Wednesday, August 20, 2014

Installing Rotora's Big Brake Kit On Our 981 Cayman

While all the glitz and glamour is given towards making your car faster, the unsung hero in automotive modifcation is improving your ability to stop. The stock Porsche brake setup may be adequate enough for many people, but for many of those that like to drive their car often and hard, it's not quite up to the challenge of their driving style.

When you brake, the pedal pushes hydraulic fluid through your brake lines to push on the pistons in your brake calipers, which in turn pushes your brake pads into your brake rotors, and that friction between your pads and rotors is what causes you to decelerate. That friction is converting your kinetic energy into heat, and that heat is absorbed by the rotors, which then release that heat into the air.

With day to day normal driving and the braking that goes along with it, you typically don't have to try and stop or slow down from a high speed to low speed in a short distance, which means that you are not generating a large amount of heat for the rotors to absorb, and your rotors also have ample time to shed whatever amount of heat they have taken in.

During more aggressive driving situations, or when you're on the track, your brakes are going to be seeing much larger amounts of heat caused by frequent hard braking in short periods of time. Your rotors can only hold so much heat capacity before they reach their limit, and once that limit is reached, trouble starts to happen. If the rotors are maxed out as far as heat capacity, that heat has to go somewhere, and that somewhere is the rest of your brake components. If you overheat your brakes, you risk damaging your seals, drying out the lubricants, glazing the brake pads, and boiling your brake fluid. The net result of that damage is that you will have significant reduction in your braking ability, to the point that your car may be considered too unsafe to drive until the problems are fixed (by replacing damaged seals, reapplying lubricants, replacing the brake pads, and doing a complete flush and fill of the brake fluid).

Rotora's Big Brake kit helps to prevent dangerous brake system overheating and the subsequent resulting damage, as well as noticeably improve your overall braking performance. Larger, forged aluminum brake calipers with more pistons (that are sequentially sized) will give you stronger clamping forces with longer brake pad life, and their larger than stock slotted rotors not only give more leverage for the calipers and pads to generate more braking force, they also give the rotors the ability to store more heat in them and shed that heat faster.

Stock front caliper vs Rotora's front caliper.
Stock rotor vs Rotora's front rotor. Light hats mean more rotor mass with less overall weight.

Rotora has designed their big brake kits for easy installation with little to no modifications of your vehicle required. We installed Rotora's big brake kits on the front and rear of our 981 Cayman to show you that it's a project that a DIYer can tackle themselves with not too much effort, and still get maximum results.

Stock caliper and rotor. It's not going to look like this after we're done.
Before you get started, please read the instruction manuals that Rotora provides with their kits. The manuals are very comprehensive and well thought out, and include detailed images and all necessary torque specs used.

It would be in your best interest to read the manuals completely before starting.

First step like always, is to securely raise the end of the car you plan on working on first. We opted to start with the front brakes, and while we have access to a lift, this can be done using the traditional jack and jackstands method.

Once the car is secured and raised, go ahead and remove the wheel by removing the lug bolts.

With the wheel out of the way, you can start removing the brake caliper. The first step is to disconnect the stock brake pad wear sensor. The Rotora brake system does not use or need the stock brake pad wear sensors, but the sensors will ultimately still need to be connected to the car to prevent any error codes from appearing (we'll revisit this point near the end of the installation). If you are unable to remove the sensor by hand, use a pair of needle nose pliers to carefully wiggle out the sensor from it's holder. With the sensor free from the pads, remove the sensor line from the retaining clip by using a small screwdriver to disengage the tab.

The brake pad wear sensor has a notch that corresponds with the notch on the brake pad.
This small clip is what keeps the sensor from sliding out of the notch. Squeeze this clip together first before sliding the sensor out.

With the brake pad wear sensor and line disconnected, it's time to disconnect the upper rubber brake hose that connects from the chassis-side brake hard line to the caliper side hard line. Rotora's kit comes with replacement braided hoses to use with their system, so you will reuse the stock crush washer and spring clips located on the hard lines.

When disconnecting the brake lines, be sure to have a container and a rag ready to catch any brake fluid that may spill. Please keep in mind that brake fluid will damage any painted surfaces, so be careful about any errant drops, and if some lands on something painted, blot it dry (wiping will only spread it around) quickly.

To disconnect the brake lines, use a properly sized flare nut wrench to do so. We've mentioned before about the use of using a flare nut wrench to do this, as the use of a standard open end wrench will greatly increase your chances of irreparably damaging the fittings.

The connection between the chassis-side hard line and the brake hose should be easy to access; use the flare nut wrench on the hard line side, with a wrench on the machined flat sections of the rubber hoses' connector to prevent rotation while you loosen the fitting. The caliper-side end of the brake hose may be harder to access with the wrench, so temporarily moving the ABS sensor line from it's holder adjacent to the brake line will give you more room to work with.

With the brake sensor and stock brake line removed, you can now focus on removing the stock rotor and caliper. The caliper is held on by two bolts with 10mm Allen heads. Make sure to be careful when removing the bolts so that the caliper does not have the chance to fall off and onto the ground. With the bolts removed, the caliper itself can be pulled off the rotor.

The rotor is attached to the hub via two small countersunk screws. These screws only serve the purpose of keeping the rotor from rotating when there are no lug bolts installed, and your vehicle may not even have them (if for example, the rotors were replaced before). If they are present though, they will have to be removed so that the rotor can be freed from the hub. As mentioned in our wheel spacer installation post, you will need to use a manual impact driver to prevent the rotor screws from stripping (which is a common occurrence, as heat and time often makes the screws seize).

With the screws removed, the rotor can now be removed from the hub. Much like the rotor screws, heat and time may make the rotor not want to easily pull off the hub. If that is the case, then you will need to give the rotor a few taps around it's outer circumference with a soft mallet to break it loose from any corrosion. It helps as well to partially thread a lug bolt into one of the lug holes so that the rotor doesn't suddenly dislodge and then fall to the ground.

With the rotor off the car, it would be good to clean the hub with a wire brush, and do some cleaning in general to the dust shield and surrounding area.
With hub exposed, it would be a good time to take a wire brush and clean the hub of any loose rust or dirt.
As the Rotora caliper is larger, there is an included bracket that acts as a spacer between the stock mounting location, and where the caliper will ultimately sit. There are two sets of bolts included for this installation, and the shorter bolts are the ones you will use to attach the bracket to the holes that your stock calipers originally attached to. Please refer to Rotor's instruction manual for bracket orientation and torque specs.

Relocation bracket as seen on the rear
With the new caliper bracket installed, you can now install the new rotors. The rotors are directional, so ensure that you are installing the correct rotor on the correct side (the rotors are labeled, and there is also a diagram in the instruction manual that indicates the visual orientation of the slots). Once the rotor is seated on the hub, use the rotor screws removed previously to secure them in place (again, using a manual impact driver to prevent head stripping).

Use the manual impact driver to reinstall the rotor screws to prevent stripping of the heads.
The calipers can now be installed, using the longer provided bolts and washers. First insert the bolt/washer combination into their respective holes on the caliper, and then attach the caliper to the bracket, tightening the bolts with the specified torque specs using a 10mm Allen bit.

Rotora's replacement lower braided hose use a more familiar Banjo bolt fitting for the end that connects to the caliper. Refer to the instruction manual for proper preparation and orientation of the Banjo bolt (you should have a copper washer on both sides of the Banjo fitting for a proper seal that prevents leaks). Hand tighten the Banjo bolt into the caliper (you will tighten it to spec later). Using the spring clip removed from the stock lower hard line, slide it over the end of the new lower brake line. Take the new upper brake line, insert it into the bracket that the old lower brake line resided in, and connect it to the lower brake line, tightening it by hand for now (to prevent cross threading). Use your flare nut wrench to tighten the male side of the brake line, and then slide the ABS sensor line that you removed from it's bracket earlier back to it's regular position. With the banjo fitting oriented perpendicular to the caliper (with the hose pointing towards the bottom of the caliper as shown in the instructions), tighten the banjo bolt to the torque specs as specified by Rotora's instructions. The remaining end of the brake line can now be attached to the upper hard line in the opposite way that the stock brake line was removed. We suggest hand tightening it first before using the flare nut wrench to snug the line.

Remove the spring clip from the old line...

And reuse it on the new line.

Our car already had aftermarket upper braided lines, so we opted to mate Rotora's lower line to our existing upper.
If you are installing the front brake kit, after installation of the brake lines, check to make sure there are no clearance or binding issues by turning the steering wheel from lock to lock. If there is any binding or clearance issues, you will have to adjust the position of the brake lines or banjo fitting to resolve them.

As mentioned before, the Rotora Big Brake Kit does not require the brake pad wear sensors, but the sensors still need to be connected to prevent error codes. Rotora provides a heat-resistant cable tie so that the sensor can be attached, installed in it's stock bracket, and then the end that would normally go to the pad secured out of the way. Trim the cable tie once you have found a suitable position for the end of the sensor that is clear of any moving parts.

This is how we chose to position our brake pad wear sensor. It's still connected to the car, but out of the way of any moving components.
Repeat this process for the remaining hubs. If installing the rear kit, installation is similar to the front, but with one less set of brake lines to replace.

Once you have completed full installation of your Rotora Big Brake kit, you must bleed your brake system to purge all the air that was introduced when the new lines and calipers were installed. We've described the brake bleeding process before, but the recap is that you want to bleed your brakes in order from furthest away from the master cylinder to the closest (so the order would be rear right, rear left, front right, front left). While bleeding, use a rubber mallet to tap the calipers to free any air bubbles trapped in the caliper passageways. It may take a few tries to completely remove the air from your brake system. We prefer using positive pressure bleeding systems like the Motive Power bleeder, but even the traditional method of having an assistant pump the brakes while you open and close the bleeder will work as well.
After bleeding the lines, and checking to make sure there are no leaks, and then cleaning the rotors of any grease or dirt with a brake cleaner spray, you can now put the wheels and lug bolts back on the car. Rotora's brake kit is designed to fit underneath factory wheels with no clearance issues, but if you have aftermarket wheels, check to make sure that the wheel rims, wheel spokes, valve stems, and wheel weights do not come in contact with the caliper. If there are clearance issues, you may have to run a spacer to push the wheel outwards to create more space.

Our car is currently running a 7mm spacer, but even without it, there would still be ample clearance.

Brake bedding is the process of applying an even layer of brake pad material to your rotor. Without bedding your brakes, your brakes will vibrate and be much nosier than a properly bedded set of brakes, as well as perform less than ideally.

Rotora has a specific set of instructions for the proper bedding in of their Big Brake Systems. Please refer to their installation guide for the proper bed-in process to ensure optimal performance. Incorrect brake bedding will give you issues similar to unbedded brakes: vibration, noise, less than ideal stopping power; so make sure that you follow their directions to a tee.

And there you go. For not a tremendous amount of effort, you not only have a fantastic looking set of brakes, but the stopping power to back it up.

Stock on top, Rotora on bottom. Even sitting still, the kit looks great on the car.

#schnellautosports #981 #cayman #bbk #rotora #becauseracecar

1 comment:

  1. Still a great article 5yrs later!
    Repairing my Rotora's on my 350Z.