Mounting Hydroboost Over the Fender

[Skiddy]

Let's just put this in perspective - the brake pedal pin is 7/16" in diameter where it goes through the pedal arm, which means that it has a cross sectional area of .150 in^2, is in single shear, and it takes the full brunt of braking force.

If the weld made is .0938" (quite small) and goes around the full circumference on both sides of the shaft, then it would have an area of .588 in^2. So, almost 4x the cross-sectional size. That, and the joint is located twice as far out as the pins diameter, so we get double the strength there. Should be, at minimum, 7 or 8x as strong just using a back of the napkin calculation.

*Edit - the pin is actually 7/16" where it goes through the pedal arm*

don't forget to take into account the depth of the weld

 

[nvrstuk]

For a couple pics of where my HB/MC ended up...

Go here: http://classicbroncos.com/forums/showthread.php?t=278607&page=7

Check posts # 92-4
and then the later pics show the "new and improved" m/c which pushes 3X more fluid to the 3 5/32" diameter JB7 calipers on each corner...

# 202
# 211

I can find more...

 

[ransil]

Has anyone measured the pedal ratio of the donor and tried to duplicate that ratio when adapting it to the Bronco?

 

[68ford]

Has anyone measured the pedal ratio of the donor and tried to duplicate that ratio when adapting it to the Bronco?

Can't answer exactly, but if the pedal travel is similar, the ratio is likely close. Broncos likely have a higher leverage ratio than a donor because the pedal was designed for manual brakes and to my knowledge it was not changed when power became an option. I increased my ratio when I went with an aftermarket pedal/dual master assembly so I would not have to push as hard. Obviously increased pedal travel a little.

 

[nvrstuk]

You run dual m/c's 68 Ford?

One on the firewall and one mounted remotely? Curious as to how you like it...I was seriously looking into that when I was dealing with my mc bore size issue

 

[68ford]

You run dual m/c's 68 Ford?

One on the firewall and one mounted remotely? Curious as to how you like it...I was seriously looking into that when I was dealing with my mc bore size issue

https://goo.gl/images/RjF6Sm
https://waynesbronco.shutterfly.com/377
http://www.pictaram.life/post/1215644876574938756_219479468
Dual side by side. 1 front 1 rear. No need for proportioning valve. You balance front to rear bias between the 2 masters.

 

[nvrstuk]

I was looking at a very small one (essentially hide it) that would operate a larger one that would be remote mounted out of the way... hydraulic over hydraulic

 

[nvrstuk]

Do you do the balancing on "paper" or do a best guesstimate and then try a different bore size to dial them in? Just curious... I like different...

 

[68ford]

Do yp do the balancing on "paper" or do a best guesstimate and then try a different bore size to dial them in? Just curious... I like different...

I. When I first got te assembly I used 2 1in bores same as stock EB because I did not want to make too many changes at once. Truck stopped great but had a firm pedal and little travel. Talked to cnc and jamar, they both suggested smaller bore. Talked to more guys and found almost every vehicle that has close to same size calipers all around run a smaller bore for the front. Went with a 3/4 front and 7/8 rear. Set the balance bar in the pedal to center which applies equal force to both masters. Rears seem to lock up a little early so I moved balance over to take away a little from the rear and at the same time adding to the front. It's nice, unlike a proportioning valve, when intake away from the rear, it puts it to front. Proportioning valve is simply a limiter. It stops extremely easy. Pedal travel would feel more than normal but makes it easier to modulate when 2 footing and bouncing around going fast like I do. It is not the set up for everyone. Obviously if I have a stock column it would be left foot brake only. And it required a custom bracket under the firewall. But it does utilize all the stock pedal/clutch bracket mount holes. It's simple, reliable and if my engine dies it's always easy to stop.

 

[EricLar80]

Ok, making some progress over here.


Here is the ugly bracket I want to get rid of:

As mentioned, I beat the brake pedal mount out of the brake pedal arm so that I could remount it (more on that to come):

Test fitting the bracket on the firewall + dimensions:

Cut the pushrod end off, leaving some flat spot so that I could grab onto that while tapping with the 3/8-24 die. I used the Irwin self-aligning one; I would suggest using it since it makes it really easy to get it going straight.

Huge pain in the butt trying to tap it while still in the truck.

I used this pushrod from Speedway (Part # 9107486):
https://www.speedwaymotors.com/Power-Brakes-Conversion-Pedal-Rod-Extension-for-1964-66-Mustang,88097.html

More to come...

 

[toddz69]

Has anyone measured the pedal ratio of the donor and tried to duplicate that ratio when adapting it to the Bronco?

I did that with my SD booster - the pedal ratio on Super Duties and EBs is the same.

Todd Z.

 

[EricLar80]

Ok, some more progress. Anyone ever seen a custom straight bronco brake pedal arm? Brake pedal swingarm tacked in place and ready to be welded. Everything is fitting very nicely. It's going to be awesome!

 

[bmc69]

Nice design..nice work. Such a simple concept too....an elegant solution, as we engineers like to say.

 

[EricLar80]

Nice design..nice work. Such a simple concept too....an elegant solution, as we engineers like to say.

Thanks, BMC!

I guess I should add a few of the mounting location... First the new 2 3/8" hole in the firewall:

Then a couple of the hydroboost where it will be positioned. The hole in the plate for the hydroboost mount is 1 5/8"; I welded a small blob onto the inside of the hole and filed it to the shape of the tab that clocks the booster.

 

[EricLar80]

Alright, it's all installed and working. I am very happy with the way that it turned out. I just need to put a little black paint on the fender where it was scratched.

Can anyone tell what color my bronco was originally? haha

Hard to see what exactly is going on in this last pic, but the pedal arm is the very black vertical item squeezed in just to the right of the column. I need to extend my wires over to the brake like switch.

 

[EricLar80]

Here are a few of the final welds:

 

[mp]

Very nice.

 

[ransil]

Nice... when will they be available for sale??

 

[red hot71]

I moved my hydro boost over the fender also.
I found the brake petal out of a full-sized 96 ford f250 with auto has a petal with the proper bend should work (I came with the petal mounted on the left side of the column), but it's to long and the pivot is smaller diameter. Cutting shorter and adding the new pivot was the direction I was going, but I like your over all design.

 

[bmc69]

That came out very nice. Looks factory.