Chasing down a Porsche, Cobra and BMW at Blackhawk Farms. - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 18 Old 08-30-2016, 11:42 PM Thread Starter
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Chasing down a Porsche, Cobra and BMW at Blackhawk Farms.

This was at the Northwoods Shelby event this past weekend. Had a fun time.



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post #2 of 18 Old 08-31-2016, 11:05 AM
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Getting smoother!

Save your downshift until just before you turn into the corner. It's messing up your car's balance in the braking zone when it's most vulnerable. The point of the downshift isn't to slow the car, it's to be in the right gear to accelerate out of the corner. If you do it really late, before you turn in or as you turn in, the revs will practically match themselves and not upset the car.

It's good form to offer a wave of thanks to people after they give you a point-by. It's VERY good form to wave thanks to the corner workers on your cooldown lap

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post #3 of 18 Old 08-31-2016, 12:02 PM Thread Starter
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Thanks man, been working on it. I had some great instruction from the SCCA guys last week. Not so much from the Shelby guys on this day. I will work on that downshift and you notice I kept my hands at 10/2 for the most part, it felt good.

I am pretty sure I waved to both of them...but will check on it and do it from now on. Thanks for the constructive criticism. I appreciate it.

BTW, this one was not so good.

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post #4 of 18 Old 08-31-2016, 01:58 PM
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OK, no offense, but that's what I meant by "group 2 syndrome". With more experience, you'll feel that about to happen, almost a second before it does, and you'll be better equipped to not let it, or catch it when it does. Also, remember: Slow hands when you have traction, FAST hands when you don't. You need to slap steering correction into it quickly, and then be prepared for it to snap back the other way suddenly when the rear end catches and the suspension unloads. Skip Barber calls it CPR: Correct, Pause, Recover. Specifically, Correct (QUICKLY), Pause (wait while the skid stops and the suspension wants to unload), Recover (QUICKLY).
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post #5 of 18 Old 08-31-2016, 02:25 PM Thread Starter
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No offense taken. I understand what you are saying. I had a couple of those types of incidents that day...one of them was chasing one of those cars but I got out of it and corrected right away, this one was a bit different in it came out right out of that corner which I had done many times before and just didn't get it. I understand what you are saying and will work on it. Thanks.

BTW, I am still driving in the Novice groups....lol.
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post #6 of 18 Old 08-31-2016, 09:59 PM
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I find my video quality is significantly improved if I put the camera on the windshield. Not sure how you're mounting it farther back, but I've got a triple suction cup mount that I can use on the inside of the windshield. Putting it up there gives the camera more exposure to the external light conditions so it can adjust exposure better (thus the view out the windshield isn't "whited out").

Of course, if you've got the camera mounted farther back so you can see your own inputs, then mounting it on the windshield won't accomplish what you want.

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post #7 of 18 Old 09-01-2016, 08:45 AM Thread Starter
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Patrick, I am actually mounting it on the rear window. I don't have a roll bar and I do want to see my inputs until I feel more comfortable. I would rather put it on a roll bar. I think those shots look the best. You can see the driver and the cars in front. Once I get a roll bar, I will mount it there. Thanks.
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post #8 of 18 Old 09-02-2016, 07:50 PM
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Get rid of the stock seats. They flex massively. They make it very difficult to drive as they don't keep you in place. As your corners speeds increase, the flex will get worse and worse and the seat backs or rear legs of the mounting rails will all crack and break.

The first thing I would get is a G-lock or something else to make the stock seatbelt functional. This will both save you in a crash and make it much easier to drive as the seatbelt doesn't end up with 6" of play in it. On some year cars, there is a plastic button as the base of the B-pillar that detects when the door is open or closed. Cut the top 1/4" or so off this button. Once this is done, the seatbelt retractor will think that the door is always open and keep the seatbelt relatively tight all of the time.

What parts are in the rear suspension? Looking at your second video where you spun, something is really wrong back there. With a properly functioning setup, if you use too much throttle, the rear should step out, you countersteer at a fixed angle, feather the throttle, WAIT a few seconds at a constant steer and throttle angle, then straighten the steering out. No spin, no damage.

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post #9 of 18 Old 09-02-2016, 08:13 PM Thread Starter
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I will look into those Jack, thanks. My wife loves the seats and that is why I have not swapped them out yet. I have been looking for some comfortable race seats but have not found any yet. When I do, I will make the swap and get a harness as well.

My rear suspension is the Griggs GR40 system. I have the heavy duty torque arm, pan hard bar, lower rear control arms, coil overs with Koni yellows, subframe connectors and 3.55's in the rear. I am leaning toward tire pressure as being the issue. I had it at 40 psi based on a friends recommendation. I since moved it back down to 35 in the rear. That seems to work best on the Kumho Ecsta XS tires I am running. Have not tried lower pressures yet. I saw some guys running 25 to 30 but they were on race tires. Not sure what works best, but I have gone 3 times and had 40 psi in all four corners when I spun out. 35 in all four corners seems to work the best so far. Thoughts?
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post #10 of 18 Old 09-02-2016, 08:34 PM
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I have only had one set of those tires on my street car and I didn't like them. It is a totally different car so the pressures are likely to be very different.

I would take a white bottle of shoe polish that has a foam applicator at the top. Make two white strips on each rear tire with it. Each stripe should start on the sidewall about 0.75 of the way to the tread surface and then go directly towards the tread surface and about an inch onto it. Do this at two locations on each side of the tire. After your first session, you will be able to see where the white is worn off of the tire. The goal is more or less to have it worn off to where the tread meets the sidewall. If the stripe on the sidewall is worn off, then the pressure is too low. If there is white line on the tread surface, then the tire pressure is too high. My guess is that the pressure is about 5-7 psi too high. Your car has about 58% of its weight on the front tires. With the same size front and rear tires, it needs lower rear tire pressure to have the same contact patch loading.

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post #11 of 18 Old 09-02-2016, 10:30 PM Thread Starter
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I had plans to do the polish on the tires. My friend who races out at Lime Rock told me to try chalk across the whole tread in 4 inch lines. I think he is on track with what you are saying. I will do the shoe polish next time out and see where I should be.

Right now I have 275/40/17's in the back and 255/40/17's up front. I bought the car this way. When I get new tires I will be using 255/40/17's on all four corners. I am running the OEM 95 Cobra R C58's right now. Kumho recommends a 9 inch rim for the 255's. What tire do you like and why? Again, the car came with the Kumhos so I am running with them until I need a new tire and will hopefully have a better grasp on what works and what doesn't. I honestly like the Kumho with the 35 psi but if there is something better in a street/strip tire then I am all ears. I am learning.

I liked that article you posted. I am a big fan of the SCCA events. The people are very cool, nice, and willing to help. There track nights are the funnest I have had so far. They just canceled there September Track Night here at Blackhawk because it is getting darker sooner and they don't think they can get everyone their time, so I might run with them at the Milwaukee Mile on the 15th. That looks like a very wide open track compared to Blackhawk. Same idea on the tire pressure regardless of track? Thanks for the help. Appreciate it.
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post #12 of 18 Old 09-04-2016, 09:31 AM
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You could try using a helmet mount for your camera. Should catch everything you'd want to see except probably your feet.




I'd definitely stagger the tire pressures a bit, and I wouldn't be drawing limits as narrow as 9" and 255 unless there flat-out isn't room for any more.


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post #13 of 18 Old 09-04-2016, 10:27 AM Thread Starter
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I have a Go Pro, Norm. Is that what you are using in that picture? I think it would mount to my helmet, never considered that. Not sure how that would feel having that weight on the side of the helmet.

For my 88 it appears the 9 inch is wheel is about as wide as I can get without issues. I have the 255's up front and 275's in the rear right now. I looked at a couple GT350 R's that had smaller tires on their wheels to the point of them looking stretched. They come right from Ford like this. That is why I was leaning towards the 255 or maybe even the 245 to see how that works. I have read it is a more responsive car with that type of setup. Thoughts?
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post #14 of 18 Old 09-04-2016, 10:58 AM
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Yes, it's a GoPro . . . and no, it's not something I ever notice after fumbling around and using the mirror to find the buttons to turn it on and record. I used one of the sticky mounts that I got with the camera (think it was a curved one). And that's another sticky mount on the top of the dash over by the glove compartment, for an alternate camera location.

A slightly stretched tire will sharpen transitional response and extend linearity out a little further. Not the crazy Euro-appearance stretch, just something wider than "measuring" up to (about) max recommended. On my '08 GT I'm running 285/35's on 18x11's all around for the track (max recommended, roughly comparable to 255/45's on 9.5's). I can't go any wider with the tire up front without too much spacer for my taste - strut clearance is less than 1/16" as it is. But I'm not at all sure I'd want to go more than 295 on 11's anyway. My current street setup is 265/40's on 18x9.5 all around, and it's noticeably softer-responding and less precise than the bigger track day arrangement is.


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Mine: '08 GT, 5MT, black/light graphite, un-Fstock (DD, occasional track day)
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Spare:'01 20AE Maxima, 5MT (also my bad weather alternate)
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post #15 of 18 Old 09-04-2016, 12:23 PM Thread Starter
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Ok, got all that so what should I consider on the 17x9 Cobra R's I am running.....255/40/17 or 245/45/17? My car weighs 3240lbs with me in it.
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post #16 of 18 Old 09-06-2016, 01:55 PM
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I'd probably go with the 255/40's, mostly on the strength of it having a wider tread (durability should be just a little better). But you may want to check speeds in gears because it is about 3/4" shorter than the 245/45. Use mfr revs/mile data if at all possible.

I was in a similar situation recently (255/45 vs 265/40, for street driving) and went with the 265/40. Another half inch or even a whole inch wider wheel was possible with the 265's (and likely a bit better for ultimate performance), but not by enough to invest in yet another set of wheels . . . for street driving.


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Mine: '08 GT, 5MT, black/light graphite, un-Fstock (DD, occasional track day)
Wife's: '10 Legacy 2.5GT (DD, six-speed manual)
Spare:'01 20AE Maxima, 5MT (also my bad weather alternate)
Various Loose Parts: '79 Malibu
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post #17 of 18 Old 09-06-2016, 03:10 PM
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Remember, it is the total volume of the tire that determines its load capacity. A small increase in tire OD, results in a large increase in the air volume.

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post #18 of 18 Old 09-06-2016, 03:23 PM
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I did check that as well. The 255/40 is one load index smaller than a 245/45, which can be crutched by inflating it only 1 psi higher.


Norm

Mine: '08 GT, 5MT, black/light graphite, un-Fstock (DD, occasional track day)
Wife's: '10 Legacy 2.5GT (DD, six-speed manual)
Spare:'01 20AE Maxima, 5MT (also my bad weather alternate)
Various Loose Parts: '79 Malibu
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