RJC Fury R1 Design Build Drive Gallery Video Contact Me Misc
Last page update was 01 Oct 2014

Brakes

My brakes need to stop the car effectively and consistently under very hard track conditions as well as providing excellent feedback. This is so that I will have confidence in them at the edges of the cars performance envelope and be happy to spend all day driving hard round a track. They also need to be as light as possible, particularly as some of the components contribute to the unsprung mass.

Effective braking is largely dependent on the front brakes and quite often light-weight kit cars can get away with drum brakes at the rear. My brother's Striker has a live axle rear-end with drum brakes and there has never been any noticeable drop in braking performance, even after a whole day with the three of us, taking it in turns to hammer it around Llandow circuit.

I've opted for all-round disk brakes to minimise weight, provide excellent feedback and to guarantee that brake fade will not be an issue. Brakes are also the most important safety feature on any car, so I'm not cutting corners.

Front Brake Disks & Calipers

I've bought some new HiSpec 4-pot calipers. These should save on unsprung weight and provide awesome stopping power. The calipers are 925g each. The 247mm and 260mm disc versions come with mounting ears, to avoid the need for a mounting bracket.

These are the matching 260mm x 7mm grooved discs.

Standard Mk2 Escort discs are 247.5 mm in diameter and the internal diameter is 139.8 mm. For SVA, the caliper bolts need a locking plate with tabs that are bent to stop them shaking loose. Having worked out which side of the disk is bolted to the alloy bells, you can choose which way you want the grooves pointing. The disks are bolted to the bells with 8 bolts, torqued to 11Nm and with some Loctite thread locker 242 for extra security. The disk assembly is then bolted to the pattern alloy hubs up to 50lb-ft with spring washers and thread locker for safety. The mating faces between hub and disc have to be spotless.

There are now several other cheaper options:

Rear Brake Calipers

These are from a Ford Sierra. I bought an old pair to exchange for some reconditioned ones from Used Ford Spares . Part no. is DC71346.

You also need to do this as Ford Spares don't supply the caliper carriers with the calipers. These allow the caliper to float across the disk. The caliper has a piston on one side so must be able to move in and out to apply even pressure to both sides of the disk. The reconditioned calipers also came with the little rubber boots and some grease for the sliders. I'd been struggling to find these rubber boots on their own. The reconditioned calipers weigh 2060g each and the caliper carriers weigh 615g. For SVA, the caliper bolts need a locking plate with tabs that are bent to stop them shaking loose.

An alternative is to use Hi-spec rear calipers with built-in handbrake mechanism. The trouble is that these things don't exist commercially yet and people have been waiting literally years for them to be developed and launched as a product. As much as I'd like to use them and save several kilograms in weight, I've had to draw a the line here to stay within my budget.

Normal Sierra rear disk hubs (from an XR4x4) have elongated ears on the hub to which the caliper assembly is mounted. On kit cars, custom caliper brackets are required to duplicate this function. I ordered mine from The Kit Car Workshop .

The rear calipers are mounted upside down, which puts the bleed nipple and inlet at the bottom of the caliper. The calipers must be turned the correct way up to bleed the brake fluid, otherwise the caliper will remain full of air. Because the calipers are upside down, the bleed nipple and flexi inlet need to be swapped over. In the pictures below you can see the bleed nipple is at the front of the caliper (with the red tag) and the main inlet is at the rear. You take out the bleed nipple and move to the rear inlet hole, then attach the flexible hose into the front hole. This positions the flexible hose out of the way of the wheel.

Alternative Rear Brake Calipers

Rear Brake Discs

The standard rear brake discs are 253 x 10mm and solid. I bought mine from Eastern Auto Spares for £38.92 the pair. It is best not to touch these with your bare hands as they will rust very quickly. I used latex gloves when handling them. You must also avoid getting oil on the braking surfaces. These discs weigh 3455g each. I used Halfords brake cleaner to clean these before fitting and then again before fitting the brake pads. Lucas TRW part number is DF1654. Ford no. is 5022666.

Brake Pads

The front pads to fit the Hi-Spec calipers are from a Lotus Elise. The rear brake pads are for the Ford Sierra rear calipers. Use Copaslip on the back of the pads. There are loads of options and some of the common ones are:
EBC Greenstuff
The recommended front brake pads for road use are EBC greenstuff for the Lotus Elise.

Hawk Blacks
Sold by Rally Design and offer better initial bite on road. Seem to be well recommended in BEC forums.

Mintex 1144
These are a fast road/track compound, offering higher friction. They have significantly better stopping power than the EBC Greenstuff. They are more prone to squealing. A pair cost around £54.

Pagid RS14
Expensive, track focussed, carbon ceramic pad that can stand 700C disk temps. Work well from cold and even better when up to temperature.

Pagid RS4-2
A carbon metallic pad, not as high a temp rating as RS14 and slightly lower coefficient of friction, but still way ahead of most other pads.

The Mintex 1144 pads seem to be good and at a reasonable price, so and I'm going to start with these on my car. Mintex have an application guide  on-line but this didn't help me find the required parts numbers. The ones I've got are labelled: CTECH MDB1890M1144 (FMSI:D109, WVA: 20323 144) for a Lotus Elise 96 onwards.

Mintex no longer do Sierra rear pads so I'm using standard off-the shelf items, since the rear brakes don't do much in terms of stopping the car. These are TRW Lucas parts number GDB472 (Girling 3322936404729).

Handbrake

My Fury handbrake was bought on eBay and was from a Ford Escort. It has an electrical switch to show when it is on/off [650g]. It is not brillaint quality and has some lateral movement.

Handbrake Cable

The handbrake cable on my Fury is from a standard 2.0 Sierra and is one long unbroken length of cable. The outer sheath routes along the rear wishbones at either side then fits through the chassis brackets. It is very over engineered and very heavy. I plan a much thinner and lighter solution in ths car.

Handbrake Switch

The handbrake warning switch typical connects to ground.

Pedal Box

See Instruments & Controls section for more details.

Brake Master Cylinders

I've opted for the twin cylinders with bias bar, to provide better control over front to rear bias. This is supplied by Fisher Sportscars . You can buy a twin master cylinder unit with the front/rear bias preset. You need to specify which one you want up front or you will get a spare hole to fill in the bulkhead. The two cylinders are different, the .625 is the front and the .75 is the rear.

Some people claim that the bulkhead has a tendency to flex under hard braking. Fisher Sportscars  have addressed this with an additional bracing bar above the brake cylinders in the 2006 chassis.

The brake fluid reservoir has a 'low fluid' sensor (switch), which drives the brake lamp on the Digidash. The same lamp is also driven by the handbrake switch.

The sharp edges rule and projects rules apply to the footwell area.

Brake Bias Adjustment

You can get dash mounted bias adjustment knobs to allow you control the braking bias (front/rear) whilst on the move. These will not pass the SVA test though. There is not a lot of room to fit these and the cable is often routed through the side of the footwell as shown above, to avoid too tight a radius in the cable. You can get 90° bevel gear adaptors though, which allow the cable to go straight up to the dash area. Personally, I don't want the added complexity, cost and weight this adds but I can see they make sense for frequent track work.

The Wilwood Engineering web site  describes the best way to set up the balance bar.

I've gone for an adjustable brake bias bar but, for the test, this must be locked in place. There are several options to achieve this:

  1. Use some 10mm i/d steel tube and run a suitable tap (7/16" UNF) down the centre. Add the threaded the tube onto the ends of the balance bar and drill through the ends for a 2mm roll pin. The advantage of this solution is that you can easily adjust the length of the tubes to get the balance right and they don't interfere with the clevises that connect to the master cylinder pushrods.

  2. Welding or drilling the locknut and inserting a roll pin, both of which may weaken the bar slightly but a <2mm hole should not have much impact in this respect.

  3. To fabricate a box that fits round the balance bar with the pedal extending through the top. This box is riveted in position once you are happy with the balance, for as long as it takes to pass SVA. There is then no way of adjusting the balance without dismantling permanently attached parts of the car.

  4. To knock up a spare bar that you don't mind welding up if necessary, then bin it post SVA in favour of the original.

Brake Pipes

The brake pipe is 3/16" (4.8mm) copper pipe and is fixed to the chassis using aluminium or stainless-steel, rubber-lined, p-clips from places like Automec  or Zeroclips . These are riveted to the chassis at 100mm intervals (maximum distance specified in SVA manual). The front pipe runs to the front of the chassis where a 3-way union splits the pipe into two, one to each chassis tab for attaching the front braided hoses. The rear pipe runs down the centre of the car to a 3-way union in front of the differential. This also splits the circuit into two runs, one to each bulkhead fitting for the rear braided hoses.

Copper/nickel (90%/10%) pipes are sometimes referred to as kunifer brake pipes and are slightly more expensive. The added nickel provides improved corrosion resistance. All the fittings used are metric (M10x1) with the exception of the master cylinder ports. For Girling master cylinders the brake port is 3/8" UNF and the feed port is 7/16 UNF which needs 1/4" or larger feed pipe. A male/male union with a short length of rubber hose will connect to the brake fluid reservoir, which is a twin item with level sensor for SVA.

A decent cam-action flaring tool is required to connect the braking system up.

Parts List

This parts list is based on prices and part numbers from Vehicle Wiring Products . This list assumes no hydraulic brake light switches are used in the pipe work (as described below).

QuantityDescription / UsagePart
Number
Price each
(ex. VAT)
13/16" copper-nickel brake pipe, 25' rollT14M£13.65
23-way connector, 10mm x 1mm thread, for front and rear splitB544£6.10
6Brake nuts, male, 10mm x 1mm thread, to 3-way connectorsB620£0.26
4Brake nuts, female, 10mm x 1mm thread, to through connectorsB627£0.44
2Brake nuts, female, 3/8" UNF x 24tpi thread, to master cylindersB576£0.42

Brake Hoses

Goodridge stainless-steel, braided hoses are used at each wheel, to connect the brake pipe to the calipers. These needs to the correct length for the Fury installation so I bought mine from The Kit Car Workshop . They supply front hoses with a 90° hose fitting to get better clearance on the hoses.

Brake Fluid

The brake system will use a quality, Dot 4 brake fluid. The brakes will not get hot enough to require anything more. Castrol SRF seems to be the best choice but it is about 35 per litre. Castrol Response Super Dot 4 is a decent, cheaper alternative.

Brake Light Switch

There are several ways to implement the brake switch function:

Rear Pressure Switch

Most people put a pressure switch at the back of the car, because this is handy for connection to the brake lights and power from the fuel pump. You can also use a simple 4-way union to connect it.

Richard  used a 4-way union, just in front and to the right of the differential to connect the brake light switch. These type of switches don't work too well in practice and require a fair push on the pedal to operate but, are fine for normal road use and to pass the SVA test.

Front Pressure Switch

This option mounts the switch near the brake fluid reservoir and to use simple 3-way union for it. The downside to this approach is that the cable runs the length of the car to the rear lights.

Pedal Switch

This is my preferred approach and implementation because I want to also connect this switch to the 'brake sense' feed on the . A micro-switch mounted within the footwell is more sensitive and responsive to brake pedal movement. This switch also drives the rear brake lights and the high-level brake light.

All of my brake lights are LED so I can use a low current switch to drive them directly (Maplin part number is GW73Q and is rated at 3A).

I need to mount the switch in such a way that pushing the pedal closes the 'normally open' contacts on the switch. Because the pedal has quite a lot of movement, the switch is mounted half way between the footwell wall and the pedal's normal resting point. This ensures that even with all the pedals pushed as far down as they go, my foot will not hit the switch and the activation bar on the brake pedal arm will not hit the back of the footwell.

SVA

The brake components will all be new and need to be run in before they will work effectively. This means that I will need to do some miles before the SVA test. My plan is to do some pre-SVA testing at a track or airfield. All caliper bolts need to have locking tabs to meet SVA requirements.

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