hydroboost issue

bigmuddy · Nov 27, 2006

Here is what I have, astrobooster on the angled bracket with a corvette master (soon to be a camaro master) I have a big filter and a cooler on the low pressure side. Oh yeah, I am using the Lincoln dual return PS pump too. My problem is that after bleeding, I have a really hard pedal.

little more info: rear 77 drums, front t-brd calipers, all new line etc.

By the way the reason I am jumping to the camaro master cylinder is that I can't get the rearend from locking up even with and adjustable prop valve

Ben

eb66to77 · Nov 27, 2006

You should go to a smaller diameter master to force less fluid back there and keep the prop valve. The prop valve needs to be mounted as close as possible to the master to be the most effective. At most, keep it a close or closer than the stock one. Your brakes are very off set being that the front are large piston calipers and the rear small wheel cylinders. I would almost say go back to the stock size piston, ~1". The one you have now is 1 1/8.

bigmuddy · Nov 27, 2006

I was thinking of going to a Camaro disc/drum master 1-1/8 bore and keeping the prop valve. What do you think?

Ben

bigmuddy · Nov 27, 2006

I also found a master from a 89 Monte Carlo that has a bore of 24mm or less than an inch.

Ben

eb66to77 · Nov 27, 2006

That will bolt up and is going to move less fluid than the vette. I would not try anything over a one inch bore for disk/drum. These hydroboosters can move whatever you put in front of it. You will have more pedal travel than before so make sure you have the push rod adjusted out. I would press the brakes hard without the engine running to see if it is even close and once slowly and lightly with the engine running. This will also give you better "manual" brakes if your belt or anything in the pressure supply area goes bad.

bigmuddy · Nov 27, 2006

Thanks eb66to77 for the replys! Any of the experts want to chime in here?

Ben

Amac70 · Nov 27, 2006

Use the astrovan master. Works just fine for disk drum set up just like what was in the astrovan.

TOFIC · Nov 27, 2006

hard pedal after bleeding?? want a guess?
you have a filter and a cooler on the low pressure return line. If there is one thing that will really cause grief with a Hboost install is back pressure in the low pressure system. Take both of these out and rebleed the system and try it. If this cures the hard pedal issue you know you have to add one component at a time until you find the one causing you grief.
As to the master, you have a GEN2 GM unit. Use a standard GM truck or Blazer master cylinder of the early 90's vintage on it. LOSE the prop valve for the initial install of this master. You may need it but I doubt it. with this master it should work just fine without.
Another cure is file fit a 76 or 77 Bronco master onto the booster. Again, lose the prop valve and start from there.
There are other reasons for a binding booster but try these first before we go to them.
TOFIC

bigmuddy · Nov 28, 2006

TOFIC, thanks for the reply. Yes I have the filter and cooler in the return. It had done this same thing with the cooler on, so I am guessing that is probably the bad actor but will remove both and start over.

I will report back after trying and let you know how it works.

Ben

TOFIC · Nov 28, 2006

KEWL!!!! as BroncoGirlie says "Get her done""
TOFIC

bigmuddy · Nov 28, 2006

I removed the cooler and filter from the low pressure circuit and am in the process of swapping to a blazer/monte carlo/Camaro master disc/drum master cylinder (1-1/8 bore) and I will report back as to how this works?

Ben

bigmuddy · Nov 28, 2006

OK Tofic, here is what I got. Removed the filter and cooler from the return and I know get a kickback at the pedal but don't really think I am getting much boost? Maybe it needs to be bled more?

Second I replaced the corvette master with a blazer master disc/drum and I had a really hard pedal and now I have somewhat of a soft pedal but I can feel the hydroboost a little? Kinda frustrating is that I am still get rear wheel lockup no matter which way I turn the wilwood prop valve! I would have thought the blazer would have fixed most of that problem since it's 1-1/8 but made for a disc/drum setup. Bad valve? Brakes need to be bled more?

Ben

TOFIC · Nov 28, 2006

you have air in the system!!
soft pedal and a "kickback" on the pedal indicates this. There is another reason for the kickback but it is not likely in this setup.
bleed the P** out of it and try again.
before you bleed the system pump some fluid through it and into a can. I have my suspicions that you may have some crud in the system.
I have my doubts about a big bore master, can you trade it for a standard 1" bore master hopefully.
TOFIC

Hazegray · Nov 29, 2006

Are you sure you don't have the brake lines reversed? That could explain the rears locking up first..

bigmuddy · Nov 29, 2006

TOFIC, I shall try again and rebleed. The PS fluid level stays low and I don't see any bubbles?

Nope the brake lines are correct as I had to redo them last night because the rear brake reservoir on the blazer is closest to the firewall unlike the corvette master that I was using. But I will recheck that today as well just to make sure.

Ben

bigmuddy · Nov 29, 2006

TOFIC, what fluid do you recommend using in the hydroboost? I am using some synthetic ATF which I have read is acceptable according to hydroboost.com
Ben

TOFIC · Nov 29, 2006

bigmuddy said:
TOFIC, what fluid do you recommend using in the hydroboost? I am using some synthetic ATF which I have read is acceptable according to hydroboost.com
Ben

That is Paul Clarkes outfit he would never give you a bum steer NEVER!!
I use synthetic power steering fluid myself, just because the bottle says it is and it is about a dollar cheaper than ATF. No other reason.
How is the install going?? Inquiring minds want to know.
TOFIC

TOFIC · Nov 29, 2006

answer

bigmuddy said:
TOFIC, I shall try again and rebleed. The PS fluid level stays low and I don't see any bubbles?

The level on your can should be the same as before and NO bubbles is good.
Get the bleed sequence off the hydrotech site and follow it religiously.

Nope the brake lines are correct as I had to redo them last night because the rear brake reservoir on the blazer is closest to the firewall unlike the corvette master that I was using. But I will recheck that today as well just to make sure.

Ben a tip for you, the large reservior is for the disc brakes, the small reservoir is for the drums. check this.

bigmuddy · Dec 9, 2006

Hey does it matter which where the hydroboost return goes to on a dual return PS pump. I am using the Lincoln dual return pump which has a high return and low return. I have the hydroboost return to the upper or high side of PS pump return and the box going to the PS pump low return. Wondering if this might the cure for the issue I am having?

Ben

eb66to77 · Dec 9, 2006

No, they both empty into the can. The steering box should empty into the cooler too as I screwed up my drawing earlier.

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