Quote:
Originally Posted by Rail Jockey
I also have an early 08 built third week of June, I haven't received it ether.
Just curious, has anyone that has had it done noticed any performance change besides the brakes good or bad.
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I've noticed no other performance changes other than much more responsive OHB brakes on start up.
The engineer in me is now very curious about the electro mechanical design of the brake "input" considering the system seems capable of brake deflection independent of vacuum compliance. This suggests a wee bit more linkage complexity than what one would normally encounter.
A normal brake vacuum system can basically have the mechanics hard connected to the vacuum diaphragm. When vacuum is present, the brake pedal is easy to push. When no vacuum is present, the brake pedal is hard to push.
An OHB system seems like it would need additional "gearing". I use the term "gearing" loosely to describe some kind of linkage that allows the brake pedal to drive two functions....one function being the normal vacuum initiation and the other function the OHB. The normal vacuum linkage will need to be designed to disconnect from the diaphragm on no vacuum start in order to allow the pedal to deflect. The brake pedal deflection would thus drive the OHB. Once vacuum builds, the reverse would occur. The system would need to back off the OHB function and allow the normal vacuum process to work.
The initial problems with the brakes suggest the transition to/from OHB and from/to vacuum had some programming issues. This is a very interesting process since it involves programming an electronic response (OHB), the need for which is determined by the feedback from a rapidly changing mechanical response (vacuum), when the input for BOTH responses is the same (user applied pressure on the brake pedal).
How does one use the SAME input (driver's force on the pedal) to drive two different processes (an electronic OHB and an mechanical vacuum assist), when the response of each process is dependent upon the response of the other process, which is dependent upon the driver's input on the brake pedal?