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Astro van cat conversion

Snowy Rivers

Well-known member
Hi all.

My name is Snowy and I'm a retired machinist, welder, fabricator, field service engineer turned truck driver.

I played with Snowmobiles years ago and on occasion drove the clubs Thiokol groomers.

I always wanted to own a Thiokol Spryte, but never seemed to have time to gitterdone.

Well, after retiring from trucking (Local heavy haul sand and gravel ) I have bounced around and have been bored to tears.

Recently while surfing the net I ran into some info on Snow cats and some of the mods that folks have done.

I decided that at 64 yo it was now or never if I was going to have a cat now was the time.

My days running the Groomer left a permanent impression of how few creature comforts were in the Thiokol Spryte.

With the idea of comfort in mind I set out to do some snooping to see what had been done by others and what tickled my fancy.

Also there was the issue of COST $$$$$$$$$:unsure:

The project must be affordable on my retirement $$$$

I found all sorts of Cats out there that had been modified, tweaked, tricked and on and on.

I wanted LOW COST, easy to find parts and something comfortable to drive when it was finished.

Decided to go with the Spryte 1200 series, or at least in that direction.

The finished rig needs to be no more than 102" wide MAX so I can take it down the road without being over legal width.

Now for creature comforts ???????

We recently sold a GMC Safari van and purchased a Smart Car for every day stuff (real cheap to drive)

I loved the van as it had great forward visibility and was easy to get in and out of.

The Safari's are plentiful and can be had CHEAP :biggrin:

So
Next I started a search for a used cat and a Safari van.

CRAIG'S LIST :biggrin::biggrin::biggrin:

Placed some want ads and sat back to see what shakes out.

Only took a couple days and a pretty good looking 1992 Safari AWD became available.

A fellow called me and we made a super deal.

Great little van that runs out nice and a full tank of fuel for $250 (Not a misprint)

So

With the body issue taken care of the next hurdle is finding a cat.

After looking at a few used cats and the $$$$$$$$$$$$$$$$ cost for them and most were in sad shape ??????????????????

It became real obvious that buying a used cat and tossing most of the thing on the scrap pile just to get the frame and such was just a bad idea.

I decided to build a custom frame to allow the use of the GM 4.3 V6 and the 4L60 tranny.

The few cats I looked at had cracked frames, cracked axles and were just a mess.

I also decided to build my own axles and instead of using the Torsion rubber device on the trailing arms, to build simple articulating trailing arms and add a small air bag to each one with positive up and down stops
.

This set up will alleviate the twisting on the axle and frame and the tendency to break things.

My search has turned to finding a rear diffy (An OC12 or a C4)

We shall see what shakes out.

I am no stranger to gear boxes so rebuilding the box is all in a days work.

I am looking for a good used diffy now.

With the find of the diffy the rest can take shape readily.

The plan is to mount the Safari body on a set of parallel rails on the main frame that will allow it to roll rearward far enough to fully access the engine for service/repair that would otherwise be a real pain through the hood or dog house access.

An access panel in the rear floor area of the body will allow access to the diffy for service of the steering cylinders and ?????


The plan is coming together slowly, but we are moving ahead.

The next item will be a set of the 3 foot Spryte tracks.

A rear diffy and tracks will get this beast off to the rodeo.

Looking forward to this build.

Gonna be a slow go me thinks.

I will be in and out and add what I can as it happens.

Snowy
 

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Re: An introduction/hello and my project.

Hi Snowy and welcome. Sounds like an ambitious project with some good ideas. You might look around for a 2100 Thiokol for the rear diff as those can be found fairly cheep. It would require narrowing the axels but you would get a hydraulic power assist too,
A spryte would be best if it had a good diff and tracks as those are going to be the most expensive pieces of your project no matter how much fab work you do.
 
Re: An introduction/hello and my project.

buy an all wheel drive van and bolt on a set of mattracks----ive put tracks on a lot of stuff ----ive talked about a van on tracks ----buy the van /buy the tracks/ and a set of wheel adapters----one day in the shop and hit the trails
 

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Snowtrac Nome

member formerly known as dds
GOLD Site Supporter
Re: An introduction/hello and my project.

I might could help you on tracks and diff I know of a good 0c 12 and a set of tracks with crappy rubber from a burned out sprite. I talked with the owner once in the past about salvage he was kind of wishy washy about it. I could try again this summer if you wish
 

Snowy Rivers

Well-known member
Re: An introduction/hello and my project.

Welder

The mattracks are nice, but $$$$$$$$$$$$$$$$$$$$$$$$$$

My project is a low budget one.

The big tracks of the thiokol are far more appealing to me.

The rig will not be used other than on my acreage in good weather and on the roads in Snow times to get to the store.

I like the little yellow rig.
 

Snowy Rivers

Well-known member
Re: An introduction/hello and my project.

36 inches is the magic number

I want 3 foot tracks on the beast

I am interested in the gear box/axle and whats left of the tracks.

Thanks
 

PJL

Well-known member
Re: An introduction/hello and my project.

IMG_1617.jpg

IMG_1618.jpg

Sorta like this but nicer? This one was spotted last winter just off I-90 east of Snoqualmie Pass.
 

nikos

Active member
Re: An introduction/hello and my project.

PJL

Sorta like this but nicer? This one was spotted last winter just off I-90 east of Snoqualmie Pass.
 

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Snowy Rivers

Well-known member
Re: An introduction/hello and my project.

Cool pix.
Thank you for posting.

I am going to use the entire Safari body from bumper to bumper

The mods will be to remove the front sub frame and rear springs/axles ect.

Fab up a new frame similar to the Spryte's factory frame, a tad stouter.

The Safari body will roll onto a pair of rails on the "cat frame" and fasten down for operation with the ability to roll back enough to gain access to the engine for service.
 

Snowy Rivers

Well-known member
Re: An introduction/hello and my project.

A question

Does anyone know the axle rating on the individual axles of the Spryte 1200 series.

Thanks
 

PJL

Well-known member
Re: An introduction/hello and my project.

The shop manual which can be downloaded here says "Trailing arm type, load rating 2400 ca lbs".
 

Snowtrac Nome

member formerly known as dds
GOLD Site Supporter
Re: An introduction/hello and my project.

if you are using torsion axles use cast rubber axkes like sw trailer has don't use the press together ones loke northern hydraulics sells
 

Snowy Rivers

Well-known member
Re: An introduction/hello and my project.

I have been looking at Flexiride individual (Half axles) and building the frame with a cross member instead of a bolt in axle.

I can beef up the area that the Flexiride unit bolts on with a weld on doubler plate and bolt on the axle units.

The Flexiride units can be indexed 6 degrees at a time on the spline shaft.

Was going to use the 3500# unit on the forward axles and the 2000# units on 2 through 5

The front end can take a good whallop when dropping off a berm, plus the engine and such are over the front axle as well.

Thanks for the info.
 

Snowy Rivers

Well-known member
Re: An introduction/hello and my project.

My main concern is locating the OC12 C/L and the bogie spindle C/L by the original design, as well as setting the longitudinal locations by the print.

The rest of the frame, cross members and goodies can be modified to suit the need.

I want to fit the GM 4.3 V6 with the 4L60 tranny and the V6 is a tad wider than the old Ford I6, but there should be enough room.

May have to widen the tunnel a tad, but we shall see.
 
Re: An introduction/hello and my project.

You can buy new torsion axels and order them to you specific width. Trailer wheels and tires will probably be strong enough for your needs but by the time you buy all that plus the sprockets and tracks, these homemade projects start to get expensive. That is why I still think you would be money ahead to buy a Spryte/2100/Skidozer with a blown motor. There is a complete 2100 here in Alaska(which I understand in not feasible) for $3500. There was a Spryte project not to long ago in the states for about the same amount. It will be very hard to get all the undercarriage goodies for less.
 

Snowy Rivers

Well-known member
Re: An introduction/hello and my project.

Alaska

Definitely a possibility on the 2100

I have snooped up a couple cats so far, with one being a badly wrecked Spryte 1200 series and a 2100.

Both were pretty sad and still the $$$$$$$$$ were way too much for what I would actually get from them when I get them torn down.


I really need a fairly good set of 3 foot Spryte tracks and the Diffy.

I been sitting here in the cold weather at my drawing table getting some basics sketched up on the frame and undercarriage, with the needs for the mods to get things to integrate with the Safari body the actual usable list of parts from an existing machine is slim at best.

Steel box tube to build the frame is relatively cheap (Used/surplus steel yard close by)

For $1000 I can get a real jump on things and not have a pile of debris to haul off to the scrap yard.

I have time to snoop and be choosy at this point.

I have lots of feelers out there too.

One thing to keep in mind.... So far I have a great body, engine and tranny for only $250 out of pocket.

I have a line on a pile of trailer wheels and tires and we are negotiating on them.

I love "wheelin and dealin" and we live in a location that has lots of goodies laying about.
Crags list always seems to produce whats needed.
I am willing to travel some distance, but living close to Portland Ore, Seattle to the North and several metro areas to the south we have a good area to go "picking" in.

Last year my son in law wanted to do a crew cab on an Army Deuce and a half and repower with a V8 diesel.

We ended up with three 1953 M211 6x6 trucks to work with.
Sold what we don't want or need on Craigs list and came away with 1 running truck in stock trim and two others to build the crew cab custom and $0 out of pocket.

I think at last tally we were up about $200 and have all our goodies to work with.

But that's his project.
I just used my wheelin dealin know how to get what was needed to start with for Zip cost.

Oyut snooping we picked up several things we really did not need, but made $$$$$$$$$$$ on them to help offset the cost of what we did need.

We were looking for an auto tranny for the 6x6 and came across this huge Allison for CHEAP
Dragged it home and turned it in a few months for big $$$$


The Franken Cat project will likely be similar type thing.
Buy a little, sell a little, keep a little.



Snowy
 
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Re: An introduction/hello and my project.

ok--been watching and reading ---its great that you want to build a cat---the very first thing you need to do is forget the word budget----ooooooops sorry I mean affordable ---I have built lots of things from the ground up--its very costly buying all the parts and pieces ---u state that you want to build frame up----it is a real pain in the ass fitting this and clearing that if you know what I mean---just to make it steer u will need to build frame add the rear end and set body to figure out where stuff goes and fits than pull body and fit motor set body fit all that crap including fuel tank in the frame somewhere near the drive shaft and than shoe horn a ex. system in there with a cat. and 02 sensor because your running tbi-----and btw trailer tires will work till you go for your first ride and a track guide takes out a side wall------just sayin ---lol----o ya did you see the track van for 12,500 that's a good deal----here is a small scale of what your building and it was tough clearing and hiding all internal workings and this is hydroststic which saved me room ----------and always remember---your tracks stop on the bottom
 

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Snowy Rivers

Well-known member
Re: An introduction/hello and my project.

Cool little "cooler kitty"

No TBI
Swap to carb intake and standard HEI ignition.
No cat can, just simple stuff.
Exhaust will likely be split and run down each side ????

Safari fuel tank is in a handy spot on the LH side.
Swap the high pressure pump for a non pump sender and inlet and run a simple electric pump to feed the carb.

I want this thing as simple as it can get.

Two wires to run the engine... Electric choke and HEI 12v
Obviously there are other wires like temp sender, oil pressure, fuel pump and such.

Just no way am I building things that require a computer to operate.

They are the first things that quit under the worst case conditions.

I been through some interesting projects.
Bought a HMMWV "Hummer" kit car thing a few years ago.

Body kit went on a Burb frame.

GAWD WHAT A PITA.

Came out fine though.

FAR more details than the cat project as the Hummer thing required everything in the body, including wiring and creature comforts.

Things like fitting a radiator became a nightmarish abortion.
Used a 6.2 gm diesel.

The 92 Safari has a non electronic tranny too. (great thing)

Will keep the body lighting, heating/AC systems as well as the power seats, windows etc.

I just had a call on 5 sets of trailer wheels tires for cheap.

I am patient.

Budget ???? wassssat. ITS A TOY :yum:
 

Aaron Tucker

Active member
Re: An introduction/hello and my project.

the astro spryte is a 1200b with the 3ft wide track that would be a powder monster . ive only seen a couple 1200b , if i was to go spryte that would be the way I would go . and oc 12 only
 

Snowy Rivers

Well-known member
Re: An introduction/hello and my project.

Yup
THE OC12 box will handle pretty much any reasonable sized engine.

I have seen the 391 Ford V8 up front and a local fella has a 2100 with a 428 Ford in it.

My little 4.3 V6 is not gonna strain it much :biggrin:

For my purposes the V6 is plenty of power.

Likely the most SNOW use is gonna be when when get 4-12 inches of slop that gets real slick and the steep grades into the ranch here can be nearly impossible without tossing iron on the 4x4

Several 10% grades with switchbacks in them.

When we do get a real snow the switchbacks blow full of fluff and even my big 4x4 will not deal with it.

We have only 5 miles into town and can creep into the shopping center without having to traverse any main major highways.

Around here 4 inches of slick mushy snow will bring the city to a halt.

Too many young ones that never learned how to drive.

The watch too much TV with those SUV's plowing through deep drifts and they listen to all the hype about "Traction control, anti lock brakes" yada yada yada.

I hate those anti stop brake systems :sad:

I learned back in the 50's and 60's about getting around in the snow.

Don't need the stinking magic electronics to get through some snow.

As I explained to one youngster a few days ago that had managed to land in a bar ditch... "Son, when the coefficient of friction between the tires and the road is limited at best, and MA GRAVITY discovers your skinny butt, your finished, and no magic box is gonna SAVIOR BACON"

Kid gave me the deer in the headlights look. :unsure:

My Franken Cat is gonna be simplicity at its best.

Looking at installing a block heater in the V6 while its on the dirt too.

Replace all the soft plugs.
 

undy

New member
Re: An introduction/hello and my project.

I'm curious why you chose a 4x4 version of the van? Seems like it would be more straightforward to use a 2wd transmission into the OC12, if for no other reason than to save space.
 

Snowy Rivers

Well-known member
Re: An introduction/hello and my project.

Good question....

And here we go with the answer.

When I decided to do this project I placed an Ad on Craig's List for a decent Astro or Safari van.

Took about a week and I get a call from a fella and he has a clean 1992 Safari AWD and wants it GONE.

We go take a peek and its a nice rig.

We BS a bit, kick a tire or two and then get to the negotiating on the price.

He has a clear title and wants $250 cash for it.

Sweeeeeeeeeet.
Done deal.

The Tranny is no worries.
Will pop the T case off the back end of the tranny and stick it on the shelf for future ?????

The engine, subframe and tranny all come out in one chunk.

The engine cradle will be relocated to the new frame in the Franken cat.

The sub frame gets to go back into the body to support the fenders and provide a location for rollers and attaching points to allow the body to roll back far enough to fully access the engine without requiring a 6 armed spastic monkey to reach stuff.

I will freshen the 4L60 and while its apart I will swap in a longer 2x output shaft and tail housing.

Bottom line, the van was available CHEAP and runs great.

Never look a gift horse ya know :biggrin:

I just wanted a clean fairly straight body to work with.
The beast has a decent interior that is not nasty moldy yucky.

All the doors including the side slider work fine as well.

All the glass is good too.

If it had been a 2x for the price, it would have been fine as well.

The beggars and choosy thing. :biggrin:
 

Snowy Rivers

Well-known member
Re: An introduction/hello and my project.

Got a question for anyone who can answer.

On a Spryte 1200 series

What is the dimension from the center of rear most spindle (bogie, NOT THE OC12) to the center of the front axle wheel spindle ????


I have decided to use the Flexiride "Half axles" as they can be easily replaced as single units should it be needed.

Going to use 3500 lb fronts and as yet still vacillating between the 1400 and 2000 lb units on axles 2 through 5

Got the details on the two track tensioners worked out pretty well.

Decided to go with a simple slide frame similar to the original but it will be more like an H with a tube welded across the front end (Like the way some folks print and A with straight sides and a hozizontal top)

A plate welded across the unit will provide the platform to bolt the Flexiride unit to.

The main cat frame will have some added structure to allow two tubes extending forward to slide the front axle/adjuster into. (Each side)

Decided to use a small hydraulic cylinder to adjust the unit.

A simple solution of pumping the cyl full of grease to tighten the track up.

A stock off the shelf cylinder about 2" diameter ??? with appropriate length to handle the needed adjustment.

The basics are coming into a much clearer picture now.

No doubt there will be changes in things as the project gets under way, but I want a fair working drawing with some decent dimensions to work with as things get started.

Trying to get available items all sorted out and sources nailed down as well. :hammer:

Spent yesterday trying to sort out the amount of chopping that's gonna be needed to get the front sub frame of the Van massaged to the point that the entire body can be rolled onto the cat frame and slide by the engine and then lock to the frame.

Looking like the Van grill may end up as an integral part of a fixed and extended radiator guard that is separate from the body.

The engine cradle will need to be removed from the subframe as will the front cross member that the bumper attaches to.

At this time my thought is that the body will be high enough and the angine location low enough that a pair of steel tubes can be welded between the two side rails of the original subframe aft of the engine to replace the structural rigidity lost when the engine cradle and front cross member are removed.

Once the body is in the normal operating location the front subframe and the area of the original rear spring hangers will bolt to the cat frame and the body will share structural integrity all the way.

At present the plan is to fab up a pair of tube sub assemblies that will fasten to the bodies existing rear spring hangers and these along with the front subframe will align on a level plane to allow 6 or 8 rollers to support the entire body on the cat frame with 4 anchor point that bolt the entire assembly together.

Farther out in the design parameters will be allowances for easy roll back of the body without interfering with electrical or steering brake control connections. (READ THIS AS LONG PRESSURE HOSES AND ELECTRICAL CABLES THAT CAN MOVE AS THE BODY IS ROLLED BACK FOR SERVICE)

The plan is starting to look pretty sound, butttttttttt, as is normal with any design, there is usually a fly in the ointment somewhere that will pop up.


Am thinking on retaining the Vans fuel tank in it's factory location and just swapping the high pressure in tank pump out and installing a simple pickup with an external (Read this as easily accessed) electric fuel pump.

The factory tank is located on the drivers side aft of the drivers seat and is tucked up nicely under the body. (Simple and paid for)

The fuel tank issue will possibly evolve/morph into ?????

Simple is the key.

Considering an access hole in the aft deck right above the OC12 to allow any service of the unit to be done easily. (Steering cylinders, ????)

Beyond these ideas things start getting pretty gray :unsure:
 

Snowy Rivers

Well-known member
Re: An introduction/hello and my project.

Thanks

Already got those great manuals.

So far I have not found the info needed.

Likely the numbers I am looking for are strictly engineering items and do not apply to regular maintenance.

In general a mechanic or maintenance individual would care less about the distance between the front and rear axles.

Since I am fabricating a custom frame it is imperative to get those dimensions correct so a set of standard tracks will fit the machine.

Again... Thank you for the reference info. :biggrin:
 

undy

New member
Re: An introduction/hello and my project.

Snowy,

From having fabricated a tracked wheelchair using a given (power-buggy) track once, I'm not sure whether the dimension you are seeking is important.

If you use the axle center-to-center dimensions from a given snowcat, they will only work as intended if you also use similar diameter bogey wheels. (I'm unsure what you're using for wheels.)

I used a common track, with a given pitch (distance between sprocket teeth, essentially). I designed sprockets to fit that track. I spaced the bogeys such that there was clearance between each plus room for debris, etc. I ensured that the track adjustment distance (front bogey to 2nd bogey) exceeded 1/2 of the pitch - in fact is was probably twice the pitch. But those tracks could not be separated anywhere to ease installation, so they needed the extra adjustment distance.

Space your bogey axles so as to accommodate whatever bogey wheels you are using. Give enough adjustment room between the front two bogeys. You can always shorten or lengthen the tracks depending on the length of the cat and the length of the tracks, just so long as the pitch is right at the drive sprocket.

Maybe others with more wisdom than I will chime in to say I'm wrong. (I'm the first to admit that my advice is worth what you paid for it.) But that's what my common sense tells me.
 

Snowy Rivers

Well-known member
Re: An introduction/hello and my project.

Undy

10-4

I want to stick with a diffy from a Thiokol 1200 series and the same 3 foot tracks.

My aim is to duplicate the frame "with a custom touch" to accommodate the Safari body and then allow stock tracks to fit.

5.30 x 12 bogie tires
 
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