Astro Van Hydroboost
I have a ’74 Bronco w/stock ‘76 power brake angled bracket, power steering, and front discs.
This write up is for those using the stock angled bracket not the angled bracket that comes on some hydro boosters.
One day for shits and giggles I took the stock booster off the bracket and set the Astro in its place looking for measurements. Turns out the hydro boost is 1/8th inch off top to bottom and perfect left and right. The only problem I had was the length of the pushrod.
Astro Booster Mods
I cut the “eye” off of the pushrod and left that flat portion on there. I then threaded the rod with a 10-1.5 die all the way ’til it narrows. That metal is pretty shitty so it was an easy task. I then cut approximately 1″ off the rod with the tap still on the rod and rounded the edges, just to clean the cut up. Then removed the die to clean the threads and threaded on a nut all the way to the narrowed portion. I then threaded on a clevis that measures 3/8 threads / 3/8 rod / 7/16 gap. I mounted the booster and in order to get it to sit right you must manipulate the bracket a little to spread it top from bottom. I did this by placing the lower two stock Astro studs in their holes and then pushed down and pushed the top two into place. If it is giving you a lot of problems then loosen the bell crank bolt a few turns. Don’t put any nuts on it yet. While holding it in place pop the clevis on and see if the pedal height is where you want it. If it is too high you must thread the clevis closer to the booster. If clearance is a problem on the bell crank on the angle bracket then you must remove that and shave the bell crank a bit. Once the clevis is mounted and clear from the bracket mechanics and the pedal is at the correct height add some lock-tite to the pushrod at the rear of the clevis then thread that nut and lock it to the clevis. You now have a clean setup with no extra parts. Make sure to tighten the bell crank bolt if you loosened it and ensure the cotter pin is good if applicable.
Power Steering Pump w/Dual Return
I used a power steering pump from a ‘79 Lincoln Mark V with the BC Broncos’ bracket. I bought the needed pulley from Pep Boys (It is not the same size as the Thompson pulley). This setup requires running one size larger belt than the stock setup with the Thompson pump and pulley. I mounted the long bolt with the bracket already on it and tightened the nyloc nut but stopped just before it put pressure on the bracket. Then put in the adjuster bolt on the bottom of the bracket and left loose.
Pressure/Return Lines:
The first line you will need in the loop is the power steering pump high pressure out and the hydro booster high pressure in. The pump I used was a ’79 Lincoln Mark V with dual return and it’s fitting size is 5/8th” flare using 3/8th” line. The other end of the line is the hydro boost high pressure in. The hydro boost high pressure in is an 18mm bubble fitting and is 10mm line (same as 3/8th”) that mounts nearest the reservoir. Next step was to get hydraulic line cut to length. I used approximately 15” of hydraulic rubber line and pressed on compression fittings on both ends for 3/8th” line. I connected the hydro boost bubble fitting to the compression fitting and tightened it. I cut a 4” piece of 3/8th” line and deburred the ends and then flared one end (outer flare). I then lined it up to the power steering pump to see the bend angle needed to safely clear the headers. It is not much of a bend which is good since I broke two tubing benders trying to bend it. I finally did it manually with a spring kit over my knee. I then mounted that to the pump finger tight and saw how much I needed to take off to make the line sit right. I wanted to use as little as possible since rubber insulates better than metal and it wasn’t too close to the header. The amount you cut off is personal preference. I left it at four inches. I then tightened both ends until snug.
Next line is the Hydro boost high pressure out to power steering pump high pressure in. The hydro boost out is a 16mm bubble fitting on 10mm line. I cut that just before the first bend in the three or four bend series. That leaves enough for the compression fitting. I then cut a 6” piece of 3/8th” line deburred and flared one end. You will reuse the fitting that is on the power steering box by cutting the line and removing. I mounted the bubble fitting finger tight and mounted the 11/16th” flared end to the steering box (closest to the engine). I used approximately 15” of hydraulic rubber line and pressed on compression fittings on both ends for 3/8th” line. I then slipped the compression fitting over the line on the hydro booster and eyeballed the bend needed on the steering box. It is almost a 45 degree bend needed gradually over the whole length. I then slipped the compression fitting over that end and tightened both ends until snug. I then measured how much reinforced 3/8th” rubber hose was need to return the hydro boost to the pump neatly and attached that. You will reuse the return line from the power steering box.
Master Cylinder Brake Line Fittings:
The master cylinder I used was the ’80 Corvette disc/disc master. The reservoirs are almost the same front to rear. One brake line will match the threading size and one will have to be changed. I took the master to Pep Boys and tested fittings until one fit. It will be a regular flared fitting. I cannot remember off hand which size it is but it is an easy “in store” solution. You must re-bend the lines from the proportioning valve to the master cylinder. (Caution: the line must be able to flex as the master cylinder attached to the body moves independently from the proportioning valve which is on the frame.) I have this routed to my stock ’76 proportioning Valve with the plunger removed**. Once connected bleed the brakes.
**To remove plunger simply unscrew the large fitting on the end of the proportioning Valve being careful to not let it fire across the lawn/lava rock as it is spring loaded. Once removed replace the fitting with spring in place. I have had no problems with this and the brake warning light which is functional is off.
Update Photos (30 July, 2010)
Parts:
- Clevis $14: tractor/industrial supply store
- Astro-booster w/ lines $80: Jkreig70/awesome cat
- New lines made $40: hydraulics supply store
- ‘80 Corvette master cylinder (disc/disc) $28.99: Advanced Auto
Part No.
131749
- ’80 Camaro (disc/drum) $ 28.99: Advanced Auto
Part No.
131521
- New brake line flared fitting $5: Pep Boys
- ’79 Lincoln Mark V power steering pump $85.94: Advanced Auto
Part No.
208606
- Power steering pump bracket and long bolt $55: BC Broncos
- Power steering pump pulley $20: Pep Boys
Total: $328.93