Brake discs

Lotus OEM Fitment

S1 Elise

MMC

When originally conceived and released, the Elise was supplied with Metal Matrix Composite (MMC) brake disks in combination with specific MMC brake pads. In general it is agreed that an MMC brake setup provides excellent brake performance and feel. The only real complaint seems to be that in wet weather the initial bite and performance is poor until the disks are dried by application. (From VIN 2260 a splash guard was introduced to reduce this problem - Source elises.co.uk)

MMC's differ from normal 'iron' disks in that the friction generated is mostly Adherent Friction rather than abrasive friction (a very good article on the nature of braking can be found here). Essentially when the disk and pad come in contact some of the pad material transfers onto the disk surface, so the contact patches between the two are effectively the same material. As the disk rotates the bonds between the surfaces break and reform creating friction.

One of the benefits of Adherent Friction is that under normal use the disks last a very very long time. When braking the pads transfer their material to the surface of the disk, and it is this layer that is broken down, not the disk suface. Therefore the disks suffer very little wear. Under very heavy use however, the bonds between the pad and disk cannot reform as fast as they are broken down, meaning areas of the disk can loose the material layer entirely. When this happens the abrasive friction of the pad can score away the disk surface making it too rough to rebuild the original material layer. If this happens braking performance from the disk is permanently damaged and the disk must be replaced. For this reason car used on track or running semi-slick tyres may wish to use traditional setups.

MMC brake systems were supplied up until VIN 3714, when increased part costs forced Lotus to introduce standard iron brake disks. Recently Lotus have had trouble sourcing replacement pads, and have offered discounted conversions to iron disks for affected customers. Third party replacement pads are available from Elise Parts and Elise Shop. These alternative pads are also said to improve wet weather performance. MMC disks are no longer available.

Standard cast iron

Vented S1 OEM Disc

These discs followed the MMC disc as the standard brake disc for the S1 Elise.

Standard discs (Vented)

Lotus Part Number: A111J0128F

Cross drilled

Cross drilled and Vented S1 Disc

Lotus Motorsport discs as fitted to the 111s, Sport 160 and other models (Cross drilled and Vented).

Lotus Part Number: A111J0141F

S1 Exige, 340R

The Lotus Series 1 Exige, and 340R, was equipped with the same cross drilled disks as seen on the Series 1 111s and Sport 160 editions as shown above. These have a better ability to handle the heat generated with hard track use than the MMC disks

Lotus Part Number:A111J0141F

S2 Elise

288mm Vented Discs

The disks on the S2 are different to those used on the S1. They are the same diameter, but have a different offset and venting.

The S2 discs feature longer, curved internal flow passages which increase the disc stability and reduce hot spot formation. The revised hole pattern has been specified to complement the new vane arrangement.

The discs are not handed, so the same disc is used on the right and left hand sides of the car. The cooling air flow through the left and right discs is identical and the flow rate is purely a result of pressure differential between the centre of the disc and its rim; the shape of the vanes and the direction of rotation does not affect the flow rate significantly. Some noise from the brakes themselves is to be expected but there is a fix to stop brake pads banging in the callipers.

Pads sticking to the disc

The unservoed brakes on the S1 were criticised for not having enough initial bite when first applied, so Lotus used higher "grab" pads on the S2 to improve this. A byproduct of these pads is they tend to stick to the disc over a period of time, in damp or humid conditions this can happen within a couple of hours. This is something that affects the S1 as well but not to the same extent. Normally the stiction is limited to a clunk on pulling away, but with wet weather or if the car has recently been washed, the stciking can be quite severe. This however is not a problem its just Something you just need to be aware of, it is also just another case of TADTS