Wilwood Disc Brakes

[Aliracer]

Curious if anyone has used the Wilwood disc brakes setup over the more standard option. Worth the extra cost? Any pros / cons? Any modifications needed for the Wilwood setup?

I have a 1973 undergoing frame off... restomod keeping the original 302 in it. Thanks in advance!

 

[Broncobowsher]

Don't see the value in the small kit. But the ones that need bigger wheels show promise.

 

[samamarshall]

I'm going with their rear disc kit so i can get an inner drum e-brake - not a fan of the caliper ebrake

 

[sprdv1]

Was considering this myself for the front... Can't have too much brake on them steep slopes...

 

[68ford]

Inrun their 6 piston 15in wheel kit. The piston surface are is very close to oem, so the force against the pads would be about the same as oem. However I noticed a improvement over my stock 77 disc when installing them. Not huge but noticeable. I use their calipers in the rear but I use their much large 4 piston superlites being in welded on my own brackets since I have a full float housing. End result, I am very happy.

 

[WILDHORSES]

I can tell we have had great results with the Wilwood kits. Go with the largest kit your wheels will allow. I'm getting ready to do this swap on the front of my own rig after years of fighting with an experimental kit we are giving up on.

Jim

 

[Apogee]

Inrun their 6 piston 15in wheel kit. The piston surface are is very close to oem, so the force against the pads would be about the same as oem. However I noticed a improvement over my stock 77 disc when installing them. Not huge but noticeable. I use their calipers in the rear but I use their much large 4 piston superlites being in welded on my own brackets since I have a full float housing. End result, I am very happy.

Are you talking about their Dynapro 6-piston kit with the 11.75 x .81 rotor, 140-13303-**? If so, my only concerns with that kit are the meager rotor weight of 9.15 pounds and difficulty in finding a pad that will work well due to the rapid a large temperature swings such a small rotor will typically experience under a 3500# plus rig with some horsepower and tire size. The caliper piston area is 5.06 square inches, a 22% reduction in piston area versus the factory 2-7/8" piston Ford calipers, or 25% reduction relative to the Chevy D52 single piston calipers with 2-15/16" pistons. That said, the assumption is that you'll be running 25% higher line pressures, higher CoF compound pads, or both. Aren't you running a dual MC with a balance beam? Since you said you like how your brake perform, what pad manufacturer and compound have you settled on running?

Tobin

 

[68ford]

They are the 6 piston that come in the 15in wheel kit with the narrow rotors. Im running the pads that came with the calipers. Yeas I have a balance beam dual master. I had the entire set up minus the front brakes and didn't change anything except the fronts. The truck stopped easier, which leads me to believe it's the pad compound if the piston surface area is as much less as you stated. I wanted to run the same superlites on the front but there just no way due to the width of the caliper. At the time of installing the fronts, I had 2 1in bore masters so it was compatible to stock eb. Had short pedal travel and still had to push harder than I thought I should. I have since gone to a 3/4 front and 7/8 rear. Obviously have increased pedal travel but barely have to step on it to stop really fast. Truck weighs 5300lb as well.

 

[Apogee]

They are the 6 piston that come in the 15in wheel kit with the narrow rotors. Im running the pads that came with the calipers. Yeas I have a balance beam dual master. I had the entire set up minus the front brakes and didn't change anything except the fronts. The truck stopped easier, which leads me to believe it's the pad compound if the piston surface area is as much less as you stated. I wanted to run the same superlites on the front but there just no way due to the width of the caliper. At the time of installing the fronts, I had 2 1in bore masters so it was compatible to stock eb. Had short pedal travel and still had to push harder than I thought I should. I have since gone to a 3/4 front and 7/8 rear. Obviously have increased pedal travel but barely have to step on it to stop really fast. Truck weighs 5300lb as well.

Thanks for the additional details. It's important to keep in mind that when running a dual master cylinder setup with a balance beam, the effort to generate the same pressure as a tandem master cylinder with the same bore size would be double since you're dividing the force in half through the balance beam when centered, or some fraction if not centered. Mathematically, two MC's with .707" bores will provide the same outlet pressures as a tandem MC with a 1" bore for a given input force, so I'm not surprised that the 3/4 and 7/8 bore units work that much better for you, especially given the smaller piston areas of the Wilwood calipers.

In general, most dual MC setups are geared towards racing applications and pad compounds with much higher CoF's. You most likely have the Wilwood BP-10 pad compound if you're still running what came with the kits. Wilwood does a pretty good job of providing CoF vs. temp data on their various pad compounds, however something like an EBC Yellowstuff pad may do more to help stop a quick-ish 5300# rig with respect to temperature range and CoF than what you have...I'm a little surprised you haven't cooked your BP-10's up front to be honest, but dirt is definitely less punishing on the brakes than asphalt.

 

[markw]

Diversion! Sorry...Say 68ford what are the specifics of your rear brake set up? Do you have any pictures? Thanks, Mark
ps I can start a new thread if you'd like.

 

[68ford]

Thanks for the additional details. It's important to keep in mind that when running a dual master cylinder setup with a balance beam, the effort to generate the same pressure as a tandem master cylinder with the same bore size would be double since you're dividing the force in half through the balance beam when centered, or some fraction if not centered. Mathematically, two MC's with .707" bores will provide the same outlet pressures as a tandem MC with a 1" bore for a given input force, so I'm not surprised that the 3/4 and 7/8 bore units work that much better for you, especially given the smaller piston areas of the Wilwood calipers.

In general, most dual MC setups are geared towards racing applications and pad compounds with much higher CoF's. You most likely have the Wilwood BP-10 pad compound if you're still running what came with the kits. Wilwood does a pretty good job of providing CoF vs. temp data on their various pad compounds, however something like an EBC Yellowstuff pad may do more to help stop a quick-ish 5300# rig with respect to temperature range and CoF than what you have...I'm a little surprised you haven't cooked your BP-10's up front to be honest, but dirt is definitely less punishing on the brakes than asphalt.

There is no way that it takes double the force. When I first installed the the dual master I made no other changes other than the pedal has a slightly higher leverage ratio. Which makes sense because it made it easier to stop the bronco. No brake changes were made at that time. I can not see how 2 pistons side by side verses tandem can require more pedal force to make the same output pressure. When I had 2 1in bore mc it stopped with half the effort of a normal non power assist eb with disc. Now that I went to the 3/4f and 7/8r it little rally takes the weight of my leg to make an average stop at a red light. So if it would take .700 dia mc's to be like a stock 1in mc and my brakes don't have that much more piston area, how is it my bronco stops very well with very little effort while weighing more than most eb's? That just doesn't make sense about dual master side by side taking double the pressure.

 

[68ford]

Diversion! Sorry...Say 68ford what are the specifics of your rear brake set up? Do you have any pictures? Thanks, Mark
ps I can start a new thread if you'd like.

I think they are 12.75 rotors with wilwood superlites 4 piston calipers. I think there are some pics in my gallery or garage. Lots of photos on my Instagram if you want Waynetodd68
https://www.summitracing.com/parts/...Y1pmGABaHpSrrSSkK_RZTgZ4aDfoF_iBoC2EkQAvD_BwE
Those are the calipers I have on the rear.

 

[Apogee]

That just doesn't make sense about dual master side by side taking double the pressure.

I'm not saying that your brakes don't work well, but I didn't make the rules...the universe did with respect to the laws of physics. In a tandem master cylinder, the primary piston generates pressure between it and the secondary piston, thus pushing it with the pressure of the fluid trapped between the two pistons, but there is no mechanical contact unless the system isn't fully bleed or there is something wrong in one of the brake circuits.

For a simplified example, let's say we have a 1.125" bore tandem master cylinder since the piston area is equal to 1 square inch (.9935 in^2) and it makes the math easier to do in our heads. Let's say we apply 100 pounds of force to the brake pedal with a 6:1 pedal ratio and no power brake booster. This means that you have 600 pounds of force into the master cylinder. Since Pressure = Force/Area, the outlet pressure would be 600 PSI, and this would apply to both outlet ports on the tandem master cylinder.

Now look at the same system with a dual MC setup, also with 1.125" bore MCs. That same 600 pound force is divided between two master cylinders, each with a primary piston connected by a balance beam between them. Assuming a centered beam, you will end up with 300 PSI outlet pressure at each master cylinder for the same force applied at the pedal.

I was actually just talking about this with another member here a few days ago, and while the math is pretty simple, there does seem to be a fair amount of confusion on how a tandem master cylinder works. I gave a mechanical analogy that I don't particularly think is the best, but it's what I got, so stand on two cans of the beverage of your choosing, half of your weight will be carried by one can and the other half by the other. In my case, that's 100 pounds on each can. Now stack the cans on top of one another and stand on the top can. Both cans now carry all of the weight, 200 pounds neglecting the additional 12 oz of weight of the top can, they're equal.

To quote Fred Puhn and the Brake Handbook (page 49), "When designing a brake system using a tandem master cylinder, remember that all force applied to the master cylinder is applied to the primary and secondary pistons equally. Force it(sic) is not split like a dual master cylinder system using a balance bar."

Tobin

 

[markw]

Thank you!

 

[68ford]

Then how did my brakes improve by going to a side by side master set up with the same size bores and only slight pedal leverage increase? I'm thinking your equasion is missing something. Possibly needing to pressurize 2 piston in a inline master? It just doesn't make sense.

 

[Apogee]

Then how did my brakes improve by going to a side by side master set up with the same size bores and only slight pedal leverage increase? I'm thinking your equasion is missing something. Possibly needing to pressurize 2 piston in a inline master? It just doesn't make sense.

That's a good question, and one that I can't answer without more info. Even if I did know more variables about the system you replaced (rotor diameter, pad CoF, caliper piston area, etc), it can still be tough to take a guess at the condition or serviceability of those components and how that may have negatively impacted performance. I have replaced/upgraded a lot of muscle car brakes in my life, and anything is better than old worn out 4-wheel drum brakes, so if that's the bar, then it's not very high.

That said, you should be able to take a brake pressure gauge and confirm the math without doing any of the calculations if you like, but at the end of the day, does it really matter so long as you like how your brakes perform?

 

[68ford]

That's a good question, and one that I can't answer without more info. Even if I did know more variables about the system you replaced (rotor diameter, pad CoF, caliper piston area, etc), it can still be tough to take a guess at the condition or serviceability of those components and how that may have negatively impacted performance. I have replaced/upgraded a lot of muscle car brakes in my life, and anything is better than old worn out 4-wheel drum brakes, so if that's the bar, then it's not very high.

That said, you should be able to take a brake pressure gauge and confirm the math without doing any of the calculations if you like, but at the end of the day, does it really matter so long as you like how your brakes perform?

When I originally went to my dual master set up they were both 1in the same as the stock mc I removed. I changed nothing else at that time. The pedal ratio increase minor. The result we're better brakes. My slight pedal ratio increase was nowhere near enough to make up for the 50%reduced power you're stating I should have experienced. The improvement I felt was about exactly the amount of pedal ratio I increased. I do not think you loose any pressure with a side by side set up.

 

[toddz69]

Wayne: I think you have a Bronco with magical brakes . As another mechanical engineer and brake geek reviewing all of Tobin's posts, his and physics are all sound (we just went through this with another guy on another forum). And I don't doubt what you say about the performance of your rig.

Sounds like we need to have a brake geek meet-up sometime in SoCal and do a ride-n-drive in your truck!

Todd Z.

 

[68ford]

Party at my house!!!!

I still think there is more to it. If in a inline master, your making x psi out 2 lines and in a side my side master set up you're making the same psi out of 2 lines, should not the pedal force be the same for both? Why not, why hasn't anyone built a master with 4 pistons and 4 outputs and have even twice as easy pedal pressure? another thing, to my knowledge with hydraulics, when you decrease pressure you also decease pedal travel. When I installed the dual 1in masters, It required no extra force and pedal travel was the same as the stock 1in master and pedal.

 

[68ford]

Just read multiple post from racing forums that state with a inline tandem mc, you still have to push 2 pistons and pedel effort is the same as side by side set ups. This makes perfect sense because I never felt any pressure loss or had to push harder to stop when only changing to my dual set up.