The Billet 4 is Hi Spec’s most popular caliper. A classic, tried and tested four piston design machined from 6082 T6 billet aluminium with matching billet pistons and external boots to keep dirt out. Low maintenance, high performance.
This is a direct bolt-on big brake conversion for the Ford Sierra Cosworth 4WD, built around a 325mm disc (28mm thick) and the Billet 4 caliper. Designed to clear 17″ wheels.
Conversion includes:
- 2 x Billet 4 Radial Mount Calipers
- 2 x 325mm two piece floating rotors
- 2 x Mounting bells
- 2 x Vehicle specific mounting brackets
- Fitting hardware
Brake pads and braided hoses are not included and can be added at extra cost. Caliper colour options: Black, Red, Blue, Gold or Silver.
All Hi Spec calipers and rotors are made to order in the UK, please allow up to 28 working days for manufacture. Image shown is a generic family image and may not reflect the exact parts supplied.
Which kit would you actually recommend for this car?
We wrote it up properly: Our Top Recommended Big Brake Upgrade Kits For Your Ford Sierra compares the kits we rate for this car across budgets, from our own fitting experience. Worth five minutes before you decide.
Will it fit my car?
This kit is built for the car named in the listing, and the generation matters: hub design, hub bell shape, and caliper bracketry are car-specific even when the disc size looks the same. If your car is near a facelift year or an unusual variant, send us the registration and we will confirm the exact kit before you order.
Will it clear my wheels?
For this 325mm HiSpec kit, the minimum wheel diameter is 17in, and that figure belongs to the kit rather than the car, so it holds whatever you drive. Diameter is only half the story though: spoke depth is wheel-design-specific, so if you run aftermarket wheels with deep spokes, send us a photo and the wheel model and we will check clearance properly.
Do I need to upgrade the rear at the same time?
No. The front does the large majority of the braking, so a front kit alone is the normal first step and a balanced one. Upgrade the rear later if you want matched looks or you are building for sustained track work, and if the car has an electronic parking brake, read our guide on rear kits and electronic handbrakes before planning that side.
Which pad compound should I run?
It depends on use, not on the kit: fast road, track day, and race compounds behave very differently when cold and when worked hard. Our guide on brake pad compounds explains the choices for HiSpec kits in plain terms, and heading to a circuit, our track day brake prep guide covers pads, fluid, and bedding in.
What does the 4-piston caliper actually give me?
More pistons spread clamping pressure across a bigger pad more evenly, which improves pedal feel and pad wear rather than raw stopping power, and the bigger disc adds the leverage and heat capacity. The honest summary: consistency lap after lap, and a pedal you can modulate, not a party trick emergency stop.
