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      12-07-2011, 10:24 PM   #89
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Originally Posted by RandysV10 View Post
So I got the new "OEM" rotors and PFC06 pads installed on all four corners. Bedded in the new rotors and pads, pads squeal like a stuck pig, do you guys get that as well? Decided to give the Solo gear calibration another try and bingo. I guess when I tried before I wasn't getting into sixth gear long enough so I guess third time was the charm. Hopefully all set for the 18th for some open lapping on full course. Hopefully the weather will cooperate. Since it's open lapping will even be able to give the GF some rides along on some hot laps.
Yep, my PFC 06s were very noisy without heat in them. They were even noisy during the whole session where we did the leapfrog and off-line exercises at the October school, when taking it a little easy. (Well, at least I was taking it easy--you and the ZR1, not so much!) Didn't notice any noise on hot laps, where they were pretty amazing compared to the OEs, so maybe noise is a good warning that they aren't in their sweet spot.

Let us know how thw 18th goes. Have you had a chance to look at your data from teh other weekend, and find areas to focus on?
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      12-07-2011, 10:33 PM   #90
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Originally Posted by MFGJR View Post
Hmmm... I'd like to understand this. Is the Solo's predictive lap timing feature based on segment splits? I thought it was a constant thing, at any position on the track. But, i haven't thought much about this part as it's not allowed at events I run.
... not so sure it's AiM specific but more of a general rule of thumb when it comes to est. accurate predictive times.
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      12-08-2011, 05:23 AM   #91
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Quote:
Originally Posted by MFGJR View Post

Let us know how thw 18th goes. Have you had a chance to look at your data from teh other weekend, and find areas to focus on?
Not much as of yet Frank, have been trying to get the Zed set up as I have to leave on Sunday for a week in San Francisco then return on Saturday and immediately head out to VIR. I do feel that I'm getting a little more comfortable with the software but still have a ways to go.
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      12-08-2011, 01:21 PM   #92
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The Solo does not use segments for the predictive times. It does them based on start/finish only. Other AIM products and other loggers use predefined segments to determine predictive times. The SOLO's only segmenting is done in RS2. The actual unit does not have any segments in it.

The location of the segments should be before braking zones so that a small difference in braking doesn't ruin the segments. This can make a big difference in your segment analysis.
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      12-08-2011, 05:39 PM   #93
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Originally Posted by Matt Romanowski View Post
The Solo does not use segments for the predictive times. It does them based on start/finish only. Other AIM products and other loggers use predefined segments to determine predictive times. The SOLO's only segmenting is done in RS2. The actual unit does not have any segments in it.

The location of the segments should be before braking zones so that a small difference in braking doesn't ruin the segments. This can make a big difference in your segment analysis.
Thanks for clarifyin, Matt. So, if I understand, while segmnets won't affect the Solo's predictive lap times, in RS2 we want "quality" segments for analysis in the Split Report view? And, do we want to start a segment BEFORE the braking zone so that braking is inclusive in the segment, or do we want the segment to start AFTER the braking zone, so that the braking is included in at the end of the prior segment? Or, do we want major braking zones segregated and excluded from all of the corner/corner or corner/straight segments?

I was probably somewhat inconsistent with where the braking zones were located in the VIR segment map that I sent you, so I'll re-work it based on your input.

Thanks!!!!
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      12-08-2011, 07:27 PM   #94
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Originally Posted by MFGJR View Post
Thanks for clarifyin, Matt. So, if I understand, while segmnets won't affect the Solo's predictive lap times, in RS2 we want "quality" segments for analysis in the Split Report view? And, do we want to start a segment BEFORE the braking zone so that braking is inclusive in the segment, or do we want the segment to start AFTER the braking zone, so that the braking is included in at the end of the prior segment? Or, do we want major braking zones segregated and excluded from all of the corner/corner or corner/straight segments?

I was probably somewhat inconsistent with where the braking zones were located in the VIR segment map that I sent you, so I'll re-work it based on your input.

Thanks!!!!
You're correct on the quality segmenting. I'm not a pro when it comes to segments, but I do know it's somewhat of an art. You don't want the segment to include a highly variable area - like catching just the beginning of a brake zone. That would make for a spot where later braking (that might blow the corner) could make the prior segment look really good but not attainable in practice.

I'll see if I can get someone to write an article for TrailBrake about segmenting. I'm sure we'll all learn a lot.
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      12-09-2011, 06:28 PM   #95
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Originally Posted by Matt Romanowski View Post
You're correct on the quality segmenting. I'm not a pro when it comes to segments, but I do know it's somewhat of an art. You don't want the segment to include a highly variable area - like catching just the beginning of a brake zone. That would make for a spot where later braking (that might blow the corner) could make the prior segment look really good but not attainable in practice.

I'll see if I can get someone to write an article for TrailBrake about segmenting. I'm sure we'll all learn a lot.
Makes sense... start the segments comfortably before braking begins, then all the braking is included with the upcoming corner.

Thanks
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      12-09-2011, 07:02 PM   #96
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I know a number of you out there have felt that squirmy feeling in the rear end when braking hard on the track.

I frequently experience it when braking into turns 10/11 at VIR, the infamous "Oak Tree" corner. For those unfamiliar with VIR, this section of the track involves a fast left hander followed by a short straight that goes downhill (where you gain speed FAST) and then it changes to uphill as you come up to the major braking zone for the slow right-hand hair pin. Because of the uphill braking, you can brake late and hard. It's here that the rear end often gets "happy"--not like it's coming around, just unsettled and uncomfortable. My instructors have sometimes thought it was because I was giving steering input while braking here, which I thought was BS and I've been anxious to have data to see what's really going on. Problem--I'm not going out any time soon.

I readily found the same squiggles in Randy's data from VIR. Here's an example:

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The green line is throttle/brake pedal input, and you can see in the highlighted section he's rapidly building braking force. The red line is lateral acceleration, and you can see the sharp swing of about a quarter G when the car gets unsettled. Speed when this begins is ~75 mph, having already decelerated from 90 and on the way down to ~ 50 at turn-in. You can see on the blue steering angle line that Randy's steering inputs aren't fluctuating by much at all before the twitch--but note that the angle wasn't at zero, but rather he has a constant input of 8 or 9 degrees right dialed in throughout the braking. I think this is what the car doesn't like.

The track is bending to the right very subtly here, leading up to the turn, and I think there's a subconscious need to get lined up parallel to the left-hand curbing before turning into the right hander at the end. I think I'll try ignoring that curbing, and just focus on braking in a straight line toward the correct turn in point, striving for zero steering input.

Having this kind of data really lets you play detective on these weird little situations!

Last edited by MFGJR; 12-10-2011 at 01:51 PM.. Reason: typo
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      12-09-2011, 07:16 PM   #97
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Frank,

Since I have modified my braking technique, the rear end sqerming has gone away.

That being said, you are spot on about braking with a little steering input.
A couple of months ago, I was dong full course VIR and running a very hot lap. Hotter than I normally run. Coming up the uphill S's, I brushed the brakes coming into turn 10 and the car was scary.
After the run, I asked the instructor who I had asked to ride along what he saw.

"You had maybe 5 degrees of steerig wheel input. You were at the limits of the car and just that little bit of input combined with the slight braking unbalanced the car."

5 degrees... holy crips..

Turn 10 is the most dangous turn on full course and 90% of all incidents happen there.
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      12-09-2011, 07:26 PM   #98
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Frank,

Since I have modified my braking technique, the rear end sqerming has gone away.

That being said, you are spot on about braking with a little steering input.
A couple of months ago, I was dong full course VIR and running a very hot lap. Hotter than I normally run. Coming up the uphill S's, I brushed the brakes coming into turn 10 and the car was scary.
After the run, I asked the instructor who I had asked to ride along what he saw.

"You had maybe 5 degrees of steerig wheel input. You were at the limits of the car and just that little bit of input combined with the slight braking unbalanced the car."

5 degrees... holy crips..

Turn 10 is the most dangous turn on full course and 90% of all incidents happen there.
Makes you *almost* yearn for the M3's longer wheelbase, huh?

So what have you changed up on your braking, besides minimizing steering inputs while adding brakes? (That latter must sound like someone who failed Track 101, but it's really pronounced on the Z4M...)
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      12-09-2011, 07:46 PM   #99
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Smoothing out the braking input. Starting gingerly and add more progressive force.
Seems simple but took awhile to get it down.

If you start applying too much peddle, too quickly, there is an abrupt transistion of weight from rear to front. Starting gingerly and adding force, smooths out the weight transision and the car is happy with that.
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      12-09-2011, 08:11 PM   #100
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Smoothing out the braking input. Starting gingerly and add more progressive force.
Seems simple but took awhile to get it down.

If you start applying too much peddle, too quickly, there is an abrupt transistion of weight from rear to front. Starting gingerly and adding force, smooths out the weight transision and the car is happy with that.
Conventional wisdom is to squeeze into the brakes as quickly as you can without upsetting the car, and then come off more gradually as you begin to trade off braking for steering entering the turn. Key word are "without upsetting the car", and with the Z4M it may well be that we simply have to come into the brakes, as you said, more gingerly than one might in another car.

This is really valuable to highlight as we're dissecting our data, comparing to other cars, and consulting the experts' literature on data interpretation--our braking profiles probably should be a little less steep coming in beacuse of our inherent (short wheelbase) instability.

That thought, and what we've seen about the incompatibility of heavy braking and even a little, teeny bit of steering input, make for a pretty good day's work. Miller Time! (Actually, Spaten Time!)

Thanks, Jay!
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      12-10-2011, 01:08 PM   #101
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Hey Frank,

I'll keep a mental note on that segment and see if I can clean up the braking there, it does tend to lean to the right. Going to be interesting on the data after the next run, just hope the weather is not a factor as that will probably change everything.
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      12-10-2011, 04:59 PM   #102
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Originally Posted by RandysV10 View Post
Hey Frank,

I'll keep a mental note on that segment and see if I can clean up the braking there, it does tend to lean to the right. Going to be interesting on the data after the next run, just hope the weather is not a factor as that will probably change everything.
Randy,

I hope you don’t mind me using your data as a test bed for analysis. I’m not AT ALL criticizing the driving—you’re going faster than the 2:30+ish times that have been my best at VIR. It’s just really useful to have real-world, relevant data to use when thinking about the things that I know I need to work on, and how to see the related good or not-so-good in the data.

That said, yeah, it’ll be enlightening to have the new data, and I’ll have my fingers crossed that it’s dry for you.

The brake pad differences between the two track days should be real interesting. I know your brakes weren’t very confidence inspiring last time out, and I think we can see that in the data.

RS2’s “Toggle Delta” feature lets us easily measure the distance and duration between two points on the graph. If you haven’t already figured out how to use it, first click the red delta button on the tool bar (circled in the below screen shot). Then click the first location on the graph—that point then becomes fixed. When you click a second point, RS2 measures the time and distance between the two, and also in the legend(s) provides the delta for any channels you have on the graph. You can move the second point around by clicking at another point, but you can’t move the first point without turning the Toggle Delta feature off, and then on again, using the tool bar button.

In the below graph, which has a pretty representative lap from run 14, I measured between getting off the throttle coming down the front straight approaching Turn 1, and getting off the brakes and back on the gas right around the turn-in point. RS2 measures that as 5.832 seconds in duration, and 792.299 feet in distance. The brake markers at VIR are, I believe, measured in 100 foot increments, so this is starting the braking before even the 6 marker. (Had it been me, the way those brakes were complaining, I’d have started braking for Turn 1 at, say, Oak Tree!)

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Further, if you look at the throttle on the front straight—which is divided between the right and left sides of the graph as start/finish is in the middle—you were full-throttle for about 1,000 feet out of Hog Pen, and then started steadily coming out the gas for the next 650 feet/6 seconds before going to brakes. Should be a good bit of speed to be had with another 5-6 seconds of 100% throttle, vs. the 65% that you averaged across that time. Of course, there’s the resultant trade-off in braking point.

Similarly, braking on the back straight was 800+ feet and 5+ seconds, though here you weren’t trailing off the throttle prior to braking.

So, next time out with the Big Boy Brakes, it will make for an interesting contrast in terms of how much longer you’re comfortable staying in the throttle, and how much you can compress the braking zones. Now, we just have to remember what Jay’s taught us about keeping the car settled on the brakes…

Next thing I'm going to try to look at is consistent and accurate turn-in at Nascar, which seems to elude me.
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      12-10-2011, 05:03 PM   #103
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You can also just hit the D key to toggle the Delta function on and off.
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      12-10-2011, 05:08 PM   #104
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You can also just hit the D key to toggle the Delta function on and off.
"D" is for "Damn, wish I'd known that for the last month!"

Thanks. Matt!
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      12-10-2011, 06:17 PM   #105
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Frank,

Don't mind at all using my data, will provide more soon. I'm a lot thicker skinned than that, so believe me I'm not taking it as criticism but pointers on better runs. That is after all why we are doing this. I know in the M6 my braking zones were compressed much more, also I think my instructor was a little nervous at times. On one run coming up to Turn 14 he asked me to back down a little as the back end got a little wiggly with the hard braking. But in his defense I did want to be smoother. So with the PFC06's and new rotors on board I am ready for next Sunday.
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      12-14-2011, 08:18 PM   #106
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smarty cam arrived late today but was able to easily set everything up, just have to run one more wire to where I'm mounting the smartycam to complete the install. Ill post up pics and video this weekend.
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      12-16-2011, 09:22 PM   #107
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Frank,

Don't mind at all using my data, will provide more soon. I'm a lot thicker skinned than that, so believe me I'm not taking it as criticism but pointers on better runs. That is after all why we are doing this. I know in the M6 my braking zones were compressed much more, also I think my instructor was a little nervous at times. On one run coming up to Turn 14 he asked me to back down a little as the back end got a little wiggly with the hard braking. But in his defense I did want to be smoother. So with the PFC06's and new rotors on board I am ready for next Sunday.
Looks likes the weather is going to clear up for you this weekend--looking forward to hearing about it.
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      12-18-2011, 05:46 PM   #108
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Spending some more time on Matt Romanowski’s excellent site, www.trailbrake.net, I came across this neat little “throttle and brake map” depicting, as you might guess, throttle and brake application (see http://www.competitiondata.com/downl..._brk_map.htm):

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This looks to be a handy way to see places where you’re getting in and out of the throttle, or prolonging braking, etc. I put together the same thing, pretty much, in RS2 using my “Throttle_Brakes” math channel (combines throttle position and brake pressure into a single channel/line—see post #84) feeding the Track Report view.

Here’s the result for a single lap:

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While you can see the same thing in the Measures Graph, shown this way it’s maybe easier to see. You can also select multiple laps to display in the Track Report view, though things get kind of smushed if you select too much.

To build this, in the Track Report view, select the “Settings” button in the upper right corner. In the Track Representation area, change the “3D Channel” to the appropriate channel in the drop-down, and click on “Bands” to see the crispest delineation in the map.

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Of course, this could be done separately for throttle using the ECU throttle channel (“Z4M_PPS” for us) or brake pressure channel (“Z4M_BRAKE_PR”), I just like to see the two inputs in the same channel. I thought maybe using the longitudinal accel channel would work, for those not getting ECU data, but it’s not nearly as granular as the ECU throttle/brake info.

Matt—if you’re reading this, what do you think about also letting your readers share math channel stuff—ideas, successful syntax, etc? Structuring specific math channels would need to be logger-specific, and would depend on availability of certain channels (e.g., the ECU data above), but the ideas and concepts and techniques might cross different loggers. Just a thought.
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      12-18-2011, 08:29 PM   #109
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Originally Posted by MFGJR View Post
Matt—if you’re reading this, what do you think about also letting your readers share math channel stuff—ideas, successful syntax, etc? Structuring specific math channels would need to be logger-specific, and would depend on availability of certain channels (e.g., the ECU data above), but the ideas and concepts and techniques might cross different loggers. Just a thought.
I'm all for it. And actually, I think what you did here is worthy of a featured article! You did a really nice job with the math channels and graph to get that info into one map. I'm sure a lot of people have not come up with that in RS2.

I'm all for sharing math channels as well. I'll shoot you an email about that in a little bit.
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      12-19-2011, 06:20 AM   #110
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I'm all for it. And actually, I think what you did here is worthy of a featured article! You did a really nice job with the math channels and graph to get that info into one map. I'm sure a lot of people have not come up with that in RS2.

I'm all for sharing math channels as well. I'll shoot you an email about that in a little bit.
Thanks, Matt.

It occurred to me in the middle of the night that the formula behind that math channel, which is simply "throttle position - brake pressure" will produce weird results during heel-toe downshifts when both pedals are being applied--it will whack up the slope of indicated braking when the throttle is blipped.

We don't see the problem in Randy's data, as it appears he wasn't heel-toeing that weekend (first time out with the M Coupe, coming from an M6 with a sequential gearbox).

The solution is using an IF-THEN-ELSE statement in the math channel to identify conditions when the throttle blip should be ignored. Essentially, it's "IF the clutch is in. THEN only use the negative of brake pressure, ELSE use throttle position - brake pressure" Note that "throttle position - brake pressure" gets used at times when only one pedal is being applied, and is a streamlined way of getting throttle above the line when it's applied, and brakes below the line--it's subtracted, so negative--when they're being applied.

In AiM RS2 syntax, and using the channels from the Z4M ECU protocol (channel names and/or availability may vary for other ECU protocols), the formula is as follows:

IF(EQ(Z4M_CLUTCH_SW,1),-Z4M_BRAKE_PR,Z4M_PPS-Z4M_BRAKE_PR)

I still need to test this with some real data including heel-toeing, but I'm highly confident that this'll work. However, if someone's using left foot braking and throttle simultaneously--say, they have one of those Kramer 935 K3 monster turbos and need to keep the boost up, then this math channel won't work well while applying both throttle and brakes.
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