Hand throttle play

Stingray70

Stingray70

Senior Member
I have done a search and haven't found anything on this. When I operate the hand throttle lever on the steering column, it does not change RPM until reaching the 3 o'clock position. That first third of its travel is just play in the linkage. I can see the reason when looking at the linkage.

There is a rod connecting the arm on the steering column to the assembly at the back of the engine. The short rotating lever on the assembly that this rod connects to does not rotate immediately, it moves up and down. Is there supposed to be a bushing in there? Possible to adjust it somehow? Feel free to educate me on the proper names of these components! BTW the rod is nice & straight.

I can't seem to find diagrams/pictures of this in any of my manuals. If someone can point me in the right direction it would be appreciated.

Cheers
 
Here is the part with excessive play
 

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Thanks Alexiskai. Looks like the loose part is called the pivot arm or bell crank. It is very loose on the shaft. Now, how do I fix it?
 
Loose rivet?
You could also have a mismatched assembly.
You will probably have to remove the throttle assembly to fix it.
Hard to tell what you have from the picture.
 
The arm itself may have been bent out of plumb at one time. I used a little heat from a hand torch and very gingerly tapped it back with the help of a workbench vise. It takes a lot of patience by constantly shaping and cooling and re-mounting and test fitting. At one time I had totally tweaked all the pivots and dismembered 3 separate throttle controls to make one really nice one that operates as fine tuned as I could make it.
 
P.S. you will have to remove the floorboard and contort your body to get in and under the firewall to access the throttle assembly.


An easier solution might be to bend the short linkage rod that you pointed to and remove the end-play by making that short straight rod into an arch, making it "shorter"
 
This part tends to wear. To my knowledge, I do not think there are replacement parts available. I welded up the center hole and re-machined it and made a new pivot pin. How there is no slop and the throttle starts to open at the second notch down of the throttle lever.

You can also bend the arm to take up some of the slop which will help.

Chris W.
 
Throttle control assembly's are almost always bent. People remove/install the engine with the assembly on and it bends when it hits the firewall. They can be straightened without heat - just put it in a vise and go at it. It is hard to straighten it correctly - especially if you don't have a "good" one to copy. I think I had it in and out of the car about 8 times, but finally got it working correctly. Used originals are available and they are not expensive, but there is no guarantee that they are any better than what you have. Patience and perseverance is the key.
 
It is either loose from the block, bent, or the nuckle is off of a different car and put on the A assembly. Id' be surprised if the nuckle is bent that much. Id think it would break before it bent that far.
 
Here is a follow up with what I found and the solution:

My throttle assembly is in remarkably good shape except for the worn pivot arm. This one is correct for the late 1930 date of the car too. I have picked up several others at swap meets, etc trying to find one that wasn't worn, but they all have other issues.

Welding up the pin or machining a new one and re boring the pivot arm to round is the way to fix this, but I cannot find a machine shop that will do it. So my fix for now was to insert a small piece of brass shim stock between the pin and the pivot arm. This took up most of the play and the hand throttle works correctly.
 
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