Hydroboost Installation question

[Oldtimer]

Picture of bracket with pushrods:

Pushrod angles, at rest
Brake pedal: 124°
Booster: 64°
As brakes are applied brake pedal angle decreases, and booster angle increases. They may both be near 90° at full travel?
I am a product of public education, and don't have access to CAD software, so somebody at a higher pay grade will need to figure out what this all does to bellcrank ratio.

(Used what I had to mimic booster pushrod)


Brake pedal pushrod is a fixed length of approximately 8-5/8" long.
It has about a 10° twist to allow for the downward angle of booster/master cylinder assembly, so it clears the hood.

 

[ksagis]

I’m assuming the angles shown are in relation to “pushing” straight on the bellcrank arm, i.e. 34 degrees out of square on short arm and 26 degrees out of square on long arm. If so…..

I did some quick math and it looks like in the position you show in the picture that the bellcrank ratio is reduced to 1.178.

Maybe @jamesroney or somebody else can check my trig.

Interesting how this geometry would give an increasing bellcrank ratio (and therefore decreasing pedal ratio) as pedal is pressed. And if it does get to 90 degrees than any side load is vastly reduced at max pedal force.

Brakes are truly a delight!

 

[Oldtimer]

Yes to your assumption, 34 & 26 degrees from square.

 

[ksagis]

@Oldtimer, thanks for the pics and confirming angles.

Not sure if you’re looking for opinions, but I think you can’t go wrong with a bellcrank ratio of roughly 1.2 to 1.3 as that would give you pedal ratio of 5.0 to 4.6.

If you end up with push rods not square to the “arms”, just multiply the square bellcrank ratio by cosine of each angle to get effective bellcrank ratio.

1.58 x cos (34) x cos (26) = 1.178

I’m sure there are others on the forum better informed than me.

 

[jamesroney]

@Oldtimer, thanks for the pics and confirming angles.

Not sure if you’re looking for opinions, but I think you can’t go wrong with a bellcrank ratio of roughly 1.2 to 1.3 as that would give you pedal ratio of 5.0 to 4.6.

If you end up with push rods not square to the “arms”, just multiply the square bellcrank ratio by cosine of each angle to get effective bellcrank ratio.

1.58 x cos (34) x cos (26) = 1.178

I’m sure there are others on the forum better informed than me.

@Oldtimer

I just received a text from the Ebay HB horizontal bracket seller. He has incorporated an offset / tilted bellcrank into the design. He said he lowered the pushrod side 3/4 inch, and raised the booster side 3/8 inch. IDK what that ratios out to...but it is definitely better, and in the right direction.

Sorry for the late replies. I'm on vacation, and I'm not on my computer much.

 

[big blue]

@Oldtimer

I just received a text from the Ebay HB horizontal bracket seller. He has incorporated an offset / tilted bellcrank into the design. He said he lowered the pushrod side 3/4 inch, and raised the booster side 3/8 inch. IDK what that ratios out to...but it is definitely better, and in the right direction.

Sorry for the late replies. I'm on vacation, and I'm not on my computer much.

Even if you bend the tab to make it straight on the h-boost side you would get some twist on push rod so you couldn't overtighten it.

 

[Oldtimer]

James, vacations are good
ksagis, thanks for trig lesson

I also tilted the bellcrank.
I left the booster side pivot where it was, lowered the pushrod side pivot 1 inch, moved it toward engine 1/4 inch, and bent the pivot to be perpendicular to bellcrank.
Left booster arm at 1.9 inches, and shortened pushrod arm from 2.5 to 1.5 inches giving a ratio of 1.26.
Moving the pushrod pivot over 1/4 inch allowed the arm to be welded to shaft without having to bend it to be centered in pushrod clevis.

No photos, cause my welds are fugly.

 

[catfan]

James, vacations are good
ksagis, thanks for trig lesson

I also tilted the bellcrank.
I left the booster side pivot where it was, lowered the pushrod side pivot 1 inch, moved it toward engine 1/4 inch, and bent the pivot to be perpendicular to bellcrank.
Left booster arm at 1.9 inches, and shortened pushrod arm from 2.5 to 1.5 inches giving a ratio of 1.26.
Moving the pushrod pivot over 1/4 inch allowed the arm to be welded to shaft without having to bend it to be centered in pushrod clevis.

No photos, cause my welds are fugly.

Where are you measuring from , bottom of tube to center of hole?

 

[Oldtimer]

Center line of pivot points (tube, hole, pin).

 

[catfan]

Center line of pivot points (tube, hole, pin).

That is almost identical to how I did mine. I didn't bend the tabs I angled them .

 

[ksagis]

@Oldtimer

I just received a text from the Ebay HB horizontal bracket seller. He has incorporated an offset / tilted bellcrank into the design. He said he lowered the pushrod side 3/4 inch, and raised the booster side 3/8 inch. IDK what that ratios out to...but it is definitely better, and in the right direction.

Sorry for the late replies. I'm on vacation, and I'm not on my computer much.

Based on your previously posted dimensions of 2.5” and 1.8” gives:

1.75” pedal side and 2.175” HB side and pedal ratio of 1.24

 

[ksagis]

James, vacations are good
ksagis, thanks for trig lesson

I also tilted the bellcrank.
I left the booster side pivot where it was, lowered the pushrod side pivot 1 inch, moved it toward engine 1/4 inch, and bent the pivot to be perpendicular to bellcrank.
Left booster arm at 1.9 inches, and shortened pushrod arm from 2.5 to 1.5 inches giving a ratio of 1.26.
Moving the pushrod pivot over 1/4 inch allowed the arm to be welded to shaft without having to bend it to be centered in pushrod clevis.

No photos, cause my welds are fugly.

I’m sure your welds are plenty strong, but I’d consider mashing the brake pedal pretty hard before driving to be sure they are up to par. Would suck to break a bracket and lose brakes.

Look’s like a lot of us are converging on 1.2 to 1.3 on either bellcrank ratio or modifying pedal ratio.

I was hoping to have a look at the vendors bracket on ebay, does anybody have a link?

 

[catfan]

I’m sure your welds are plenty strong, but I’d consider mashing the brake pedal pretty hard before driving to be sure they are up to par. Would suck to break a bracket and lose brakes.

Look’s like a lot of us are converging on 1.2 to 1.3 on either bellcrank ratio or modifying pedal ratio.

I was hoping to have a look at the vendors bracket on ebay, does anybody have a link?

I'm the vendor.

Early Bronco Hydro Boost Shorty inline mounting bracket 66-77 ford new | eBay

Find many great new & used options and get the best deals for Early Bronco Hydro Boost Shorty inline mounting bracket 66-77 ford new at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Early Bronco Hydro Boost inline mounting bracket 66-77 ford new | eBay

Find many great new & used options and get the best deals for Early Bronco Hydro Boost inline mounting bracket 66-77 ford new at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[ksagis]

I'm the vendor.

http://[URL]https://www.ebay.com/it...d=link&campid=5335857059&toolid=20001&mkevt=1

[/URL]

http://[URL]https://www.ebay.com/it...d=link&campid=5335857059&toolid=20001&mkevt=1

[/URL]

Appreciate the links.

Looks like the difference in two products is one aligns the HB and MC closer to the fender, or is there more than that?

 

[catfan]

Appreciate the links.

Looks like the difference in two products is one aligns the HB and MC closer to the fender, or is there more than that?

That's right , the short one is if you have a hydraulic clutch.

 

[bigmuddy]

I'm the vendor.

http://[URL]https://www.ebay.com/it...d=link&campid=5335857059&toolid=20001&mkevt=1

[/URL]

http://[URL]https://www.ebay.com/it...d=link&campid=5335857059&toolid=20001&mkevt=1

[/URL]

Rather disappointed, I have this unit sitting on my shelf to install soon. Bought it last year and the project drug on.
Do you have any advice for the changes to operate better? TIA

 

[catfan]

Rather disappointed, I have this unit sitting on my shelf to install soon. Bought it last year and the project drug on.
Do you have any advice for the changes to operate better? TIA

This is the first feedback I have gotten on it , a lot of guys on here have used the bracket and seem to like it.
I have sold hundreds of them but if I can make it better I will. When you get ready to do yours I will be
available by phone or email to help you if you need it.

 

[bigmuddy]

This is the first feedback I have gotten on it , a lot of guys on here have used the bracket and seem to like it.
I have sold hundreds of them but if I can make it better I will. When you get ready to do yours I will be
available by phone or email to help you if you need it.

Thank you, I think that says a lot.

 

[ksagis]

My view of the world is this vendor cares about his product and shipped me hardware for free. He has also been been making continuous design enhancements we all will benefit from.

@catfan and @bigmuddy

 

[Oldtimer]

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.

James,
To answer your original question: Pedal travel goes from is 6.5 to 5 inches from floor.

Ebay short bracket, modified to ratio of 1.26 (see post #87)
Cardone 52-7333 (95 AstroVan HB)
Raybestos MC36306 (80 Camaro 1-1/8" piston MC)
77 D44 front disc
71 BB rear drum