Removing ABS from an MX5

A crash course...

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If you haven’t already, go read Mikes post about our decision to go without ABS on the Exocet.

He details how the ABS system works and why we don’t want it. This post follows on and covers some of the details about how the non ABS system works and the parts we need to make the conversion.

In Mikes post he explained that the MX5 has a 3 circuit brake system. The braking force is shared between each front wheel (2 circuits) and the rear wheels together (1 circuit). This makes sense as the front wheels have the most grip under braking as the weight shifts forward.

The non ABS cars also have three circuits, however rather than using electronics the braking force is split using ‘proportional valves’.

To remove the ABS we just need to add some proportional valves and swap to a compatible master cylinder and we’re done.

For an MX5 there would be some extra work relocating hoses, but for the Exocet were fitting new hoses so it’s simpler.

For anyone wondering we think the master cylinder, brake circuits and hoses are connected according to the following diagram:

Image

A. Master cylinder output to proportional value input. C. Proportional valves rear circuit output B. Proportional valves front right circuit (mounts to master cylinder) D. Proportional valves front left circuit E. Proportional valves front right wheel connector.

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Welcome to Twits with Spanner. A blog following two chaps as they attempt to build an Exocet kit car with bits from a donor MX5, spanners and lots of hope. Read more about us


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