I just spoke with Bosch and with the head of their major west coast distributor
Not going to quote anyone directly but basically the theories discussed in this thread are correct. The DOT approved versions of Bosch ABS induce ice mode when the wheel rate sensors detect variation across the four sensors. I am not clear if it is front/rear overall or any one wheel or both, nor did I find out what % difference the computer looks for nor timing involved in the algorithms... but it is a safety mode designed to help in the majority of street situations... hard to blame them for that
There are two systems available for dedicated track vehicles. One produced by Bosch and one produced by Continental. These systems are only provided for vehicles not used on public roads and purchasers are required to sign a waiver that is kept on file with the mfgr. The systems are sold through distributors. The Continental system is apparently a modified BMW ABS that is not configurable. The Bosch system is a bottoms-up race ABS with config options. Bosch has two major US distributors, one east coast and one west coast. The west coast distributor is Brian Sekata with MS Electronics.
I realize this is not all that helpful for those of you that will keep your cars street legal. Sorry, I have nothing to offer you folks. The only possibility I can think of is to find someone that can crack the computer and re-write the code... but then there is an issue of liability and intellectual property
For anyone reading this that has a dedicated track Z (either 370 or 350), it may be possible for us to work out a group buy on Bosch Motorsports ABS systems. I have no commitment from Brian or from Bosch, but they are interested in starting the conversation with us and asked me to carry the idea forward. If there are enough of us willing to sign that waiver, there might be a break off the system price... as many of you know, it is $10K today
... but
what if it were $6K ??? better braking performance and safe guard against ending up in a concrete wall... the system is also highly configurable - from the cockpit you can adjust proportioning and how the ABS reacts
In any event, please spread the word if you know anyone else with a dedicated track Z
Thoughts?