Thiokol Snowcat Project

Snowy Rivers

Well-known member
Pretty well have to use the planetary axle for steering.
Others have used a standard diffy ...and used the brakes to lock up one track or the other.

I thought about that but then thought better of it.

The OC-12 is nearly bullet proof.

If you get the diffy all the way down and go through it you should be fine,

Now you did have issues with some breakage on the R&P if I remember correctly ??????

The biggest part of the OC-12 is keeping them in good shape.....
Once thrust washers and things start wearing out and junk goes through the gear and can and will get ugly.....

Water getting in....RUST ruins bearings then they grind themselves to bits and shed all sorts of metal scrap.

When you get ready to do the diffy...let me know, and we can come up and give you a hand.

I made several special tools to deal with the big box
I should have asked if there was a trick to getting this tranny back in by myself, as there isn't room in the cab for even one extra person. I ended up strapping the back of it up to the hand-rail and starting a couple long bolts, then just wrestled with it while basically standing on my head for a few hours. But the freshly rebuild NP435 is in and bolted down! Tracking down brake shoes and springs for the emergency brake was less than fun, but a local Potter Webster supplier found what I needed! Now for the Overdrive contraption! New Axle should be on it's way Monday, so I have about a week to get this all bolted together enough to move it up by the shop. Then the real work starts on the final drive, and repairs to the tracks.


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Well, While I had the tracks off, I figured I would correct the problem in the picture. This is the worse side, but neither one of them are straight. Upon inspection, it is not the axle spindles which are bent, but the suspension axles holding the arms. That gives the whole front end toe-out. The only option at this point was to buy new torsion axles. Unfortunately, they only come in half axles right now, from the production shortages everyone is having. The question I have is: Is it beneficial to toe-in the front wheels, to compensate for track tension? The 3500 point axles come with a bracket to provide about positive 1-2% camber, so I am thinking a similar amount of toe-in. I am going to have to build these into an axle, so I can arrange it however I need to.


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Snowy Rivers

Well-known member
A small amount of toe in will not hurt.
The front axle gets beat hard from all the pull of the tracks.....This is the biggest reason the front torsion units go south....The others are just along for the ride and wear far less. (The front torsion rubber cords have failed and this allows the inner bar to crawl back....causing the "out of line)

I looked at using the half axles and going that route....but nobody local had any that I could go and get a hands on "Touchy Feely"
I was not keen on dropping the big coin$$$$$ to take a guess....Hence the reason I chose to build my own.

Camber is there to help keep the tires flat on the road once under load.....In this application the track is all over the place as it moves with the terrain and likely will make zero difference in actual operation.....Unless it was really off in the ozones ....

The Snow cat "Smoothies" (Tires) are dome shaped on the contact opposed to the flat surface of the treaded tires.

The Toe is a good thing....A little bit.

One important thing is to have all 5 road wheels in a straight line....This will make things easier on the sidewall of the tires
Also make sure the tire guides are sitting centered in the sprockets and the tires are all lined up

Any misalignment will cause a bit more wear......Subjective....As the machine is turned the tracks move all over anyway.

Good luck on the axle project.

Keep us in the loop......
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