Wilwood front breaks 13.06 or 12.19 Rotors?

[JGross]

I'm planning on upgrading the front breaks on my 65, I already have junkyard discs but the stopping power isn't where I would like it to be. I will be upgrading to the Wilwood 6 caliper kit but I'm going back and fourth between the 13.06 inch and 12.19 inch rotors. I like the 12 in. rotors because you can get soiled rotors but I want really good stopping power.

Do ya'll think there really is any significant deference in the stopping power between the 12 in and the 13 in rotors?

[vin63]

What are you doing with your truck? Are you autocrossing, or doing a lot of road course racing? If you are, the 13" rotors will help with repeatable hard braking and heat dispersion.

I just use my truck for street use and I run 12" rotors on my C10 with no power assist and the braking is on par with any street vehicle of equal weight that I've driven. I've run this front brake setup for almost 20 years.

[JGross]

Thanks my truck is for street use only so the 12 in. Would work.

[Richard]

For a street driver I suggest looking into a hydroboost unit using oem parts for easy maintenance (maybe suggest later model parts for brakes). Will provide a lot more stopping power due to increased clamping pressure. Drilled and slotted performance rotors actually provide less initial braking power than a solid rotor. Yes, they do not heat up as fast in heavy use. No need for a driver, but if you want the look, that is cool. Used all oem stuff on rear of my truck for maintenance reasons. The front caliper brackets are the only aftermarket part used on the front.

[theastronaut]

What exactly do you mean by "stopping power"?

Any stock drum brake or disc brake in good working condition should have enough "braking power" to make 100% use of the grip that any street tire has, even without a brake booster. If your brakes can't make use of your tire's grip then you have a brake issue or a weak leg.

Are you just looking for an easier pedal? Do you think your current setup takes too much effort to stop, or does it actually not have enough brake strength to stop the truck reasonably well? Can you lock up the brakes at any legal speed?

I have the usual squarebody style discs on the front of my '66 C10, nothing fancy, with semi-metallic pads. It has a manual 1" bore master cylinder and stock rear drums. It has plenty of braking power even when towing 3500 pounds. The brakes are plenty strong enough to overpower how much grip the tire has, so if I wanted to stop shorter then I'd have to swap to grippier tires, not better brakes. If I added a booster it would just make it easier to lock up the tires but it wouldn't actually stop better/shorter.

Brake pads make a big difference. Ceramic pads last a long time and don't make much dust but they don't generate nearly as much friction as semi-metallic pads. If you have ceramic pads then it won't stop as easily- more pedal pressure is needed to make the same amount of friction compared to semi-metallic pads. Pads are rated by how much friction they make- look for a two letter code on them. C is the lowest rating, usually FF on better street pads or as high as HH on race pads. One letter is the cold rating, one is the hot rating.

Pads also need to be properly bedded in or they won't make as much friction as they should. If you haven't bedded in the pads, look up that procedure and try it, it'll make a very noticeable difference in how well the brakes work.

Big aftermarket brakes or hydroboost- tons of extra braking power is really a waste unless you also have really sticky tires that grip better to actually stop shorter. Bigger brakes are also somewhat of a waste with ceramic/lower friction pads. On a system that doesn't have abs you can have brakes that have too much braking power with very little pedal effort and that makes it difficult to brake hard without locking the tires up because they're hard to modulate.

[bigmoe]

My thoughts exactly Astronaut. At a certain point the wheels will lock up. The limiting factor will be tire grip.
The OP might also want to consider wheel fitment with the bigger brakes.

[theastronaut]

Originally Posted by bigmoe

My thoughts exactly Astronaut. At a certain point the wheels will lock up. The limiting factor will be tire grip.
The OP might also want to consider wheel fitment with the bigger brakes.

One good thing about bigger brakes is that they need bigger wheels which opens up the option of better tires with more modern designs and better tread compounds. Just having wide 15" wheels/tires doesn't help all that much if it's outdated and the compound is on the harder side, which is 95% of 15" tires I normally see on trucks. With 17"+ wheels you can get a variety of better tires in grippier compounds, especially so in 18-20".


My autocross car has completely stock brakes. They're tiny 8.6" non-vented disc with tiny 2" bore single piston calipers up front, and even smaller 6.7" drums in the rear.

With good semi-metallic pads it stops well with the usual sized street tires. There are a fair amount of people in the facebook group for these cars complaining that the stock brakes aren't very good, but they haven't been maintained or they're using ceramic pads, or haven't done proper bed-in, or all of the above.

With my 100tw track tires it will stop from 80 within 4-5 seconds. It's downright violent how hard it stops, and anyone that's rode in it has said its the hardest stopping car they've ever been in. Now, they will fade if I do 10-12 hard stops back to back from 80-20, so for track use with more power I'd need to get vented rotors and pads that work at higher temps, but for street and autocross stock is all it needs, and they're exceptionally easy to modulate because it isn't over-braked with too much braking power. It will still lock up track tires at 80 so it has more than enough braking power. The added tire grip is what makes it stop so much harder.


I don't see much ever mentioned on truck forums other than "you need a booster" or "you need better/bigger brakes". There's no need to waste big brakes on a street truck with the usual street tires, it just makes the wheels lock up and slide easier. Without abs you don't want an easy/light pedal, you want it to take some effort to lock up the brakes so you can modulate the brakes easier.

[vin63]

Originally Posted by JGross

Thanks my truck is for street use only so the 12 in. Would work.

Got it. Yeah, I have to drive in a lot of stop-and-go freeway traffic in the Los Angeles area, and the brakes on my truck have served me well.

Not sure if this matters to you, but the 12" rotor setup, also allowed me to run the American Rebel Mfg. 15" vintage-style wheels, which are faithful reproductions of the Halibrand Sprints. So, it doesn't restrict you to only running 16", or larger diameter wheels.