• Welcome to ClassicBroncos! - You are currently viewing the forums as a GUEST. To take advantage of all the site features, please take a moment to register. It's fast, simple and absolutely free. So please join our community today!
    If you have problems registering or can't log into your account, please contact Admin.

Wildwood Front Disc Brake Concern

TX SS

Contributor
Sr. Member
Joined
Aug 29, 2013
Messages
751
Loc.
Houston
Yes they fit stock 15" rims but you have to run a .25" spacer as noted on bottom of page 3 of instructions. I'm running this kit on my Bronco.
 

Attachments

  • IMG_1251.jpg
    IMG_1251.jpg
    111.6 KB · Views: 210

Apogee

Contributor
Bronco Guru
Joined
Nov 26, 2005
Messages
6,033
It's Wilwood...not Wildwood. Instructions and fitment templates are avialable for download on Wilwood's website here.

Fitment will depend in large part on the wheel.
 

toddz69

Sponsor/Vendor
Bronco Guru
Joined
Nov 28, 2001
Messages
10,080
It's hard to beat the sexiness of 6 piston calipers and aftermarket rotors, but I always wonder if this is really an 'upgrade' or not.....the rotor is almost 0.5" thinner than stock and the combined piston area on those calipers don't equal the surface area of one stock Ford or GM single piston caliper.

Todd Z.
 

Apogee

Contributor
Bronco Guru
Joined
Nov 26, 2005
Messages
6,033
It's hard to beat the sexiness of 6 piston calipers and aftermarket rotors, but I always wonder if this is really an 'upgrade' or not.....the rotor is almost 0.5" thinner than stock and the combined piston area on those calipers don't equal the surface area of one stock Ford or GM single piston caliper.

Todd Z.

Aside from Wilwood just having something to offer for the 15" wheel crowd, I don't really see the justification for the 11.75x.81 rotor Dynapro kit, at least not from a performance perspective. It leverages components they already have, and people clearly buy them, so I guess that's answer enough.

But you're right Todd, the Dynapro kit it has less thermal mass and roughly comparable pad volume to the factory brakes Ford or GM disc brakes, but about 25% less piston area. The smaller piston area can be overcome with the master cylinder bore size/booster/pedal ratio, however you then create a situation where you mess up the front/rear brake bias if you're not "upgrading" the rear brakes at the same time with a matched kit. I don't have a weight comparison, but I'm sure the Wilwood kit is lighter by a significant amount, but how concerned are most of us with our rotational, unsprung weights?

With all that said, the larger 12.88x1.25 and 14x1.25 rotor Wilwood kits do appear to be a step up in terms of thermal mass, but the same issues apply with respect to caliper piston area and front/rear brake bias.

Tobin
 
OP
OP
75Denver

75Denver

Sr. Member
Joined
Jun 5, 2007
Messages
571
Yes they fit stock 15" rims but you have to run a .25" spacer as noted on bottom of page 3 of instructions. I'm running this kit on my Bronco.

Thank you! That's the info I was looking for. In fact, I read through that and even called a couple places that sell Wilwod and they didn't know. That answers that. Unfortunately, I'm not a fan of wheel spacers so I'll weigh the pros and cons to keeping this set.

It's Wilwood...not Wildwood. Instructions and fitment templates are avialable for download on Wilwood's website here.

Fitment will depend in large part on the wheel.

Thank you MacBook Pro for the autocorrect and thank you Apogee for the copy edit;D

It's hard to beat the sexiness of 6 piston calipers and aftermarket rotors, but I always wonder if this is really an 'upgrade' or not.....the rotor is almost 0.5" thinner than stock and the combined piston area on those calipers don't equal the surface area of one stock Ford or GM single piston caliper.

Todd Z.

My initial plan was for a complete factory kit but my connection for a set of '76 stock setup fell through. I was hoping these would be far greater but if what you say is true, that doesn't seem like a great advantage to cost difference?:?. But damn they are sexy!


Aside from Wilwood just having something to offer for the 15" wheel crowd, I don't really see the justification for the 11.75x.81 rotor Dynapro kit, at least not from a performance perspective. It leverages components they already have, and people clearly buy them, so I guess that's answer enough.

But you're right Todd, the Dynapro kit it has less thermal mass and roughly comparable pad volume to the factory brakes Ford or GM disc brakes, but about 25% less piston area. The smaller piston area can be overcome with the master cylinder bore size/booster/pedal ratio, however you then create a situation where you mess up the front/rear brake bias if you're not "upgrading" the rear brakes at the same time with a matched kit. I don't have a weight comparison, but I'm sure the Wilwood kit is lighter by a significant amount, but how concerned are most of us with our rotational, unsprung weights?

With all that said, the larger 12.88x1.25 and 14x1.25 rotor Wilwood kits do appear to be a step up in terms of thermal mass, but the same issues apply with respect to caliper piston area and front/rear brake bias.

Tobin

As I mentioned prior, this was an impulse purchase so more research will be required before setting up the right balance, but is it safe to say that I'll be forced into matching the kit with a Wilwood PDB booster/master cylinder? Or can I get away with a factory design booster and offset the braking force with a p-valve? I plan on keeping factory drum in the rear.
 
Last edited:

Apogee

Contributor
Bronco Guru
Joined
Nov 26, 2005
Messages
6,033
...As I mentioned prior, this was an impulse purchase so more research will be required before setting up the right balance, but is it safe to say that I'll be forced into matching the kit with a Wilwood PDB booster/master cylinder? Or can I get away with a factory design booster and offset the braking force with a p-valve? I plan on keeping factory drum in the rear.

You gotta love autocorrect. As for the final brake setup, brand doesn't matter as much as the specific details of piston area, rotor diameter, pad compound, etc. If I were running the Wilwood Dynapro kit you have up front, I would pair that with something like a Explorer rear disc brake kit, adjustable proportioning valve and a 15/16" to 1" bore master cylinder mounted to a dual-8" booster assuming adequate vacuum levels at idle to support vacuum assisted brakes. The Explorer rear calipers are single-45mm piston units with ~2.47 square inches of piston area, paired with a 285x12mm [11.22"x.47"] non-vented rotor.

There are some Wilwood kit options with their 4-piston Dynalite or Dynapro kits that could pair up pretty well too, so if you want it to be all matchy-matchy, you have that choice. You would need to determine which 9" housing ends you have, axle offset, etc, so that you can pick a matching kit.
 

ntsqd

heratic car camper
Joined
Jan 30, 2005
Messages
3,229
Loc.
Upper SoKA
Leave the Dynalite kits on the shelf. The Dynapro's are a much better caliper design even if their pad volume isn't huge.
 
OP
OP
75Denver

75Denver

Sr. Member
Joined
Jun 5, 2007
Messages
571
You gotta love autocorrect. As for the final brake setup, brand doesn't matter as much as the specific details of piston area, rotor diameter, pad compound, etc. If I were running the Wilwood Dynapro kit you have up front, I would pair that with something like a Explorer rear disc brake kit, adjustable proportioning valve and a 15/16" to 1" bore master cylinder mounted to a dual-8" booster assuming adequate vacuum levels at idle to support vacuum assisted brakes. The Explorer rear calipers are single-45mm piston units with ~2.47 square inches of piston area, paired with a 285x12mm [11.22"x.47"] non-vented rotor.

There are some Wilwood kit options with their 4-piston Dynalite or Dynapro kits that could pair up pretty well too, so if you want it to be all matchy-matchy, you have that choice. You would need to determine which 9" housing ends you have, axle offset, etc, so that you can pick a matching kit.

That's SO much more work necessary for a bone stock Bronco. I'll continue my hunt for a factory setup. Thank you for all the great information though! I'm sure it will help the next guy. I don't think these brakes are for me.

They are sexy! Look great on a rock crawler! ;)

Wanna build a rock crawler next?? I have a set of brakes for you!;D
 

toddz69

Sponsor/Vendor
Bronco Guru
Joined
Nov 28, 2001
Messages
10,080
They are the Dynapro 6 calipers. They have 6 Pistons measuring 1.62'' / 1.38'' / 1.38'' Bore Sizes on each half. The T Bird piston is size is 3 3/32 inch on one side.

The T Bird area is 7.518 and the Wilwood total area is 10.105, about 25% Greater than the T Bird.

Except that in braking calculations, you only count the piston areas on one side of the caliper, which in this case is 5.05 sq.in.

http://www.wilwood.com/Calipers/CaliperProd.aspx?itemno=120-10123

Todd Z.
 

American180

Full Member
Joined
Sep 22, 2017
Messages
184
Loc.
Mount Washington, Ky
Except that in braking calculations, you only count the piston areas on one side of the caliper, which in this case is 5.05 sq.in.

http://www.wilwood.com/Calipers/CaliperProd.aspx?itemno=120-10123

Todd Z.

Thanks for the correction Todd Z. What is the real benefit of pistons on both side then? All high end brakes use them.

Edit: This really craps in my Cheerios. I was going to get this kit and the disc rear for my 74. Now I don't know what to do.
 
Last edited:

toddz69

Sponsor/Vendor
Bronco Guru
Joined
Nov 28, 2001
Messages
10,080
Thanks for the correction Todd Z. What is the real benefit of pistons on both side then? All high end brakes use them.

Edit: This really craps in my Cheerios. I was going to get this kit and the disc rear for my 74. Now I don't know what to do.

Well I wouldn't let the info dissuade you from using the kits. I'm sure they work just fine. No personal experience with them myself.

You're right - high end kits used fixed calipers. They are usually more rigid than floating calipers and engage the pads to the rotors more squarely than floaters. The multi-piston calipers usually mean better pad engagement and more even pad wear too.

Todd Z.
 

ntsqd

heratic car camper
Joined
Jan 30, 2005
Messages
3,229
Loc.
Upper SoKA
I'm not really sure why this standard was chosen, but it could easily be piston areas of both sides although the "piston area" of the non-piston side of a sliding caliper isn't real obvious. So it is a math thing and not indicative of any design superiority of either design.

As to why a fixed caliper vs. a sliding caliper, let me dig out my soap-box.....

Sliding calipers are an economic to mfg design, but they are an inferior braking solution at the outer limits. For an appliance type vehicle they're fine. Until they quit sliding, then not so much. Later designs, like the Exploder RDB's are better at shrugging off grit & dirt so they don't lock-up and fail to slide. I think that the GM caliper sliding design is superior to the Ford design. When I was more frequently involved with brakes I saw the Ford design not easily moving a lot more often than I saw the GM design doing so, but both suffer when not maintained. A thin smear of dielectric silicone grease on the sliding surfaces goes a long ways. Finely detailed and well maintained a sliding caliper usually wears out the inner pad by somewhere between slightly faster to moderately faster. Poorly maintained and the wear difference can be really significant. The culprit is the friction in sliding the caliper subtracting from the force on the outer pad. When you see the outer pad worn out and the inner is still serviceable you know the caliper isn't sliding much if at all and it is bad enough that it is causing the the outer pad to drag excessively.

Sliders flex a LOT more than a well designed fixed body caliper. The way that caliper flex was measured when I was doing design work in brakes was to use a block of aluminum between the pistons. We strived to use a block that was a snug fit between the pistons when they were fully inserted in the caliper body. Then a master cylinder was bolted to a very rigid bracket that allowed the use a big bolt to move the m/c piston. Attached to the m/c piston was an LVDT, a position sensor, and on the output port there was a pressure transducer. There was a braided SS flex hose used to couple the caliper to the m/c assembly. A data acquisition system gathered up the pressure sensor and LVDT outputs and we imported that into Excel where we could plot pressure vs. travel distance.

Before each test the far end of the hose was plugged and the m/c was run up to max output pressure. Then we would run the caliper flex test. In Excel we used the plugged hose data as our relative zero so that in flex in the hose etc. wasn't included in the results. I do not recall specifics (it was ~15 years ago!), but as a general rule sliding calipers flexed roughly twice as much as the worst (most flexy) of the fixed body calipers.
That flex shows up as excess pedal travel and a slightly more "mushy" feeling brake pedal. Most people won't notice this or don't care, but some will and do. Or say they do because they've spent a big chunk of cash on such systems.... ;D

As Tobin mentioned above, the whole thing is scalable, with a smaller piston area caliper you simply use a proportionately smaller piston area master cylinder. I feel that it is much more important to get the front areas ratio correct first. Can then work out how or what to do to get the overall brake system balance i.e. the front to rear balance. It is most ideal when the ratio of front to rear caliper piston areas is such that minimal proportioning correction is needed, but that isn't always possible and is what proportioning valves try to address.
 

American180

Full Member
Joined
Sep 22, 2017
Messages
184
Loc.
Mount Washington, Ky
Thank you ntsqd for the write up, it's very helpful. I'm doing a Coyote swap and I wanted an equally updated braking system. My thinking is if I go with the Wilwood disc kits for the front and back. Plus get the wildwood power booster and master cylinder, I'd have a good balanced system designed to work together. My heads about to explode thinking about what system to use. Plus that way is more expensive. Plan B is going with the one of the new 76-77 kits with beefed up knuckles and T Bird calipers, the keep the drums on back.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
Now if you go above 15" rims, Wilwood does have some big brake kits that are a good upgrade. But you need the bigger rims to fit them. It is still impressive today that they managed to find a was to put 12" rotors inside 15" rims back in the 70's. A few years back I had a car that got a 12" rotor big brake upgrade and it required high clearance 17" rims (not just 17" rims but special ones with extra clearance).
 

ntsqd

heratic car camper
Joined
Jan 30, 2005
Messages
3,229
Loc.
Upper SoKA
No experience with the T-bird calipers; can say that the GM front calipers with Exploder rear discs and H-B using the Strange Engineering 1.125" m/c from Summit (Mopar m/c) stopped 37's impressively well. With 35's it works even better. There is an adjustable proportioning valve in the rear system though at the moment I've no idea where it is set. A large difference is that my wheel base is 130"

Pedal feel comes from the hydraulic ratio of the m/c to the hydraulic actuators at the wheels, coupled with the booster's force I/O curve if there is one. Braking balance comes from the ratio of available brake torque at each axle. Stopping power comes from the rotor diameters more than the caliper piston area. Fade resistance comes from rotor width. These are generalizations, there are qualifiers and exceptions to every one of them, but in general they are true.
 

Mike Bernard

Newbie
Joined
Dec 4, 2015
Messages
30
I have the Wilwood set up front and back for the 15 wheels, Wilwood MC, and hydratech hydroboost. It is amazing how well it works. the Bronco Stops on a dime now, it is better than my 2003 f250.
 
Top