That's it, I'm DONE with this thing! From start to finish the install took me about 6 hours, including the tools cleanup afterwards. A few notes:

1) the pushrod is 2.5" too long, to correct for this the booster needs to be offset from the firewall. I ended up with 2" spacers this bringing the pedal up 1/2" at the pushrod pivot and about 2" at the pedal pad. the stock studs that come with the booster are too short for that, so I just replaced them with grade-8 bolts and nuts from Lowe's .

2) the the bolt patter of the Chevy plate is near identical to the Ford one, but the booster is about 3/4" higher between the holes, to correct for this the spacers at the bottom holes need to be about 1/8" longer than the ones for the top holes, this tilts the booster and the master cylinder a bit more and makes for a near straight pushrod.

3) pressure hoses for a Superduty of the same year as the truck undergoing surgery (1990 in my case) are a direct bolt-on to both the PS pump and the hydroboost unit, but need a bit of reshaping of the hard lines so the hoses end up with nice and smooth bends.

4) the master cylinder can be reused, but needs some modifications - the holes for the booster studs need to be elongated outwards a bit as the hydroboost studs are a bit further apart than those on the vacuum setup. Also the master cylinder piston bore for the booster plunger is very deep, much deeper than what the hydroboost needs, so a spacer will need to be fabbed up that is about 1" long and 3/8" or so in diameter - this slides in the piston bore between the piston and the booster plunger, the plunger end still resides about 1/4" deep in the piston bore so it will not slip off sideways or anything like that.

5) the eye in the pushrod where it slips on the pedal stud is just a bit on the small side, take a Dremel to it and it's fixed in about a minute. However, if you got a brake switch that mounts on the pedal, your brake lights will now not work. To correct for this I slightly elongated the eye of the pushrod, this way the rods slides back a tiny amount when brakes are applied and actuates the switch.

Now the results of that - turns out that Thursday night I didn't measure the piston bore spacer right, so my brakes were dragging a bit, drove it like that for good 20 miles on Friday, but nothing overheated and if anything the rotors got nicely polished Also, I forgot that this particular booster had developed a leak through the pushrod seals, so when I replaced the seals last year the whole thing started getting sticky at the end of its free travel. So yesterday I trimmed the piston bore spacer to the correct length, added a helper spring to the pedal (like some old hydroboosted Chevy trucks have from the factory), and also moved the whole booster 1/4" further away from the firewall to bring the pedal down 1" - all is good now, everything works like it should. Pics:











That's it - not too complicated, just a bit of PITA to tighten down the booster to the firewall as it's a two-man job. Very brutally powerful brakes now, I better be careful next few days till I get used to them.

One problem tho - when I cleaned up the goop from the PS pump last night I apparently opened up an old fluid leak - the goop was acting like a seal against it, now I'm slowly losing fluid. It's leaking between the plastic tank and the big nut the hose attaches to in pic #3 (blue nut is part of the hose), any ideas how I can seal this?

 

Looks about like my conversion, with more headaches.



97 Superduty hydraboost is a bolt in fit.

 

Yah, I know the supreduty stuff is a direct bolt-in, problem is I could not find one, and I already had the Chevy booster from my old truck. Actually for the sake of cheap parts an Astro/Safari van may be a better choice of a donor truck, as they have the hydroboost with much shorter pushrod, close to the ford stuff - just redrill the top two mounting holes further down on the mounting plate, or even swap in a Chevy truck plate, and it'll be close, if not a direct fit.