Hydroboost Installation question

[jamesroney]

Yes, my config was inspired by Jon for sure!

James, I can measure and take a video for you today and text. Just got back from San Diego last night.

Thanks! I was thinking of coming over to visit your build...but it's going to be hotter than the surface of the sun this week.

Mostly I need to know how far the pedal moves before the brakes "work" and then how far it goes when you push past that.

I'm guessing 2 inches to get it stopped, and 4 inches at the bottom. Which would leave about an inch of pedal to the floor if the brake pedal were in the right place, and 2 inches if you adjust it "tall" to be even with the clutch (if you had one...) at 6.5 inches off the floor.

I'm learning that Hydroboost doesn't exhibit pedal collapse like a vacuum booster. There's just a ton of pedal over-travel after the optimal braking effort has been achieved. I never saw it in my Cummins, because I never pushed the pedal super hard. I'm going to check that today.

I drove mine yesterday, and I can get full "face in windshield" braking at 1.5 inches of pedal travel. I can get 2.5 inches of "over-travel" before the pedal firms up. Turn out that in normal operation, I will never need to push the pedal that far. So there is some wierdness.

My only concern with short stroking the master cylinder is that you lose the redundant dual braking if you don't have enough pedal travel. 1 inch at the input piston is enough. (Since that is the amount that Ford put into the factory drum brake MC) GM master cylinders seem to have a little more travel. I would have to take apart this corvette MC to see where the transfer port is located, and just how much total travel is needed. My recent experience with a 1-1/8 GM cylinder is that it is hard to bleed the rear brake circuit with less than 1 full inch of travel.

Once I built the new bellcrank, and gave myself 1.25 of travel, the brake bled normally, and the MC behaved like it should. And yes...this thing has vastly "better" brakes.

 

[jamesroney]

So I’m going to say that this kit has some great potential. After swapping the new ratio bellcrank, I have an acceptable solution.

I bought a $200 bracket, a $50 Astrovan hydroboost, and a $50 Amazon Raybestos master cylinder.

Also built a few hoses, and borrowed a Saginaw pump reservoir. And some -AN fitting adapters.

Aside from the 16 hours of machining, welding, and rework…it came out OK.

 

[Shimmy]

looks great man!

 

[ba123]

Thanks! I was thinking of coming over to visit your build...but it's going to be hotter than the surface of the sun this week.

Mostly I need to know how far the pedal moves before the brakes "work" and then how far it goes when you push past that.

I'm guessing 2 inches to get it stopped, and 4 inches at the bottom. Which would leave about an inch of pedal to the floor if the brake pedal were in the right place, and 2 inches if you adjust it "tall" to be even with the clutch (if you had one...) at 6.5 inches off the floor.

I'm learning that Hydroboost doesn't exhibit pedal collapse like a vacuum booster. There's just a ton of pedal over-travel after the optimal braking effort has been achieved. I never saw it in my Cummins, because I never pushed the pedal super hard. I'm going to check that today.

I drove mine yesterday, and I can get full "face in windshield" braking at 1.5 inches of pedal travel. I can get 2.5 inches of "over-travel" before the pedal firms up. Turn out that in normal operation, I will never need to push the pedal that far. So there is some wierdness.

My only concern with short stroking the master cylinder is that you lose the redundant dual braking if you don't have enough pedal travel. 1 inch at the input piston is enough. (Since that is the amount that Ford put into the factory drum brake MC) GM master cylinders seem to have a little more travel. I would have to take apart this corvette MC to see where the transfer port is located, and just how much total travel is needed. My recent experience with a 1-1/8 GM cylinder is that it is hard to bleed the rear brake circuit with less than 1 full inch of travel.

Once I built the new bellcrank, and gave myself 1.25 of travel, the brake bled normally, and the MC behaved like it should. And yes...this thing has vastly "better" brakes.

You're welcome any time but yeah, hotter than HELL, literally, this week.

As fas as matching your clutch pedal level, you know I don't have one, but I used this adjustable pedal push rod from WH:
https://www.wildhorses4x4.com/custom-brake-pedal-push-rod

On another hot note, on the way home from San Diego there was a spot that was 105° and traffic came to a stand still at one point because there were fires on both sides of the road....don't stop, idiots! Anyway, there was a truck carrying melons and the back half of the truck was on fire, dropping melons all over that caused the fire. WTF, causes MELONS to catch fire?

 

[ksagis]

Wanted to revive this thread to see if anybody had thoughts on my previous question about MC stroke when designing a system.

My thinking is sizing a system that nominally strokes the MC an inch, and still has remaining pedal height, is a poor design since if you lose a circuit, the MC is going to travel further, and possibly blow seals (most MCs are pretty specific on this topic when bench bleeding)

Yes, probably depends on specific MC and its internal design…..

That said, I was thinking of targetting less than 0.65” to 0.75” of MC stroke at my desired pedal travel. That approach would leave me roughly 1.5” of pedal travel before over stroking the MC for my pedal ratio.

Thoughts from the brake gurus?

 

[jamesroney]

Wanted to revive this thread to see if anybody had thoughts on my previous question about MC stroke when designing a system.

My thinking is sizing a system that nominally strokes the MC an inch, and still has remaining pedal height, is a poor design since if you lose a circuit, the MC is going to travel further, and possibly blow seals (most MCs are pretty specific on this topic when bench bleeding)

Yes, probably depends on specific MC and its internal design…..

That said, I was thinking of targetting less than 0.65” to 0.75” of MC stroke at my desired pedal travel. That approach would leave me roughly 1.5” of pedal travel before over stroking the MC for my pedal ratio.

Thoughts from the brake gurus?

I'm gonna say it, and leave it to those brake gurus to propose an alternate hypothesis.

The standard dual chamber brake master cylinder relies on piston travel to expose ports and close ports in addition to moving fluid. Even if a person had a MC with a single piston pushing a single wheel cylinder, it still needs to travel enough to close the reservoir port. So we can all agree that a certain amount of travel?

The factory engineers, who rely on the Tier 1 OEM engineers, (who do their best to obscure facts and preserve IP...meaning they lie.), have ALL determined that 1 inch to 1.5 inches of piston travel in the bore is where they landed. The input rod compression, input piston port, dual piston transfer, all require movement.
So the answer is "about" 1 inch for a Ford master cylinder, and 1.25 for a GM cylinder. And 90% of the available travel for any other master cylinder. So yeah, take the master cylinder on a bench, determine how far the piston CAN move, use 90% of that number. Then change the pedal ratio and travel to accommodate that number.

If you don't like the pedal effort at that point...change the caliper bore, (or add some caliper pistons...)

Let the flames begin...

 

[toddz69]

Can someone with a hydroboost that has "great braking" tell me how much pedal travel you get in your early bronco?

With the engine running, can I get a measurement from the pedal to the floor, before and after applying the brakes.

My new Hydroboost with an AstroVan HB, and a 1-1/8 Corvette MC is going from 6.5 to 3 inches from the floor. Pedal is solid, and brakes stop the Bronco. But an awful lot of travel?

Thanks.

OK, back in the States and home again and I pulled the Bronco out of the garage this morning. Got a few measurements. My pedal (top of pad to floor) is 4.5" at rest. 3" when I'm applying the brakes to stop. So it appears it takes about 1.5" of pedal travel for me for at least slow speed stopping.

Todd Z.

 

[toddz69]

I'm learning that Hydroboost doesn't exhibit pedal collapse like a vacuum booster. There's just a ton of pedal over-travel after the optimal braking effort has been achieved. I never saw it in my Cummins, because I never pushed the pedal super hard. I'm going to check that today.

Correct me if I'm wrong but I think what you're describing is the squishiness in the brake pedal that you get in a lot of hydrboost systems? You can press the pedal to stop and then keep on pushing it almost to the floor? That's the number one complaint I've had on most of the conversions (including mine) that I've driven over the years. My Super Duty doesn't do it - or it's at least greatly diminished compared to conversions. I do have a much firmer pedal, i.e. a lot less squish on mine now after I changed the master cylinder bore. Mine used to be such that when someone other than me would mash on the brake pedal when starting the truck, the pedal would almost be pushed to the floor.

Todd Z.

 

[jamesroney]

Correct me if I'm wrong but I think what you're describing is the squishiness in the brake pedal that you get in a lot of hydrboost systems? You can press the pedal to stop and then keep on pushing it almost to the floor? That's the number one complaint I've had on most of the conversions (including mine) that I've driven over the years. My Super Duty doesn't do it - or it's at least greatly diminished compared to conversions. I do have a much firmer pedal, i.e. a lot less squish on mine now after I changed the master cylinder bore. Mine used to be such that when someone other than me would mash on the brake pedal when starting the truck, the pedal would almost be pushed to the floor.

Todd Z.

YES!

I don't want to say "to the floor" but there is a fair amount of pedal travel that happens long after impending lockup. If my Cummins had only 4 inches of pedal travel, it would be "to the floor" But the truck has stopped and the wheels are locked long before that. Since it has 6 inches of pedal travel, it doesn't get to the floor. But truth be told...I drove this truck 150,000 miles, and never noticed that I could "over-travel" the brakes. Because all of the stopping happens in the first 2 inchs. Now of course, I do it every time I'm sitting at a stop light.

Thanks!

 

[ksagis]

I'm gonna say it, and leave it to those brake gurus to propose an alternate hypothesis.

The standard dual chamber brake master cylinder relies on piston travel to expose ports and close ports in addition to moving fluid. Even if a person had a MC with a single piston pushing a single wheel cylinder, it still needs to travel enough to close the reservoir port. So we can all agree that a certain amount of travel?

The factory engineers, who rely on the Tier 1 OEM engineers, (who do their best to obscure facts and preserve IP...meaning they lie.), have ALL determined that 1 inch to 1.5 inches of piston travel in the bore is where they landed. The input rod compression, input piston port, dual piston transfer, all require movement.
So the answer is "about" 1 inch for a Ford master cylinder, and 1.25 for a GM cylinder. And 90% of the available travel for any other master cylinder. So yeah, take the master cylinder on a bench, determine how far the piston CAN move, use 90% of that number. Then change the pedal ratio and travel to accommodate that number.

If you don't like the pedal effort at that point...change the caliper bore, (or add some caliper pistons...)

Let the flames begin...

Yes, I generally agree with the statements on stroke based on my debuild of limited number of MCs, what I’m trying to back out is how much to reserve for MC stroke/pedal travel if one circuit fails.

I’ve haven’t had one fail in over 40 years so maybe am remembering wrong, does anybody know if pedal travel is increased when one circuit is open? Seems to answer must be yes since when one circuit has air, the pedal travel is increased.

Yes, this is mainly a thought exercise! Best to expend the effort to be sure the circuit doesn’t fail.

 

[ksagis]

Correct me if I'm wrong but I think what you're describing is the squishiness in the brake pedal that you get in a lot of hydrboost systems? You can press the pedal to stop and then keep on pushing it almost to the floor? That's the number one complaint I've had on most of the conversions (including mine) that I've driven over the years. My Super Duty doesn't do it - or it's at least greatly diminished compared to conversions. I do have a much firmer pedal, i.e. a lot less squish on mine now after I changed the master cylinder bore. Mine used to be such that when someone other than me would mash on the brake pedal when starting the truck, the pedal would almost be pushed to the floor.

Todd Z.

What do we think would cause this? Seems to me that there is nothing in hydro system that would cause squishy brakes, its simply assist.

Glad you’re back in states, if you have a chance to get the pic of SD pushrod angle, would love the data.

 

[toddz69]

What do we think would cause this? Seems to me that there is nothing in hydro system that would cause squishy brakes, its simply assist.

Glad you’re back in states, if you have a chance to get the pic of SD pushrod angle, would love the data.

I'm not sure what causes it but my unimformed opinion is that it's due to the combination of pedal ratio, master cylinder bore (smaller than ideal?), etc. Just like when you have manual brakes with a large pedal ratio, small bore master, etc. You get a lot of pedal throw and the pedal is often a little softer/squishier. The car stops fine but the pedal feel can be a little unnerving.

As for the pedal angle, I immediately thought of it when I got back but it's been 110+ here for days so my motivation to check things was a little muted . It wasn't too bad this morning so I checked both the Bronco and the pickup. I think my memory must be failing because the pushrods are at about the same angle, actually. Vertically, they're both about 0.5 deg off of being perfectly flat. I couldn't get my phone up in there to measure the angles in the horizontal plane but it couldn't be more than a degree or two. I had forgotten how straight of a push they both have.

Todd Z.

 

[ksagis]

I'm not sure what causes it but my unimformed opinion is that it's due to the combination of pedal ratio, master cylinder bore (smaller than ideal?), etc. Just like when you have manual brakes with a large pedal ratio, small bore master, etc. You get a lot of pedal throw and the pedal is often a little softer/squishier. The car stops fine but the pedal feel can be a little unnerving.

As for the pedal angle, I immediately thought of it when I got back but it's been 110+ here for days so my motivation to check things was a little muted . It wasn't too bad this morning so I checked both the Bronco and the pickup. I think my memory must be failing because the pushrods are at about the same angle, actually. Vertically, they're both about 0.5 deg off of being perfectly flat. I couldn't get my phone up in there to measure the angles in the horizontal plane but it couldn't be more than a degree or two. I had forgotten how straight of a push they both have.

Todd Z.

Well, crap. Now I need to worry about an off angle into hydro maybe causing faster wear per internet lore and what Vanco told you. Appreciate the followup!

I’m thinking of debuilding a hydro and seeing if there is really something to fuss about. Anybody have advice of a donor vehicle for a cheap one to take apart?

 

[jamesroney]

I’ve haven’t had one fail in over 40 years so maybe am remembering wrong, does anybody know if pedal travel is increased when one circuit is open? Seems to answer must be yes since when one circuit has air, the pedal travel is increased.

Actually, you already know the answer to this. And while you might not have had one "fail"...every time you bleed the brakes you are basically creating a hydraulic circuit failure.

And as you well know, if you open a single bleeder on either circuit, the pedal sinks, then the imbalance valve moves, then the light goes on. It all requires fluid to be displaced.

and the answer is "yes."

 

[toddz69]

I’m thinking of debuilding a hydro and seeing if there is really something to fuss about. Anybody have advice of a donor vehicle for a cheap one to take apart?

Cheapest pieces, and probably the easiest to find, are still the Astro units. I used to have several of them, and bits and pieces, laying around but they were all donated to science at some point.

Todd Z.

 

[ntsqd]

I really don't care how far the m/c piston is being stroked. I don't have to care because if I've got the hydraulic ratio in the range of where it needs to be for the pedal to feel right I'm not using all the service stroke in the m/c. People get way too caught up in fluid delivery volume, and it's just not that important to the use of the system.

Figure a GM caliper with the Ø2-15/16" bore. Caliper pistons nominally retract about .015" That means that you only need ~0.2 cubic inches of fluid to go from at-rest brakes to pads in contact with the rotor. To get that 0.2 cubic inches from a Ø1.125 m/c the piston in it needs to move 0.2" past the transfer port. Assuming that it is a 6:1 pedal ratio (a WAG, likely less ratio in a power pedal) that is 1.23" of pedal stroke after the transfer ports are closed. Compare that 0.2ci of fluid to what is available from the m/c if the full stroke is used. If that full stroke past the transfer port is only one inch that is still .994 cubic inches of fluid. What is needed is ~20% of what is available. That's why I don't worry about the fluid volume.
Since the transfer ports inhibit the actual use of the brakes until the m/c piston is past them they are placed *right* at the edge of the m/c piston seal. Most of those ports are pretty small. I'll guess about Ø.06", so the total pedal travel with the 6:1 ratio should be somewhere in the range of 1.59"

FWIW the push-rod in my Vanco supplied H-B unit for Snowball (FSB/OJB) has an offset pin hole. So the rod itself is level or nearly so, but the force LOA is a significant angle.

 

[ksagis]

Cheapest pieces, and probably the easiest to find, are still the Astro units. I used to have several of them, and bits and pieces, laying around but they were all donated to science at some point.

Todd Z.

Any specific years on the Astro to look for?

 

[ksagis]

I really don't care how far the m/c piston is being stroked. I don't have to care because if I've got the hydraulic ratio in the range of where it needs to be for the pedal to feel right I'm not using all the service stroke in the m/c. People get way too caught up in fluid delivery volume, and it's just not that important to the use of the system.

Figure a GM caliper with the Ø2-15/16" bore. Caliper pistons nominally retract about .015" That means that you only need ~0.2 cubic inches of fluid to go from at-rest brakes to pads in contact with the rotor. To get that 0.2 cubic inches from a Ø1.125 m/c the piston in it needs to move 0.2" past the transfer port. Assuming that it is a 6:1 pedal ratio (a WAG, likely less ratio in a power pedal) that is 1.23" of pedal stroke after the transfer ports are closed. Compare that 0.2ci of fluid to what is available from the m/c if the full stroke is used. If that full stroke past the transfer port is only one inch that is still .994 cubic inches of fluid. What is needed is ~20% of what is available. That's why I don't worry about the fluid volume.
Since the transfer ports inhibit the actual use of the brakes until the m/c piston is past them they are placed *right* at the edge of the m/c piston seal. Most of those ports are pretty small. I'll guess about Ø.06", so the total pedal travel with the 6:1 ratio should be somewhere in the range of 1.59"

FWIW the push-rod in my Vanco supplied H-B unit for Snowball (FSB/OJB) has an offset pin hole. So the rod itself is level or nearly so, but the force LOA is a significant angle.

Thanks for the solid math, makes sense.

Are you saying the Vanco unit didn’t have much vertical angle but had a fairly substantial horizontal angle (between the LOA of brake pedal and the LOA of hydro? If so, any idea of how big an angle?

That would be interesting with what he told @toddz69 previously.

 

[toddz69]

Any specific years on the Astro to look for?

I'd have to go dig around on Rockauto to see the exact years but I think they started around '93 and ran until the early 00s?

Todd Z.

 

[toddz69]

FWIW the push-rod in my Vanco supplied H-B unit for Snowball (FSB/OJB) has an offset pin hole. So the rod itself is level or nearly so, but the force LOA is a significant angle.

I couldn't find a pic online but as memory serves, Hydratech's F-Series/Bronco unit for those years has a similar offset mounting hole.

Todd Z.