pro's &con's throttle linkage Vs cable

[xlr8tr]

Originally Posted by Cobra #3170

Lets see, there have been approximately half a billion cars sold in the US since direct throttle linkage was dropped. There have been instances of throttles sticking for sure, but a tiny percentage of total vehicles produced.
Throttle cables must be routed correctly observing minimum bend radii and staying away from high heat sources. They are extremely reliable when installed properly with far fewer moving parts than conventional linkage with rod ends and clamped arms that can slip on shafts. Drive by wire is even better if you can program opening rates but if you can't, linkage would be a
2nd choice over cable. I can see using linkage on a show or concours car that must be absolutely correct from a judging stand point. Conversely from a functional stand point they can be very trying. My linkage broke at the arm that mounts on the pedal cross shaft in 1966 when the car was new. I then had a series of slippages on linkage arms till I welded then to the engine to body cross shaft. I broke a motor mount at an autocross in the late 1970's that gave enough throttle to slide the front wheels and over ride the rear brakes while headed toward a group of people at the finish of an autox. Turning the key off saved the day, it wasn't full throttle but it was enough.
Slowing down the throttle opening rate really improves car control unless you are dealing with less that 400 HP where you probably don't need it. I would bet that some of the accidents that have occurred with Cobras over the years could have been avoided with a long pedal slow opening throttle.

Personally, I would much rather have a car that is drivable over a car that is eye candy but that is an individual choice that only you can make.

3170, Do you happen to have a picture of the cam setup you can share with us? I like that idea of more travel on the gas pedal.

[Rick Parker]

No linkage on any current cars. Cables or Drive by wire.

[strictlypersonl]

You can build progressivity into a simple mechanical linkage by creating this geometry:

Have the pull on the carburetor perpendicular to the line to the throttle axis.
Have the pull on the cross-linkage arm almost inline with it.

[Cobra #3170]

You cannot beat a throttle cam for controlling throttle angle vs pedal travel.
I have to go to Nevada today will post pictures of cable routing and cam design next week.

[mdross1]

As with so many of the things we can personalize on these cars throttle control is one of the many.I chose cable for my own reasons there was no discussion,both choices work well.When building kit cars have to keep in mind we have that option and as you have read their are plenty of opinions.

[tuska]

thanks guy's, thats why i posted it up....everyones been there and had their experiences...i'm still scratching my head about this one....maybe i'll start on steering first!

[itstock]

Does anyone make a carb-drive by wire setup yet? I remember reading a couple places working on it 2 years ago, but never anything in the real world. I'm sure demand isn't high, but it seems like something simple enough to do.

There is my plea. I'd buy one. Obviously I'm thinking price is far enough away from the efi conversion stuff, which I don't know I want to do.

[Cobra #3170]

Originally Posted by xlr8tr

3170, Do you happen to have a picture of the cam setup you can share with us? I like that idea of more travel on the gas pedal.

I posted some pictures in an album titled Throttle Cam in my Gallery area, I think. It is public so if you can get to it you can view it, there are several pictures with descriptions for each photo. Hope it helps

[Cobra #3170]

Originally Posted by Cobra #3170

I posted some pictures in an album titled Throttle Cam in my Gallery area, I think. It is public so if you can get to it you can view it, there are several pictures with descriptions for each photo. Hope it helps

Well, my picture posting abilities continue to suck. Apparently I used too many words in the picture showing the cam and neither the picture or the words came through. I'll try again but the essence of the design consists of (3) .090" pieces of aluminum, the inner piece is the actual cam that the cable rides on the outer two pieces are shaped like the cam but are larger to trap the cable.
the cam initially is 2" from the throttle center line and ends up at 1". This gives a very slow and smooth throttle opening. The cable is multi-stranded and teflon lined with rod ends at each end to retain the cable and allow for angle change. This particular design has a threaded stop for initial tension and is designed so that the pedal hitting the floor is the full open stop. I have some really big throttle return springs that would give mechanical linkage fits but work fine with the cable. It has a very nice smooth feel to the throttle now.

[Cobra #3170]

Originally Posted by Cobra #3170

Well, my picture posting abilities continue to suck. Apparently I used too many words in the picture showing the cam and neither the picture or the words came through. I'll try again but the essence of the design consists of (3) .090" pieces of aluminum, the inner piece is the actual cam that the cable rides on the outer two pieces are shaped like the cam but are larger to trap the cable.
the cam initially is 2" from the throttle center line and ends up at 1". This gives a very slow and smooth throttle opening. The cable is multi-stranded and teflon lined with rod ends at each end to retain the cable and allow for angle change. This particular design has a threaded stop for initial tension and is designed so that the pedal hitting the floor is the full open stop. I have some really big throttle return springs that would give mechanical linkage fits but work fine with the cable. It has a very nice smooth feel to the throttle now.

I have posted a picture of the throttle cam assembly that will give an idea of general shape.

[Dr. Hydraulic]

Initially, my car had cable. The steel cable cut a groove in the ID of the end fitting. The cable would get caught in this groove and if I was at open throttle I had a big problem! Also, since the cable conduit is made of Teflon, the steel cable saws into it easily! Go with linkage!

[Mtgauvin]

Originally Posted by Dr. Hydraulic

Initially, my car had cable. The steel cable cut a groove in the ID of the end fitting. The cable would get caught in this groove and if I was at open throttle I had a big problem! Also, since the cable conduit is made of Teflon, the steel cable saws into it easily! Go with linkage!

Just had same thing happen...I own a BDR and had a Lokar throttle cable...what happens, looking at mine is, the mount under dash that cable goes thru isn't aligned properly with pedal, which is causing it to wear a groove in cable sheath and then fray and bind. Mine stuck at near full throttle on way home last week...and I thought the car was exciting enough already! Showed pics to Lokar who told me this...I'm going back to the factory cable from BDR, it might not be stainless steel, but hopefully it WORKS better than it looks.

Mark BDR 312 Edmond, OK

[mdross1]

Another one of those personal preference items in our hot rods and our reasons why.Cable here, it's all in how you set them up.Do it right they work the same as linkage.Looks? certainly an argument when shooting for original.

[Mike6467]

You could mount the carb backward and avoid the S bend. I've had no problems with set up for 3 years.