Just because your brakes are bigger doesn’t mean your vehicle stops better
Part 4 of Jeff Melnychuk’s series on rebuilding a 1965 Mustang.
So we know that stopping is good, and we know that stopping better than anyone else gives us the edge on the street in terms of safety and on the track in terms of performance.
But, there’s a curve ball in all this: Just because you transplant bigger and better brakes onto your vehicle doesn’t necessarily mean it will stop any better than before.
Granted, it would take a lot to really mess this up, but there is a big difference between parts that simply fit and parts that actually fit and work properly. Here is where the word ‘tuning’ enters into your vocabulary.
Take the Project Plymouth. The Stoptech-brand brakes were part of a complete package that had been designed inside a computer and verified on the racetrack along with the chassis and suspension.
The company — New York-based XV Motorsports (now XV Racing) — had some big money in the development, which is more than can be said for the budget brake conversion kit for the Mustang.
We just weren’t that lucky.
Swapping rear drum brakes to a non-matching disc setup may be foolhardy
To possibly makes matters worse, when we think we’re doing a good deed, we swapped the rear drum brakes to a non-matching disc setup.
OK, if you haven’t figured this out yet, we’re bolting in parts that fit, but parts that haven’t actually been engineered to work together on this particular car, with only the seat of our pants to tell us if we’re making any progress at all.
Foolhardy, perhaps, since we’re dealing with such an important system as brakes, but this experience actually squares with what goes on in many shops around the country.
But, let’s say that you bolt in a kit and you take the car out on the road and there’s an improvement and it is, in fact, noticeable. Great, but is it the best it could be? And can you ever find out?
The relationship between the front and rear brakes is critical for vehicle control.
Too much rear brake bias, in particular, creates a premature rear lockup condition that can pitch the vehicle out of control. To vary this bias requires a proportioning valve that attaches inline with rear brakes to make it easy to adjust the ‘proportioning’ of the front/rear braking force.
Still, messing around with this takes time and a wide-open parking lot to even get close to being optimal.
The thing is that new systems are so much better than the old systems that it would be tough not to see some kind of improvement, even with very basic tuning.
1965 Mustang has rear brakes from Wilwood and front brakes from a 2004 Mustang Cobra
The Mustang’s front kit uses 13-inch rotors and two-piston calipers from a 2004 Mustang Cobra, while the rear kit is from Wilwood Disc Brakes, which includes 12.2-inch rotors and four-piston calipers. Clearly not intended to work together and clearly not intended to work together in this car, but that’s what we got that fits.
Once the parts were put on the 1965, an afternoon was spent attempting to get the right proportioning between the front/rear brakes, via the proportioning valve, of course.
Is it perfect? Nope. Is it even optimal? Probably not. But, it’s a damned sight better than the stock brakes, which is kinda-sorta the point.
The bottom line is that if you have the choice between purchasing a complete engineered brake system for your vehicle or one that simply fits, requiring you to be the engineer, take Option A every time.
You’ll be money, performance and peace of mind ahead.
1965 Mustang Rebuild – Catch up on the series here:
Part 1, click here.
Part 2, click here.
Part 3, click here.
Part 4, click here. (You are here)
Part 5, click here.
Part 6, click here.
Part 7, click here.