Fortes Mechanical throttle linkage slipping.

[rponfick]

I have the Fortes mechanical linkage on my Mk4, 351W, Holley carb. I am having trouble getting the throttle fully open as the lever on the pivot shaft connected to the carb keeps slipping. I have tightened the through bolt as much as I feel safe and fear stripping it. The shaft is polished smooth and the clamping force on the lever does not keep the mechanism from slipping when full-throttle opening force is applied. I have removed some of the return springs to lessen the load, but that hasn't helped.

I noticed a tiny drilled hole in the base of the lever, as if there for drilling into the shaft and inserting a roll pin to lock the shaft and lever together. Has anyone else had this issue and how did you solve it? Did you drill into the shaft, and if so, what size drill and roll pin did you use? Was it an easy task, or a learning experience of a lot of new words?

Thanks, Ralph

[cv2065]

Many use a roll pin to lock the lever arms to the SS rod. I think I used a 1/16" cobalt drill bit and then pinned it. Carbide is the best but it's expensive. That rod is hardened steel, so not the easiest to drill through. Slow drill speed, oil and drill press will help. Just don't push the pin all the way and leave it out 1/8" or so to pull it out later down the road if you need to.

You might also check out how easy your rod is able to spin as it goes through the footbox. There shouldn't be much friction there. Some don't pin them and find the lever clamping force sufficient.

[egchewy79]

i used a roll pin at both lever arm locations after I recognized that my foot pressure is stronger than the set screw. use a good new sharp bit, use slow speeds and plenty of cutting oil.
the SS rod is a b*tch to drill through, so a carbide bit helps. Most hardware stores will have a section with roll pins. Can't remember what size I used.
I remember recognizing once I was through the rod and getting into the other side of the aluminum as the metal starts coming out of the bit in a long thin twisted ribbon. The SS rod comes out of the bit as small chips of metal.
I had no issues tapping the pin all the way in on the engine side. You can reach that area easier with a punch to get the pin out should you need to. In the footbox, leave a portion of it out that can be easily grabbed with vice grip from underneath. Otherwise you'll be hating life if you ever needed to remove the linkage in a finished car.

[David Williamson]

yes 1/16 inch roll pins will fix it.
David W

[CraigS]

I dumped the SS rod and grabbed a plain mild steel rod.

[rich grsc]

Just loosen the lever slide it to the side, add a small drop of LocTite and reposition

[Mike.Bray]

Just loosen the lever slide it to the side, add a small drop of LocTite and reposition

That would work. just use 609 Bearing & Seal retainer. The green stuff.

[F500guy]

I tapped the roll pin hole for a set screw and plan to put a small flat spot in the rod and a little lock tight on the set screw.

[phileas_fogg]

Roll pins in both lever arms for me as well. I drilled the lever arm holes 1/64th larger than the SS rod so that I could push the pins in by hand (still took a bit of force though). Then I finished pushing the pin in with a C clamp. I left ~1/4” pin sticking out.


John

[Buzzsaw]

Roll pins are in your fastener pack if you still have it. I just checked since I am installing my throttle linkage tomorrow. Mike Bray and Rich are you saying the Loctite or Seal retainer can be used in the place of a roll pin? I am not doubting you, that would be easier that drilling round stainless steel.

[rich grsc]

Blue or red are just fine. The green will make it almost impossible the remove or reposition the arm.

[rponfick]

Roll pins are in your fastener pack if you still have it. I just checked since I am installing my throttle linkage tomorrow. Mike Bray and Rich are you saying the Loctite or Seal retainer can be used in the place of a roll pin? I am not doubting you, that would be easier that drilling round stainless steel.

I feel your pain. I really don't relish trying to use a 1/16" drill bit to puncture a round SS rod either.
Ralph

[rponfick]

I am the second owner of my Mk4, and the previous assembler installed the levers contrary to what I usually see here. I am not sure if to avoid the problem of the upward positioned lever hitting the compartment upper panel. The lever under the footwell points downward, which makes the engine bay lever push forward. Therefore I have to use the lower carb lever hole position, rather than the more standard upper hole. I think the leverage distance is the same regardless of which position you use. I hope this makes sense and makes no difference mechanical linkage operation.
Using Russ Thompson pedal.
Sorry for the photo positioning, as I am really old.
Ralph

[CaptB]

Call Mike he can tell you the size of the pins, probably will send them to you for free, he sent me some extra rod. Both ends with pins on my side.