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OUT OF BUSINESS / M.I.A.
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Discussion Starter · #1 ·
This is a copy off my webpage http://fireguy50.com/bronco/brakes.html
For discussion here on the forum


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2002-04 Lightning 4wheel disk 1-1/4" bore Master Cylinder
Stock 1980-96 Bronco Power Brake Booster
Proportioning Valve from Summit Racing
1967 Mustang Distribution Block (no proportioning valve)
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1972-79 ThunderBird 3-1/8" bore Front Calipers
Stock 1980-96 Bronco 11.72" Front Rotors
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1983-97 4WD S10 2-1/2" bore Rear Calipers
1977-86 Jeep CJ-7 11.75" Rear Rotors
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I had brake problems, and I drive too fast to depend on the stock brakes. My first problem was the combination valve mounted on the frame. After 20+ years I could tell a buildup of sludge was in there. I couldn't blow air through it, so I knew brake fluid couldn't freely flow to the front calipers. Replacing it would be costly and I didn't need the built in drum brake proportioning valve. I replaced it with a simple distribution block from a 1967 Mustang, and a separate adjustable proportioning valve.


My second problem was finding a good rebuilt master cylinder. I didn't trust the rebuilt master cylinders using 20+ year old cores. So I choose a newer style aluminum master cylinder from a 2002 Ford Lightning Truck. It has larger 1-1/4" bore which fill the larger calipers pistons quicker. I am very happy with this decision, the whole system works great!

I kept the stock power brake booster because I've never had a problem pushing the brake pedal.

PLEASE DO YOUR OWN RESEARCH, MY IDEAS MAY NOT WORK FOR YOU!

Master Cylinder, Adjustable Proportioning Valve & Stainless Steel Lines


Distribution Block & Stainless Steel Lines


Front Brake setup

Must have the early 80's knuckles to use these larger calipers


Rear Brake setup
 

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Satyr of the Midwest
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Was the ratio of master cylinder bore-to-caliper piston bore the same or did it change? I only ask because a larger master cylinder bore yields higher force required to create an equivalent force on the brake pad assuming the same size caliper piston.
 

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OUT OF BUSINESS / M.I.A.
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Discussion Starter · #6 ·
so you have no parking brake?
In Michigan rust belt, I've never owned a vehicle with a working e-brake. The cables rust solid. I did the rear disk brake swap in May of 2004, never needed a parking brake.
Was the ratio of master cylinder bore-to-caliper piston bore the same or did it change? I only ask because a larger master cylinder bore yields higher force required to create an equivalent force on the brake pad assuming the same size caliper piston.
The ratio is lower but I don't think the force is a problem, but like I said smaller master cylinders need more travel to fill the pistons. Here are some numbers:
Caliper surface area ÷ Master Cylinder surface area
1978-86 BRONCO F-150 ratio 8.25:1 (1" master cylinder / 2-7/8" calipers)
1987-96 BRONCO F-150 ratio 7.32:1 (1-1/16" master cylinder / 2-7/8" calipers)
1972-79 THUNDERBIRD ratio 7.72:1 (1-1/8" master cylinder / 3-1/8" calpiers)
2002-04 LIGHTNING ratio 5.36:1 (1-1/4" master cylinder / dual 2" calpiers)
1999-04 SUPER DUTY 4.77:1 (1-3/8" master cylinder / dual 2-1/8" calipers

My old setup was 6.53:1 (1-1/8" master cylinder / 2-7/8" caliper)
My Bronco ratio is 6.25:1 (1-1/4" master cylinder / 3-1/8" calpiers)

3 other variables I don’t know how to calculate are........
Rotor diameter, which effects the mechanical advantage of the caliper on the rotor.
Tire diameter, which effects the mechanical advantage of the rotor on the tire tread.
Tire width and tread, which effects the how much force before lockup.

Like I said, personally I've never had a problem with the stock booster, maybe I just have real strong legs :shrug If the force required was a problem I could go to a larger vacuum booster, or a hydroboost system. But I don't see the need :thumbup I'll let my 5ft 110lb wife drive and get feedback.

I can assure you my new setup STOPS dramatically faster than the old setup, which was better than stock. With my performance street tires this truck
STOPS!
 

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Satyr of the Midwest
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Schweeet. :D That's all that counts in the end.

One other variable you'll probably never be able to really obtain is the coefficient of friction between the brake pad and rotor. The brake pad companies regard it as a trade secret, and it's the same way with auto tires, too. We can get close on the approximate calculations, though.

My master cylinder feels like it wants to go south, and I've been putting it off forever, it seems. Sometimes if I'm coming off of the accelerator and HARD onto the brake, as in city traffic, or if I've been cruising for quite some time, it will require a couple of pumps to gain good "feel." Everything else in the system is new, adjusted, bled, and set up properly, so I'm starting to think about using a slightly larger master cylinder for better response. The brakes have NEVER been hard to push for me either, so a slight increase in force in the name of displacement wouldn't really hurt. I'll give it a look-see. :thumbup

Are the fittings on the Lightning master cylinder the exact same as the original's?
 

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In Michigan rust belt, I've never owned a vehicle with a working e-brake. The cables rust solid. I did the rear disk brake swap in May of 2004, never needed a parking brake.



I can assure you my new setup STOPS dramatically faster than the old setup, which was better than stock. With my performance street tires this truck
STOPS!
hmmm. i may have to look into my system to see if i can get better stopping. i've upgraded everything minus the rear wheel cylinders and i can't for the life of me get the tires to lock up.
maybe someone here may have some input.
i have 350 booster and mc, t bird calipers and stainless lines everywhere. 35x12.50 baja claws

do you think rear discs would be much of an improvement?

i do however want to retain a parking brake
 

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Satyr of the Midwest
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Yeah, yeah. Same as the original on MINE though. :D Thanks.
 

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Discussion Starter · #12 ·
I guess it wasn't a must have, but it has the brake warning light switch

Yeah, yeah. Same as the original on MINE though. :D Thanks.
No, 1987-96 Bronco master cylinder is M18-1.5 and 9/16x18
All those larger master cylindres are 7/16x24 and 9/16x18
 

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Master Bater
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huh, yours isnt on the pedal? never knew that.

To me, it just seems like one more thing that CAN go wrong with the brakes. Im stupid, and therefore like things simple. This topic has been discussed lately on another forum Im on, so was curious as to your view point.
 

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Discussion Starter · #14 ·
That's not for the brake lights in the back, it's for the brake warning light in the dash. As shown in that picture, a leak in the brake line will cause the slider to move towards the low pressure side. Which grounds the warning light
 

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Satyr of the Midwest
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No, 1987-96 Bronco master cylinder is M18-1.5 and 9/16x18
All those larger master cylindres are 7/16x24 and 9/16x18
:scratchhe

Wow. I know that's right, but it strikes me as so...counter-intuitive. I figgered Ford went completely metric by about 2000 or shortly thereafter. Weird. I think I'll just bypass a whole lot of time & effort, and just go with a factory replacement m/c. I'm having too much fun, and spending way too much time, messing with my Moates & Binary Editor these days. :toothless
 

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Discussion Starter · #16 ·
I'll let my 5ft 110lb wife drive and get feedback.
I let her drive it this afternoon, she had no problem pushing the brake pedal. In fact she said "the brakes are awesome"
I think I'll just bypass a whole lot of time & effort, and just go with a factory replacement m/c.
It would take 2 minutes to cut off the one fitting adn re-flare the right fitting on there. :smilie_slap
 

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hmmm. i may have to look into my system to see if i can get better stopping. i've upgraded everything minus the rear wheel cylinders and i can't for the life of me get the tires to lock up.
maybe someone here may have some input.
i have 350 booster and mc, t bird calipers and stainless lines everywhere. 35x12.50 baja claws
do you think rear discs would be much of an improvement?

i do however want to retain a parking brake
I suggest your tires are overwhelming your brake system even with the upgrades due to the increased leverage larger diameter tires provide.

I cringe everytime I see a vehicle with 20's mounted and still carrying the stock brake system. Last time I was in the DFW area I saw several SUVs with huge decals advising onlookers about their 24's.
 

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Finally went to the j/y and got one of these because the parts guys at the ford dealership are idiots and didn't know about a part used on their trucks for 10 years.



I gutted it out because i'm using 2005 sd axles with rear disks. Dual piston calipers and 14" rotors.

and then I started to gut the stock 79 bronco combination valve. I could only get #1 out. It looks like the bolt that takes #2 out is not actually a bolt and I cant get it out (at least I haven't tried hard enough to strip it out until I found out if it could come out)



So where i'm at now is I have no limitation on the fluid going to the rear, and some limitation on the front by the factory combination valve.
My question is.....I could just take the lines directly from the m/c to the front and rear axles without a combination or prop valve? What was the purpose of having both going to a single point before distributed to the axles?

If I had a failure from one cylinder of the m/c I would still have brakes on either the front or the rear, which is the whole purpose of the two chamber master cylinder. Right?

Am I just completely off here?

Also, I have an 02 lightning m/c, will that push enough fluid for the dual piston calipers?
 

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Discussion Starter · #19 ·
I gutted it out because i'm using 2005 sd axles with rear disks. Dual piston calipers and 14" rotors.
Very nice!
My question is.....I could just take the lines directly from the m/c to the front and rear axles without a combination or prop valve?
That is what I would do now, if I could redo it….
What was the purpose of having both going to a single point before distributed to the axles?
That is so the brake warning light will work if there is a leak in the system. The good high pressure side pushes the slider over and turns on the light.

BUT, the new master cylinders have a low level sensor built into the reservoir, so you can use that for the brake warning light. That’s what I would do if I had the time and money to redo those brake lines.
If I had a failure from one cylinder of the m/c I would still have brakes on either the front or the rear, which is the whole purpose of the two chamber master cylinder. Right?
You would still have brakes, there is a divider inside that plastic reservoir, which would keep the brakes working on the good side.
Also, I have an 02 lightning m/c, will that push enough fluid for the dual piston calipers?
2002 Lightning M/C was 1-1/4in bore, while the 2005 Super Duty trucks had both 1-5/16 and 1-3/8 bores. I’m sure it’s better than 1979 Brakes, but a slight downgrade from the Super Duty.

I originally got a 1-3/8in bore M/C for my truck, but it wouldn’t mount to my brake booster, it was so much bigger than the 1-1/4 M/C. I would have had to get a Super Duty vacuum booster or hydroboost, and I wasn’t sure if the booster would fit my firewall, and didn’t want hydroboost. Here is my post on Master Cylinders:
http://fullsizebronco.com/forum/showthread.php?t=107273
 

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I originally got a 1-3/8in bore M/C for my truck, but it wouldn’t mount to my brake booster, it was so much bigger than the 1-1/4 M/C. I would have had to get a Super Duty vacuum booster or hydroboost, and I wasn’t sure if the booster would fit my firewall, and didn’t want hydroboost. Here is my post on Master Cylinders:
http://fullsizebronco.com/forum/showthread.php?t=107273
I work at advance while in school. So I did the same thing. I measured the inside of booster hole with calipers and then went to work and pulled every ford master cylinder we had till i found the one with the biggest bore that would still fit in my booster and ended up with the 02 lighning m/c. I didn't want hydroboost and I don't want touchy brakes cause they're dangerous on the rocks imo.
 
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