Robert Younjohns was over the house a while ago and I had an Alle I was making the marker lights workable and he mentioned he stopped running his because it couldn't pull very well. My friend Ray Louis had told me the same about his so I invited Robert to come over and we could explore the problem together.
It turns out that he had actually done some mods before which helped a little but it was still feeble.
We set up a platform and kitchen scale to measure the weight on the trucks.
The total weight is 31.5 lbs
On the stock engine the weights were (all in pounds)
Front drivers - 8.5
rear trailing truck - 10.5
center drivers - 12.5
This is a static test. As torque is applied to the drivers, they want to pop a wheelie so the front would be less in action
Roberts engine was better with 10.5 lbs on the front but the front pivot spring was bottoming out causing the front and center drivers to alternate spinning and with very little forward thrust. I was able to get a 2 pound draw bar pull by feathering the throttle and then my electronic pull meter failed so that was the only test we could do.
The main problem that is not news to most of you is the tremendous overhang in the rear and the weight pivot points being in the wrong place.
![Image]()
As you can see, the pivot above the rear cylinder set is way too forward.
First, we removed the front engine and we wanted to retain the strong spring without bottoming out so I cut 2 coils off and it is now these dimensions.
![Image]()
Now it doesn't bottom out till it reaches the bottom of the throw.
![Image]()
![Image]()
![Image]()
now for the fun part. We removed the rear engine and frame to study the mounting. It has a two part mounting above the cylinders with plates that are mounted to the boiler shell and the frame (Shown at the far left of the engine below). The part on the boiler shell was removed after the mod was made
I found a spot between the second and third drivers where two existing screws could be used to mount a new front boiler support.. It would need to be slotted to clear the reverse levers and stepped back to clear more linkage and the faux leaf springs
![Image]()
It is two parts. An annealed and bent 1/16" strap for the boiler shell mounting and a an angle bracket to the dimensions below and silver soldered together
![Image]()
Because the annealing softened things up a bit, I made two supports and soldered them on with Staybrite as not to disturb the silver joint.
![Image]()
You can see the clearance for the reverse linkage and the high point of the springs.
![Image]()
![Image]()
The engine appears to be level and the new support is barely noticeable
![Image]()
![Image]()
Using the kitchen scale again, it exceeded the 5 KG capacity on the front driver and was only 7.5 lbs on the rear truck which still has the stronger springs Robert had put in years ago. He will probably reinstall the factory ones later.
The pull now seems to be what it should be
Track testing to follow.
It turns out that he had actually done some mods before which helped a little but it was still feeble.
We set up a platform and kitchen scale to measure the weight on the trucks.
The total weight is 31.5 lbs
On the stock engine the weights were (all in pounds)
Front drivers - 8.5
rear trailing truck - 10.5
center drivers - 12.5
This is a static test. As torque is applied to the drivers, they want to pop a wheelie so the front would be less in action
Roberts engine was better with 10.5 lbs on the front but the front pivot spring was bottoming out causing the front and center drivers to alternate spinning and with very little forward thrust. I was able to get a 2 pound draw bar pull by feathering the throttle and then my electronic pull meter failed so that was the only test we could do.
The main problem that is not news to most of you is the tremendous overhang in the rear and the weight pivot points being in the wrong place.
As you can see, the pivot above the rear cylinder set is way too forward.
First, we removed the front engine and we wanted to retain the strong spring without bottoming out so I cut 2 coils off and it is now these dimensions.
Now it doesn't bottom out till it reaches the bottom of the throw.
now for the fun part. We removed the rear engine and frame to study the mounting. It has a two part mounting above the cylinders with plates that are mounted to the boiler shell and the frame (Shown at the far left of the engine below). The part on the boiler shell was removed after the mod was made
I found a spot between the second and third drivers where two existing screws could be used to mount a new front boiler support.. It would need to be slotted to clear the reverse levers and stepped back to clear more linkage and the faux leaf springs
It is two parts. An annealed and bent 1/16" strap for the boiler shell mounting and a an angle bracket to the dimensions below and silver soldered together
Because the annealing softened things up a bit, I made two supports and soldered them on with Staybrite as not to disturb the silver joint.
You can see the clearance for the reverse linkage and the high point of the springs.
The engine appears to be level and the new support is barely noticeable
Using the kitchen scale again, it exceeded the 5 KG capacity on the front driver and was only 7.5 lbs on the rear truck which still has the stronger springs Robert had put in years ago. He will probably reinstall the factory ones later.
The pull now seems to be what it should be
Track testing to follow.
