New brake kits

[ntsqd]

Take a C-Clamp and put ~8000 lbfs on it, watch how it distorts. That is effectively a typical sliding caliper and it behaves in the same way. That more pads aren't extremely tapered when they're done is a testament to their not being severely tasked as best as I can surmise. Usually it is the outer pads that fair the worst. There's enough rigidity in the caliper body that the inner pad isn't nearly as affected.

 

[lars]

And ultimately, so what? The designers’ priorities were different than ours, and what I care about is what happens when I step on the pedal. While I was sweating away in Sacramento Valley heat this afternoon working on (gasp) a different Bronco project I found myself searching for a word to associate with the nebulous “brake feel” and I thought of one: predictably. My current setup is the best it’s ever been. I wish I could say it was by design, but really it was more like trying (increasingly expensive) things until I got to this place. That, and having a few friends in high places to help me.

 

[ntsqd]

How far do you suppose the outer pad centroid is moved when the caliper flexes? My point was that worrying about aligning the force centroid with the pad centroid is noise until they are misaligned by quite a distance. What "quite a distance" is I don't know, but no one that I know of has complained about the misalignment that currently exists in sliding calipers.

My comment about machining the pad to deliberately move the pad centroid really isn't something that would matter here. Not unless someone is Auto-Xing their EB anyway.

 

[LittleBeefy]

The clamping forces aren't flexing a cast caliper enough to move the pads a measurable distance. My point is more that moving the pad around without moving the piston in the same direction isn't going to have a net benefit on brake torque. Really, brake torque is best calculated using the radial distance to the center of the piston. Ignore the pad centroid; at best its lined up with the piston, and at worst it's not lined up and just adding to the flexing force or distortion of the pad. As pointed out earlier, there isn't that much of the piston in contact with the back of the pad and the pad is the least rigid part so you can expect it to distort and wear in uneven ways. Net/net, the best way to compare brakes is the simplest: piston SA and piston distance from the axle centerline.

Using that math, it's easy to see why 2 pistons are better than 1 even if total SA is the same and the rotor diameter is the same. The smaller radii in the two piston setup moves the center of force further from the axle centerline. Full stop.

 

[ntsqd]

We're going to have to differ there, on several counts.

At wilwood 20 years ago we built a simple tool the check caliper flex under pressure. With it we could monitor fluid displacement volume required to reach 1200 psi, and we could measure exterior dimensional changes. We tested every caliper that we could lay our hands on. The flex of the sliding calipers was very significant with the aftermarket GM aluminum bodied calipers being the largest. (To be fair, those calipers are made because some racing rules require front brakes and those calipers' first priority is low unsprung weight and far down the list is actual braking effectiveness.) The stiffest calipers required very little fluid volume to reach 1200 psi and their external dims changed the least. With the way that the GM D52 caliper flexed to say that this flex doesn't influence the pad's orientation and location relative to the rotor would be a large erroneous statement.

Regardless of where the centroid of the clamping force is, it is distributed by the pad's backing plate. It may not be a perfectly uniform distribution (though we want it to be), but it is there and that makes the centroid of the pad's friction surface the centroid of significance. It is flex in the backing plate and flex in the caliper body that causes pads to wear in a taper, not the centroid of the clamping force's location.

As to the reason why multiple pistons are used it comes down to a balance of two competing factors, piston area and force distribution on the backing plate. When you look at a caliper with two pistons you can't really see it, but with three or more you can see that their bores are arranged in an arc. That arc is a compromise between the arc thru the pad centroid from the smallest and largest diameter rotors that caliper is expected to work with. This can be done with multiple pistons because wheel fitment is not the problem that large bore single piston calipers have.

And all of this is moot because the small gain from my proposed pad modification would never be noticed outside of some very restricted racing rules, which I highly doubt an EB will ever be raced under. Just not the right vehicle choice. I've come to regret even mentioning the idea.

 

[66Uncut]

Since deciding not to sell my 66, I've been considering a few safety upgrades for it and brakes are on the list. I've only been casually looking at upgrades (mostly Wilwood) so it's nice to see this kit as an alternative option.

This kit comes with a new master cylinder.

Will the new master cylinder have enough room to keep the oil bath cleaner? Alternatively, if the included MC doesn't have clearance, could the OE 66 master cylinder be used with these brakes? I know that the single reservoir MCs are not as safe so it's probably not the smartest idea.

(not my engine)

 

[toddz69]

I'm pretty certain a manual master cylinder would fit just fine and clear your oii bath air cleaner. Frankly, I'd look at one of the kits that clear your stock wheels rather than one of these big brake kits that require >15" wheels.

Todd Z.

 

[66Uncut]

I'm pretty certain a manual master cylinder would fit just fine and clear your oii bath air cleaner. Frankly, I'd look at one of the kits that clear your stock wheels rather than one of these big brake kits that require >15" wheels.

Todd Z.

Good to know. Thanks!

I thought I linked to the kit that fit 15" wheels but I might've got the wrong one.

 

[jamesroney]

I'm pretty certain a manual master cylinder would fit just fine and clear your oii bath air cleaner. Frankly, I'd look at one of the kits that clear your stock wheels rather than one of these big brake kits that require >15" wheels.

Todd Z.

Pretty sure it won’t. The 67+ dual chamber master cylinder won’t clear, and the corvette mc is even bigger.

I think if you used the 67+ air cleaner bracket for the 6 Cyl then it should work fine.

Of course someone needs to take a good look at the master Cyl push rod retainer in the corvette cylinder and figure out how to keep the rod from falling out. Also going to need a brake lamp switch provision for the 66.

It scares me to death to see people use a unclipped rod against a manual pedal.

 

[jamesroney]

Pretty sure it

I just clicked on the link in the post. The marketing literature and application notes are garbage.

The kit referenced is NOT COMPATIBLE with a 1966 Bronco. It is barely compatible with the 1967-1975 Drum brake Bronco. Absent knowing the caliper piston diameter, I am skeptical of the brake bias as well.

You will also have to change the plumbing on a 66. (Hydraulic lines, distribution block, brake lamp switch.)

Do yourself a favor and talk to a Bronco specific supplier. They will tell you things you don’t want to hear. There’s a supplier in Lodi, CA that won’t steer you wrong.

 

[toddz69]

Good to know. Thanks!

I thought I linked to the kit that fit 15" wheels but I might've got the wrong one.

Sorry - I totally skipped over the link that you had in your post. That kit uses the GM/Corvette master cylinder and there may be fitment issues as @jamesroney notes. I still think a stock drum brake master would fit, but as I recall, the calipers in that kit are 80mm dia. so a larger than stock master would be required.

I also agree with @jamesroney that talking to WH would be a good idea.

Todd Z.

 

[toddz69]

Pretty sure it won’t. The 67+ dual chamber master cylinder won’t clear, and the corvette mc is even bigger.

I think if you used the 67+ air cleaner bracket for the 6 Cyl then it should work fine.

Of course someone needs to take a good look at the master Cyl push rod retainer in the corvette cylinder and figure out how to keep the rod from falling out. Also going to need a brake lamp switch provision for the 66.

It scares me to death to see people use a unclipped rod against a manual pedal.

You would know better than me. I was going by eyeball with the pic provided, , knowing the 67-newer stock drum master measures 7 3/8".

Back when I ran manual brakes with my Mopar master cylinder, I had a spring on the pedal assy that held the brake pedal/rod in place but didn't actuate the brakes. Not the smartest move in the world but it worked while I had that configuration. There are other, better strategies for retaining the pushrod from several vendors now.

Todd Z.

 

[jamesroney]

You would know better than me. I was going by eyeball with the pic provided, , knowing the 67-newer stock drum master measures 7 3/8".

Back when I ran manual brakes with my Mopar master cylinder, I had a spring on the pedal assy that held the brake pedal/rod in place but didn't actuate the brakes. Not the smartest move in the world but it worked while I had that configuration. There are other, better strategies for retaining the pushrod from several vendors now.

Todd Z.

66 air cleaner crossover is straight. The 67 is angled forward to clear the MC. You can’t fit the 66 bracket on the 67+. (Although I did try…)

 

[toddz69]

Got it!

Todd Z.

 

[Yeller]

Since we have a lot of big brains with brake experience watching this thread. Not caring too much about rotor wear other than lasting the life of the pad and it lasts 30k on a DD. What is the most aggressive low temp pad on the market for let’s say the typical GM disc brake swapped bronco?

 

[toddz69]

Since we have a lot of big brains with brake experience watching this thread. Not caring too much about rotor wear other than lasting the life of the pad and it lasts 30k on a DD. What is the most aggressive low temp pad on the market for let’s say the typical GM disc brake swapped bronco?

@Apogee would know that better than anyone else here.

Todd Z.

 

[ntsqd]

20 years ago that was wilwood's 'D' compound. They don't even make it any more. Likely from complaints about just how badly they dusted the wheels, and they did do that with gusto!

10 years ago that was CarQuest's "Fleet Service" pad. Those worked as good as and maybe better than the D's and they didn't dust any more than normal. They still offer that pad, but the vendor and the compound have both changed and they aren't the same.

Today I don't know. Seems like for a Bronco that doesn't see much pavement that looking at short course dirt circle track pads might be a good place to start.

Hoping Apogee has words of wisdom for all of us.

 

[LittleBeefy]

All brake pads sold in the US have edge codes printed on them. The edge code includes two letters. The first letter is low temp performance (200-400 degrees) and the second letter is high temp performance (300-650 degrees). The letters equate to the following friction coefficients: C= up to 0.15, D= over 0.15 up to 0.25, E= over 0.25 up to 0.35, F= over 0.35 up to 0.45, G= over 0.45 up to 0.55, H= over 0.55, Z= unclassified. The Automotive Manufacturers Equipment Compliance Agency governs the tracking of all of the codes. You can find the spreadsheet for all covered pads on their website at ameca.org. The latest list was published on August 18th and is at this link. There is other information like year of manufacture, composition materials, etc. in those codes as well, but if you are just looking for friction coefficient, just look for those two letters on the side of the pad. The most aggressive pads will be marked HH.

 

[gunnibronco]

All brake pads sold in the US have edge codes printed on them. The edge code includes two letters. The first letter is low temp performance (200-400 degrees) and the second letter is high temp performance (300-650 degrees). The letters equate to the following friction coefficients: C= up to 0.15, D= over 0.15 up to 0.25, E= over 0.25 up to 0.35, F= over 0.35 up to 0.45, G= over 0.45 up to 0.55, H= over 0.55, Z= unclassified. The Automotive Manufacturers Equipment Compliance Agency governs the tracking of all of the codes. You can find the spreadsheet for all covered pads on their website at ameca.org. The latest list was published on August 18th and is at this link. There is other information like year of manufacture, composition materials, etc. in those codes as well, but if you are just looking for friction coefficient, just look for those two letters on the side of the pad. The most aggressive pads will be marked HH.

Sort of off topic, but this thread has some awesome info and I feel like there is great advice here.

Is there any way to know what rating a specific pad (brand/model) has without actually seeing the pads in person.

I've looked at some pictures of pads on Rock Auto and a few pics show these codes, but most do not. I can't find this info on the manufacturer's web sites or catalogs either. The AMECA list doesn't tell you what pad uses which materials.

Specifically, I have too much rear bias with a new 1-ton brake set up. It's not terrible, but I'd feel more comfortable with a little more front bias. I'm running 96 F350 fronts, typical Chevy 1-ton disk conversion rears (aka 85 Chevy K5 Blazer front calipers). The 2 pad sets I have do have pictures on Rock Auto (I don't know if they are actual pics of the pads or "representative images"), I haven't disassembled my brakes to look at the actual pads. According to the Rock Auto pics I have a "FF" rated front pads and "GG" rated rear pads. I feel like the pads are causing some of the bias, and could be easily swapped to help pull the bias forward. Is this an acceptable method of pulling bias forward, or am I pissing in the wind? I can swap to the smaller Eldo calipers, but my master is already arguably too big for what I'm running and my pedal is super stiff. I like it as is, but don't want to decrease the caliper size and make the pedal even stiffer. So pads seem to be an easy way to adjust the bias a little bit without a lot of expense and work.

Thanks

Side Note Edit: Neither of the codes I'm seeing on the Rock Auto pictures are in the AMECA list.

 

[LittleBeefy]

Sort of off topic, but this thread has some awesome info and I feel like there is great advice here.

Is there any way to know what rating a specific pad (brand/model) has without actually seeing the pads in person.

I've looked at some pictures of pads on Rock Auto and a few pics show these codes, but most do not. I can't find this info on the manufacturer's web sites or catalogs either. The AMECA list doesn't tell you what pad uses which materials.

Specifically, I have too much rear bias with a new 1-ton brake set up. It's not terrible, but I'd feel more comfortable with a little more front bias. I'm running 96 F350 fronts, typical Chevy 1-ton disk conversion rears (aka 85 Chevy K5 Blazer front calipers). The 2 pad sets I have do have pictures on Rock Auto (I don't know if they are actual pics of the pads or "representative images"), I haven't disassembled my brakes to look at the actual pads. According to the Rock Auto pics I have a "FF" rated front pads and "GG" rated rear pads. I feel like the pads are causing some of the bias, and could be easily swapped to help pull the bias forward. Is this an acceptable method of pulling bias forward, or am I pissing in the wind? I can swap to the smaller Eldo calipers, but my master is already arguably too big for what I'm running and my pedal is super stiff. I like it as is, but don't want to decrease the caliper size and make the pedal even stiffer. So pads seem to be an easy way to adjust the bias a little bit without a lot of expense and work.

Thanks

Side Note Edit: Neither of the codes I'm seeing on the Rock Auto pictures are in the AMECA list.

DO NOT trust the picture to give you the correct edge code. Many of the pictures are old and the edge code and pad formulation have changed. Here is a great example of that:

I pulled this pic from RockAuto. These pads are for a 77 Bronco. You can see it is an FF. However, you can also see that that the last two digits are "15". That means that this picture was taken way back in 2015 because those two digits represent the year of manufacture. If you search for this edge code on the AMECA site you won't find it because its registration has expired. Likely the formulation of the pad has changed since then, so until you have the pad in your hand you won't really know the edge code.

You can thank California for this. They are passing ever more stringent standards on things like pad composition, trying to drive down the use of components like copper. If California were a country, it would be the fifth largest economy in the world. If a manufacturer can't sell it in California, they won't make it, so the rest of the country gets what California allows. Check out the standards and timeline here: https://dtsc.ca.gov/scp/brake-pad-legislation/.