Kings Control Throtle

[CraigB]

Told that my electronic throttle is failing. Doesn’t have the power that it should. Mechanic said operating at 70%. It is a king control throttle. Need to find someone that can tell my mechanic what to do. Was told may have to change to air throttle. 

[Nosmo179]

I'm really sorry that the expert is no longer available. I had mine rebuilt and then checked out by Steve (?). But I've been in mind and believe there are 'fix it's places that can fix it, just got to find one. 

FYI - Mine needed rebuilding because the electric motor that moved the cable lost a bushing. I had it checked out because my rig just wasn't shifting properly. I later found out later that I installed it incorrectly. I put the cable pull in the middle hole but it needed to be in the hole closest to the armature.

[Tom Cherry]

Lots of information….there is, supposedly, an alternative. BUT, if you search our topics and use KING THROTTLE…..BINGO.

https://www.monacoers.org/search/?q=King throttle &quick=1&type=forums_topic

USE the above and learn…..then, more information   Read on…all pages….

https://www.foreforums.com/index.php?topic=40033.0

These are from googling …. Lots out there, but this one was the best.  You can keep googling…..there are some good alternatives.

Good Luck…

[jimc99999]

Mine recently failed, but I was able to repair it. The drive motor uses some kind of friction bushing to drive the belt drive pulley and the throttle position sensor. That friction bushing had pretty much disintegrated. At the top of that drive shaft there's a pin that holds the TPS and drive pulley on the shaft, and that had also broken on mine, which is what ultimately caused it to stop working completely.

I repaired mine by wedging a little piece of bicycle inner tube between the drive shaft and the belt drive pulley, and then using an o-ring between the TPS and drive pulley to hold the piece of inner tube in place and provide a bit more friction. A new pin from a stiff piece of wire and it worked much better than before.

NOTE: if anyone knows the proper friction bushing to use here I'd appreciate being told how wrong I was to fix it this way so I can do it properly. 

In fact, I discovered I must have only been hitting about 80-90% throttle previously. I used to have to lift to make the 4th-5th shift, now the transmission will make that shift automatically. Boost only increased about 1 psi but EGT dropped about 50F, a good indication there is now more fuel flow at max boost.

There is also a huge improvement in throttle responsiveness. It used to take about a second between pressing the throttle and getting much throttle response, for example hitting the throttle to pull out onto a road, it used to take a full second for the throttle to start ramping up and another full second or more before the motor started producing enough power to do more than ease out. Now there is much less slip when the throttle pedal is pushed, so throttle response is greatly improved. 

This is the drive pulley on the electric drive motor shaft. The gap between the pulley and shaft is where I wedged a bit of bicycle inner tube. I cut a piece about 4mm wide, long enough to go around the shaft. Using a jewelry screwdriver I was able to push about 2mm down between the drive pulley and shaft. I then push a small o-ring down on top of the bit of inner tube that was still sticking out.

Note that the drive motor spins a lot farther than the throttle pulley will turn, so it seems required to have a friction drive instead of gluing the drive pulley to the shaft. So far my repair lasted 500 miles, and worked a lot better than the 7 miles I drove from one campground to another using a 50-foot cord to manually pull the throttle.

 

I couldn't pull the circuit board far enough out of the way so I taped the edge so those ancient (30+ year old) components would be protected a bit. The little tabs on the drive pulley spin the TPS. The outer shell of the TPS is stationary, with the connector being held by the tab in the top of the bracket next to the drive shaft. 

Sorry I didn't get better pics. I usually end up taking a couple pictures to see how things were put together before I started and I must have deleted those. And by the time I finished I was annoyed it had taken me so long and I had to spend a nice afternoon doing this instead of going to ride my mountain bike.

 

Edited October 23 by jimc99999

[Craggar]

I'm sure Charles will see this and chime in, he has come up with a kit that gives you all the pieces you can't buy off the shelf to convert it to air. Mine hasn't failed yet but I bought the kit so if it does all I would need to do is buy the pedal and air cylinder which are common parts.

[RoadTripper2084]

I also bought the kit to convert air if required someday, but honestly I think I would put a lot of effort into fixing the King Control system first. Seems like a relatively straightforward setup.

On 10/23/2023 at 11:30 AM, jimc99999 said:

Mine recently failed, but I was able to repair it. The drive motor uses some kind of friction bushing to drive the belt drive pulley and the throttle position sensor. That friction bushing had pretty much disintegrated. At the top of that drive shaft there's a pin that holds the TPS and drive pulley on the shaft, and that had also broken on mine, which is what ultimately caused it to stop working completely.

I repaired mine by wedging a little piece of bicycle inner tube between the drive shaft and the belt drive pulley, and then using an o-ring between the TPS and drive pulley to hold the piece of inner tube in place and provide a bit more friction. A new pin from a stiff piece of wire and it worked much better than before.

NOTE: if anyone knows the proper friction bushing to use here I'd appreciate being told how wrong I was to fix it this way so I can do it properly. 

In fact, I discovered I must have only been hitting about 80-90% throttle previously. I used to have to lift to make the 4th-5th shift, now the transmission will make that shift automatically. Boost only increased about 1 psi but EGT dropped about 50F, a good indication there is now more fuel flow at max boost.

There is also a huge improvement in throttle responsiveness. It used to take about a second between pressing the throttle and getting much throttle response, for example hitting the throttle to pull out onto a road, it used to take a full second for the throttle to start ramping up and another full second or more before the motor started producing enough power to do more than ease out. Now there is much less slip when the throttle pedal is pushed, so throttle response is greatly improved. 

This is the drive pulley on the electric drive motor shaft. The gap between the pulley and shaft is where I wedged a bit of bicycle inner tube. I cut a piece about 4mm wide, long enough to go around the shaft. Using a jewelry screwdriver I was able to push about 2mm down between the drive pulley and shaft. I then push a small o-ring down on top of the bit of inner tube that was still sticking out.

Note that the drive motor spins a lot farther than the throttle pulley will turn, so it seems required to have a friction drive instead of gluing the drive pulley to the shaft. So far my repair lasted 500 miles, and worked a lot better than the 7 miles I drove from one campground to another using a 50-foot cord to manually pull the throttle.

 

I couldn't pull the circuit board far enough out of the way so I taped the edge so those ancient (30+ year old) components would be protected a bit. The little tabs on the drive pulley spin the TPS. The outer shell of the TPS is stationary, with the connector being held by the tab in the top of the bracket next to the drive shaft. 

Sorry I didn't get better pics. I usually end up taking a couple pictures to see how things were put together before I started and I must have deleted those. And by the time I finished I was annoyed it had taken me so long and I had to spend a nice afternoon doing this instead of going to ride my mountain bike.

 

Thanks for sharing this, the more detailed information on this system works and fails that we can share the better.