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Discussion Starter · #1 ·
To start off im going to include the conversion threads i used/referred to before i started.

Hydroboost Brake Conversion on an F-series Pickup

HOWTO - Stop Me - Hydroboost Write Up - Ford Truck Enthusiasts Forums

!!!!!! Read: Those with hydroboost conversions - PowerStrokeNation : Ford Powerstroke Diesel Forum

My Truck is a 1984 F250 SCLB with a 1994 12 valve. I did a lot of research on the subject and had planned to do it when i was ready but when i got back from being away from my truck for three months the vacuum booster was dead and i began the project.

First I tried to start off like all the other guys, go to the junkyard and get the whole setup out of a donor. I couldnt find one, so i decided to go the route of buying from the parts store (a costly decision in not only money but time. I decided to use the hydroboost used in F450s up until 1997. When i went to look up parts i told them i had a 1990 F-450. The pn for the hydroboost i use was 52-7079. i found the best deal at autozone for just under $200. I decided to get the appropriate master cylinder as well for said f450. I went to a hydraulic hose shop nearby to have them custom make my lines with the fittings i needed. After three different trips there and having to buy two new hoses from o reillys for the fittings and bends all the pressure hoses were done. Now when i mounted the hydroboost to the firewall the arm that protrudes into the cab, it does not go onto the existing stub on my pedal. I will have to take the pedal off grind off the stub and reweld it higher to connect to the arm correctly (note the arm that connects to the brake pedal should be able to move back and forth smoothly and shouldnt be at an angle) also my brake lines will need adapters to be able to connect to the master cylinder.

but the biggest headache of them all is a certain note that comes with the re-manufactured hydro boost unit that i missed until a few days after i bought it. The note states that you must re use your original rod, spring and spring retainer from your old hydroboost unit. this is the rod that will protrude into the master cylinder itself.

I have been trying to find the parts but with no luck so far, i saw in a post once that power brake exchange can sell these parts. i called them once with the promise of a return call and no such luck yet.

Also if you are going to use the new master with the hydroboost unit, you need to swap the proportioning valve as stated in the third link.

The biggest thing i can say to anyone looking to do this is to use buying a reman from the parts store as your last option. It will be way less of a headache if you pull one from a donor.

Currently the project is waiting on
rod, spring and spring retainer
adapters to fit my brake lines into the new master
the grind/reweld of the stub on the brake pedal

pictures to come
 

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Discussion Starter · #2 ·
UPDATE.

I was doing research on the web and found on another forum where a member posted you can use any spring, spring retainer and rod from any hydroboost unit. This may be partly true because when i talked to the man from power brake exchange he said there were two different sizes of rods. Anyway i pulled the spring, spring retainer and rod from two separate 2003ish f250 psd trucks. Now im kicking myself some because the units look indentical to the one i have (from the 1990 f450). I installed the parts into mine and the rod seems to stick out the same as when it was in the truck at the junkyard, so it should work.

Also O'Reillys didnt have the correct adapters for the brake lines (not that they werent in stock just plain out didnt carry the ones i needed) so i checked napa and they hooked me up.

The project is now waiting on....
the correct proportioning valve,
the bracket im going to have made for the brake pedal hookup
final hookup and bleeding of the system

I will post pictures soon, i keep forgetting

My plan is to have this done by at the latest on May 8, as im going out of town on May 9
 

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When I pulled the proportioning valve off the side of my old master cylinder it was the exact same as the one on the F-450 master cylinder. It was a straight through adapter. No clue why, but that's what it was.

Yeah I picked my hydroboost up used and also was able to round up the correct pedals for it.

Thanks for the post. The details of these projects are often what makes them harder than they appear.
 

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Discussion Starter · #4 ·
thats interesting that they were the same, which truck did you do the conversion on and whats it set up with ie( disc front, drum rear) (disc all the way) mine didnt have a proportioning valve at all, both brake lines were hooked straight into the master.

UPDATE, I was dead set on finishing this project before i left so i focused hard on the brake pedal connection, which was the only real thing stopping me. I came up with ideas for brackets and all kinds of combinations of metal and bolts etc. I was frustrated with the idea of having to have anything like that at all, so i dug a little deeper and looked into how others dealt with this problem. I came up on a thread someone did and what they did made it all click in my head. Instead of changing the pedal or making a goofy bracket this guy slotted the holes in the firewall to slide the whole HB unit down. I checked and yes it would work for me as well. So i bought a file and went to work. I filed a lot of metal and i will admit it was a pain. Looking back i should have just drilled where i needed the holes instead of taking so much metal off, but hey i learned.

So okay i slotted the holes, mounted the HB and connected the brake pedal, I put some electrical tape around the stub on my pedal to thicken it up so there wasnt any play as the rod hole was a bit bigger. Connected all the hoses, bench bled the new master and then bled the brakes. started her up, bled the HB and took it for a little drive.

Well she definitley stops now, im not 100% thrilled after the amount of time and money i have in it, but there are some things that i believe are still holding it back from being great. We found a brake line that leaks at the tee (in the rear) and the brakes might need another bleeding as the front bleeder screws were acting up, also i dont know how old the rotors, pads, shoes and drums are.

The only thing that really needs to be done now is the brake lights arent working, not sure exactly which parts trigger the lights themselves, (If ANYONE knows i would appreciate the advice)

This project isnt 100% done yet, but im still very happy with it, this is my first real project of the year and the satisfaction of driving her again made it all worth it.

One last thing, during this project i found a hole in my radiator, well at least now i can get some different hoses and install a drain setup like i wanted to haha. My truck sure does love my wallet.
 

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My Master cylinder came from a 88-97 F450. So it would have had disc/disc. Now the master that I checked came from either an 89 F-350 or 91 F-250 so Disc/drum.
 

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Discussion Starter · #8 ·
Thanks for that, i thought about that way of dealing with it, but i had never taken a brake pedal off and when i started to i knew it was gonna be a pain. I think the slotting of the firewall option is ok, probably not the best option but im not worried about it one bit. Also what was that page 17 thing, it wouldnt load
 

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Slotting the holes iin the firewall to align the actuator rod between the booster and brake pedal is way less than an optimal solution. Billy's fix is the correct one.

The hydroboost requires additional force but less travel which is accomplished through the greater lever ratio of moving the pin up on the brake pedal. Moving the booster down will align the actuator rod, but the lever ratio is incorrect and you'll need to push harder on the brake pedal then you did with the vacuum assist.
 

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As previously posted some of the hydroboost units do not come with the actuating rod. The Motorcraft BRB-37 hydroboost unit does come with the rod, its not noted in the parts description at RockAuto but I've bought three of them and they all came with the rod.
 

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Discussion Starter · #11 ·
I agree that slotting the holes in the firewall isnt the best solution, but in my opinion its still an option. Depends how you do your conversion, it may be a little harder to push it down, but its a truck and i know im a man. I have been driving with it and its not bad to use, sure it may be harder than a normal pedal, but any guy who still has their man card will be able to hit the brakes just fine. If you cant mash the brakes on it than you probably have no business in a truck.
 
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