Option 2 - Performance Front Disk Brake Upgrade Kit

LAST UPDATED: 12/1/08

NOTE: This kit is designed for racing use only. It is not for use on public roads, or on street registered vehicles. Read the bottom of this page for further details.

Bolt on kit designed for any rear wheel drive Gemini, models TX-TG.

I personally use this kit on my race car which I regularly use for circuit racing and hill climbs and it performs brilliantly. Perfect for any form of motor sport. Supplied with semi-metallic brake pads with a higher temperature rating than standard OEM brake pads. This kit will improve braking performance and dramatically reduce brake fade.

This is a complete bolt on kit consisting of all new components, designed to replace your original 239mm diameter, 10mm thick solid front rotors with brand new 258mm diameter 22mm thick ventilated units. Brand new big single piston floating calipers, new semi-metallic brake pads, new brake hoses and fitting kit with brand new parts are also included. Every part needed to fit this brake kit is included along with comprehensive instructions to make installation a breeze.

When braking hard, approximately 60%-80% of total braking (depends on weight transfer, heat and brake specifications) is done by the front brakes. As the front brakes are required to do the majority of the work, they generate an enormous amount of heat. A larger disk (within reason) can be used to dissipate that heat more effectively.

I am currently using this kit on my race car, whilst still retaining the factory rear drum brakes. Even after the rear drum brake's performance starts to decline after a few hot laps, both from brake fade and from simply wearing out of adjustment, these front disks have heaps of stopping power and seem to pull the car up all by themselves. I can virtually race all day like this without experiencing severe brake fade, and my car is no slow coach! so I am stopping from high speeds, meaning the brakes are absorbing and dissipating a lot more heat than a slower vehicle. It would be nice to have a bit more braking at the rear at times, but that's drum brakes for you!

For a description of brake fade and the performance of the standard braking system compared to ventilated disks, check out the Option 1 - 241mm Economy Ventilated Disk Kit for more info.

The calipers used in these kits have been carefully selected to have a piston diameter comparable to that of the original Gemini calipers. Due to this, no master cylinder modifications or upgrades are required. The factory brake booster and master cylinder are a great combination with this kit, making it a truly bolt on set up. NOTE: Some conversions available from other suppliers using different calipers require a replacement 1" (piston diameter) master cylinder because the standard Gemini master cylinder does not supply enough fluid volume. My kit uses the standard master cylinder and has excellent pedal feel.

The combination of the size of the piston in the caliper, the diameter of the brake rotor, and the swept area of the pad, all add up to a level of brake retardation for the front of the vehicle, which is not that much greater than the original front brake assembly. This means that use of this kit does not alter the vehicles braking balance. Therefore, the brake bias is not upset, as it is would be when installing really large diameter rotors, such as 300mm units for example.

Remember though that as the temps start to skyrocket whilst circuit racing, the stock brakes quickly overheat, and the small area of the stock Gemini brake pads will only give a short service life. These larger ventilated rotors will dissipate huge amounts of heat by comparison, plus the area of the brake pads in the new calipers is about 4 times greater, meaning much longer pad life, especially whilst racing.

You also use the original Gemini hub which means no changing of wheel stud patterns or offsets. You keep the original 4x100 stud pattern and can use alloy wheels made for a Gemini or similar, as long as they are at least 15" in diameter. This also means that if you decide to sell you car, and want to keep the brake upgrade kit, you can simply unbolt it and install the factory disks and calipers easily, as no modifications to the vehicle are required.

The rotors used in this kits are 258mm diameter units, 22mm thick and are ventilated. The rotors are machined to bolt onto the original Gemini hub using new cone lock nuts and washers supplied. The photo below shows the standard solid Gemini rotor compared to the larger ventilated unit.

Also supplied are big single piston floating calipers and new semi-metallic brake pads to suit. The calipers are machined to bolt onto the original Gemini stub axle.

The semi-metallic pads provide a higher temperature operating range compared to normal OEM brake pads. Also, due to their design, they are very effective when cold, unlike some race pads that don't generate much friction with the rotor surface until they warm up.

The higher operating temperature range means that at the higher brake component temps experienced whilst racing, these pads continue to bite hard, and resist fading and surface glazing. Other lower spec pads can deteriorate when they get hot, as the bonding chemicals (glue) that holds the pad's friction material together seeps out of the pad, and glazes the mating surface of the disk and pad. This leads to reduced braking torque, and also causes the annoying brake squeal many cars get.

Kit includes:

2 x new 258mm diameter ventilated rotors, machined to bolt onto original Gemini hub.

2 x new PBR big single piston floating calipers, machined to bolt to Gemini stub axle.

Full set of new brake pads.

8 x new cone lock nuts and washers to secure rotor to hub.

2 x new PBR brake hoses to connect Gemini brake line at inner guard to new caliper.

4 x new copper washers for banjo fittings for brake hoses and calipers.

2 x brake hose mounting bolts, nylocks and washers to secure new hoses to inner guard.

Complete simple to follow fitting instructions that guide you through the installation.

The installation is literally a bolt in job. Just follow the comprehensive instructions provided, bolt the hardware on the vehicle, bleed the brakes, and that's it!

I am asking $545 for everything included in the list above. Email me at benw@ncable.net.au to discuss. Kits originate from Ballarat, VIC. and are posted to anywhere in Australia or New Zealand. I would need to know your post code before quoting postage costs.

NOTE: Slotted or cross drilled rotors will substantially increase the price of a kit. Slotted rotors appear to have a performance benefit in my opinion, however the price increase would be an extra $200 (approximately) for slotted, and an extra $300 for slotted and cross drilled.

The kit will require at least 15" diameter wheels due to the size of the caliper. Some 14" wheels will fit, but I cannot guarantee it, and I am not prepared to send kits out and then have them sent back because your 14" wheels don't clear the caliper.

NOTE: This kit is designed for racing use only. It is not for use on public roads, or on street registered vehicles. I am offering this kit for people with Gemini race cars, the kit is not aimed at being "Engineer Approved" so I sell it for racing use only. The disks are re-drilled to suit the Gemini stud pattern and this is not technically allowed in some states. The steering stop packers required with the kit, as with any other kit on the market that uses brakes of this size, reduce the amount of steering angle that can be applied. These are not critical issues on a race car, but it can effect vehicle compliance with the standards for registration. Every state has different requirements, you should consult a local Engineer if your goal is to use this kit on a street registered car.

The following photos show the components of the kit, and the kit installed on a Gemini showing how it all fits together.