Brake Upgrade - What Lies Beneath

We install a new brakes system on our '72 coupe

Jeremy D. Clough Jul 30, 2012 0 Comment(s)
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...Shorter Stops

With the new master cylinder, calipers, and rotors installed, I was curious to see what kind of real-world difference the new system made, so I contacted Summit Racing and acquired an Autometer D-PIC. A standard 21?16-inch gauge, the D-PIC is an accelerometer capable of measuring parameters such as acceleration, deceleration, and lateral g's. Since the C3 isn't known for having a lot of extra dash space, and I'd already hidden a nitrous gauge in the ashtray, I looked for a way to mount the D-PIC on the A-pillar. Unfortunately, while Autometer offers a blue million gauge pods, they've inexplicably missed the C3. I did, however, acquire one for an '82-'92 Camaro/Firebird, which I was able to modify with a heat gun to fit my A-pillar and mount using trim adhesive.

Wiring it up was simple: Autometer suggests including a 1-amp fuse, so I picked one up at the local auto-parts store and wired that into the positive power, which I got by tapping into the switched-power line going to the electric fuel pump. I similarly tapped into a ground wire that went to the engine block, then wired the third white wire to the headlight circuit. While you technically only need positive power and ground to run the D-PIC, the white wire causes the gauge to dim when the headlights are on, which is a good thing, as it would otherwise be bright enough at night to be distracting.

Tuck all the wires out of the way, scrape off the excess adhesive, and off you go. Thanks to the kindness of our local sheriff and chief deputy, I was able to get a section of road closed off to allow for safe testing both before and after the installation of the new brakes. Setting up the D-PIC was easy: First I used the setup menu to make sure it was calibrated properly, then lined up the car to run it.

While the D-PIC measures 0-60 times, rear-wheel horsepower, lateral and forward/backwards g's and quarter-miles, the 60-0 feature is what mattered to me. Press the "mode" button on the left until "60-0" appears, and click "enter." The unit will show "cal," then the word "GO." Once you start accelerating, it will indicate speed until you're above 60, when the whole dial will flash and command you to "STOP," and then display the braking distance once you have.

I got in six runs with the stock calipers before picking up a nail in a rear tire. Stopping distances averaged 148 feet using threshold braking, with a best of 143 feet and a worst of 153. With the new brakes installed, my best six runs out of 11 averaged 138 feet, with a best of 135, putting the car about halfway between a stock C3 and a C4 or C5, which both stopped in something like 125 feet.

I should note, however, that the rear tires locked up before the fronts did, which tells me the bias needs to be adjusted, since it should be the other way around. With that changed, I'd expect to see the stopping-distance numbers drop even more. As it is, the brakes have a much firmer, more responsive feel. While they are by no means grabby, it requires a lighter touch to threshold brake, as the greater clamping force means they tend to lock up quicker than stock brakes, requiring more skill to hold the tires at the limit of traction. This is as it should be.

Of course, one of the greatest limiting factors on how quickly you can stop a car is how much road traction the tires give you--and I think it's about time we did something about that next.

Special thanks to Bob Ingram, April Owenby, Paul at Arrowood's Automotive, and William Stoner.


Wilwood Brakes
Camarillo, CA 93012


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