Restoration Project Snow Cat

Thiokol Spryte 1200C 

Januray 2003 through April 2003



This past season the board Members decided that we need more reliable snow cats for transporting our guest to the Chalets.
























The result of hard work - an all new restored Thiokol Spryte 1200 nicknamed “Goat”                  Before restoration Old and Beat-Up   


In order to improve reliability for transportation we studied various alternatives and investigated the possibilities. This preliminary work was done primarily by Richard Barry and Robert Rickenbach.


Factory new Snow Cats of the same style as our Thiokol Spryte 1200 would typically cost anywhere from 65,000 to 100,000. Robert Rickenbach attended a Snow Cat exhibition in Auburn California and once more confirmed that the above prices are definitely proper for a new snow cat. It became also clear that our use of the snow cat is classified as “Light Duty”.  That means we do not drive the machine for an extended period of time such as driving it all night for slope grooming. We also do not use it for snow plowing.


The board gave Robert Rickenbach a budget of 10,000 to rebuild the existing snow cat. Richard Barry determined that the older more used cat should be number one for restoration.


Goals were defined to make the cat mechanically reliable and spruce it up inside and out to make it presentable again. It was fully agreed that cosmetics was secondary, with mechanical reliability being priority.


Robert Rickenbach contracted with Kurt Hauser from Road Bear Intl. a builder of  Campers and RV’s in Agoura Hills for the restoration project. Road Bear agreed to rent the space and provide their mechanics and labor at cost if Robert Rickenbach would help locating parts and oversee the project. Deal!


On the weekend of January 5th we rented a trailer and retrieved the snow cat in Mammoth. The tracks needed to be removed since they are in good condition, we left them in Mammoth.


Transporting the old beat up cat from Mammoth to Agoura Hills. Although the exterior suggests it, at that time we did not know how sad a condition that unit was in.



Over the next three weeks we removed and bisected everything in order to determine what we have, what works and what needed to be replaced. We did know that the engine probably needed to be rebuilt because it had a “knock” and we certainly budgeted for that. That proved to be case. It turns out that everything we touched needed work one way or the other. Before we go into detailed description of what was broken and needed to be repaired and/or replaced I like to describe how this snow cat is constructed.







The base of the cat consists of a strong steel frame constructed out of  3 inch square tubular steel. This frame sits atop 5 trailer type axels with the axels attached by screws to the frame. The axels are filled with rubber into which the suspension arms for each wheel engages.  Welded on top of the steel frame Over the entire length of the frame are two U beams, which hold the Drivers cabin and the rear bridge and passenger cabin. In the front and in between the two U-beams is the engine mounted with an automatic transmission attached to it. A drive shaft powers the differential steering gear that sits in the rear of the vehicle.  The steering of the vehicle is simply accomplished by breaking one side of the differential gear slowing down that side of the track resulting in a turn. Alltogether the entire vehicle is constructed logically. I was able to locate an original datasheet from Thiokol and in that brochure they say that the vehicle was built using standard parts for indefinite maintenance.




We knew that a lot of things would have to be fixed, replaced, repaired and repainted.


First we removed the drivers cabin and cleaned out a tremendous amount of trash left by many generations of managers. The drivers seat was a rusted metal frame and foam. No passenger seat. On the passenger side the bottom was held by a rubber cord. The battery was dangling around loose. Electrical wires were frayed and only a few wires were left just enough to keep the engine going.


The drivers cabin was in very sad shape. The front and sides were totally banged and dented. So many parts of the front had to be redone. We used 0.092 inch aluminum, double the original thickness. Both doors needed to be redone. The old aluminum needed to be taken off the frame and replaced with new thicker aluminum.


Before reapplying the new aluminum skin the frames were stripped and primed to avoid electrolysis. New skin was applied to both doors, the front and top ledge of the upper cabin. The corners were severely dented and so needed to be reformed. Numerous holes needed to be patched before the new paint could be applied. 







We removed the engine, a Ford 300 CID 6 cylinder, and the automatic transmission then we determined that indeed the engine had a broken main bearing and immediately sent it in for a rebuild. The rebuilder called and stated that the engine block was already at its maximum and we needed a new block. In clear text the engine was at least already rebuilt twice. A new engine block means plus $100 for the rebuild. All ancillary parts water pump, oil-pump, alternator, starter are new or rebuilt parts. The radiator was beyond repair and needed to be replaced.














The differential gear is the one thing special on the snow cat. We removed the entire gear and axels and replaced bearings, gaskets and the steering bands. We also found that the slave cylinders were corroded. The company who originally built them would only make new cylinders if ordered a 100 pieces of them!! I found a machine shop in Idaho who custom makes those cylinders for $210 a piece. We had to buy those, see picture to the left.. One of the steering bands was broken, that explains why the cat was almost impossible to steer? I suppose that, since we operate these units light duty we got just enough braking action so that it was maneuverable. The brake drums are well worn but not enough to justify that they be replaced. We can get many years of service out of them with proper care such as annual oil change and checking the steering liners.

New bearings, liners, gaskets, repaired one broken brake band and readjusted the gear.






New stainless Steel Break Cylinder











The electrical system was essentially non existent. All the wires were old brittle and frayed. Evidence of electrical fire was there too, because we pulled out a burnt cable bundle. The instrument panel was repopulated with new instruments and the entire cabling is all new. The only two instrument that seemed to be useable was the fuel gauge but the sender unit in the fuel tank was burnt out and needed to be replaced. Since the fuel level sender comes with the gauge we decided to replace it all. We serviced the hour meter and reset it to 000.0 hours. During electrical tests however we run up approx. 22 hours on it. New instruments are:


        • Tachometer
        • Fuel Gauge
        • Tachometer
        • Water Temperature
        • Differential Oil Temperature
        • Oil Pressure
        • Hour Meter (Refurbished)
        • Voltmeter
        • Safety Oil Pressure switch.


We rebuilt the cable harness in such a way that it is all contained in one protective tubing and actually can be pulled out if necessary. The instrument panel can now be disconnected and removed for easier repair. In the lower left hand side you can see the two connectors that are used to disconnect the instrument panel.

The reason for this was that we could build all the electrical harness outside the unit, test it and then after the engine was installed we lay the harness into place. It will also help for maintenance later on. An electrical schematic diagram is now also available.









In the rear of the engine compartment we manufactured a panel with the starter and auxiliary relay.

The picture shows the starter relay at the lower left and the auxiliary circuits relay is on the upper left. Two fuses located between the two relays protect the wiring from burn-up in case of a short circuit.  The voltage regulator is also located on that panel. This picture does not show the terminal stripe that is used to connect the wires feeding the back of the vehicle. On this terminal strip, the rear passenger lights, differential temperature sensor etc. are conveniently situated for disconnection in case of service.








We also wired a 110V power line from the outside of the passenger cabin side to the engine panel and permanently put in a small 12V trickle charger. When the cat is parked then it should be plugged in so that the battery is always freshly charged. The oil/block heater is also connected to that same circuit so the engine stays warm in cold weather. Provided it is plugged in. 








We serviced all other electrical equipment. One windshield wiper motor was missing completely and the other was broken. We replaced both wipers with two new marine type windshield motors and wipers. One headlight bezel was broken and we decided to replace it. The overhead cabin lights were replaced with new brighter ones.




The right rear passenger cabin floor was bent, apparently from a roll-over and we needed to heat the steel pull it up and fix it in place with heavy screws.


Inside the passenger cabin we took out everything including  the gas tank and the seats. The seats were re-upholstered using a high quality masonite and new foam padding.  The seat frame was rusted and bent so we also had to strip, straighten and repaint these frames.


The Plexiglas windows (the ones that were not missing) were badly scratched, but we elected to simply repolish them as we figured they would get scratched again and new windows would add quite a bit to the cost. The rear doors were dented and broken so the aluminum skin was removed and replaced with new thicker 0.092 inch aluminum skin. The right corner of the cabin was missing and needed to be replaced.


The roof trim in the rear was torn and also needed to be replaced.












The finished passenger cabin offers space for up to eight persons. The heavy duty rubber floor and the gravel guard paint job provide excellent sound absorption. It’s really quite in that cabin now.

Two bright dome lights provide ample light during loading and unloading.











The gas tank up front in the cabin is enclosed and atop we added a convenient shelf for baggage etc.

For safety we added an anti slip stripe to the edge of the cabin.



The picture to right shows the passenger cabin with the seats up for larger cargo hauling.  .








As door stops we added oil damped door springs to each rear door. They serve to hold the doors open during loading and unloading especially in windy condition. Such door stops will also prevent the door from flapping if driven with open doors and thus protect the hinges.










The rear stair step for passenger entry was badly deformed and bent, apparently from backing into a tree. The lower step needed to be remanufactured and the upper stair was put back in shape then the entire thing was welded back together. To prevent it from rusting again we sent it in for a Hot Dip Galvanizing surface treatment.












The biggest surprise to us was that the undercarriage steel frame which was totally torn, ripped and bent in many places. I am not talking about sheet metal, I am talking about quarter inch steel that was broken twisted and torn. There is evidence of a lot of  less-than professional welding jobs. About the worst repair that was made is in the front where the U-beams were torn and at some point they were reinforced with angle iron. Problem is that on one side the angle iron was welded under the U-beam while on the other side the angle iron was welded on top of the u-beam. The result is that the cabin sits angled on the chassis. Unfortunately this botched repair can not be undone, at least not at a reasonable cost.  So even in the future the cabin will be slightly cocked but likely will only be noticeable to people who know. After two and a half days of welding work the thing is now structurally sound again. Richard Barry believes that this snow cat was once used for snow plowing and that would explain the abuse to the frame. Upon completion of the welding the entire frame and undercarriage was sanded, cleaned and then repainted. At one point the cat must have been driven with loose tracks because we could see that the steel frame and axles showed a lot of wear to a point were permanent damage could occur. We   welded angle brackets on top of these areas to protect from further such erosion.


There are five rolling axels and one drive axel. That makes for 10 wheels and two drive sprockets. The two front wheels are solid filled rubber tires because they have to bear a higher load. The tires were split and cracked and so needed to be redone. The drive sprockets needed to be redone and new sprockets were molded on using polyurethane. The other eight wheels have regular pneumatic tires and looked rather good. They must have been replaced not too long ago. Of course we use them as they are except that we had to replace the bearing on all the wheels.









The entire snow cat is now repainted. The engine compartment is painted in grey, the undercarriage in black and the body is a pleasant radiant rebel red. The paint is high quality aviation grade and should not fade in UV rich sunlight. Before painting could start we needed to strip and clean all the surfaces. Again the body was very dented in many places we found holes and deep gouges. Aluminum surfaces were washed with an acid solution and then alodyned for surface protection. Scratches and gouges were spackled and sanded over as good as possible. The process of the surface restoration took many hours, with the end result we feel it is worth it.


The picture to the left shows Tom applying the final coat of Rebel red.


















Other parts that needed to be remanufactured were the engine cover. This cover was made from aluminum. It is simple to remove and attaches with spring latches. On top of that cover a frame and anti slip matte provides a convenient place to store while making the rounds to the Chalets.










One headlight Bezel needed to be replaced.

The spot light was taken apart and serviced.

New Rear-View mirrors were fitted.

We added the Mammoth Mountain Chalet Logo and stripes for a snazzier look.







In the following is a list of  major parts replaced or overhauled:




Front Tires

New Tire and refilled


Wheel Bearings

10 new wheel bearings were replaced repacked and re-greased.


Hub caps

Hub caps were cleaned and repainted in yellow



Stripped and molded new Sprockets in Polyurethane



Welded, sanded and painted black



Weld protection on top, sanded and painted black



Welded, reinforced sanded painted red


Passenger Cabin

Benches new upholstered, frames  stripped  and painted.

Legs replaced with  suspension chains.

Removed and polished windows

Two new windows up front toward driver cabin.

Rear Doors, Removed skin replaced primed painted

Floor rubber mat

Replaced Right Corner

Replaced roof drip edge

Inserted ¾ inch rubber floormatting

Built gasoline tank enclosure.

Replaced missing gasoline tank cap.

Added two interior lights and rewired to panel.

High Performance Door Stops



Drivers Cabin

Replaced doors

Replaced front

Straightened out dents

New engine cover

New seats (used)

Rebuilt seat base.

Replaced floor panel

Repaired cabin heater.

Overhauled cabin heater core.

New Battery and Battery Holder

New Mirrors

Repaired Door Locks

Painted inside with Gravel Guard

Added industrial high strength floor mat

Stripped and repainted steering handles and master cylinders.

Overhauled master cylinders.

Fabricated new aluminum engine covers.

Refitted engine covers on each side.

Rebuilt Handbrake holder because it would not fit with the new seats.



Rebuilt Engine (longblock)

New Starter

New Flywheel

New Alternator

New Waterpump

New Oil Pump

New Distributor

New Ignition Cables

Cleaned existing Carburator

New Airfilter

Fixed Accelerator linkage

New radiator

New Choke Cable



Automatic Transmission


New Shifter Cable

Fixed and straightened transmission oil cooler.


Differential Transmission

Removed Transmission

1 Steering Band replaced complete

1 Steering Band relined

2 new slave cylinders

Replaced Bearings”

Replaced gaskets

New shock-mounts

Added missing temperature sensor

Added 6 Gallon of Tractor Oil

New Brake Cable for Stand Break



Repaired holes and tears in instrument panel and repainted gray.

New Tachometer

New Voltmeter

New Water Temperature Meter

New Oil Pressure Meter

New Differential Temperature Meter

Reworked Fuel Gauge

Reworked Hour Meter

New FuseBlock

Rewired Instrument Panel

Rewired main cable Harness

Rewired sub panel behind engine

New cabin lights

New Passenger Cabin Light

Reworked existing headlights

One new headlight bezel

Two new wiper motors and wiper blades

Repaired spot light

Generated electrical schematic



Replaced aluminum skin Driver cabin front and top front.

Plugged numerous wholes

Fixed dents

Stripped paint


Painted with Rebel Red

Fixed rear entry steps and hot dip galvanized the steps.

Rear View Mirrors.








The board did authorize $ 10,000 to rebuild the snow cat. As we worked on this cat it became evident that really nothing was working and every screw needed to be touched and every part required some work. The entire project cost now nearly $18,000. This is a major cost overrun but considering that this older cat was virtually ready for the junk yard and the virtually factory new condition it is in now the price is a bargain.


Kurt Hauser, President of Roadbear Intl. generously provided all the material and labor at cost. Imagine that we pay $15 for the labor where an auto repair shop charges $60 or more. We all must thank Kurt Hauser for his generosity.


In summary we got a snow cat that is like factory new for less than 18,000 dollars. It is now up to the managers to take care of  it and preserve it in that condition.





Specifically we thank Mr. Kurt Hauser of Roadbear International for his generosity in providing labor and material at cost. We thank him also for providing coffee and all the other valuable advice during the project.







Mr. Ben von Muellenen for the automotive expertise and upbeat and spirited helpfulness. Ben is still in a high from applying the grey undercoat paint!















Heinz for rebuilding  the differential and rear axel drive.


Tom Haenny our mechanic whose smile I still remember when the engine started up at the second kick. Of course we thank Tom also for the body and paint work.


Mr. Pat Foster, Wallace Idaho for building new break cylinders and relining the breakbands. Most of  all for his patience in advising us on the inner workings of the differential gear. Look him up at


Richard Barry for his moral support and organizing the paint at discount.





April 30, 2003

Robert Rickenbach

Treasurer Mammoth Mountain Chalets