Hydroboost Conversion Questions

JadeMonkeyStang

TRs on the Brain
@Cryptic Thanks for the service manual link!

I got the mounting plate off the firewall but I had to cut one of the bottom studs with a reciprocating saw and use several Dremel cut off wheels on the other side. Once I had them cut off, a punch and a hammer got the remains of the studs cleared out from the holes in the firewall. I re-primed and re-painted the firewall. Still not sure why this was such an issue for my car but I'm glad I'm past it now. I also re-painted the hydroboost unit since I wasn't happy with the way it looked when I got it. Paint on the HB is drying so I started running the new PS lines (pro tip, install the line from the PS pump to the reservoir first to give yourself more room to work).

I'm also replacing the old cast iron brake proportioning valve with the updated brass one. Have the fittings soaking with Seafoam Deep Creep (penetrating oil) overnight since they didn't want to seem to budge. I am hoping not to have to cut the lines but if I can't get them all off they'll be replaced with new SS lines. In addition I did some test fitting of the PSC Reservoir and I am going to see if the PSC adapter bracket will work with the factory PS reservoir bracket for a clean and easy mounting solution. You need to be careful with the PSC reservoir as the brake lines for the master cylinder will scratch the black anodized finish very easily; thankfully I don't think the minor scrapes I caused will be visible once the install is done.
 

Cryptic

Active Member
@Cryptic Thanks for the service manual link!

I got the mounting plate off the firewall but I had to cut one of the bottom studs with a reciprocating saw and use several Dremel cut off wheels on the other side. Once I had them cut off, a punch and a hammer got the remains of the studs cleared out from the holes in the firewall. I re-primed and re-painted the firewall. Still not sure why this was such an issue for my car but I'm glad I'm past it now. I also re-painted the hydroboost unit since I wasn't happy with the way it looked when I got it. Paint on the HB is drying so I started running the new PS lines (pro tip, install the line from the PS pump to the reservoir first to give yourself more room to work).

I'm also replacing the old cast iron brake proportioning valve with the updated brass one. Have the fittings soaking with Seafoam Deep Creep (penetrating oil) overnight since they didn't want to seem to budge. I am hoping not to have to cut the lines but if I can't get them all off they'll be replaced with new SS lines. In addition I did some test fitting of the PSC Reservoir and I am going to see if the PSC adapter bracket will work with the factory PS reservoir bracket for a clean and easy mounting solution. You need to be careful with the PSC reservoir as the brake lines for the master cylinder will scratch the black anodized finish very easily; thankfully I don't think the minor scrapes I caused will be visible once the install is done.

You’re welcome! I hope the link worked for you.

It’s not too bad to replace the front lines with new stainless. The passenger side is a little bit of a pain but the drivers side is straightforward. I went ahead and did it while I had the system opened up and I was bleeding anyway.


Sent from my iPhone using Tapatalk
 

JadeMonkeyStang

TRs on the Brain
I followed directions to get the bolts for the Hydroboost unit through the firewall and just barley start the 4 nuts to hold it in place while getting the arm on the HB unit attached to the brake pedal. I spent entirely too much time today fighting to get the hydroboost arm onto the brake pedal pin. I greased the arm and the pin, moved the HB unit in all directions, used screwdrivers and long pliers for leverage, cut my hands up reaching up behind the dash, and tried connecting to the brake pedal at different points along its travel with no success. I will try polishing the brake pedal pin with a Dremel tomorrow to remove some of the corrosion and may try loosening the pedal itself if that is unsuccessful. If that doesn't work I'll remove the HB unit again and try connecting the arm to the pin that way... This should be the last difficult / annoying part of the conversion right?

Edit: Reading @TexasT 's old install thread it sounds like the first thing I should do is just unbolt the HB unit and get the brake pedal attached first. I should have re-read these install threads again before I headed out to the garage today. *sigh*
 
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JadeMonkeyStang

TRs on the Brain
Does anyone know the part # for the Powermaster / Hydroboost to firewall gasket? The one I got is a slightly different shape and I'd like to get the stock one if possible. I know a few vendors carry them but I was hoping to be able to get one locally so I don't have to wait for shipping (also, most vendors are charging more for shipping than for the gasket).
 

TexasT

Texas, Where are you from
I had to undo it all, attach the rod to the pedal and then reattach the pedal and hb unit to get it installed. Mighty fun laying under the dash. I did our suburban a few weeks ago and it wasn't near as much work.
 

JadeMonkeyStang

TRs on the Brain
I had to undo it all, attach the rod to the pedal and then reattach the pedal and hb unit to get it installed. Mighty fun laying under the dash. I did our suburban a few weeks ago and it wasn't near as much work.
If only I had remembered that or re-read your thread before I went to install it I would have been a lot better off. At 6'3" and 295 lbs being upside down under the dash puts me a little out of my element. Hopefully I don't have much more time in that position ahead of me.
 

JadeMonkeyStang

TRs on the Brain
Finally getting back to this. Have the hydroboost unit and the master cylinder mounted and ready to go. Brake proportioning valve has been replaced. Need to get the PSC reservoir mounted and then it's just refilling the fluids and bleeding the lines I should (hopefully) be good.

@1KWIKSIX do you happen to have the pictures you posted in the thread below that you could share? Would love to see what you did for a PSC reservoir mounting bracket.
 

1KWIKSIX

Well-Known Member
Here’s some pics
Made a mock up from a piece of PVC angle , them transfered shape & dimensions to a piece of aluminum angle I picked up at Home Depot
 

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SpeedRacerX

Well-Known Member
I did my conversion a little over two years ago so I don’t recall some of the reasons I made some of those choices. As far as that particular reservoir goes I called PSC, spoke with and ordered directly from them and that was what they recommended.

I’ll see if I can’t get some better photos tomorrow but I’ll attach one as well as a diagram of how it all works (the original drawing I stole from someone else, the notations are mine).

99faf1b2f9ccda963308c1e82df9f2ea.jpg

236b3f3ae031421b487a68fab59f4643.jpg



Sent from my iPhone using Tapatalk
Feel free to use my schematic any time you want! LOL. Glad it helped someone.
 

conn84gn

Well-Known Member
Well after 36 years my 84 hydroboost had a big time leak after all the changes it doesn't surprise me
Hard to find a 82-85 hydroboost unit rebuilt I ordered one from Oreilly but wrong unit picture was correct but wrong
took mine out and set it to Rockauto online they have Cordone rebuild YOUR unit got it back in a week
Did not have the problem removing the hydroboost from the firewall four bolts had the wife rock the unit to get in off the pedal
Do yourself a favor remove the driver seat so much better under the dash
Install same way wife help rocking the unit to getting the pedal on first before bolting it in place
New master cylinder too but I did not bench bleed so I'm dealing with that now bubbles bubbles no pedal
Got a spare from Intercooled88 and I will send it out for rebuild as a spare on the shelve
 

conn84gn

Well-Known Member
The new Proportional valve was the source of my troubles. I did not tighten the lines enough
I was afraid to over tighten the lines going into the valve
I got a set of open end box wrenches and bleed the brakes again got a good pedal now
Took her for a drive and no leaks we are ready for the next project :giggle:
 

Jerryl

Tall Unvaccinated Chinese Guy
@Lockman
That's because the 84-85 pump is much better suited to support hydro boost. The 86-87 pump is very different.
 

Lockman

OH, OK .......Now I get it
Thanks for the reminder . I did read that once , in my research. I really like this Hydro boost system.
 
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