How Do You Fix a Stiff Throttle Pedal?

I'm not sure if this is endemic to all SPF GT40's, but my accelerator pedal is very stiff. It really becomes an issue during heal-and-toe downshifting. A friend looked at it and feels it's due to the design and not the spring.

Whatever it is, I'd love to find a way to lessen the tension. Any ideas?

Kim
 
Press harder! - :thumbsup:
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Sorry - couldn't resist as I'm in one of them moods...

Seriously though, have you tried isolating the components? - i.e. disconnect the cable from the pedal and throttle linkages and then check each end and the cable in isolation for 'tight spots'. Might help determine where the bind is.

If all still feels free-n-nice when disconnected, I'd be looking at the angles of the cable pulls, should be nice and smooth and as light as you like I would think.
 
Had a similar problem with mine and it turned out to be rust in the cable run (damn british salty roads). I forced some oil into the open end by the carb and worked it down the cable - freed it up nicely.
 

Jack Houpe

GT40s Supporter
Kim, I had the same problem and someone in SA had over tightened the little bolt and lock washer on the clevis at the pedal. Its not easy to get to but I had to replace the cable as it had caused it to break several strands of the cable. Get a flashlight and a short stick, ,move the gas pedal with the stick as your looking at the clevis, see if its swings freely, if not then thats a problem if it does without binding then its elsewhere.
 

Trond

Lifetime Supporter
Hi

I had the same problem on my SPF. I changed the wire inside the cable-housing (was that correct language?) to a wire that is more "fine-corded", inserted this with a teflon based lube. I checked that the linkage by the pedal box was smoothe, and applied grease.

The linkage on the carb was set up in a way that made the "gearing" heavy. I sort of changed this 180 deg. and that made the gearing a lot lighter.

All in all this made the pedal good.

Regards
Trond
 
On my old GTD I had a similar problem turned out to be the cable getting too hot near the exhaust and melting the liner which grabbed the cable. I tried numerous cables till I found one with a teflon 2nd liner. Place some cool tube and heat resistant material around the cable near the exhaust. Problem solved.
 

Steve C

Steve
GT40s Supporter
My pedal force OK too.

Maybe it's carb linkage or too heavy a spring ( I use 2 springs, one at pedal the other at carb for safety).

Steve P2125
 
Mine is heavy also. I think it maybe from the double springs on the carb linkage (Holly4150-750HP style) that is required at track events. I'm thinking about removing one on the carb. That still makes two counting the pedal itself.

Oh, Merry Christmas to the world.

Grady P2124
 
I had this same issue w/2214. I had to adjust everything down by the pedal plus I had too tight of a bend infront of the engine(Weber throttle pull is in the center, pulls from the front, not the side). I also added a compression spring over the end of the cable so that it would push back.
I still am not happy with the feel but it works ok.
Dave
 
Control Cables, Inc.

When I purchased my car it had an extremely stiff throttle. I had my builder switch to a hydraulic CNC set up but noticed that when the motor warmed up the throttle would stick. I called CNC and informed them of the problem. They then went on to tell me that the setup was designed and intended for sandrail applications and to be mounted outside because the fluid expanded with heat. Next solution was to have a custom cable fabbed up. That's where these guys came in. I gave them the dimensions and a schematic of its path of travel. Within a week I had a cable with the right ends and diameter. My throttle is now as smooth as glass and I couldn't be happier.

BTW, also check all your heimjoints. A couple of mine were sligthly rusted and needed to be cleaned up.

Rich.
 
Kim:
Aside from some of the solutions offered I have seen very stiff pedals caused by the cable connection being too close to the pivot at the throttle. The response is quick, but difficult to modulate. Moving the connection away only a small amount will greatly reduce pedal effort, and give you greater control. The only give back is increased pedal travel, but most pedal assemblies have more than enough travel to acheive WOT and then some.
Also if you have any angularity at either end where the cable connects you may want to use a heim joint to eliminate any binding that may be occuring.
Hope this helps
Phil
 
Reviving an old thread, as I'm having similar issues with throttle pedal effort . . .

Last night, my buddy and I isolated the components (pedal, pedal spring, carb linkage, carb linkage springs). The excessive effort I have been feeling is definitely the throttle cable. I have checked all cable routing and the bends don't seem excessive between pedal and carb. The most severe bend is just as the cable leaves the pedal box, heading to the port side and then turning aft toward the cockpit.

We're going to try disconnecting the cable at both ends and working some dry graphite lube in there, perhaps with compressed air assist. I have used dry graphite on several speedo cables in the past, with very good results. I don't want to resort to wet lube/oil, unless it's the last resort.

The springs on each end (pedal and carb) are definitely NOT the primary cause of the stiffness. They contribute some, but aren't the culprit.

Any thoughts?
 

Larry L.

Lifetime Supporter
The most severe bend is just as the cable leaves the pedal box...

Assuming your definition of a "severe bend" mirrors my own, and assuming there are no 'kinks' anywhere else along the cable's length, my bet is the above is the source of your problem.

Probably the most direct/easiest way to find out is to lube only that section of the cable and see what happens...further assuming said bend isn't so severe that lubing alone will in fact be able to 'fix' the problem.;)
 
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Mike

Lifetime Supporter
One thing that may not help is the pedal pivot it sloppy and does not ride on a bearing. I cut the pivot off and replaced with a new one that utilizes bearings. Mine was not horribly stiff to begin with but is like butter now ;)
 

Rick Muck- Mark IV

GT40s Sponsor
Supporter
I improved the throttle action on my car by tweaking the bend as well as fastening the cable to the tub sidewall in the footwell. I used tie wrap adhesive anchors and routed the cable up from where it was floating to make the most gentle bend possible. With no additional lubrication I got he pedal effort to be very reasonable and comfortable.

Originally there was a nasty "off idle" stick I found to be a bolt of incorrect length catching on the throttle pedal. The bolt was NOT a factory supplied bolt (you can tell as all SPF hardware is coated) but had been installed by the installer when he moved the pedal box.
 
My car had very stiff return spring on the throttle pedal that I replaced. Seeing as how I also added two more springs on the carb end the one up front is only needed to return the pedal back up.
 
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