Custom application - looking for input/ideas.

[aquavette]

Well here it is:

Basic setup is a 4.5HP Robin Subaru with a jackshaft and a live rear axle with a single disc brake.

I have a handful of issues, so I'll simply list them-with my thoughts, and let folks throw out some ideas on how to address them.

1.) Clutch hangs a little and squeals like a stuck pig. I suspect just needs some grease on engine shaft? (Shaft size is not a standard keyed shaft, whole 'nother story. I'll need to photograph to explain.)

2.) Carb is leaking fuel from everywhere so it seems. Can't seem to find a rebuild kit online, but found an entirely new carb?

3.) Understeer is insane, (I assume due to the live axle). This cart will see pavement use only, and will also be ridden by an 8 year old. (Does not need to be crazy fast.)

Looking to tame it a bit, and make it more manageable on pavement.

Should I loose the 4.5HP and go to a 2.5 or 3.5HP?
(I'm a lot bigger than the 8 year old, and would like to ride also.)

Need ideas on the easiest way to go to one wheel drive.
Add a differential?
Machine one end of the 1" live axle to 5/8" and add a freewheel hub? (Keeps current look.)

Current setup has a jackshaft, and while I haven't counted all of the sprocket teeth, the engine is a 12 tooth clutch, and the axle is a 2 piece 59 tooth sprocket. Just guessing the jackshaft has a 18-24 tooth input and a 12-14 tooth output. (I would need to verify)

Let me know your thoughts.
Thanks.

 

[r_chez_08]

Type in camber castor Ackerman in the search bar. That will probably be what is wrong with your steering.
What is your gearing? That may be the problem with the clutch, also a drop of oil on the bushing ONLY may help.

 

[theo]

Can you show use a pic. of your front end?

 

[aquavette]

The only other pics I have at the moment:

I am pretty sure that my front end geometry is far from perfect and could use some additional tuning, but with a wheelbase only a few inches longer than the rear track width, I'm pretty sure the live axle is my main understeer issue.

 

[Doc Sprocket]

Yup- you got it. All the engineering in the world is not going to make that have perfect road manners. Your options are to install a diff or convert to a 1wd, as you suspect. Machining one axle end down seems like a good, cheap option.

For the clutch, put 1-2 drops of engine oil on the bronze clutch bushing. Repeat occasionally as a maintenance item.

If the carb is peeing fuel, my money is on the inlet needle valve and/or float. Take the bowl off the carb and ensure the float is intact and working properly. Inspect the needle valve that the float actuates and try to ascertain whether is is sealing properly with the float in the up position.

Since you already have a jackshaft, regear it lower for the little one to drive safely. Reducing the horsepower will likely have zero effect on speed with something that small and light.

Beautiful wagon!

 

[Jake.B]

Wow this is really cool!
Yous should machine a straight pipe or technically curved pie through the bottom of the frame and along the bottom to the rear end. Im not sure if there would be power loss though

 

[aquavette]

Yup- you got it. All the engineering in the world is not going to make that have perfect road manners. Your options are to install a diff or convert to a 1wd, as you suspect. Machining one axle end down seems like a good, cheap option.

For the clutch, put 1-2 drops of engine oil on the bronze clutch bushing. Repeat occasionally as a maintenance item.

If the carb is peeing fuel, my money is on the inlet needle valve and/or float. Take the bowl off the carb and ensure the float is intact and working properly. Inspect the needle valve that the float actuates and try to ascertain whether is is sealing properly with the float in the up position.

Since you already have a jackshaft, regear it lower for the little one to drive safely. Reducing the horsepower will likely have zero effect on speed with something that small and light.

Beautiful wagon!

Thanks for the input. Got a machine shop lined up to take care of my axle. Hopefully that will give it some street manners, then I'll be cracking open that carb...

 

[slideways]

You could just pull they keyway out of one of the hubs. I do that on my barstool racer with the same problem.

As for the speed.. those motors should have a throttle limiter screw on them. Just turn it in until it still takes off for the kid.

 

[Doc Sprocket]

You could just pull they keyway out of one of the hubs. I do that on my barstool racer with the same problem.

As for the speed.. those motors should have a throttle limiter screw on them. Just turn it in until it still takes off for the kid.

These are what I would call "quick and dirty" methods. While there is some functionality there, I would offer the following cautions-

1) Removing the key- your steel wheel hub will be spinning directly on your steel axle shaft. Liberal greasing will only get you so far, the hub and shaft will start chewing each other up.

2) Using engine RPM to limit speed creates a bit of a pitfall. If the RPM is well below the lockup speed of the centrifugal clutch, the clutch will be constantly slipping. This leads to an untimely death for the clutch.

IMHO, it's better to do things "properly". Use bearings (or at least bushings) between moving parts, and use gearing to limit road speed.

 

[bighead]

Cannot help you much with your questions but thats one sick looking wagon. Very nice work.

 

[slideways]

I agree... i was worried about it too but i have zero wear on my "dumb" tire side. It helps alot to take a file and just file the leading edge to a taper on the hub so its not grinding as it goes by.

He should be fine with limiting the throttle as long as he gets it so it takes off. This would just keep the kids from gaining speed once they are already off and moving.

 

[briggs-overhaul]

you should put an exhaust that flows through to the back, and maybe headlights would be nice for detail

 

[aquavette]

These are what I would call "quick and dirty" methods. While there is some functionality there, I would offer the following cautions-

1) Removing the key- your steel wheel hub will be spinning directly on your steel axle shaft. Liberal greasing will only get you so far, the hub and shaft will start chewing each other up.

2) Using engine RPM to limit speed creates a bit of a pitfall. If the RPM is well below the lockup speed of the centrifugal clutch, the clutch will be constantly slipping. This leads to an untimely death for the clutch.

IMHO, it's better to do things "properly". Use bearings (or at least bushings) between moving parts, and use gearing to limit road speed.

That was pretty much my fears with the quick and dirty method.
This thing will rarely, if ever see use off road, but if the next owner wants to convert it back they can simply replace the rear axle and one hub.

 

[aquavette]

Cannot help you much with your questions but thats one sick looking wagon. Very nice work.

I can't take credit for the build, as it was a craigslist find for me, but I have researched several of these builds, and was contemplating starting one myself before finding this one.

you should put an exhaust that flows through to the back, and maybe headlights would be nice for detail

The previous owner welde a pipe to the outlet of the muffler, and ran it under the wagon to a fake "dual exhaust" that you can't see in the photos. The weld has broken at the back of the muffler, so I will need to address in some way or the other.