Mechanical throttle linkage back to cable.

[rponfick]

Has anyone used the Russ Thompson pedal assembly with a cable setup? I have a Mk4 with the Forte linkage and Thompson pedal assembly, but I cannot get enough travel to open my secondaries. The previous owner installed the system, I think backwards, maybe for clearance issues, as the throttle shaft is pushed forward rather than pulled toward the firewall. I have pinned the accessible shaft to the lever, and adjusted what I could, but cannot get enough travel.
I am considering ordering a complete throttle pedal assembly from FFR or using some modification of the existing Thompson pedal system.

Any comments out there?

I am expecting my Mk5 any day now and will certainly stick with the tried-and-true cable assembly.
Thanks, Ralph

[michael everson]

FFRs throttle pedal will gain you nothing.
Mike

[Papa]

To answer your question, yes the Russ Thompson pedal will work with a cable. I'm using the Russ Thompson pedal with a Lokar cable on my Inglese 8-stack. I would not recommend the FFR cable.

Dave

[MB750]

If your linkage doesn't give you enough travel, perhaps investigating where the obstruction is and eliminate it.

Also, the nice thing about the linkage is you can change pivot points all along the way to gain sweep at the output. Can't do that with a cable.

And yea, the FFR throttle pedal is crap.

[CraigS]

Show us pictures of your linkage and maybe we can help.

[egchewy79]

yes, show pics.
You can adjust the arms or shorten/lengthen the linkage connected to your throttle body w/ the Forte kit that might allow you to get more travel.

[Windsorpower]

Near-infinite adjustability with the Forte kit. I absolutely love mine….and I also set it up to push.

[burchfieldb]

Probably worth a call to the man that designed it. Mike is super helpful.

[Mike.Bray]

I have the same setup as Papa and love it. Smooth as silk. One trick is to secure the cable between the firewall and the bracket on the other end to keep it from flopping around. Mine is clamped about halfway to the valve cover.

[rponfick]

Will try to add photos. Sorry for the poor orientation.

[egchewy79]

try to lengthen your rod connecting the lever arm to the throttle body. Those ends should be able to be lengthened by loosening the jam nuts and spinning the central rod. If you don't have enough travel before the ends total unthread, you can get longer ends. The rod should be LH threaded on one side and RH threaded on the other, allowing you to lengthen/shorten by just twisting the rod.

[rponfick]

Thanks, but I have adjusted that throttle rod as long as I can with the lever against the firewall to allow for the most forward motion. My rod attachment points are also at the ends of the levers for most movement. My rod under the dash is at its longest length.
Let the fun continue.
Ralph

[FarmerDave1321]

I have to believe that it wasn't properly installed in the first place. Likely that the rod wasn't cut to the correct length. I would give Forte a call and see if you can get them to send you a new rod to recut to the proper length.

FWIW - I just ordered my kit yesterday :)

[cv2065]

I wouldn't go back to a cable. The mechanical linkage is superior if setup properly. Looks like you might have two issues. One, maybe the threaded rod wasn't cut to the correct length and is too long as the arm shouldn't be resting against or touching the firewall. Mine is about 30 degrees forward and then almost straight up at full throttle. And two, looks like you would just need to move that rod arm on the inside of the footbox to the top instead of how it is on the bottom. That will change to a pulling action for the engine bay arm instead of pushing. Easy to fix and Mike can send you new threaded rods with fittings if needed.

Are you getting any obstruction from that throttle return spring bracket? I wasn't able to find one like that which would give the proper clearance to the rod.

[MB750]

Will try to add photos. Sorry for the poor orientation.

In that first pic, where the linkage arm is up against the firewall, is that at WFO throttle?

Because if it's not, there's your problem. FYI, I had to cut my rod down a bit to make it clear better.

Take the linkage off the linkage arm, pull the carb throttle mechanism WFO, then see how much linkage you need to remove. Assuming that's the issue, of course.

[CraigS]

I did mine a little differently. The bellcrank inside the footbox was above the shaft. It was almost perfectly parallel to the bellcrank on the other end of the shaft at the firewall. It was connected to the carb I 'think' where the black socket head bolt is on your carb. If you consider the top of pedal and the arm on the carb as additional bellcranks, all bellcranks are above their shaft. The carb bellcrank gets pulled toward the firewall. BTW, I had a cable for about 10yrs. When I changed to linkage, the effort was reduced so much, I had to add an additional carb return spring. I would never consider a cable again.

[egchewy79]

If you need more travel on your rod to get the throttle body to WOT, I'd either get a new aluminum tubing/rod and tap them or longer end pieces. Both are likely available on McMaster Carr if you can figure out the pitch/count of the threads. Remember to order a RH and a LH thread to be able to adjust the length without having to disassemble the whole thing. Mike Forte might be able to send you another rod that has already been tapped as well.

[rich grsc]

Move the throttle shaft out to the end of the bell crank, and move the bell crank so it isn't against the firewall. It should be almost vertical

[egchewy79]

also looks like you should be able to extend the heim joint that closest to the firewall. Looks like there's a jam nut but no visible threads there.

[rponfick]

As I stated, my setup pushes the carb throttle lever forward, rather than the more standard pull toward the firewall. That is why my lever is against the firewall at idle to get maximum forward push. I think the proper installation for the under dash lever to be facing upward, but mine is opposite. Someone said "easy fix". Changing the orientation would be almost impossible for access and probably the cross shaft would also have to be moved and lever pinned.
I had adjusted under dash rod to full length to get the gas pedal to level with the clutch/brake plane (to try to get more throw), but now the pedal is much lower indicating slippage in the under dash lever on the shaft. I had previously pinned the lever under the hood, so that is not the problem, but I am too old to try to move, drill and pin the lever under the dash to the shaft. If I was working on a body-off car, I would do that, but not now.
So, this is all why I want to go to a cable setup. I agree the mechanical is superior in most respects if installed properly, but that is not where I am.
Thanks, Ralph

[egchewy79]

As I previously mentioned, are you able to get more threads out on the heim joint closest to the firewall?

[MB750]

As I stated, my setup pushes the carb throttle lever forward, rather than the more standard pull toward the firewall. That is why my lever is against the firewall at idle to get maximum forward push. I think the proper installation for the under dash lever to be facing upward, but mine is opposite. Someone said "easy fix". Changing the orientation would be almost impossible for access and probably the cross shaft would also have to be moved and lever pinned.
I had adjusted under dash rod to full length to get the gas pedal to level with the clutch/brake plane (to try to get more throw), but now the pedal is much lower indicating slippage in the under dash lever on the shaft. I had previously pinned the lever under the hood, so that is not the problem, but I am too old to try to move, drill and pin the lever under the dash to the shaft. If I was working on a body-off car, I would do that, but not now.
So, this is all why I want to go to a cable setup. I agree the mechanical is superior in most respects if installed properly, but that is not where I am.
Thanks, Ralph

Damn, I wish I was closer, I'd offer to come help you out. It sounds like an easy solution, but it needs a more limber body to fit in the footbox to physically see what's going on.

[rponfick]

egchewy79, no, the lever is against the firewall already to get the maximum throw on the rod.

[rponfick]

Damn, I wish I was closer, I'd offer to come help you out. It sounds like an easy solution, but it needs a more limber body to fit in the footbox to physically see what's going on.

You are a kind gentleman. It is not very far from Colorado to Florida in a FFR.
Thanks

[danmas]

I’m getting ready to do my install. It would be great to come see your config. I’m about 10minutes from Loveland…. Pm me if you are up for a show and tell….

[rponfick]

Anyone using the Breeze pedal assembly (no. 70810)? It looks like a viable option to the Russ Thompson, so there are choices out there, if it is of robust construction.
Thanks, Ralph

[mrglaeser]

I have Foxbody footbox (I see Wilwood pedals in the attached pics here so not like for like) and the geometry required me to install the mechanical linkage as a push style as well. However I was able after hours of adjustments to get a full range of throttle. So it is possible. From the pics I think rponfick is right and the angle of the arm under the dash is probably the issue. Especially if it is slipping. I'm not sure how one could even get a drill in there pin the lever.

Also it looks like the steering shaft needs a little help with that spring washer 75% sticking out.

[egchewy79]

egchewy79, no, the lever is against the firewall already to get the maximum throw on the rod.

Don't think you understand what I'm trying to say. Do you see the visible threads on the heim joint connected to the throttle body? There are no visible threads on the opposite end by the lever on the firewall. This suggests you can make the rod longer and get more throw getting to WOT if you unthread the heim joint on the part closest to the firewall. I'm guessing there's at least a 1/2" of threads in the rod that might fix your issue.

[rponfick]

I have Foxbody footbox (I see Wilwood pedals in the attached pics here so not like for like) and the geometry required me to install the mechanical linkage as a push style as well. However I was able after hours of adjustments to get a full range of throttle. So it is possible. From the pics I think rponfick is right and the angle of the arm under the dash is probably the issue. Especially if it is slipping. I'm not sure how one could even get a drill in there pin the lever.

Also it looks like the steering shaft needs a little help with that spring washer 75% sticking out.

Help me understand your last comment about the spring washer 75% sticking out. I am unsure of what you are referring to.
Thanks, Ralph

[rich grsc]

Move the throttle pedal about a 1/2" closer to the steering wheel. Just loosen the 2 Allen screws and slide it back.

[rponfick]

Move the throttle pedal about a 1/2" closer to the steering wheel. Just loosen the 2 Allen screws and slide it back.

Thanks, will do. I was wondering about that.

[CraigS]

AT 76 I sure get the too old to work there. One recommendation is remove the driver seat from the car. 2nd, if your bellcranks have set screws, as I mentioned above, I found that both bell cranks on the shaft being parallel worked out. So if you take it all apart you can drill a small divot in the shaft for each set screw and then reassemble. I just put a vice grip in the middle of the shaft so it could hang down while I had the ends in the drill press. gravity lined up my divots.

[mrglaeser]

Help me understand your last comment about the spring washer 75% sticking out. I am unsure of what you are referring to.
Thanks, Ralph

212366212366

I circled in your original Photo what I was looking at. I believe the upper shaft is supposed to be tapped in far enough that the whole spring washer is in the lower shaft. I'd have to go back to the manual. But in this pick it looks like it is just in a small part of the way .

[rponfick]

AT 76 I sure get the too old to work there. One recommendation is remove the driver seat from the car. 2nd, if your bellcranks have set screws, as I mentioned above, I found that both bell cranks on the shaft being parallel worked out. So if you take it all apart you can drill a small divot in the shaft for each set screw and then reassemble. I just put a vice grip in the middle of the shaft so it could hang down while I had the ends in the drill press. gravity lined up my divots.

Craig, have I have 7 years on you at 83, so yes, we are getting too old for this. But, to show you I haven't given up yet, my Mk 5 should be here any day now.
My bellcranks do not have set screws in them, just the pinch bolt on the end. As I said, I pinned the crank in the engine bay, but the other one is a bear. I am thinking of taking the entire mechanical system out and install it on my Mk5 while I can get to all the tight places, and pin all the bellcranks. I plan to go to the cable system PaPa used, and be done with it on my Mk4.
My main issue with the long cable under the old system was the "S" shaped orientation of the cable to get to the carb. On my Mk3.1 I had installed the carb on backwards and that allowed a gentle bend in the cable around the front of the engine. It was interesting for me to see in Breeze's pedal install instructions that they suggest this install method. The carb does not know it is on backwards, but you have to remember which fuel bowl to fill when you are priming it. Ask me how I know?
Ralph

[rponfick]

212366212366

I circled in your original Photo what I was looking at. I believe the upper shaft is supposed to be tapped in far enough that the whole spring washer is in the lower shaft. I'd have to go back to the manual. But in this pick it looks like it is just in a small part of the way .

Thanks, I will have to look into that.

[CraigS]

Ralph, you having ordered a MkV is fantastic. When I had a cable, I also installed the carb 'backwards'. It definitely helped.

[rponfick]

Ralph, you having ordered a MkV is fantastic. When I had a cable, I also installed the carb 'backwards'. It definitely helped.

Great minds think alike.