While we're having a great deal of fun here at Jaguars Unlimited, we are extremely concerned about your safety. We have been designing the cars to go faster and faster, and we have also been improving the braking system as well. The series I XKE and the MK II seem to have the poorest braking systems. The XKE II & XKE III have an improved Girling system.
The XKE I basically has two different designs (early & late) they are quite similar, but require some different modifications. The power booster portion of the early XKE is vacuum operated and the late style is hydraulic, as is the MK II. Before we talk about what's at the wheels, let's begin with the brake pedal, and what's behind it.
As your foot depresses the brake pedal, you are pushing a lever, which is connected, to an arm that operates the brake master cylinder. The brake master cylinder is the unit that holds the brake fluid in reserve until you depress the brake pedal, and then it pushes the fluid out to the wheels to stop the car. With power brakes, the fluid pressure to the wheels is multiplied by the power booster. Therefore, applying more fluid pressure to the wheels with less effort by the driver. Early series I XKE uses a vacuum booster system, which works very well, and requires no modification other than an overhaul. Late series I XKE uses a hydraulic booster, which we replace, but is also a good system. The MK II brake system requires a modern style hydraulic booster to be fitted. We also increase the hydraulic pressure ratio. Which means less petal effort equals more braking power.
The brake fluid that flows through your hydraulic brake system is "Hydroscopic". Which means it attracts water. Since most of the internal parts of your brake system are steel, the water creates rust and damage; some you can see some you can't. Since these cars are 35-40 years old, we discard all hydraulic brake related steel parts, or rebuild them with stainless steel or brass sleeves. We don't take any chances with your brakes and safety. We offer lots of stainless options, which of course eliminates the rusting problem, but not the need to flush the brake fluid regularly. (Every year)
At the wheels is actually where the braking occurs. The XKE I and MK II have the same front brakes, poor. In early racing days, the Jags often lost their brakes because they overheated. The brake pedal would fade (get spongy) because the brake fluid would boil.
With the small brake pads and the thin solid brake rotors, too much heat would develop too fast without slowing down the car. In severe cases the rubber seals would actually melt and the fluid would leak out. (Then the brake pedal goes to the floor.)
Since we have been making these cars really fast, we needed to improve on an "old Jag" problem, the brakes.
There are many different upgrade kits available. We choose to use a cast iron brake caliper, which bolts directly to the spindle upright without the use of adaptors. We believe it's the best system available. We upgrade to a vented style front rotor (which dissipates the heat faster than a solid rotor). And is also a direct bolt up, no crazy adaptors. We believe the cast iron brake calipers will perform better than the alloy (aluminum) calipers because of the heat created. The alloy is clearly a better heat conductor, but in this case we don't want the calipers to heat up so fast. The increased size of the brake pad itself is enough to slow the car down faster, but we want you to feel safe even after 100 stops, not just 1 or 2 quick ones. Without the use of adaptors and brackets, it's a more positive action, by eliminating the flex of the brackets. We also use stainless steel brake hoses, which "firm up" the pedal and really count on those quick stops.
The rear XKE brakes are mounted inboard, which means the brake calipers and brake rotors are at the center of the car at the differential. Since the power is generated through the differential, it's best to stop it there. (Too bad, but even smaller rear brakes than the front and still the same design). We upgrade the rear brake rotors to a vented style (which dissipate the heat faster) and custom fit a Girling cast iron caliper as well. Again, we increase the brake pad size; we increase the brake caliper size, and add vented brake rotors. "Now" we have a brake system, which will efficiently stop the car at almost any speed, over & over.
The rear MK II brake system is different than the XKE. The solid rear end of the MK II allows the brakes to be at the wheels. There is little room to add much more, but we do increase the size of the rear caliper halves to equalize the pressure due to the larger front brakes. With the larger brake (volume) system we've created the bigger more modern power boosters compliment the system very well.
This combination of upgrades makes the MK II stop well. Generally the MK II driver is a bit more conservative than the XKE driver, but it's nice to know that you have more brakes than you'll ever need.
With the XK's, we can upgrade the 120's & 140's to front disc brakes. We can add rear disc brakes and add a power booster as well. There are many combinations to choose from, depending on your needs. The 150's already have (4) wheel power disc brakes; we can even improve on that system.
We spend a lot of time and really care about your brakes. In fact, we'd rather have your car not start than not stop!
The biggest enemy of your braking system is rust. Not only does the water "inside" your system cause damage, but the water rusts the system from the "outside" too.
We take pride in our braking systems and believe that there are none better. We are extremely "detail" oriented here at Jaguars Unlimited. We protect against rusting, everyway possible. With the steel parts, we acid dip them to remove all the rust, then we plate or powder coat them for a long rust free life. All of our calipers, unless cast iron, are stainless steel. We plate all the hardware and use an anti-seize lubricant on all the threads. We "know" the problem areas and don't miss anything. Let us help you stop!