Astro van cat conversion

Snowy Rivers

Well-known member
I would agree.....
The castings are thinner than the old "Bricks" used in decades past.

Now here is a question I am hearing multiple answers for...

HEAD BOLTS
The bolts that came out of the Vortec are marked with the standard 6 marks in the head indicating a grade 8 bolt.

GM says that the bolts are to be torqued to 20 ft lb and then using a torque angle meter tightened to so many degrees more
55" on the small bolts, 65" on the medium bolts and 75" degrees on the long ones.

The net is full of statements on these bolts being TORQUE TO YIELD "TTY"
GM TECH bulletin says the bolts may be reused as long as they are in good condition and the threads are not damaged or the bolts stretched....

The L31 VORTEC head bolts look just like the head bolts that small block Chevies have used for many decades.

We used to torque to 20 lbs on pass 1........45 lbs on pass 2 and then finish with 65 lbs on pass 3

After reading the writeup on the reason for using the torque angle meter .....it makes sense that tightening a specified amount more past the 20 lb pass 1 will put the tension where the engineers think they want it......Every threaded hole is different and torque readings can vary from what the actual tension needed is in the real world.

I am quite familiar with TTY bolts and have replaced them in several engines that use them....

From what I can glean from all the articles on the subject....There seems to be a lot of folks that believe that just because the mfg says to use a Torque angle meter that the bolts are TTY.

This makes a simple job far tougher than it needs to be......
 

Snowy Rivers

Well-known member
Weather was good today (At least for working)
More Fab and machine work on the RH Axle adjuster assembly.

Getting most of the major stuff done on the RH unit.
Tomorrow it's time to machine the actual threaded adjuster unit......

Things are pretty much up to the same level as the LH unit is.

With the rain and crap weather I have had stuff on and off to keep the new bright metal from rusting.

Some pics
 

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Snowy Rivers

Well-known member
More work today.

Dug the chunk of brass tube outta the rig....Got it in the saw....Takes about 20 minutes to make a nice clean cut.....minimal taper.
Part is within .010"

Toss in the lathe, trim to .500" thick...bore the inside to 2.002"
The brass washers go between all the thrust surfaces.

The black round hub is keyed and was originally designed to weld a sprocket to.
The air bag arm will get machined and welded to the hub.
The arm is 2" x 4" x 1/4" Rectangle tube.......
The RED urethane bumper is a Jeep Wrangler suspension bumper......

The Bag arm lays against the bumper when the spindle (Front bogie) is all the way in the down position (Axle off the ground)

Air bag kit ordered this morning.....
Can't go much farther without the bag and brackets .......

The pics for the most part are self explanatory...

The actual axle shaft is in there this time through.

The spindle/casting needs to be heated up hotter than hell and damnation and slipped onto the shaft and then welded.

For now....having that heavy chunk off the axle makes life a tad easier........

The two center brass washers are being held apart by a piece of Exhaust tube.....(I may machine a heavier tube to go in this spot....but the exhaust tube will actually do fine......Just keeps the two adjuster units apart.........

Not shown well...there are marks on the inner slider tube showing where two 1/2" lock bolts will go in to keep the inner adjuster from rattling up and down... (Two nuts weld onto the tube and the bolts thread in to place pressure on the adjuster......

With any luck this will keep the assembly from rattling around....
 

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Snowy Rivers

Well-known member
The air bag kit should be here tomorrow.....If ya believe the tracking #####
Picked up the material for the air bag arms today.

2" x 4" x 3/16" tube.
The tube lays parallel to the cat tub and becomes part of the hub assembly that slides onto the axle shaft.

The hub (Black part just outside the tub on the inner end of the axle shaft)..... is keyed to the shaft with a 1/2'" steel key and has a 3/8" hole drilled through the hub and shaft.....A grade 8 bolt goes through the entire assembly to keep the entire assembly together.

One little fly in the ointment.......While looking at the assembly I discovered that getting things all together on the cat were not going to be possible because of the bag arm and the captured key...

Once the final fab work is finished the entire assembly will need to come off the cat (The inner and outer sliders....the inner bolt on assembly stays on the cat)

The assembly will need to be put together on the floor in it's entirety and then slipped into the frame.....the hydraulic adjuster and the mechanical inner adjuster attached at this point.

The air bag and it's brackets can go on after the other equipment is on the frame.
The one piccy shows a black area near the rear of the bag arm.

There will be a slot in the tube.....BOTH SIDES The lower air bag perch will be able to slide fore and aft to adjust the bags location and keep it aligned to a vertical position after the tracks are tightened up...

I want the air bag parts here to get a good feel for position before we go farther with the build.......

The yellow chocolate jug is close to the air bags size.....Looks good.
The lower bag perch that comes with the kit will need some modifications....OH YEAH.....

I am thinking that a sheet metal shield to protect the bag may well be in order.

The bag should be plenty far away from the bag ....BUTTTTTTTTTTTTTTTTTTTTTTTTTTT.....????
 

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Snowy Rivers

Well-known member
Got a wild hair this morning to get the spindle housing on the axle and welded up.
Polished the shaft , added some never seaze on the shaft...Heated the spindle housing up hotter than Hell and damnation .....Figured the unit would slide right on.....Yeah right.

About half way and stuck...
Tried a 5 pound club...nope..no joy.

I let the sucker cool off and came back after breakfast.....

Stuff the axle in the 20 ton press and went after it......I got it within 1/8" of the outer end of the hole.....nope, not going to budge.

Dragged the beast over to the truck shop and we put it in their 50 ton press....Damned well know it moved....

Got the shaft about 1/4" past the end of the casting and called it good......

Lined the hub up with the other axles and then machined a heavy brass spacer from the same material the other thrust washers were made of to keep the assembly where it needs to be......

Some pics

Wet weather coming tomorrow....No outside work for a few days me things.

The air bag kit showed up at the post office...Gotta stop and get it tomorrow..
 

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