Upgrade front brakes

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Are you sure that Wilwood has a kit for your car? I recall theirs are only for drum-brake cars, which have a different spindle.
What do you mean by "braking power"?` Even drum brakes can skid the tires (unless big sticky racing tires) and that is the limit to braking force. Disk brakes advantage is they cool off faster and are perhaps more balanced between the wheels.
 
BillGrissom said:
Are you sure that Wilwood has a kit for your car? I recall theirs are only for drum-brake cars, which have a different spindle.
What do you mean by "braking power"?` Even drum brakes can skid the tires (unless big sticky racing tires) and that is the limit to braking force. Disk brakes advantage is they cool off faster and are perhaps more balanced between the wheels.
Click to expand...

I really, really wish you’d stop saying that skidding the wheels is the limit to braking force. That’s totally false. There is a difference between static, rolling, and sliding friction, and the relationship between all of them is not linear in a dynamic situation like braking.

If sliding the wheels was the limit to braking force, no one would have bothered to invent ABS brakes. Just jamming on the pedal as hard as you can and skidding to a stop isn’t the fastest way to stop, and it doesn’t apply the most braking force either. Threshold braking requires the most force, and stops the car fastest. Which is why ABS came about, because threshold braking is hard to do consistently even for professionals, but anyone can jam on the pedal and let the ABS system do the work of approximating threshold braking.

Sorry, I don’t mean to hijack the thread, but I’m really sick of this false information being repeated. You’re usually a great source of information, which is why it’s even more glaring that you’re completely wrong about that. If all brakes needed to do was lock up the tires we could all still run drum brakes and stop on a dime, that’s just not how it works.
 
I have never said that skidding the tires is the fastest way to stop. Everyone knows that is not true. They also know that if you can skid the tires then you can reach the ultimate in braking force, which is just before the tires skid. Thus, if your brakes can skid the tires, they are proven capable of reaching the ultimate in braking force. Keep pondering that.
 
To answer my own alarmist question, yes Wilwood does make a front disk kit for 1973+ factory disk cars. What they don't make is a kit for 1972- factory disk cars (Kelsey-Hayes spindle).

72bluNblu may want to read this link:
www.reddit.com/r/cars/comments/430c7l/eli5_why_are_drum_brakes_worse_than_disc
megacookie says exactly the same as I did, i.e. tires stop the car. If the brakes are strong enough to lock up the wheels, they can provide the ultimate braking (just before skidding). Specifically, mega says:

"If it's just a matter of providing the braking force (or torque, technically) to your tires which dictate how quickly you can stop, then drums and discs are pretty evenly matched."

mega is obviously technically educated since he/she doesn't use kid-terms like "powerful", "great pedal", and such. You do see that fluffiness in most articles, even in car magazines from those who didn't learn physics. Given equivalent friction material and such, and the same OD, drum brakes actually provide more braking force on the wheel at the limit of "fade" (where friction force doesn't increase with clamping force) because drums shoes act closer to the OD and have more friction surface area. That also generally takes less line pressure due to the self-amplifying effect of the shoe pivots. Of course, there are many other factors to compare like poorly maintained drum brakes, the amplifying effect is bad if the shoes get gummy stuff (grease, brake fluid), and drum brakes don't dissipate heat as fast. That later isn't an issue in stopping once from 70 mph, but is a big problem if riding the brakes down a mountain or constant hard braking on twisty roads.

Re tires stopping the car, a recent Motor Trend reviewed the new top Camaro and Mustang models. Both stopped from 60 mph in <100 ft, which is amazing. That is most likely due to new sticky tires. Don't rely on the factory spec's on classic Mopars which tested with bias-ply tires. With good tires, optimally proportioned F-R ratio, and good driver technique, your car should be able to stop almost as fast.
 
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Regardless of your ability to stop once or twice with drum brakes at the same rate before they get hot, there are plenty of reasons why you'd want disk brakes.

-Consistent performance in wet conditions, a "soaked" drum stops very poorly
-Modulation (its much easier to control the level of braking force near the limits of your tires)
-Heat dissipation as mentioned
-Consistent adjustment (no worry about pulling side to side)

You won't be able to get these cars to perform like the new high end camaro and mustang models. They electronic brake force distribution to get the proportioning right, ABS, in general better set up suspensions that are probably significantly better in anti-dive and dynamic weight balance. The shocks matter a lot too. I wouldn't want to lead anyone astray saying that only installing tires (I have some relatively comparable tires to some of these newer cars being 275-35-18 Continental ExtremeContact DW), and it was not easy to lock the brakes and it was still tending to rear axle lockup first with the prop valve turned down pretty far. With the hydroboost and the 4-wheel Mustang Cobra disks, it does stop excellent but if I could ever rip off a sub-120 ft stop from 60, I'd still be pretty amazed. I also have a very low ride height, good f-r balance with aluminum heads, and hotchkis suspension and shocks which make a significant difference but you just aren't gonna touch a Ford Mustang GT350R or a Camaro ZL1.

Personally, having a car with the rear disk brakes and seeing how it handles at the limit, I wouldn't build another car with rear drums for any performance driving application. I would also not drive one of these cars with 4-wheel drums on the metro detroit freeway system (or most other metro areas) at 70+
 
The O.P.'s question was upgrading disks from 1973+ factory single-piston sliders to after-market 4-piston, fixed calipers, so drum concerns don't apply (sorry I forgot and brought that in). Many people want to go "big brakes" in many cars. They won't improve one-stop performance, assuming your current rotors can absorb the heat of a 1-time stop without causing fading (discussion above). Many people at the same time change to "racing pads", which are actually bad in a one-stop scenario, since they work better only when they stay hot. So unless road racing on twisty tracks, most people wouldn't see an improvement from "big brakes". There are some advantages in a fixed caliper, but I'll let others comment.
 
The larger rotor will improve it - with everything else being equal it can create more brake torque, however, its an incremental increase and may not be enough to notice. It's the basic concept of the lever or in engineering speak, the moment arm.
 
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