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Seat Leon Cupra R Brake Conversion

BMW M3 E36 AP 4pot brake conversion

This page gets lots of hits from Cupra / M3 owners. If you have any questions on the E36 M3 or Leon Cupra R just drop us a line. We would love to hear from you and may be able to help as we have built up a fair knowledge base on these cars. Failing that we can often point you in the right direction. All emails answered as soon as we can.

Seat Leon Cupra R brake conversion kit

During tuition we have found that the main weakness of the petrol Seat Leon Cupra R and indeed our Diesel Cupra R (full Cupra R brake and suspension specification) is the brake discs. The 4 pot caliper as fitted as standard to the Cupra R is a very effective caliper, being both stiff in structure and powerful in piston force on the disc. However, the disc itself is the real weakness. Discs can be warped very easily on track with this car, yet the actual braking available is excellent, even on standard pads. And we drive these cars hard!

We have tried several, supposedly very capable, alternatives but eventually decided to develop a solution to Cupra R braking ourselves. Well, with a little help from AP! So, what have we come up with?

What we really wanted was a serviceable setup, that wouldn't warp but would give better retardation than standard. But we wanted to retain as much standard kit as possible. The CUPRA R Brembo 4 pot caliper is one that is used on a variety of performance cars, being a very stiff caliper with a large piston surface area. This we wanted to keep. So, starting with a 323mm disc of the Cupra R (323mm x 28mm thickness) we have had AP take this as a reference point to build a new disc. The solution is a bespoke bell (the centre of the disc -made for us by AP so it is a quality part) that will match up to an off-the-shelf rotor (the disc part)  -making it serviceable - but keeping the standard Brembo caliper. The new disc is also 28mm thick but is a larger diameter of 330mm. These are same rotors as used on EVO and Imprezza 6pot AP track upgrade. (A larger rotor could be used, up to about 345mm.)

So, how does this fit? Well the Brembo caliper is mounted onto the caliper carrier, face-on. So it can be spaced further out to accommodate a larger disc. This we have done with machined spacers and longer high tensile steel bolts (12.9 tensile strength rather than 8.8 standard). It still fits inside the standard 18" Cupra R wheel but now the disc is so much less prone to warping, the two piece assembly keeping the heated area on a flat plane unlike a single piece disc.

Of course we can now have a slotted disc to aid disc cooling and pad surface cleaning and also have a larger swept area for improved braking. The net result; a lighter, larger, more effective braking system.

Although we are not a parts business, if interested, we can retail this brake setup out with a complete set of parts and instructions to  swap over the original 323mm disc setup as used on most later Seat Leon Cupra R models. There are a variety of disc slot styles available. The bell design is only available through us, a bespoke AP product and not from a third party manufacturer.

Negatives: Cost - and you get a slight race-brake type squeal on your very first application from cold. After that no noise from the pads - unlike the Italian solution then!

How good are these brakes?

On trackdays, with a 1300Kg Leon on sticky tyres, this car is never out-braked. With decent high b.p. brake fluid and Goodridge hoses the braking feel of this setup is fantastic, with no snatch/grabbing, but with the ability to heel and toe down-change whilst holding the car at maximum retardation. Again, on the sticky Avon tyres, there have been no warping issues despite the car pulling easy over 1g braking several times a lap - and if you have a Cupra R you will understand how relevant that is. It gives you the confidence on a track day to take distances out of cars under braking. This is the best single conversion you can do to a Cupra R. And they look great too....

Kit Comprises

2 x AP 330mm x 28mm slotted rotors - Choice of slot design

2 x Bespoke AP alloy bells - produced by AP solely for us. Not a machine shop job with inappropriate specification alloy.

4 x High Tensile bolts

4 x Spacers

Prices £590.96 + VAT. Approx 2/3 week delivery currently as we have to wait for batches of bells to be produced for us. Replacement rotors are readily available off the shelf.

NOTE WE HAVE BELLS CURRENTLY IN STOCK  - PRICED AT £90+VAT each + carriage

Expensive? To me this sounds expensive, as it will, no doubt to you. But, these discs show negligible wear after a dozen or more trackdays plus hard road use. Warping was always an issue every time we went on track. Now, it isn't a concern.  I would have also used certainly a couple of pairs of standard Cupra R discs in this time. Pad wear is pretty good on the 1144s too - Dec 06

We can supply three different alternative brake pads for this application, or you can use the standard Cupra R pads.

Mintex 1144 Cupra R road/track pads - £64.00 + VAT,

1155 track/race pads £64.00 +VAT,

F Series race pads   £111.00 + VAT.

All plus carriage at cost.

We're not a parts supplier so we're not interested in making money on these. Prices are at cost plus about 6% to cover time. What we are is a training business, so, if you're looking at these brakes have a look at the rest of the site - some good Cupra shots on track too.

Please ring for advice on any of these options. 01925 211944 or 07947 198 957. Please try the mobile first as we are often on road or trackside. Calls will be responded to as soon as we can - please leave a message or text us.

Following on from our conversion to using the M3 for track training use we have had to find a braking solution for harder usage. The E36 M3 uses a fairly basic single piston floating caliper design for front and rear brakes. The rears you can get away with (though we will be fitting the AP 4 pots to the rear very soon). The fronts however desperately need upgrading. As you can see below we have employed the same solution as on the Leon, using a 4 pot caliper and a 2 piece disc, incidentally exactly the same size as the Leon, a 330x28mm vented disc on an M3 specific bell. AP market this as an off-the-shelf kit.

PADS: On the original setup the M3 used drilled disc rotors- as in the picture- but slotted discs are now fitted. Serious cracking of the disc occurred in about 8000 miles use. I've never been a real fan of drilled discs for that reason

We have tried running Ferodo DS2500 & 3000, Pagid-various types- and also Mintex 1144, 1155 and F series race pads. The 2500 is an excellent pad for road use, but is too "grabby" when used on track and will fade easily. Fine for the road though lacking in bite. DS3000 significantly better for track use but deposit a lot of material on the wheels and are also hard on the discs as the rubber content deposits on the disc surface.

Pagids didn't seem to inspire confidence so we have now gone the full route of full race F2R Mintex pads. Not cheap but certainly do the job. The car runs Motul 600 race fluid and can be braked as hard as you need for lap after lap.

The difference in feel between the original BMW M3 brake setup and the AP is significant. OK, hoses have been changed to Goodridge, so there's going to be less mush to the pedal, but the braking feel is massively improved with the AP racing calipers. The change is worth it for the braking feel alone. The car does, however, also now stop rather better!

If you want prices on this conversion just drop me an email and we'll point you in the right direction. If you want to try the conversion out and, at the same time, get your driving to a higher standard, book a driving session!

Next step is to add some negative camber to the front to give a bit more bite and turn in. Just have to remember the car is used for instruction not racing!

Watch this space for further M3 E36 improvements

 Amusing quote: Reading one of the advanced driving forums of a well-known driver training establishment it states that, where braking is concerned, "heat is the enemy".

Funnily enough, a car would never stop if heat wasn't generated. The whole purpose of brakes is to convert Kinetic energy (energy of motion) into heat, as effectively as possible. The harder we brake the quicker the heat has to be generated and then dissipated. Discs and pads can easily reach temperatures of 5-600 degrees Celsius in track use.

 So, don't touch them when they get hot and, when you stop, be aware that that heat can soak into your brake fluid through the pads. When you stop, don't put the handbrake on!

For reference: We have carried out trials using some well known Italian brake conversions on this car and, despite using 6 pot calipers, stopping power is nowhere near the AP/Brembo setup. The multi-piston calipers are very stylish but suffer from a lack of caliper body stiffness and also relatively small total piston area. They just can't generate the braking force. Buyers beware - we wasted time with these but they just don't work very well.

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