Astro van cat conversion


Well-known member
I always wondered how that grease filled adjuster works. Mine is the same setup.

Snowy Rivers

Well-known member
Oh yeah.
There is no sure fire solution on a machine of this age and complexity...The closest thing would be to do a "Blueprint" ground up restoration.

Sadly a lot of parts are simply not available any longer and must be made in-house....or farmed out.
I will have to say this.....Looking at the time line.....far more time is spent at the Drawing board and sitting at the cat measuring and working out solutions to problems than the actual time spent wrenching on things.

Then of course there are the change orders...."Build #1.xxxxxxxxxxxxxxxxxxxxxxxxx " :lmao:
Some ideas are just simply wonderful on the drawing board.....but in the real world either cost too much or run into snags......OOOOPS something is in the way and will not fit.

The real world facts of being your own Engineer, fabricator, machinist, electrician, hydraulics tech oh and BEAN COUNTER

Then there is the little thing......called tooling..,...drill jigs, setup fixtures and that special cutter for the mill/lathe that you don't have and this list goes on.

But progress in any positive way is always satisfying......

Then nearly a day spent running across town to get the parts needed to repair a particular item you are working on.

Being close to a major metro area does help......
The internet is a godsend...

Still took nearly a month to get all the bearings for the OC12 resto.
But the cost savings was in the many many hundreds of $$$$$$
Actually more than that....One bearing listed at $700 and the ebay search landed one at my door for only $20.....but had to come from across the continent....others came from Europe....

Keep the faith bro......
Your cat will live again.

Snowy Rivers

Well-known member
I always wondered how that grease filled adjuster works. Mine is the same setup.
They are the "CATTSASS"
Many big dozers use a similar setup....
The ones on these rigs are pretty simple.

The one negative thing is the lack of any seal on the rod end to keep water and crap out.
The design obviously worked OK....But the nasty rusty mess in the one cylinder leaves me wondering about the possibility of adding a seal on the front end to keep water and crud out..

I think there is enough room just ahead of the snap ring to install a thin lip seal.
I am going to explore this idea .

Butttttttttttt.....these cats lived a long long life as they were mfg by the factory. could always go to a stainless steel tube......Yeah...there goes the budget.

There was a post back a few years where a member was looking for seals for his cat.

These manufacturers used as much "off the shelf" stuff as they could in the build process and therefore this does make getting parts far easier even at this late date.
Another one of those "Go search it out things"

Snowy Rivers

Well-known member
A decent amount of work done today.....depending on ones view point.
Got the new cylinder done for the RH side..

I do not have a snap ring groove cutting tool....Decided to drill four 3/16" holes in the end of the cylinder and will install four 1/2" long roll pins.
This will work fine as a stop to prevent the piston from popping out of the cylinder.
The left hand adjuster slider was in sad shape.

Took some serious time at the hydraulic press, then to the big vice and some whupass with the 10 pound club to get the mounting ears back to where they should be....SORT OF

Then a trip to the mill to clean up a buttload of the extra weld that had been poured on....

A couple cracks found....way too windy to weld outside....Tomorrow it should be a lot less windy.

A couple pix of the new cylinder.

Next the new axle pivot mounting plates have to be cut, fit and machined to fit into the original slider assemblies.
Then the inner pivot tube, slider and such has to go in.

***ADDING A SECOND PIVOT POINT FOR THE AXLE and a second adjuster to keep the setup parallel to the front frame......


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Snowy Rivers

Well-known member
Got serious about the adjust brackets.
Decided to bolt the two units together and then toss them in the mill and clean out the area where the axle fits.
These were just as burned out with the torch.....absolutely nasty.

Got the pair all evened up and matched well.

Then stuffed the boring head in and opened up the slot just enough to allow the new axle pivot tubes to fit in.
Next a pair of plates need to be machined to bolt into the slider brackets and ultimately weld in.
A second plate will weld on the inside of the slider.

A second tube similar to the one in the piccy will fit in a second bracket to hold the inside end of the axle.

Parts are looking much nicer than a few days ago...

Picked up the short roll pins for retaining the piston on the one new Adjuster cylinder.
The pins tap in nice and will be fine to make sure the piston can't pop out...


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Snowy Rivers

Well-known member
Great weather is holding and good things are happening.
Best part is that the plan on paper is actually coming together in real time....

Picked up some 3/8" x 4" flat bar to machine into the new axle tube bracket "Additions" to the original slider breackets

Got one part fit into the LH slider and the bolt holes drilled to fasten it in place..

Located the bore for the pivot tube and bored the hole.

The function of the bolts will be pretty much a moot point after the assembly is finished.....the new plates will get welded in place once everything is finally located where they need to be.

The pics show the longer outer tube slipped through the slider bracket and extending in towards the tub.
The inner shorter tube will fit onto the NEW inner slider (Yet to be fabricated)
The axle shaft will slide through the UHMW bushings that fit in the tubes.

Ordered a pair of 2" bore keyed weld hubs to go onto the inner end of the axle shaft and then the reaction arm will weld to the hub.
Hub slips over a captive key in the shaft....and gets a bolt with a pilot end on it that retains the hub from sliding off the shaft.

The yellow round container sort of represents the air bag....size and such are similar.....

The white chalk mark on the frame is the approx inner edge of the track......

We may well be revisiting the idea of using the Timbren rubber these will take up less space than the air bag....and will be less vulnerable than the air bag as well.

We are moving ahead.....

Once we get the basics nailed down the other side will be a snap.

I needed something to hold the inner tube in its approximate location to mock it up....The box of CAT LITTER seemed appropriate... :lmao:


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Snowy Rivers

Well-known member
Gotta make a setup fixture to align the new axle tubes so that they are level side to side....and parallel to the frame.

I don't want to weld on the pivot tubes with the UHMW inside.....
Need some readily available bushings that will fit the shaft (2" EXHAUST TUBE IN THIS CASE FOR SET UP) 2 INCH SHAFT COLLARS WILL WORK.

Gotta head out and pick up some.

Snowy Rivers

Well-known member
Got the collars needed ....Machined them a touch to get things to fit...
Got after making some aligning fixtures to get the axle/s straight with the frame.

Grabbed some steel angle and a few other items...

Looking at the picture the cover plate behind the axle assembly has some bolts on the forward edge...

Going to bolt on a piece of steel flat bar 1/4" x 2-1/2 onto those bolts and once I get the axle set square and true I will tack weld a collar onto the steel flat bar to maintain the alignment of the axle while adding the inner bracket.....THEN TACK WELD STUFF UP.

Once its all tack welded....The assembly can come off and be finished welded......

Time consuming stuff.

I want to get the two front axles in COMPLETE ......Then once the axles are done....the cab needs to come back off to allow access into setting the drive shaft.......

The Diify can go back in soon too.

Just a few little things left to do on the diffy.....(Install the axle tubes and shafts is all....left them off for the winter to keep the beast from taking up so much room in the shop)


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Snowy Rivers

Well-known member
Stuff coming together now.

Got a bit more steel and went after setting up more fixtures to jig everything in place while I tack stuff up.
(2) angle brackets with a nut and a 1/2" x 4" long bolt welded on....(Indication point to place the axle parallel to the main frame beam.

A flat bracket with a collar on it bolted to the cats tub......this holds the axle assembly right where it needs to be until all the parts are welded up....This bracket will go away once the fab work is done.

The inner pivot tube is now ready for the inner slider tube to be mated up....(Monday we will get more steel.

I can't find any seamless square tube without buying a butt load of it.....Decided to fabricate the sleeve that the inner slider fits into...
3"x3" x 1/4" angle will work...just mate them together and weld them up to end up with the slide into portion.

Standard 2-1/2" square tube will be the same as the stock outer slider...

Need to machine the plates that support the inner bushing tube and weld them to the slider tube....

Still thinking about the adjuster on the inner slider.....likely go with a threaded rod as it will be fairly easy to get to.

The hydraulic cylinder will carry the big load and the inner adjuster will keep the pair aligned and stop the inner assembly from trying to go in and out as the axle moves.....

Adjusting the assembly will take a bit of fooling with to get it spot on....May add some reference parts to measure from to get the assembly parallel.... It will come together.......A pair of key stock chunks on both sliders that will give a reference point...

Measure and adjust things to the same dimensions on both ???????

Some pics


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Snowy Rivers

Well-known member
Well .... I do believe this plan is gonna work..

Machined the inner slide support plate and then welded up the entire outer track adjuster.

Removed the setup jig stand off bolts....

Decided to grab the actual axle assembly and get it slid into the assembly and take a peek.


The polymer bushings still need to be finished.....but the steel MOCKUP collars are fine for a quick peek see.

Got the spindle jacked up into a close proximity to where it should be.....looks great.

The 4x4 block next to the tub is about where the inner slide assembly will fit in..

I ordered up the needed square bottom U BOLTS to fasten in the inner slider assembly.

I DO NOT WANT to weld across that frame section and change it completely.

As it stands a stock set of sliders and a standard front axle could be put back into the machine....Gonna keep that option.....never want to build yourself into a corner......

Tomorrow I will get materials to build the inner slider assembly.

The keyed hubs that fit to the axle shaft are on order.....The torsion arm (Contacts the Timbren biscuit) will weld to the hub.

The arm will have a fairly wide flat bar on top to allow the track adjusters to slide in and out and the Timbren to sit where it needs to.

The arm will probably end up being 1/2" flat plate 4" wide or so with a slight elbow in it bored to fit the hub (Weld on at finial assembly to get location spot on)

Some pics


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Snowy Rivers

Well-known member
Gathered materials for the inner adjuster assembly yesterday....
I was able to get the proper size/type of square tube to fabricate the slider parts,

I have to admit....I am still undecided on the choice between the air bag and the Timbren biscuit.....

The Timbren is less vulnerable to damage.....but there is ZERO adjustment.....This worries me..
The 2500 lb air bags can be aired up until the front axle just starts to lift the cat when it is sitting static......

After doing a lot of measuring yesterday ...there is plenty of room in the area to get the 6" diameter bags fit in......
I have worried about this idea based on the bag getting damaged......but possibly a shield around the bag on the side facing the edge of the track will be a plan.
Maybe I am over thinking this a bit ???

One things for sure....the front axle on these cats gets the hell beat out of them.....
Every axle I looked at as a possible replacement was beat to rat crap.....the torsion ends were all worn out and the plastic half bushings in the casting at the tube ends were wasted.

And these are not rebuildable ......
I want to be able to quickly, easily and cheaply refurbish the front axle on the beast....

Ah yessss......and so it goes.

Snowy Rivers

Well-known member
More work on the new axles today.
Got the major parts cut and fit......
Waiting on the U bolts I ordered to fasten the inner adjusters to the frame and the second axle.
I hope they get here before the good weather goes away for a while...


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Snowy Rivers

Well-known member
Great news.
The U BOLTS I ordered for the inside slider/adjuster arrived last night sometime and I found this lovely little box on the deck by the back door........

Todays project is to get all the plates laid out and drilled and then do a temporary trial fit.....IF time permits.

Wet weather coming soon and all the new clean and unpainted materials need to be back inside so they don't rust up.....

Looks like today will be pretty decent working weather.....not nearly as warm as the past few days though.....

Glad to see those parts here....


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Snowy Rivers

Well-known member
Definitely starting to look like what I had in mind.
Got the plates all drilled, the parts located and tack welded.....

The wind was howling today....makes mig welding a bitch....tomorrow should be better....

The one piccy shows the slider with a diagonal mark on it. .....Yup...gonna cut that sucker off on a slope to match the original outside slider.

The inner slider is outside the orbit of the track....but not by a lot.

Going to slope the front of the slider and then smooth and round all edges to be sure IF THE TRACK SHOULD MANAGE TO GET OVER THAT FAR.....That it will not catch on anything and mess things up.

Removed the jigs.....Looks good me thinks.

Rain by late tomorrow.....Next will get things welded up more.....Cut the inside slider and weld in an end cover.

Then comes the air bag and brackets.


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Snowy Rivers

Well-known member
Decided to make a little Change order......
Pawing through a cabinet looking for some stuff (Unrelated to the cat project) and stumbled across some herky urethane bushings....

Hmmmmm...Urethane bushings would be sweet to support the axle shaft on the cat front axle.

Instead of the HARD UHMW.....
Urethane is used a lot in suspension bushings these days....

So I called around and found an outfit that offers STOCK LENGTH urethane tube 12" long.

I need 3" OD X 2" ID
Perfect....They have it.....About $125 for 4 pieces.

This will make the entire setup much easier.

Will not need the grease seals.....Use silicone lube on the bushings.......The brass thrust washers at the ends of the bushing tubes.

Not really much of a change.....but I think it will be better overall......

No changes to the machined parts that are already done....

And so it goes.....

The sales gal asked me...."WHAT COLOR" ????? Whaaaaaaaaaaaaaaaaaaaaat.????

RED, BLACK, SAFETY ORANGE, GREEN, BLUE, YELLOW....OMG not going to be seen anyway...... :lmao:

Snowy Rivers

Well-known member
Got all the goody out of the nice weather today.

Decided to trim up the inside adjuster assembly before I removed it. (Don't want it rusting in the rainy days that are coming up)
Got the adjuster off, laid out and ....NO WAY TO CUT THE SUCKER.....TORCH...NOOOO WAY.....Thought about tossing it in the mill..
Too much fooling around to do it in the mill.

There had been some chatter here about the HAND HELD BAND SAWS....???????????????/
Stopped off at Harbor Freight and dragged home one of their little HAND HELD SAWS.
Damn....that sucker is a sweat heart.
They had them on sale too.......

If you don't have one of these of any brand in your shop.....stop off at the Harbor and grab one.
That bad boy made quick work of the cutting needed.....and they seem pretty well made too.
I got pretty rough with the blade trying to keep things where I wanted.....worked flawless...

I need to cut a piece of 1/4" X 2" flat bar and finish closing the end of the tube.

When the other side gets done I am going to cut the pieces to match this one before welding it up....

Far easier.....


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Snowy Rivers

Well-known member
Had some decent time between rain showers....Got after building the ACTUAL adjusting mechanism for the inner track adjuster/axle support.
The little box tube with the semi circular cutout is the Adjusting nut housing.
There is a 1" steel plate that welds in the end with the cutout....the cutout is for the grease zerk to fit in.
The adjust nut gets machined from 1-1/2" hex stock and fits into the end plate.
The adjust nut assembly is held in by 2 Shoulder bolts in the outer slider tube.
A piece of 5/8" fine threaded rod gets the clevis on the front end.....Clevis slips onto a piece of flat bar that welds into the push/pull.

The nut assembly will be greasable to hopefully keep it operational...LONG TERM.
Tomorrow I will get more steel to make the rest of the parts....

The clevis is a standard class 8 truck brake part.....Easy to find...5/8" fine thread.


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Snowy Rivers

Well-known member
Yesterday turned into a nasty mess.
A buddy called up and wanted some help on his Thiokol Spryte.....
Needed to drop the tracks and get at all the wheel bearings.....(Yeah....mostly shot..rusty...)

I get to his place and the cat is in the garage..

OMG...The adjusters are the manual type and things are rusted up tight as a bulls azz in fly time.

Did not want to get the torch in there to cut things...and damage the tracks.
I had to run back here to the shop and get my air die grinder and some cut off discs.
We spent a fair bit of time getting the old crap cut off.

Got the tracks dropped loose and my buddy went to work on the bearings.

Now....WHAT TO DO with the adjusters ?????

We are considering adding the grease cylinders to the machine.
Not that much work.....

This scenario brings things to mind that my idea of using a manual adjuster on my inner front axle setup may not be at all a good plan.

To make a pair of cylinders is a snap.
My old ones make great patterns to copy.
Simply and they work great......

I will let my buddy figure out his choice.

For the moment the adjuster plans for my machine are definitely not going towards the manual threaded type device...

The mess we encountered was not worth the effort to just replace it with same.
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