Our Top Recommended Big Brake Upgrade Kits For Your Ford Sierra
A lot of the Sierra calls we get start the same way: someone has a standard 2.0 or an XR4i and wants to know if the Cosworth kits will fit. They won’t. The Cosworth runs different hub carriers and both Tarox and HiSpec list it as a separate fitment. The base Sierra, the XR4i and the Cosworth are three different cars as far as the brake kit is concerned. There is one thing worth knowing about the standard kits though: HiSpec built them to fit the Sierra, the Granada Mk3 and the Scorpio, because Ford used the same front hubs across all three.
Below are the kits we would actually fit, from the two manufacturers we stock for big brakes: Tarox in northern Italy and HiSpec Motorsport in Dartford. Every kit covers the standard Sierra front hubs. XR4i fitments are in a section of their own further down. The full Sierra range is on the site if you want to browse it raw.
- Standard Sierra kits from both brands also bolt to the Ford Granada Mk3 and Ford Scorpio, which share the same front hubs
- Tarox list the XR4i as a separate fitment; the standard Sierra kits will not bolt to the XR4i
- This guide has looked up Tarox minimum wheel sizes from their website per kit, so every kit here has a real number rather than "ask us"
- Tarox kits arrive with braided hoses and Corsa pads already fitted; HiSpec price theirs separately so you choose the compound
Two brands, two ways of building a brake kit
Both machine their own calipers from billet aluminium and build every kit for the specific car it is going on. Where they differ is what they put in the box and how they price it.
Tarox
Built at the factory in northern Italy. Calipers are CNC machined from European billet alloy and hand assembled, discs are heat treated and hand balanced to 0.05mm. The Sierra range runs from the 305mm Sport to the 340mm Super Sport, with separate XR4i fitments alongside. Every kit arrives complete: vehicle-specific braided hoses and Corsa pads already fitted. Tarox state full compatibility with ABS and ESP on every kit.
HiSpec Motorsport
Machined in Dartford from 6082 T6 billet aluminium, calipers and pistons both. Made to order in up to 28 working days, with the calipers finished in your choice of black, red, blue, gold or silver. Pads and braided hoses are priced separately so you pick the compound to match how the car gets used.
Wheel sizes: real numbers for every kit
HiSpec state the minimum wheel size on every Sierra listing, and for this guide we looked up the Tarox figures directly from their website instead of leaving them as “check your clearances”. Every kit in the table below has a real minimum diameter. The only check that stays a conversation is depth: a wheel of the right diameter can still foul a caliper at the spokes, depending on the specific wheel and its spoke profile. Give Cameron the make and model of the wheel alongside the size and he will confirm before anything goes to build.
| Kit | Disc | Smallest wheel |
|---|---|---|
| HiSpec 283mm Billet 4 | 283 x 24mm | 15 inch |
| HiSpec 300mm Billet 4 2P | 300 x 28mm | 16 inch |
| HiSpec 315mm Billet 4 2P | 315 x 28mm | 16 inch |
| Tarox 305mm Sport | 305mm | 16 inch |
| HiSpec 335mm Billet 4 2P | 335 x 28mm | 17 inch |
| Tarox 318mm Sport | 318mm | 17 inch |
| Tarox 325mm Sport | 325mm | 17 inch |
| Tarox XR4i 298mm Sport Compact | 298mm | 16 inch |
| Tarox XR4i 330mm Sport | 330mm | 17 inch |
| HiSpec 360mm Billet 4 2P | 360 x 28mm | 18 inch |
| Tarox 340mm Super Sport | 340mm | 18 inch |
HiSpec 283mm Billet 4: the kit for standard 15 inch wheels
A lot of base Sierras run 15 inch wheels, either standard steels or earlier alloys, and this is the kit for that car. The Billet 4 is the caliper HiSpec make most of: four pistons, machined from 6082 T6 billet aluminium, external boots to keep road grime out of the seals. The 283mm disc is 24mm thick and one piece, and the whole conversion bolts directly to the standard Sierra hubs without modification. Pads and braided hoses are priced separately, which keeps the entry number down and lets you choose the compound to match how the car is used.
This kit also covers the Ford Granada Mk3 and Scorpio, for anyone running one of those on 15s.
- £785.44 inc VAT
- Fits behind 15 inch wheels
- 283 x 24mm one piece disc
- Vehicle specific brackets and fitting hardware included
- Pads and braided hoses priced separately, five caliper colours, up to 28 working days
HiSpec 300mm and 315mm Billet 4: the 16 inch sweet spot
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Ford Granada MK2 Brake Kits, Ford Scorpio Brake Kits, Ford Sierra Brake Kits, Hi Spec 310/315mm Billet 4 Conversion kits, Hi Spec Road Car Front Big Brake kits
£1,283.02 Incl. VATPayPal CreditFinance availableAdd to basket -
Ford Granada MK2 Brake Kits, Ford Scorpio Brake Kits, Ford Sierra Brake Kits, Hi Spec 300mm Billet 4 Conversion kits, Hi Spec Road Car Front Big Brake kits
£1,233.29 Incl. VATPayPal CreditFinance availableAdd to basket
Most of the standard Sierra enquiries we get involve a car on 16 inch alloys or heading that way. Same Billet 4 caliper as the 283mm kit, but with two piece floating discs in 300mm or 315mm, both clearing a 16 inch wheel. The two sit about fifty pounds apart. Garreth’s call: unless a specific wheel says otherwise, take the 315mm for the extra disc diameter and the slightly better heat capacity that comes with it. Both are 28mm thick. The step up to two piece floating discs over the one piece 283mm kit is also worth noting: better heat management and less thermal distortion under repeated hard stops.
- 300mm at £1,233.29, 315mm at £1,283.02, both inc VAT
- Both fit behind 16 inch wheels
- Two piece floating discs, 28mm thick
- Pads and braided hoses priced separately
- Five caliper colours, made to order in the UK, up to 28 working days
Tarox 305mm 6 pot Sport: the complete kit at 16 inches
If you want one box with nothing left to source, this is the entry point in the Tarox Sport range for the standard Sierra. The B32 caliper carries six pistons, the 305mm two piece floating disc is balanced to 0.05mm at the factory, and the kit arrives with vehicle specific braided hoses and Corsa pads already fitted. Minimum wheel is 16 inch, so it works behind the same wheels as the HiSpec pair above. The headline price is higher than the HiSpec kits, but pads and braided hoses are in the box, and the gap narrows considerably once the HiSpec kits are specced to the same level.
- £1,860.66 inc VAT, complete
- Fits behind 16 inch wheels
- Corsa pads and braided hoses included and fitted
- B32, 6-piston caliper, hand assembled in Italy
- 305mm two piece floating disc, balanced to 0.05mm
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Tarox 305/306mm 6 pot sport conversion kits, Ford Sierra Brake Kits
£1,860.66 Incl. VATPayPal CreditFinance availableSelect options
HiSpec 335mm Billet 4: the 17 inch build
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Ford Granada MK2 Brake Kits, Ford Scorpio Brake Kits, Ford Sierra Brake Kits, Hi Spec 325mm Billet 4 Conversion kits, Hi Spec Road Car Front Big Brake kits
£1,357.50 Incl. VATPayPal CreditFinance availableAdd to basket
Once the car is on 17 inch wheels, this is the natural next step in the HiSpec range for the Sierra. Same Billet 4 caliper, now behind a 335mm two piece floating disc that needs a 17 inch wheel to clear. Disc is 28mm thick. Pads and hoses priced separately as with all the HiSpec Billet 4 kits. If you are doing regular track evenings and want the Monster caliper at a similar disc size, the 325mm Monster 4 and Monster 6 are still listed on the site; the Monster runs a longer pad with higher temperature seals, which earns its money when brakes are getting properly warm. The 335mm Billet 4 is the better answer for a car that sees road miles as well as the occasional track day.
- £1,357.50 inc VAT
- Fits behind 17 inch wheels
- 335 x 28mm two piece floating disc
- Pads and braided hoses priced separately
- Five caliper colours, made to order in the UK, up to 28 working days
Tarox 340mm Super Sport: the flagship
The Super Sport is Tarox’s fast road and track flagship and the largest kit they list for the standard Sierra. The B34GT caliper uses sequentially sized pistons so the pads wear evenly across the face and the pedal stays consistent as things get hot. One note on the listing: it says 10 pot. That is what the older B34 caliper design ran. The current B34GT uses eight pistons, and that is what arrives. Minimum wheel is 18 inch. Same as the Sport kit otherwise: pads, hoses and brackets all in the box from Italy.
- £2,610.00 inc VAT, complete
- Requires 18 inch wheels
- Corsa pads and braided hoses included and fitted
- B34GT caliper, 8 sequential pistons, hand assembled in Italy
- 340mm two piece floating disc, balanced to 0.05mm
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Tarox 340mm 10 pot grande conversion kits, Ford Sierra Brake Kits
£2,610.00 Incl. VATPayPal CreditFinance availableSelect options
XR4i fitments and bigger builds
The XR4i has its own Tarox listings and they are not interchangeable with the standard Sierra kits. The 298mm Sport Compact clears a 16 inch wheel and uses a four to six piston caliper with a single piece disc, which is a different package from the two piece Sport range. The 330mm Sport is the full two piece option for the XR4i at 17 inch and includes pads and hoses in the box. HiSpec’s 360mm Billet 4 is the largest kit they list in the Sierra range and needs an 18 inch wheel. At this end of the catalogue Cameron would rather talk the exact fitment through before anything is ordered.
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Ford Granada MK2 Brake Kits, Ford Scorpio Brake Kits, Ford Sierra Brake Kits, Hi Spec Road Car Front Big Brake kits
£1,539.90 Incl. VATPayPal CreditFinance availableAdd to basket -
Tarox 330mm 6 pot sport conversion kits, Ford Sierra Brake Kits
£2,280.00 Incl. VATPayPal CreditFinance availableSelect options -
Tarox 298mm 6 pot compact conversion kits, Ford Sierra Brake Kits
£2,040.00 Incl. VATPayPal CreditFinance availableSelect options
What is actually in each box
The headline gap between HiSpec and Tarox closes once both are specced to the same level. HiSpec price their kits without pads or braided hoses, so you add those separately and choose the compound. Tarox include both, with the pads already fitted. Compare the finished builds, not the entry prices.
| In the box | HiSpec | Tarox |
|---|---|---|
| Calipers | Billet 4, 6082 T6 billet aluminium, 4 piston | B32 or B34GT, billet alloy, hand assembled |
| Discs | One piece (283/300mm 1P kits) or two piece floating (300 2P and above) | Two piece floating, balanced to 0.05mm |
| Brackets and hardware | Included | Included |
| Braided hoses | Priced separately | Included |
| Pads | Priced separately, your choice of compound | Corsa pads, fitted |
| Caliper finish | Black, red, blue, gold or silver | Black, red, blue, green or gold anodised |
| Built in | Dartford, UK, up to 28 working days | Northern Italy |
Every kit on this page compared
| Kit | Disc | Caliper | Smallest wheel | Pads and hoses | Price inc VAT |
|---|---|---|---|---|---|
| HiSpec 283 Billet 4 | 283 x 24mm | 4 piston | 15in | Extra | £785.44 |
| HiSpec 300 Billet 4 2P | 300 x 28mm | 4 piston | 16in | Extra | £1,233.29 |
| HiSpec 315 Billet 4 2P | 315 x 28mm | 4 piston | 16in | Extra | £1,283.02 |
| Tarox 305 Sport | 305mm | B32, 6 piston | 16in | Included | £1,860.66 |
| HiSpec 335 Billet 4 2P | 335 x 28mm | 4 piston | 17in | Extra | £1,357.50 |
| Tarox 340 Super Sport | 340mm | B34GT, 8 piston | 18in | Included | £2,610.00 |
| HiSpec 360 Billet 4 2P | 360 x 28mm | 4 piston | 18in | Extra | £1,539.90 |
| Tarox XR4i 298 Sport Compact | 298mm, 1P | 4-6 piston | 16in | Included | £2,040.00 |
| Tarox XR4i 330 Sport | 330mm, 2P | B32, 6 piston | 17in | Included | £2,280.00 |
Prices include VAT and were correct on 14 August 2026. Tarox minimum wheel sizes looked up from their own product pages per kit.
Common questions
Will standard Sierra kits fit the XR4i or the Cosworth?
No. The XR4i uses a different hub carrier and has its own Tarox listings. The Cosworth 2WD and Cosworth 4WD are different again, with their own separate HiSpec and Tarox fitments. If you are not sure which version of the Sierra you have, the Cosworth is turbocharged and the 4WD version has a different rear axle layout; the XR4i has a 2.8 V6 and a distinctive bi-plane rear spoiler. Ring us if you are in any doubt and Cameron will confirm the right kit before you order.
Do these kits also fit the Ford Granada Mk3 or Scorpio?
Yes. HiSpec built the standard Sierra kits to cover the Ford Sierra, Ford Granada Mk3 and Ford Scorpio, because all three share the same front hub design. If you are fitting to a Granada or Scorpio, these are the right kits. Tarox list their Sierra kits for the Sierra only, so ring us for a Tarox fit on a Granada or Scorpio and we will confirm with Tarox before anything is ordered.
Why do some HiSpec kits have one piece discs and others two piece?
The entry 283mm and 300mm 1P kits use a conventional one piece disc, which is simpler and lighter. From the 300mm 2P upwards, HiSpec switch to a two piece floating disc with a billet steel rotor and an alloy bell. The floating design reduces thermal distortion under repeated hard stops, which matters more as disc size and braking effort go up. For a road car doing occasional track days the 1P kits are fine; for anything doing regular circuit work the 2P design is the better choice.
Why are pads and hoses extra on the HiSpec kits?
HiSpec price the hardware bare so you choose the compound to match how the car is used: a softer road pad for a daily driver, something more aggressive for track evenings. Both pads and braided hoses can be added at the same time. We will quote the finished build level so you can compare it properly against the Tarox kits, which include both as standard.
How long before it arrives?
HiSpec kits are made to order in Dartford, allow up to 28 working days. Tarox kits are built for the specific car at the factory in Italy and lead times vary through the year, so ask when you place the order and we will give you the current picture. Neither brand keeps finished Sierra kits on a shelf.
What we would actually fit
On a standard Sierra keeping its 15 inch wheels, the 283mm Billet 4 and budget separately for pads and hoses at the same time. On 16s, the 315mm Billet 4 2P is Garreth’s default answer for a car that is driven properly: the two piece disc is the better construction and the price difference from the 300mm is minimal. If you want one box with nothing left to add on 16 inch wheels, the Tarox 305mm Sport is the answer. On 17s, the 335mm Billet 4 2P for a road and occasional track day car, the Monster 4 or Monster 6 (325mm, still listed) if the car is doing proper circuit work. And for anyone wanting the best kit on the standard Sierra without worrying about the cost, the Tarox 340mm Super Sport on 18 inch wheels.
For XR4i owners, start with the Tarox 330mm Sport for the complete package, or ring us and we will spec it from there. Ring us on 0115 9893488 with your wheel size and what the car does at weekends. Working out what clears and what fouls is Cameron’s corner of the business, so have the wheel spec handy and you will get a straight answer.