All,

I have been thinking about a brake balance setup for the FD, but something just occurred to me the other day. When I spoke to the guys at Crooked Willow a while ago, they mentioned that their balance bar was interoperable with the stock ABS system. However, I have seen similar balance bars for other cars that have expressly advised against the use of ABS. I couldn't figure out why...

But then it hit me: when the ABS system engages on, say, one of the front wheels, a pump and control valve vary the pressure in the caliper in a pulsing manner. Meanwhile, the master cylinder for the front is disconnected and reconnected to the hydraulic system in rapid succession. You can feel this through the brake pedal as a "grinding" or vibrating sensation. On some cars, the pedal will actually push back on your foot.

And therein lies the problem: the balance bar (essentially a movable pivot arm) will transfer any forces from one master cylinder pushrod to the other. So if the front brakes are pulsing due to ABS, the rear brakes are also being artificially modulated at the same frequency. When you are very close to lockup, this variation could cause the rear wheels to lock and, in the worst case, encourage the car to spin.

This is my theory. Has anyone used a balance bar with an ABS system (in an FD or otherwise) who could shed some light on how this performs in real life?

Thanks,

-ch