Has anyone experienced a hb unit sometimes applying pressure w/o you pushing the brake?

 

I haven't, that seems weird.

How did you pinpoint the HB as the culprit? I have had the factory units in the Superduties and had for a short time a retro-fitted Astrovan unit in my 74.

I'm a little curious as I plan on retro-fitting another unit into my Ranger.

Josh

 

Not certain it's the booster, but to go from 65 to 35 on the freeway b/f getting off, with more psi coming, I don't know what it could b.

It is also a astro van unit. But six months ago when finishing install I was rushing and put p/s fluid in the master. It locked the next day. I flushed the system and installed new master. Now 6 months later I have this problem. I know when it is coming b/c the pedal physically gets higher. When I turn off the engine and wait two minutes it is fine again.

You tell me.

 

I have had to re-bleed the power steering system before. I had a 99 Superduty work truck that I had to re-bleed a couple times from hard pedal.

Josh

 

If you have a good system to bleed it, I'd love to hear it. I simply went forward and back in the driveway while turning the wheel all the way one way, and then back to other extreme.

But a hard pedal is not going to make the brakes gradually come on stronger and stronger until you can't move. So I'm sure this is a seperate issue.

 

It's basically a two person job.

I used some clear tubing and clamped it to the return port of the hydroboost. Start the engine and have someone rotate the wheel lock to lock while pumping the brakes.

Watch the clear tubing and also make sure the reservoir does not go dry. It can empty the system very quick if you aren't paying attention.

Made a huge difference, then the brake pedal got really firm again after a few months and had to repeat which lasted quite a while before the truck was sold.

Never had a problem with the 2003 or 2005 or any of the work trucks though.

I could't see the hydroboost applying itself on it's own unless there is some malfunction internally within the unit.

A sticking caliper can drag on the rotor eventually locking up the wheel.

Josh

 

Thx. I'll try that. Last episode I ckecked and it is all 4 wheels braking, so I ruled out a cal defect. If the master is contaminated with residue of the p/s fluid, and the plunger rubbers swelled, as happened before, I can't understand how it would gradually increase w/o pushing the pedal.

 

Wow, that's weird.

The one thing I found when I did the 74 was I used an aluminum Ford Ranger master cylinder, but the rear piston bore is recessed and the plunger on the HB unit was recessed a slight bit from the mounting face. So I had to mock up and create a spacer from round stock to make up the difference. It took some trial error to make sure there was no gap and yet not actually pushing on the MC piston as the bolts were tightened.

Josh

 

Did you phone those guys I put up on the other thread? I think they may just know your issue.

 

It's the weekend, but thanks for the #. I have an aftermarket brake specialist here that I have dealt with in the past, so I plan to call them Monday morning.

 

Well, I swapped out the mstr cylinder. Inside the hydro was dry, so I don't think it is leaking. But I now have the same problem.

The shop was of no help. I was hoping someone could point me in the right direction b/f I pull things apart. I'm wondering if it could have taken six months for p/s residue to soften up/swell my new soft lines?

 

In my last post I asked if it could have taken 6 months for the residue of the p/s fluid to soften up my front soft lines. The answer is yes. The inside is clearly swollen. Ouch for my new lines, but I found I can replace both the front s.lines for about $20 from Rock Auto. AZ wants $50 just for the left side front! You have to love RA!

I will also remove and rebuild the front calipers--$2.99 ea. for the kit. I figure I am getting off dirt cheap. Hopefully the rears are not affected because of the length of lines? Time will tell. I really don't want to have to r&r those ... Caddy cals in the rear. They are a pia to rebuild.

I bled the rears at junction b/f the soft line, so hopefully no residue or p/s fluid reached the rears.

 

What are the H/B parts from, a 1970's Lincoln/Mark or 1973/76 Thunderbird?

These cars besides having hydro-boost offered "Anti-Skid" as an option.

That applying pressure jazz is what Anti-Skid...did.

 

We are using hydroboost units from Chevy Astrovans

Josh