Thiokol Snowcat Project

PJL: Yes. Unfortunately I think he was drilling a little fast, (in terms of pressure) and was at the helm when the first bit blew up. No injuries, Luckily! I turned the drill speed up a bit, and used less pressure, but just in case, we used eye protection. And we still blew up a bit every couple grousers. That stuff is HARD!

KickerM: I'm so glad to see that logo! It's a pretty sweet sticker, so I certainly left mine on there. Lobster Red sounds like a Perfect color! Excited to see the adventures of my Kitty's Cousin!
 
So, the girlfriend, (who initially said there was no way she was going out in this contraption into the wilderness) has decided she’s game to go... as long as she doesn’t have to ride in the back. It took me a while measuring seats at junk yards, but a dodge caravan second row 2/3 seat measures 42 inches without the armrest, and has a pillar to mount the controls on. This also required a tractor throttle, because I have to be on the clutch side to drive, but we got it mounted and running.
It’s a bit wide on the trailer, but to be fair, that’s not a full width trailer either.
So, we met some co workers and their kids, and my girlfriend and kids, and headed to Skate Creek snopark. Gate was locked, so we headed up the nearest logging road until I couldn’t drive with the trailer.
The road was clear for a mile or so, but not as far as I wanted to go.
Turning around to push a tree out of the way, I blew another hydraulic line. This time an auxiliary line out the back. But, it took me hiking back to the truck for another gallon of fluid to get us out of there.
At least the kids had fun in the snow!
And the little boys were crawling around in the snow afterwards saying, “I’m a snowcat!”
All in all, not a bad day at all.
That said, if I want to clean this up, and simplify, do I just run the non-priority line back to the tank from the splitter?
I’m not going to use the ports in the back, and I don’t really want to replace 20 hoses I don’t need.
 

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I forgot to get the picture of the crack in the fuel tank, but luckily it was on top! I think I must have banded it in there too tight. I was able to repair about 6 inches on the top edge, using the Dry-Ice purging method. I didn't grind it down quite as far as the rest of it, and I think I will end up lining the inside of it anyway.
Now on to simplifying the hydraulics!
I think I can just run the priority splitter to the steering, and the non-priority back to the filter.
I really don't need the rear ports just using it for a ski-rig.
 

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Snowtrac Nome

member formerly known as dds
GOLD Site Supporter
the steering just uses bypass pressure for steering, you don't want the whole 2500 psi going to the steering cylinders it will break your bands. the system is kind of genious there is a pintle stops return to the tank, allowing pressure to build up in to the line going back to the slave cylinder .
 
the steering just uses bypass pressure for steering, you don't want the whole 2500 psi going to the steering cylinders it will break your bands. the system is kind of genious there is a pintle stops return to the tank, allowing pressure to build up in to the line going back to the slave cylinder .

Gotcha. Currently it goes to a priority splitter, then the priority side, (the brake side) runs to a regulator, and the other side runs to my ancillary, (pressure bar) controls. I guess I really don't even need the splitter, just the regulator, since I am not running anything else. I just figured I didn't want to bind up the pump, so I figured I would run the priority splitter, tie into the blow-off for the regulators, and run it straight back to the filter.
Just trying to figure out what I can take of without constricting flow and burning up the pump.
 
Well, first trip of the year is in the books. I spent the summer replacing every hose on the kitty, and I still have a leak, about 1 gallon an hour. Looking at the spin-on hydraulic filter, I think it had a pinhole in it, but I can't be sure if that was from me taking it off. We got into about 6 feet of snow, but it wasn't particularly new, and we didn't sink at all. Well, until we stepped off the cat. Interesting finding: When low on hydraulic steering oil, and heading up very steep slopes, an old Thiokol does not have steering. I really need to figure out a back-up plan for manual steering. Also, my left track is hitting the tunnel and taking a bit more than paint. Anyone dealt with that before?
 

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Snowy Rivers

Well-known member
The zero offset in your new wheels is placing the track 3/4" closer to the tub.

I am not sure as to how much clearance you had before with the stock wheels in place ???????

We did chat about the wheel offset when you were up here a while back.
Easy way to fix this is to make a set of 10 aluminum 3/4" thick spacers and put between the wheel and the hub.
This issue is why I am fabricating the custom wheels for mine.

All trailer wheels are "usually" zero offset (On center of the wheel) and the stock wheels are set outboard by 3/4" (Negative offset)

Here is a piccy of what I used as a drill jig....this would work as a pattern to make spacers (Water jet cut the alloy plate with 4.020" pilot bore...drill the holes at 17/32")
This is going to be cheaper than redoing the wheels at this time.
 

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Snowy Rivers

Well-known member
I have an extra one of these rings....You are welcome to it if it will help.
Or if you wanted to get spacers cut....C'mon over and we can use my jig and then drill the plates here.
We can knock those out PDQ.

I have the right size transfer punch to mark the holes with and all the tooling ready to go.

I am still working on my "Snowflake centers".....so the tooling is all sitting on the mill.
 
The zero offset in your new wheels is placing the track 3/4" closer to the tub.

I am not sure as to how much clearance you had before with the stock wheels in place ???????

We did chat about the wheel offset when you were up here a while back.
Easy way to fix this is to make a set of 10 aluminum 3/4" thick spacers and put between the wheel and the hub.
This issue is why I am fabricating the custom wheels for mine.

All trailer wheels are "usually" zero offset (On center of the wheel) and the stock wheels are set outboard by 3/4" (Negative offset)

Here is a piccy of what I used as a drill jig....this would work as a pattern to make spacers (Water jet cut the alloy plate with 4.020" pilot bore...drill the holes at 17/32")
This is going to be cheaper than redoing the wheels at this time.
It is weird through. The front wheels are the metric ones, and run either zero offset or whatever the stock ones were. It rubbed with the stock aluminum ones too. The 4 center axles are the 5.3/r12, but it only rubs on the Left side, top of the front wheel. I must have a bent grouser on that side or something. I think I have decided to go with a 1/2" spacer on the front, and 1" spacers for the 4 center axles. The 1" ones have counter-spaced studs so I don't have to worry about not catching enough threads.
 

Snowy Rivers

Well-known member
One thing though.

Your cat has had the frame narrowed up a bunch and the tracks had the outer bands cut off IIRC ?????

You added new outer bands back on the track to make the tracks wider....IIRC the tracks were at 28" when you got the machine ???? and you went to 43" ?????

What you might do is measure from the tub to the center of the drive sprocket.....the center of the tires need to be the same to keep the tracks running straight....

The original clearance between the inner edge of the track and the tub was about 3-1/2"
Unless there was a broken grouser or some other issue the track would not hit the tub.

Losing a front tire (Flat) could see a track derail and get into the tub.....but normally there will not be any problems with the track hitting

What is the tire center/center dimension on the axles (side to side) as they are now ????

Ideally you should have about 3" clearance between the edge of the track and the tub to allow things to move around.
At the least I would say 2" would be getting very skimpy......
 
So, The problem appears to be two-fold. First, there is a slight buckle in the frame right near the front wheel on the left side. Looks like someone got a bit over-zealous with a blade at some point, and when the frame wrinkled a bit, just welded it back in place. It is only about 1/4" out from the rest, and only at the top, but that does put it closer. Secondly, when putting the spacers on, it appears the front drop-axle has been bent at the pivot point. Not badly, but enough to see. I know it will put weird wear on the front tire, but I won't be putting enough miles on it to cause problems this year. I guess I will be looking for another front axle this summer.
As far as the track width, it had been narrowed before I got it. Both the axles and the track.
When I went to 44", I extended the inside 6" and the outside 8", slightly asymmetric, but as wide as I could get with it being balanced. The clearance on the inside to the tunnel was about 2" We are up to 2.5" now, and I haven't gotten any miles since. However, it should be great conditions very soon!
 

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Snowy Rivers

Well-known member
With this issue fixed and the oil leak stopped....life should be good.

Front axles are quite vulnerable.....Been a lot of them bent...
Mine is bent all to rat crap.....

Going to go with a morph on the twin/split type axles like what the later 3700 had.

Going to use a Timbren bumper to handle the flex on each side......

If you want to copy my front axle design....let me know.

Gonna take some fabricating and a bit of mods.
The torsion arm and spindle are salvageable......
Need to fab a new outer adjuster slider and add an inner slider that spans the front frame and then bolts to the #2 axle for stability.

Need an adjuster on the inside too...

The 3700 used a torsion flex similar to the 2100.....but had a couple of pivot points and a cylinder.

Have fun.
 
Well, The snow finally came, and we have gotten some use out of it, but still haven't found a place to do what I actually bought it for. Any suggestions on what public land I we can cat-ski in Washington or Oregon, please let me know! First big trip out this year was just the kids and me. Second trip was only two weeks later, but the snow was significantly diminished. Made it back far enough to show the snow-wheelers who is boss!
 

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Next I took it solo to Round Mountain, just off hwy12. Zero issues, aside from a significant lack of sleep. Found some stunning areas, and had a blast. Pictures appear to be in a random order,
 

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The 4th trip out hit a few obstacles… It snowed about 14 inches at my house that weekend, and trying to get ready for this trip, I backed the truck and trailer off the driveway. My son got his first taste of snowcat driving pulling my grumpy ass out of the snow, but that was probably a lot of stress on the old girl. We also took some friends for a ride that Saturday, on the non-plowed roads at our house.
Sunday we all loaded up and drove out to the 4200 road. The snow was low enough we couldn't tow the cat up the first hill, but shallow enough the cat was basically on gravel for the first several miles.
About 6 miles in, the fuel tank sprung a huge leak, and we had to jettison all but about 12 gallons. Once I got it home, I found some issues. Pinion gear is busted to crap, and the ring gear looks like it. Apparently I have a leaky seal in one of the drops, and the oil has gotten some water in it. Then I found part of a bearing. That is never good.
The bearing was easy to replace. Happened to be the pinion main bearing, and that all just comes off.
The pinion had to be un-heat treated, welded, re-milled, and re-heat treated. That took a while.
Welded up the fuel tank, and used the por-15 tank liner. I hope that stuff is as good as it says!
Next trip is March 16th, and I think we will put it through the paces!
 

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