One of the few things we did learn on the MARRS 7 test day before the engine expired was that the car wanted to swap ends any time I got hard on the brakes. Clearly we had grossly too much brake pressure on the rear brakes compared to the front. Moving the brake balance adjuster around seemed to make no difference. Once we got the car home I put pressure gauges on the front and rear calipers and took some measurements while depressing the brake pedal by varying amounts. Plotting the results showed that the Tilton lever-style balance adjuster was not working - the output pressure was basically the same as the input pressure (minus a small constant offset due to the stock VW pressure limiter mounted at the master cylinder). See the upper graph in the embedded Google spreadsheet below. We switched out the Tilton regulator for a (much cheaper) Summit Racing knob-style regulator and as the lower graph shows, we now are able to actually reduce the rear brake pressure by an appropriate amount. Hopefully next time at the track we'll be able to use the brakes properly.
The new (working) balance adjuster. It accepts 1/8" NPT fittings so an adapter to -3AN was required on each side.
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