Quote:
Originally Posted by WarrantyTracker
Dogbone I sound like I'm giving you a hard time, and for that I apologize. To me, your data makes me infer there are negligible periods of material understeer (or oversteer) during your track runs. I definitely see periods of very light front brake pressure absent brake pedal input and no comparable episodes in the rear brake pressure. What that says to me is, you're not activating MDM in any material way. You're driving the car with the requisite skill to maintain relative traction across the wheels within the MDM envelope of intervention.
Imagine instead if you were relying materially on MDM to let stay on the gas during understeer conditions without just driving off the outside edge of the corner. What would happen then?
What I want to see before I can understand exactly how MDM works is an oversteer/understeer metric, variations in that metric, and caliper pressures in response. The oversteer/understeer metric would be derived from the acceleration and yaw sensors indexed to the steering angle sensor. It takes a fair amount of processing power to collect and display that metric. Then I want to perform experiments putting the car through a range of understeer scenarios and see what the rear brake activations look like.
I can (theoretically, given enough time) wear a single rear brake pad down to nothing in MDM without ever touching the brake pedal. Put the car on a sprinkler-wet skidpad going counterclockwise, maintaining constant steering angle, and then accelerate to the point just shy of terminal understeer. MDM will be grinding away on the left rear brake until I run out of gasoline and stop.
Also, I don't have data showing what was going on in my car back when I was using MDM as my nanny and I hadn't learned car control yet. Was I under-braking in the brake zone and tossing the car in too hot, letting front tire friction and heavy MDM activation of the brake pads slow me down enough to get to the apex? Was my acceleration off the apex so over-eager that MDM cut fuel, instead of even attempting to moderate the rotation with front brake application? I'll never know.
And one other thing that's completely unrelated to my line of analysis, but about which I'm curious. Your system is measuring X bar of pedal input triggering measurements of Y, Z, psi, and omega. I cannot determine from just the graphs whether there are any functions to be derived from those relationships, but I do see an awful lot of variation. Is that all associated with tire torque variations arising from independent suspension/pavement conditions at each wheel? Or is there MDM-induced variation that's driving up the rear pressure numbers incrementally and eating more pad?
My comments here are just spaghetti at the wall, not a rigorous engineering evaluation in any sense. I'm just trying to illustrate some of the ways in which I perceive there is much more to the analysis than: Dogbone's measured experience = MDM doesn't get into the rear brakes much.
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You started with a one-line comment that asserted something about MDM. I've shown quite a bit of data to the contrary that has been collected over several years. Since then, you've written a lot of words, but you haven't provided a SINGLE shred of data or anything else to backup any of your claims. In fact, you have repeatedly said you don't even have any data. You've admitted that you're giving me a hard time. And in the end, you question the value of the data I've collected.
You want to question what I post? Great. Question it. I have no ego when it comes this stuff. I say over and over again on this forum, I am not a motorsport industry expert. I have been learning as I go, and sharing what I have discovered. Not many others are sharing their data here on the forum. But if you're going to say stuff like, "
...I perceive there is much more to the analysis than: Dogbone's measured experience = MDM doesn't get into the rear brakes much.", then you need to stop perceiving, go strap a data logging device to your CAN bus, you need to go drive a shit-ton on track and collect dozens of days of hard data that proves something different---because it will take many days and many brake pads to prove your claims. Or, at the very least, you need to provide links to someone else's data. (Good luck finding that.) After you do that, I am HAPPY to listen to any of your conclusions. In fact, I wish more people would do exactly that----post up their data charts. Then there would be more to discuss! But until you do that, all your fancy "psi, Omega" terms and all your other theoreticals and questionings are just a bunch of arm chair grand-standing with nothing to support it. I'll take my data any day over your butt dyno.
And-----now I'm done with this thread.