot of what i found looks like it applies to the cars on this site, plus it would be nice to have pics in this thread for future searches.
my motor is in the next bay over from the car, there is no throttle linkage left after the firewall work, it's cold and dark out..................................

 

Here ya go! I had the first cable ball up inside the sheath after a short time. It wasn't funny!
So, I found a bicycle cable that was much more flexible and exactly the same size and it's been on there for years.

 

This is actually the cable setup I have used for years and has been on several cars. Its a little hard to see but it is the closest I have got on this computer. I actually found this bracket in a wrecking yard on of all things a Mustang with an SBC in it, adds credence to Built Ford tough with Chebby stuff.

 

I had a throttle cable built at the boat shop, they make them for steering, explained what I wanted, got the choose the ends and length. Very smooth operation.
Google morse cables, or push pull cables if you wanna read up, all kinds of options.

 

As long as the thread has drifted into and out of general throttle linkage topics, I will add this about throttle springs. Give some thought to how you mount the return spring. the diagram below shows the proper way and the worst ways to do it. The main object in this exercise is to minimize throttle shaft wear by not installing the spring in an orientation that puts excessive stress on the shaft and its bushing hole.