When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Just putting this here for later discussion. The first picture is a normal braking event for T10. I had to use the Aim data because it has slightly better longitudinal G data. This is zoomed way in but the black line is speed, the red is brake pressure, and green is long G. The second picture is that lap. You can see a ~0.25s lag from I go to the brakes to when the car starts slowing. This is when the car was in the ABS or maybe ice mode. A quarter second isn't enough time to get off and back on the brakes but you see it did start to slow at a decent rate - just with that initial delay.
Sean, pull up the PDR steering angle. Your braking is the same as previous laps to a good extent and your entry speed was correct by turn in. It just seems your fronts locked up and then right before hitting gravel you put in 40 degrees of steering angle and the car just didn't budge at all which I understand if the fronts were sliding. But I've only experienced this on warm up laps.
Hard to tell on video.
Hindsight 20/20 of course.
Last edited by BrunoTheMellow; 08-11-2020 at 07:09 PM.
Enough is enough. Moderators! You need to either close this thread or put an age lock on it so our kids are not unduly influenced by this anti-American behavior from Poor-sha! No, I am not protecting children from the idea of taking an already fast car and pouring inordinate amounts of time and and money into it to make it faster. That, actually, is an American value.
I am very concerned at the other behaviors recently demonstrated here. Admitting you may have gone too far or made a mistake? Opening yourself up to feedback and potential criticism from the public? Using data to analyze what happened in an analytical fashion? Sharing that data publicly?
ALL OF THESE ARE OUTRAGEOUS AND UN-AMERICAN!! How do I know this you ask? Well, just look at our beloved political leaders. Do you see any of these atrocious behaviors in that esteemed group? No sir, you do not! Look at our beautiful media personalities. Do you see any of these abhorrent behaviors in that shiny, happy group? No sir, you do not! Look at our incredible social media bastions. Do you see these nausea inducing behaviors on those magnificent platforms? No sir, you do not!
So, clearly this is un-American. I wouldn't want this behavior from Poor-sha rubbing off on our children. Keep them out of here. Please.
I'LL ALLOW IT.-Bruno
Last edited by BrunoTheMellow; 08-12-2020 at 10:57 PM.
Amazing car, but... something is up with the rear end/driveline or rear suspension. You’re much later getting back to throttle and the car looks like a huge handful when you do.
edited to add: rear slicks could be shot, would do it also.
Sean,
Sorry to see you go off - I didn't even get that far in your video when I posted the comment above.
The braking event looks really familiar. I'm not sure if it's ice mode, but there's something else going on here. Some sort of delay I think. I feel like I've experienced it. I ended up blowing through some cones, I was lucky.
Here's someone else's braking (ice mode?) event that you analyzed. Maybe you could compare data in it(if you still have it) to your event.
I had a problem that might be similar or not at T8 at Mosport, where I'd brake harder and harder and my braking distance would actually increase. I deduced it might be the brake pads I was using DS3.12, I think their initial bite-in is too strong and it causes the ABS to engage. It made it hard for me to modulate the brakes. I've switched back to DS 1.11s and will try that track again in early September and see how that turn feels.
Well, this happens all the time when I work on braking later, or from a faster speed in a specific corner. At some point, my brake pedal pressure exceeds what it can take (depending on surface, tire, and amount of compression), and it starts slowing down worse. This probably happens when I exceed the available traction and ABS starts trying to help, but I DO NOT think it is the ICE mode. Your best traction is right below the lock-up threshold, and once you exceed, ABS serves you some decent traction, which is a bit below what you are used to.
I had ICE mode, too, and with it, the braking performance drops way below expectations, and it keeps the deceleration at 0.6G or so, very low for what we are used to.
Even on ABS he doesn't exit the track at that speed and carry that far. That car wasn't stopping. And the data looks to show a delay between the application and the slowing down. I'd check for air in the system. I've gotten mushy pedal on the best of fluids. Summit looks like it could eat brakes by lunchtime. Some of that extra time could be the brakes not engaging at the same point of pedal travel.
Even on ABS he doesn't exit the track at that speed and carry that far. That car wasn't stopping. And the data looks to show a delay between the application and the slowing down. I'd check for air in the system. I've gotten mushy pedal on the best of fluids. Summit looks like it could eat brakes by lunchtime. Some of that extra time could be the brakes not engaging at the same point of pedal travel.
His slowing down was fine. He was at the same speed at turn in as the previous laps. Just couldn't turn due to locking up likely.
At some point I'm going to start a new thread about this incident. I've been looking at the data and there is a lot that doesn't make sense but here are some more thoughts.
First, since I've been listening to pro coaches and started looking at data I've been trying to get the ideal brake application. That is generally considered a fast ramp up with a hard initial application followed by a trailing off as you turn in. Historically I've had a slower initial ramp up on the brakes to let the weight transfer but figured that wasn't what the pros recommended in the data trace so I've been working on my technique. Unfortunately, that seems like it was the wrong thing to do with this car.
Second, I have previously confirmed with Cosworth that the data overlay on the PDR lags the video by ~0.2-0.3s so you can't use the video the determine my speed at a given point. I *think* I was still going about 10 MPH faster at the turn in point but am still trying to sort all this out in the data. I've also been trying to find a good way to overlay braking with actual deceleration but the longitudinal G is only recorded at 5 Hz in the PDR and is 10 Hz in the Aim system.
In any case, I probably could've released the brakes and made the turn but a) I panicked because the car was not slowing initially, b) I was amped up chasing a new PB time on the predictive timer and c) we had a car earlier that morning hook it coming out of T10 and smack the inside wall which is usually what happens if you get it wrong. No matter how you slice it this was driver error even if there was a brake issue that put me in that situation.
We know that the Z07 and ZR1 ZTK cars had different ABS programming. I'm really curious to know if this can be retrofitted and if it is better with regards to high initial brake application.
Watch other guys running 2:15s (another Sean on YouTube) they brake way earlier on that corner. Like by the bridge. You were pushing the limit and found it.
Since you are "all in" if it were me I would be looking to replace the system with a Motorsports specific ABS system of some kind.
What you describe was commonplace for me in the Grand Sport. It happened so frequently I stopped paying attention to it. The brakes, during initial threshold braking application, always required a pressure adjustment. I can't imagine arriving at a corner as quickly as you are going now and having to deal with it regularly.
Watch other guys running 2:15s (another Sean on YouTube) they brake way earlier on that corner. Like by the bridge. You were pushing the limit and found it.
He's nowhere close to the limit. Once he gets that car sorted with his skill set I would not be surprised if he's in the 1:12's or faster.
There’s some thing “off” with Chevy ABS programming for sure. I had a similar incident at Buttonwillow. Coming in to the fastest part of the track, I got a pass from the car in front. Took a normal pass, went to brake to slow for the turn...NOTHING. Overshot the turn in point, car went off straight into the dirt.
At the time I blamed a late pass that I shouldn’t have taken, but in all honesty I’ve done that a hundred times in my BMW. Never had this “ice mode” type problem where it immediately locks up and pumps ABS and prevents me from being able to modulate the brakes. And this is on Carbon Ceramic brakes on the Z07 packages Grand Sport, on relatively fresh Cup 2s where I know I have braked harder and slowed down faster before.
For some strange reason if you ramp up too quickly on the brakes, it locks you out and prevents any real input and send you sliding off the track because you can’t slow down.
Limit of braking. Limit of his current abilities. Limit of the cars current setup. Clearly a limit was hit since the car went off.
I would hope he's not at the limit of the car considering a stock c7z on the same tires can run less than a second slower.
I suspect you are watching videos for the Sean that goes by @shizon'00 here. He is a very good driver.
Even with the few sessions I had the theoretical best was a 1:14.34 and I was chasing a 1:14.5 when I tossed it away. For perspective, the best I ever put in the C7 ZR1 was a high 1:14.67 and that was running from the McLaren 720S and one of only two laps I ever did under 1:15 in that car. The best I ran in the C7 Z07 was a 1:15.0. Both of those were under ideal conditions and with a rabbit. This car was consistently turning 1:15.0-1:15.1 but we are reaching a point of diminishing returns. Most of the remaining time to be gained is going to be in T3/4 and T10 - both of which are fast sweepers that I tend to over slow for - unfortunately we've also seen what happens when you get them wrong.
I’d love to see an ice mode thread because what I’m seeing written here doesn’t coincidence with my personal experience and what I was taught at the Ron Fellows ZR1 school. They told us to just mash the pedal as hard as possible in a panic situation and then we practiced it for at least a half hour. Every car stopped extremely quickly every single time. For 2 years they’ve max braked these cars thousands of times and they always stop. There’s some kind of disconnect here which I don’t understand.
08-11-2020, 03:36 PM
