It’s honestly hard too say - the Wilwood front kit actually has too much piston area compared to the OEM calipers (4.04 in^2 compared to stock 3.54 in^2), which moves brake bias way forward especially with the larger front rotors. You’re increasing front by almost 30%, So you need to do *something* in the rear or you’ll be underutilizing the rear brakes.
For reference, the stock bias with 278/253 rotors and 54/34mm pistons is 73% F, 27% rear. With the wilwoods up front only, that makes 78% front, 22% rear, which likely leaves a bit of rear grip on the table.
It’s not as big a problem with modern ABS regulated proportioning but with that much front bias, you’ll have grabby brakes that feel good and handle heat well, but if you go to the track actually have lower peak/threshold braking before the ABS kicks in (basicallly means longer stopping distance). The reason is that front tires only have so much grip, and if there’s still any weight on the rear axle, there’s extra braking grip that’s just not being used.
The rear wilwood kit uses the same as OEM piston diameter on a 300mm rotor, so while you probably won’t have any issues, (and it will probably make up for the front piston diameter)
Looking at the diagrams, the issue I’m seeing is that the Wilwood kit is designed not just for the drum hubs, but also for the drum rear torsion beam.
The difference in the service manual is that the disc hubs bolt on from the inside (threaded holes on the hub), and the drum type actually bolt in from the outside (threads on the torsion beam flange. The Wilwood bracket bolts onto the exterior of the hub, where there’s no bolt head on the disc version.
That said, I think you *can* make it work from what I see in the Wilwood diagram. What you’ll have to do is get some drum hubs, and get long enough bolts to put a bolt, washer and nut through the flanges to hold the hub and Wilwood bracket in place. Hopefully the longer bolts can actually fit behind the hub, or you’ll have to get creative.
Keep in mind this gets into custom DIY/race car parts modification kind of territory, so if you’re going to do it, make sure you are comfortable and know what you’re doing as you’ll be mounting not just the brake caliper, but also the hub (that holds the wheel on) in a way that is different from the both the Ford factory and Wilwood kit design.
The OEM bolting method uses torque-to-yield 10.9 bolts, so at a minimum you’ll need too locate appropriate class 12.9 bolts, nuts *and* washers, or better yet, ARP bolts, nuts and washers. Also you’ll have to determine the correct torque value to use, as you cannot blindly use the factory torque-to-yield method on class 12+ hardware.
If it sounds a little sketchy and out of your comfort zone, I would not do it. I’m trying to strike a balance in advice here between “go custom!” and “realize you’re trusting your life to this DIY solution”. Don’t just take my instructions blindly.
The “safer” option would be the SVT/ST180 brackets and rotor, which will would be fine.
For reference, the stock bias with 278/253 rotors and 54/34mm pistons is 73% F, 27% rear. With the wilwoods up front only, that makes 78% front, 22% rear, which likely leaves a bit of rear grip on the table.
It’s not as big a problem with modern ABS regulated proportioning but with that much front bias, you’ll have grabby brakes that feel good and handle heat well, but if you go to the track actually have lower peak/threshold braking before the ABS kicks in (basicallly means longer stopping distance). The reason is that front tires only have so much grip, and if there’s still any weight on the rear axle, there’s extra braking grip that’s just not being used.
The rear wilwood kit uses the same as OEM piston diameter on a 300mm rotor, so while you probably won’t have any issues, (and it will probably make up for the front piston diameter)
Looking at the diagrams, the issue I’m seeing is that the Wilwood kit is designed not just for the drum hubs, but also for the drum rear torsion beam.
The difference in the service manual is that the disc hubs bolt on from the inside (threaded holes on the hub), and the drum type actually bolt in from the outside (threads on the torsion beam flange. The Wilwood bracket bolts onto the exterior of the hub, where there’s no bolt head on the disc version.
That said, I think you *can* make it work from what I see in the Wilwood diagram. What you’ll have to do is get some drum hubs, and get long enough bolts to put a bolt, washer and nut through the flanges to hold the hub and Wilwood bracket in place. Hopefully the longer bolts can actually fit behind the hub, or you’ll have to get creative.
Keep in mind this gets into custom DIY/race car parts modification kind of territory, so if you’re going to do it, make sure you are comfortable and know what you’re doing as you’ll be mounting not just the brake caliper, but also the hub (that holds the wheel on) in a way that is different from the both the Ford factory and Wilwood kit design.
The OEM bolting method uses torque-to-yield 10.9 bolts, so at a minimum you’ll need too locate appropriate class 12.9 bolts, nuts *and* washers, or better yet, ARP bolts, nuts and washers. Also you’ll have to determine the correct torque value to use, as you cannot blindly use the factory torque-to-yield method on class 12+ hardware.
If it sounds a little sketchy and out of your comfort zone, I would not do it. I’m trying to strike a balance in advice here between “go custom!” and “realize you’re trusting your life to this DIY solution”. Don’t just take my instructions blindly.
The “safer” option would be the SVT/ST180 brackets and rotor, which will would be fine.
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