I'm talking modern disc brakes here, not Kinmont, not brakes hidden behind a fake Buick drum and not some GM caliper with an adapter. In these days of 2025 and beyond and the craziness of modern traffic (here in Omaha, NE for example), I've been thinking about some upgrades on my Model A Roadster and being comfortable with driving it more often. Before anyone preaches to me about the abilities of a well maintained set of drum brakes, I know, I know.... That being said, I've been thinking about converting to a full Wilwood 4-wheel disc setup on my roadster. '40 Ford style spindles up front, 9" Ford rear. Yep, you'll be able to easily see them up front, being an open-wheel hot rod. Has anyone else done this?
https://www.speedwaymotors.com/shop...sc-brake-kits~67727-10029-1-225-6-3-495-30460 I'm seeing 152 different choices (wow) for the rear. Priced from about a grand to 2 and a half times that. It appears they are really serious about street stuff, which was not as common in the past. Looks like a bunch of Ebrake choices are there too. With that kind of selection, I'd be calling and talking to tech to get proper sizing and features you want thru the entire system. Car weight and F/R balance, track width F/R and wheel/tire sizes and brands should be part of the process. If it's the Model A in your avatar, you probably don't need 14 inch rear rotors! I'll also mention that tires will make a huge difference in brake performance.
Thank you for chiming in. You are correct - the roadster in my avatar. I should have mentioned that I'm planning to upgrade the wheel/tire setup at the same time. Likely a Halibrand style set from American Rebel or 5-spokes from Team III/ET. I will definitely be making a call to help with the rear selection. Front appears to be pretty straight forward. Black calipers, for sure - Wilwood Disc Brakes - Front Brake Kit Description
Confirm fronts are sized to rears and get M/C and pedal ratio recommendations, too. They should know what works together and probably prefer providing input before the sale over trying to troubleshoot after sales. A light car with staggered tires is typical for hot rods, but is different to most other street use. It's good that they provide the note *This Brake Kit may fit 15-inch wheels. Please refer to the wheel clearance diagram to check to see if it will fit your specific wheel. But I doubt most wheel places have the radius specs for the wheels published!
Generally if it's a "disc brake" type wheel, it will clear. If it's an older "drum brake" type wheel, it probably won't, but it might if it's real skinny. My vette has wilwoods all around. I can use stock drum brake steel wheels on the back, but not the front.
My exp. : using a Ford explorer or crown vic setup on the rear is more than adequate. Not much weight to be a factor in rear wheel lockup. I have used the GM metric calipers on the front twice with dismal results. I have used the GM full size calipers with good results. As you are aware, rotating wheels are flywheels so the less weight, the more responsive the braking. I am in complete agreement on your statement about needing short stopping distances. We never know what may happen.
The wilwood stuff weighs about half as much as the OEM brakes. And costs twice as much. For some cars it's worth it, for others it isn't.
For your own curiosity as well as the rest of us, when you do the switch, try to spare a few minutes and weigh the before and after parts. It's a shame there isn't more What's This Weigh info here. Most rods are pretty light and weight savings is important, especially unsprung weight.
I dig my stock S10 finned calipers on the back of my T. No regrets on the discs, they are so easy to drive, I haven't had any issues, and honestly haven't touched them in a year or more. I bought a set of 80's finned corvette Calipers for the front of dad's car, cause it had a set of GM metric calipers on it, and they are way too big for the front of a hot rod. but the finned calipers fit the part pretty well. I might be interested if you want to sell your current front drum brakes .
I like the look of the mid 80’s vette callipers. Roadster Supply has this option for the front. I don’t see an option for the rear. But my Dad’s ‘34 has a 9” with a set of the same vintage vette rear calipers mounted on it. I don’t care for the E brake as it’s mounted on the pinion. But the car is an auto so it doesn’t really get used.
A few years ago I bought a neglected T roadster, had been purchased for the grandkids and they got the drag racing bug and the car sat for 20 years in a hog shed. It had disc brakes all around. I'd have to look but I think all/most of the brake parts came from Speedway. It stops on a dime with no power ***ist (well it only weighs 2400 pounds). The park brake is built into the disc ***embly also and works fine. I live across the river from you if you would want to look at it.
I'm curious about how you would plumb that. Would you need a proportioning valve? I ask because I am doing this to my 56 F100, when it gets to that point. Also, what type of MC would you use? Bore wise? I love the idea of Wilwoods, but there has to be a cheaper, off the shelf option.
I upgraded to 4 wheel disc on my roadster, I never thought they looked good but the way people drive distracted, the disc brakes saved my bacon a few times. HRP
I also used to be concerned about the appearance of disc brakes on a hot rod, but I'm way more concerned about brake function in today's crazy traffic.
I have 4 wheel discs on my dune buggy, best have the shoulder harnesses snug before jabbing the brake pedal. Does make for good brake turning.
Not much to add here other than I have run 40-48 ford and 39 Lincoln 16” steel wheels on my 46” with disc in front and have had zero clearance issues. 12” ( or maybe 11 3/4) 1974 ish f truck rotors on 46 spindles with the great big metric rotors off a big GM. I usually ask for a 74 impala if I need pads etc.
My Model A rod, I put 110k miles on it with 4 wheel drum brakes. My Deuce has Wilwood front, drum rear, over 60k miles. Never found either to be unsafe.
I’m not doubting or questioning your decisions, I’m purely trying to educate myself. In such a light roadster, I’m with you 100% on front disc, but rears seem unnecessary, as the fronts do most of the work. Does the added stopping power of rear discs keep the fronts from locking up? Unless we start putting ABS on our hot rods, keeping them from locking up is the goal. My 40 sedan would lock up the fronts pretty easy, but it was more the skinny contact patch of the tires. (It had f100 drums) Again, not looking argue, just learn.
You do make a very good point. I need to go through the brakes on my roadster, replace wear parts, clean, lots of general maintenance, etc. I had the thought of just going all-in and doing 4-wheel disc like a modern vehicle. In reality, doing just front disc and upgrading the rear drums would likely be more than adequate. Right now, the rears are a combination of '57 Ford car and later F100 parts that don't work the best.
I’d think that’s where a proportioning valve comes in handy to bias it to the front. After pricing old drum brake parts and new higher performing disc brake parts I can see the thought process in just replacing it all with the discs.
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