We see these post from guys upgrading their cars with expensive "horse ball" braking systems with slotted,drilled, multi piston calipers, etc.

Question: For normal driving, 0 to 60mph stopping performance, do these systems actually reduce stopping distance?

It seems to me that given modern ABS (and absent high temp racing, mountain road conditions and multiple high speed stops) no benefits would accrue. Mind you, if you have significantly up graded HP and you use it - then it may make sense. But for us regular guys is there a payback over and above what you get with stock?

What do you guys think?

 

The tire build, tire compound, ABS and brake bias control, will play the biggest part.

A lot of brake updates are done because they look good. Having nice painted calipers with embossed logo's really make a car more aggressive in style.

Grooved rotors, and to a lesser extend, slotted rotors, will make a *massive* increase should standing water coat the rotor.

Fancy rotors can help reduce rotating mass, so there is an acceleration benefit. Frankly, we use massively heavy wheel designs on the XK compared to a race car, the wheels can offer an area of significantly better acceleration benefit.

Spray your solid rotors with water, then try to stop. Do the same in a car with grooved or drilled rotors. Huge difference. All it takes is a water puddle to soak the rotor shortly before a major need for braking, and poof, braking ability is seriously inhibited.

One of my Porsche's had fancy rotors, the other stock solid disks. The difference in monsoon situations could be life saving. Most do not drive their XK in monsoon situations.

The primary reason for multi piston, is you end up with a more consistent curve of result relative to increasing pressure. Its much easier to brake accurately to the limits with multi piston brakes. Its quite noticeable to a racer. The ABS can be more precise in its actions if programmed to take advantage. I would say, but only from experience with karts, not cars, there is a noticeable difference in my ability to control the brakes with multi piston calipers vs single piston. With single piston, there are spikier results from brake pedal motion. With multi piston, the result of change is more progressive.

 

In my opinion for the average driver or weekend cruiser there is no difference in OEM vs. upgraded braking systems. I find that most who do the change do it for the cool effect . I like the looks but won't pay the freight .

 

I forgot to mention that a lot of these brake "upgrades" also require replacement of the wheels. WTF?

 

Since the XK brakes are so much better than your average vehicle to BEGIN with, even more performance is negligible. A +10 difference is way more obvious in 30-40 than it is in 90-100.

 

As noted, for the everyday driver, the XK Teves/ATE brakes with a single large piston are adequate for the task. Slotted rotors will improve braking regardless of piston quantity or caliper style. Bigger brakes & rotors usually need at least a 20" wheel to clear the barrel. Multiple small pistons modulate better and allow for more pad friction surface. Besides looks, for track use monoblocks also provide better heat dissipation as well as reliability and serviceability with fewer moving parts.

 

I think you'll find that a lot of people who go for aftermarket brake components are looking for a reduction in dust, or a cheaper price than genuine parts from Jaguar, not necessarily an outright "performance gain".

This is especially true when you consider that the initial bite from a ceramic pad is not as "good" as the softer OEM type pads. But this is a trade-off for a reduction in dust. So in someways, an aftermarket pad could even be considered a step backwards.

When I upgraded the rotors on my XJR to the R1 Concepts ones, I wanted something that was not going to warp like the junk OEM rotors from Jaguar (warped two sets on the front prior) and the additional benefits of a slotted rotor was kind of secondary in the though process. More like "while I'm at it i'll get slotted" rather than "I want slotted"

It was a similar process in choosing the pads, primarily I wanted to get away from the huge volume of dust coming off the OEM pads, the performance benefits of the aftermarket pad were secondary to the dust reduction.

 

^^^^^^^ What he said.

 

On my 2009 Jaguar XKR, I had the optionable Alcon braking system which was a $5000 upgrade to the XKR Portfolio Edition.

The Alcon system had 400mm and 350 mm rotors, the largest that Jaguar ever put on one of their cars. The brake system also had 6 piston ffront calipers and 4 piston rear calipers.

The brake system required a 20" wheel both front and rear.

From my observation driving at normal speeds, this $5000 upgrade was "not" needed or necessary for an average driver.

To replace the Alcon calipers and rotors the replacement cost is quite excessive. The Alcon rotors were slotted "moon's" cut into the rotor.

The rotors were massive compared to many other brake systems found on sports cars.

My suggestion would be to stay with the OEM brake systems unless you're a very aggressive and hard driver or plan to track the vehicle.

Other than looking "cool" the extra expensive to buy the upgrade when new or if making a modification to an existing brake system is not worth the effort, price, or the extra expense to do so.