Thiokol Snowcat Project

[Thefatsquatch]

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!

 

[Pontoon Princess]

looks like you got a lot done in a very short time, great to see ya out on the snow with it, hope to meet up with you some day.

 

[Snowy Rivers]

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.

 

[Thefatsquatch]

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!

 

[Thefatsquatch]

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,

 

[Thefatsquatch]

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!

 

[Thefatsquatch]

looks like you got a lot done in a very short time, great to see ya out on the snow with it, hope to meet up with you some day.

Marble Mountain snowpark Tuesday?

 

[DAVENET]

She's in Sun Valley this week for the snow cat serenade

 

[Snowy Rivers]

The bearing that went sour likely shed pieces that tore up the R&P

Glad to were able to fix things.

 

[Snowy Rivers]

I have a decent 2100 fuel tank from mine if you are interested.

Text me.

 

[Thefatsquatch]

Well, Tuesday I decided she was fixed, and I took Luleelurah (my coworkers’ affectionate name for the 2100,) and headed out to see what it can do. I have some friends who snowwheel with trucks near me, and these guys are Serious about it! I figured I should show them up. Turns out, their rigs are pretty impressive. There was one high mark I simply couldn’t get to. All I can figure is, 9 miles per hour doesn’t have a lot of momentum. The welded Pinion gear held, at least for now, and no flat tires this time around. The only human interaction all day was when two guys came around the corner to my empty cat, driving up the road, pulling my ram 3500 with me in it, out of about 2 feet of old snow. 22 miles in all, by far the longest trip I have taken it on.
One issue I did run into was, I can’t rev it over 2300 rpm without the hydraulic pump trying to deadhead itself. I assume it’s because I removed everything but the bypass pressure regulator, and the steering hydraulics. Does anyone know of an equation to determine what size orifices and hoses I need to keep the pump flowing freely? I assume it will work if I put back in the priority splitter, (which looks a Lot like another bypass regulator, but with a heavier spring...) but I’d like to be More sure.

 

[Thefatsquatch]

Well, I done broke it. Went on an adventure-picnic with my Girlfriend on Sunday, and it just died. It was definitely a fueling issue, and not a lot I could do about it, so we walked out until we got picked up by a couple big snow-jeeps. Buuuuut, then they both blew a tire off the bead. So we spent half the night in the back seat of a kind couples snow-jeep until we got rescued at 1 am by an EVEN BIGGER snow rig. Yesterday I took the day off work and we took a fuel pump and a new carb up there and got it running. Only on the way back, the left axle just stopped driving. I didn't really understand what was happening at the time, and it turned right into a couple sapling trees. Blew the front wheel off the bead, sucked the grousers under the tunnel and locked the whole thing up. We got the track off, pulled the cat out, and swapped the tire, but I still have a broken axle. I don't think it is the differential, because when I pull on the left stick, the right track drives. But when I pull on the right stick.... nothing. And even in gear, the left axle spins freely. It's an OC-12 differential, so I am assuming it has the gear-driven drop-boxes on it, but I haven't taken them off to see. I know it has short axles on it, so maybe it is the chain style, like in an oc-4?
My plan is to take the axle off the drop and see what parts fall out, but if someone has a better plan, I am all ears!

 

[alryA]

Help me out and tell me what "big snow-jeeps" are??

 

[Thefatsquatch]

Help me out and tell me what "big snow-jeeps" are??

The guy who rescued us had a first gen 4-runner with a supercharged 3rz motor, and ford 1 ton axles with 44" tires about 24 inches wide. There is a group of people in southwest Washington who build jeeps, old hilux pickups, or 4runners that can literally go through or over 10 feet of snow.
This is the guy who took me back up there yesterday.
The snow is about 12 feet deep where he is driving.

 

[m1west]

Thats the problem with old snowcats, you either completely go thru everything as new or chase problems and walk.

 

[Thefatsquatch]

Thats the problem with old snowcats, you either completely go thru everything as new or chase problems and walk.

I am definitely a chase-and-walk kinda guy. To the extent that I take telemark skis with me every time I take it out, lol! This is my first one, and I am still learning what parts I can overlook and which ones I can't. Turns out, whatever that was, was in the latter group.

 

[Snowy Rivers]

Did you get the cat home ????
Looked at your diffy pics.....your drop cases have the gear sets in them.....SEE PICCY

My bet is the axle snapped off just inside the bearing.

The early axles had the bearing retained with a snap ring just inside the bearing.

The axles would snap off at the snap ring groove......
The later axles do not use the snap ring.....They use a pressed on steel retainer (Wedding band) to hold the bearing on the axle.

#`14 and 17 are the inner and outer seals. (Old style...new style does not have an inner seal...bearing lubricated from the diffy)
#24 is the snap ring
#15 is the bearing (5210 double row ball bearing)
I had to get rough with mine to get things apart.....
The bearing was broken.......you can see the retainer ring....then the bearing inner race...the outer bearing retainer pate that holds the assembly and has the outer seal.

Using axles with the bearing retainer ring requires that the clearance between the ring and the axle housing inner bore NOT HAVE INTERFERENCE......IF THE RING HITS THE HOUSING...it will chew up metal and cause the bearing to fail.


You can see the broken bearing race in the piccy

Also some retro fits allow the end of the axle shaft to thrust against the inside of the drop box.
SEE PICCY.....YOU DO NOT WANT THIS ...A tube spacer must be used between the bearing outer race and the inner shoulder of the axle tube to keep the assembly from moving in and out.

Also the pressed on band must not touch the inside edge of the axle tube bore....this chews up crap that wreck stuff.

 

[Snowy Rivers]

If there was not any nasty crashing and noise from the diffy when this all happened....Good bet the axle is broken.

I am gonna recommend that you yank that diffy out and completely tear it down.....

With the issues that you have had.....there is likely other damaged bearings and things lurking in the dark just waiting to cause havoc......

These boxes are just too $$$$$$$$$$$$$$$ to take another chance at having it break in the sticks......

Not all that spendy to replace bearing and also check the planetary gears, thrust washers and other goodies in there.

These boxes are pretty stout...but do have a few places that can cause trouble.....as you have seen...

My bet is that possibly the previous damage may have contributed to this wreck...

Yank the axle shaft first.....Don't break the tube loose at the drop box until you see wassup at the outer end first.
Betcha that axle was/has been cracked at the snap ring and finally broke.


Keep us in the loop.

 

[Thefatsquatch]

Thank You!
That’s very helpful. I haven’t gotten the cat back yet, as I had to go back to work. I’m headed out with my brothers tomorrow to see what we can do to field repair it and get it home.
I do hope it’s an axle-shaft, because that’s the least amount of opening things in the snow.
I’ll keep you posted on what I find!

 

[Snowy Rivers]

Hope all goes well.
Can you get hold of anyone with a cat to drag it out and then winch it on the trailer????

 

[Thefatsquatch]

Ok. The skidozer is Home. Friday I went up with my jeep and pulled the axle. Sure enough, snapped off. Just outboard of the inner splines. I’m going to guess this unit was used hard at some point, but it’s possible I just twisted it off in reverse. (Unlikely because my drive sprockets don’t hold for beans in reverse)
Regardless, I pulled the axle, chamfered the ends, welded it up and heat worked it with a hammer/anvil until it was both straight and the stress was worked out. (Mine and the axles)
The snow was crap yesterday, as the sun was on it, so the trip in with the Jeep was treacherous, but successful. We bolted up the axle, put the track back on, and started home. The whole time I was Dreading hearing the pop of snapping axles, but it didn’t happen.
Time for a complete rebuild in that back end. Stainless brake cylinders, new axle, new bearings. And clean that carb!
I think I’ll put all new copper fuel lines on while I’m at it.

 

[Snowy Rivers]

So glad you got the Kitty home.
That axle repair looks great.
Best part is...IT HELD LONG ENOUGH TO GET IT ON THE TRAILER.....

Yes indeed. definitely need to go through the rear box.....

 

[Thefatsquatch]

So glad you got the Kitty home.
That axle repair looks great.
Best part is...IT HELD LONG ENOUGH TO GET IT ON THE TRAILER.....

Yes indeed. definitely need to go through the rear box.....

Oh Absolutely! I am not pulling it apart until I have the new axle and a few more honey-do projects checked off the list, but then I have a list of things that need to happen before it goes out again. That whole situation was a bit of a cluster-.... but it could have been So much worse. Walking out 20 miles in the snow is no joke.
No one was hurt, and though I did inconvenience some friends for a bit, we had a good time doing it.
My wife is starting her first engine rebuild (and complete car rebuild) in about a month, so I am getting my shop cleaned up so it is usable for a person who is not me, and I think I would like it pretty clean before I start in on something like that. From what I hear, that differential will tear itself apart pretty quickly if it is dirty.

 

[Snowy Rivers]

Hey
Fleetpride at 201 N Columbia Bld...(Used to be OTTS Friction) (503) 283-4165
These guys can redo your bands for you....They have been in the bizz for many years and do fine work.

I recommend removing the bands with the carrier/drum assembly and replacing them with the unit.
Snaking them out of the case is possible....but ya gotta bend them a lot.
The carrier needs to be removed and replaced on an angle to get it to fit the case.
With the bands on the drums and held with heavy tie wraps......the job is a snap.

I forgot to mention....I have a set of carrier bearings that I ID/OD ground to easily slip on and off the carrier and into the drop boxes....THESE make doing a fresh setup far easier than pulling bearing off and on to set the backlash....

Just be sure to keep all the shims tagged and bagged /marked as to where they came off.

When you get ready to do that bad boy.....I can bring over the special tools that make this sucker far less aggravating to deal with.

 

[Snowy Rivers]

Pics of the bands after the rework at the shop

A piccy of the carrier with the bands tied to the drums with HD ZIP TIES.

Also....the lock nuts on the inside of the case.....the lower ones require a bastard wrench to reach them down under the carrier .
GAWD I hate cutting up good wrenches....but these bolts/nuts are a PITA to get to down in the case....Bolt comes through the drop box then the case and there is a heavy flat washer and then the crimp top nuts.

I glued the lower flat washers to the inside of the case before I dropped the carrier in. Made life far less stressful.
Use Gorilla tape to hold the nut in the wrench to get the thing started onto the bolt

BOTTOM 4 holes.....Cleaned the washers..and case with Braklean and siliconed the washers to the case and held them overnight with some extra bolts/nuts I got. YOU CAN'T GET HANDS DOWN IN THERE........
Drop a washer and it's gonna be a bitch to get it out.....

 

[alryA]

Thanks snowy R for down sizing your photos. Some people like to DL cazillion MEG ones and I won't sit around waiting for them.

Everyone, please post reasonably sized photos.

 

[Snowy Rivers]

Your Welcome

I got in the habit a looooooooooong time ago at a truck forum I frequent...
They had a size limit on pics.

A lot of folks are loading pics straight from their smart phones....and they are huge.
I generally go at around 300Kb but it varies with each piccy
Straight out of the phone/camera they can be 1-2 Megs.....takes up a buttload of bandwidth.....

 

[Thefatsquatch]

Has anyone on here taken one of these units through a border-crossing? I want to head up to pemberton once she is all good to go, but going through the border is no joke if they think I am selling it or something.

 

[Snowy Rivers]

Call the Canadian customs and ask them what you need to do....Width restrictions...yada yada yada..../

Be specific and ask lots of ???????

A snowmobile is one thing, but one of these monsters is yet another bag of worms...

 

[Thefatsquatch]

Ok, so at this point, I’m keeping the bulletproof NP435, and adding an overdrive of sorts. I read that you can run a Chrysler 903 transmission backwards for a pretty significant overdrive, but only in the top two gears. The Driveline emergency brake, however, is giving me fits. I can’t find pads for it. It’s supposed to be the 2086 pads, but those are 3” wide, and mine are 2” wide. Anyone have any idea where to get them, or do I have to send them to be re-lined?
Hope to have the tranny back in next week, then it’s on to the final drive. The broken axle from last year is going to cost a mint, but worth it to not head into the wilderness with welded axles.
Seriously considering swapping the final drive to a Rockwell rear axle if I have any more problems. It would solve the gearing issue, and the locating-rare-parts issue. Anyone seen it done? I wouldn’t mind stealing ideas...