I've been looking at installing portals on my 81. Has anyone ever done this before? How did you do it?

 

My design constraints are as follows...

1) Must fit inside a reasonably sized wheel.

2) Must offer some fleximility in gear reduction.

3) Must not tear up spindles or wheel bearings.

 

I'd thought of using a small "outside" gear on the input side and a larger "inside" gear in the output side of the portal. Brakes would either have to be significantly upgraded or moved to the other end of the CV shaft in order to provide better cooling, since you'd effectively be braking for a speed twice whatever your real speed is, so brake fade would be a problem.

 

On the other hand, one could simply remove the rotor and hub to attach the portal directly to the spindle and drive it off of the stock cv shaft. If you relocated the brake rotor and spindle to the output of the portal, one could machine the wheel end of a cv shaft to pass air through it (fittings on each end).

 

Any thoughts?

Biggest issue I can see is reverse rotation. If you wanted to go with divorced T-case or solid axels you might have some thing.

 

I have thought about something like this that’s utilizes the reverse rotation… Imagine a VW style dune buggy, rear engine and 4wd Subie power with a 3” lift using old VW bus reduction boxes (they are portal type). Just an idea I’ve been developing since VW Vanogan Syncro gear is so expensive.

 

Gary

I had portal thoughts a while ago. It sounds like you want to build as opposed to adapt an existing portal hub. If you want to avoid the reverse rotation bit, what about a heavy duty chain connecting two sprockets? I'm not an engineer and don't know much about the strength of a setup like this but it sounds like it could work.

 

- Jeff

triple gears think gear drive timing setup on a small block chevy

 

in fact.. i think and i may be wrong but i think the hummer uses triple gears??

Just to be clear, I thought I'd post a sort of concept drawing. Its crude, but I think you'll get the idea.

 

 

 

I kinda figured on a steel box with a bearing for the CV shaft to pass through. The CV shaft would either directly drive the larger "inside" gear or it would have another gear matched to the splines on the CV shaft to drive hte larger gear. In this configuration, reverse rotation is not a problem, since both gears are running the same direction. The "inside" gear would have the outer end of a CV shaft pressed through it and the braking hardware all gets relocated to the outside. Fill the case with a 90wt bath and it should be good to go...I think.

here's a pic of a jeeper that is working on putting some Volvo Portal axles on his rig. It may help understand what is needed.

 

http://www.itsajeep.org/PhotoPost/showgallery.php?cat=500&ppuser=35

using a chain system would probably be ideal, the machining would not have to be as exact because you would not have to worry about gear meshing. The chains out of big chain drive 4x4 transfer cases could work, Im not sure if v8 timing chains would be able to handle the load though.

The problem with a chain-driven setup would be getting it to fit inside a reasonably sized wheel. It simplifies some of hte machine work, yes, but also results in a much larger unit. To get the amount of gear reduction that I'm after, the resulting unit would end up being fairly large and therefore would not likely fit inside a 15" wheel once all the braking hardware is added back in.