A couple of things to note on this first off. I did this write up 6 or 7 years ago right after I did the H-boost conversion, so in order for me to answer questions, I will have to go out, look at the thing and think real hard. Second, any pricing that I put down is old pricing and can't be relied on. Third, I did this with the assumption that anyone doing this particular conversion had a manual/floor shift, no column shifter linkage to screw with. If you have a column shift or auto, I can't answer a question correctly. Fourth, this is to help get you going into a tech day and to help anyone who can't make it to that.

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This is a complete walk through for a hydro-boost installation on an early (66-77) Bronco with power steering. I will try to be as detailed as possible, but if anyone has questions, please feel free to ask me. I did this installation over the past couple of days and it is fresh in my mind, so I won't leave anything out. I also have the power steering unit that was originally on a 73-75 Bronco, but the same directions should be able to be used for any PS set up. I used a 1990 Chevy Astro Van as my donor vehicle. The parts I took were the hydro-boost unit, master cylinder, proportioning valve, steel lines between the master cylinder & proportioning valve, and both high pressure hoses attached to the hydro-boost unit.

Car & Misc. Parts Needed:

Astro Van Hydro-Boost Unit, 90-94 (HB)
Astro Van Master Cylinder, same years (MC)
Astro Van High Pressure Supply Hose (from PS pump)
Astro Van High Pressure HB to PS Box Hose
Astro Van Steel Lines from MC to Proportioning Valve (PV)
Astro Van Proportioning Valve (optional)
Bronco High Pressure Power Steering Hose
Stainless Steel Brake Lines, 50" (or close - 2 different sizes needed)
2-4 feet of 3/8" Power Steering Hose
Bronco MC Push Rod
3/8" Brass "T" Connection
5-10 hose clamps
3/8-16 or 3/8-24 thread by 1.5" coupler nut

*NOTE: I did not reuse the AV MC. I used it as a core and took it back for a remanufactured unit. The HB unit should still be in good shape unless your donor vehicle was damaged in the front end.

Dismantle, Prep & Installation:

You are going to need to have new high pressure hoses made up to adapt the Chevy parts to the Ford parts. Take the three high pressure hoses to a local hydraulic fitting shop and have them make you two new ones. You will need to match them up as follows. The PS pump end off the Bronco hose will attach to the single valve inlet on the HB unit (this is the port on the same side as the gold fluid reservoir is on). This is the supply line to the HB unit. The other end of the Bronco hose, the PS box end, will attach to the hose from the opposite side of the HB unit (the side with the brass nozzle/hose attachment). These are two different fittings that are on the HB unit, so do not get them mixed up or it will not work correctly. The last port on the HB unit (the brass nozzle/hose attachment) is a low pressure return line that will go back to the PS pump.

Remove the original MC, steel lines to PV, PV & front steel line to termination block on the frame. You must replace all steel lines from the PV to the MC, and I replaced the front steel line from the PV to the front termination block on the frame. This might also be a good time to replace your front brake line from the termination block to the axle.

Once all things are removed and out of the way, you will see that the original MC push rod is longer than the HB push rod. Both of these should be 3/8" rods. Mine had a difference of 1 1/4" in length. Here you will need to cut the HB push rod & the EB MC rod. I cut the HB rod as close to the pedal attachment as possible. The EB MC rod was cut about 1.5" down from the pedal attachment. I threaded both with 3/8-16 threads, but for a finer adjustment, I would recommend 3/8-24. Once you have the two push rods threaded and are able to connect them together, set your HB unit aside until ready for installation.

For this installation, the HB unit will have to be flipped upside down. On the AV, the fluid reservoir is on the passenger side of the unit and here we will be installing it exactly 180 degrees opposite with that reservoir on the driver side. Measure the base of the plunger housing (right up next to the mounting plate) on the HB unit and the original MC hole in the firewall. The firewall hole will need to be opened up to fit the HB unit. I used air & a grinding stone to open it up, which took me about 10 minutes of grinding & checking progress. At this time, knock the pressed in bolts out of the HB mounting plate, and with some card stock thickness paper, make a template of the mounting plate. Try and get this as accurate as possible to get the best possible fit. Once you have your template made, measure it against the fire wall. The HB mounting plate will overlap the dust boot on the steering column. Mark the overlap on your template and cut it out. Take this back to the HB unit and mark it and cut the mounting plate to give yourself clearance. You will lose one mounting bolt, but that is ok, you WILL NOT be putting the pressure on this unit you would be on a stock MC. Once you have the HB unit cut to clear the dust boot, put it up to the firewall & mark where to drill your holes for the bolts. Check this with your template as well to be sure. You will end up drilling three holes through the pedal assembly bracket, so this just gives you added strength. You will have to notice that there is a body/firewall seam running vertical that the HB unit will not fit over or beside. Here is where I had to do some thinking because I am running an EFI set up. I took and put 2 washers under the HB mounting bracket on that side only to give me clearance of my EFI plenum. You can notch the seam or trim the HB mounting plate, the option is yours, but I put washers under mine to clear the plenum. I then mounted the HB unit up, bolted it down and it gave me perfect clearance.

When you attach your hoses, give yourself enough clearance for the valve cover and the steering shaft. The hardest of the 3 hoses will go to the PS box. The brass fitting on the HB unit will be a return line to the PS pump. When running this line, you will have to use the brass "T" fitting to get both the PS box & HB return lines to converge. Use the 3/8" hose and cut a 5-6" hose coming off the return line on the back of the PS pump and put the "T" fitting in. This fitting should have the top of the "T" coming from the PS box & strait into the pump with the return from the HB unit coming in perpendicular to this. If you are running a fluid cooler/radiator, run your PS box to the cooler then out of the cooler and into the "T" fitting. Your last hose will be the supply line from the pump into the HB unit. If you have these hoses made as I did, you should have roughly 8-12" of flexible rubber or braided hose between the end fittings.

This is an "option" you can do, although I didn't do it. You can swap out the old PV for the AV unit. Again, I didn't do it, but I did use some of the steel line fittings. Temporarily attach the new MC to the HB unit. Cut the fittings off of the old steel lines and save the MC fittings. Cut one flair off the new lines and replace one of the new fittings with the fitting for the AV MC and re-flair the line. You will now need to bend the new steel lines (with the AV MC fittings) down to the PV. Be sure to put a couple of coils into the lines for possible flexing. Attach the brake lines to the PV. You now want to bench bleed the new MC. Once you have it bled, mount it to the HB unit and attach the steel brake lines.

Attach the coupling nut to the HB push rod and EB push rod. Hook the brake up just like it originally was. There is enough play in the HB unit to give you the slight angle that is required to make the connection. Bleed the lines out the same way you would normally with manual brakes. Make sure to get all the air out of those lines.

Once everything is attached and the lines are bled, top off your PS pump to make sure the fluid level is good then jack the front end of the vehicle up high enough to turn the tires. Start the engine, let it cycle a few times, turn the wheels lock to lock 2-3 times and turn the engine off. Check the PS fluid level again, top it off if need be, tighten any hoses if you see leaks and start the engine again. Turn lock to lock about 10 times and press the brake 4-5 times to make sure the air bubbles are out of the lines. Once you have this done, put it back down on the ground and take it for a test drive.

WARNING: If you have never driven an EB with power brakes, please go gently on them at first. I have a disc/disc set up and pretty much piled myself up on the steering wheel when I took it out the first time after doing this.

Costs Associated:

Astro Van HB unit, MC, PV, Hoses & steel lines - $23 (Junkyard)
Rebuilt MC - $50.00 (Checker Auto Parts)
Steel Lines - $9.00 (Checker)
New Hydraulic Hoses - $111.00 (Hydraulic Hose Fitting Company)
Hose Clamps - $3.00 (Checkers)
3/8" Hydraulic Hose - $2.00 (Checkers)
Brass "T" Connection - $2.00 (Checkers)
Coupler Nut - $2.00 (Ace Hardware)
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Total Cost - $202

Hope this will help some of you guys out who want to do the HB Swap. I will now attest, mine will stop on a dime and give you a nickle change!!!
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HB_vs._Stock.JPGHB_Unit_Labels.JPG

More images in next post

Cut_HB_Mount.JPGCoupler_Nut.JPG

I have a few more pics with it mounted showing my EFI spacing that I can post up if you guys want as well, just let me know. But this is in response to 75DBE asking for the write up.

If you don't want to fab your own bracket, LoCoFoMoCo Racing makes a nice one for $40 that comes with a wrench specifically to remove the nut on the back of the h-boost unit. I had the metal sitting on my shelf forever waiting to get turned into a bracket finally gave up and ordered one. They're pretty nice. Also, for disc/drum setups you can use a '78 Camaro MC. I think mine was $25 at the parts store.