OT: My full Review of the 2016 Viper ACR
07-05-2016, 09:35 PM
#541
Burning Brakes
I did 3 turns on rear spring perches, putting in about 1.75" rake and still pushes, although maybe a bit less. I have found that if you really take it easy warming tires and start 30 cold all around, drive 5 min, then bleed down to 32, then a bit faster for 5-10 min, then bleed down to 33, then drive hard that the front tires don't come apart anyway. But at end of session my outside front still finishes at 37 psi. I bleed off over 10psi and no way can you start at 25, as I destroyed inner and outer shoulders trying that.
07-05-2016, 11:29 PM
#542
Allan -- I believe the 285/30/18 Hoosier is wider than the 295, and is the correct outer diameter (same diameter as the 295/25/19 Kumho). You may want to go with those.
I did have an email exchange with Jeff Speer at Hoosier and they are looking to make a 295/25/19 in the future. Would not hurt for Hoosier to hear from ACR owners about their need for the tire.
I did have an email exchange with Jeff Speer at Hoosier and they are looking to make a 295/25/19 in the future. Would not hurt for Hoosier to hear from ACR owners about their need for the tire.
07-07-2016, 12:11 AM
#545
Keith I ran into Chris Winkler ( SRT factory engineer that set the 11 of 13 track records) and asked him the same question you have, his suggestion was to put a little more rake into the car. His opinion was the car didn't push so I'm assuming SRT engineers had his set up this way.
07-07-2016, 12:28 AM
#546
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I'm running out of room and will be forced to sell mine eventually unless someone buys one of my other cars that's currently collecting dust bunnies
07-07-2016, 02:37 AM
#547
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07-11-2016, 03:27 PM
#548
As I learn how best to work with V720s and have made several setup changes, sharing the info FWIW. I have increased rake to 1.75" with front height remaining at 4.0". Zero toe F&R (actually 1mm total toe out F due to laziness). Note this is a string alignment, so precision is not perfect, but bushings are rubber. 2.5 deg F, 1.5 rear camber. And I replaced the front bar with the softer base Viper sway bar. I went down in camber as I continue to cord the inside front tire first and decided I'll take a bit less grip on outside F to improve wear, and hopefully the softer bar will be more gentle on the front.
Balance is much better for me. But as some quick left coasters say, the tires simply can't take continuous qualifying style pace. I am more and more convinced the 295/355 F/R section width is too heavily rear biased.
For example I did 3 laps on MSR 3.1 mile configuration in 85 ambient and started all 4 corners 30 psi cold. I checked pressure and RF was at 42! Others were 36-37.
It just seems the car works the outside front tire too hard. I'd prefer a 315/335 F/R stagger and think the only way to drive hard for 30 min session is something like that.
Mind you the pace is blistering. Multiple seconds a lap qucker than any street car I've come across so far, on par with 997 Cup on slicks.
I am likely to get 18" wheels to open up tire choices a bit.
Balance is much better for me. But as some quick left coasters say, the tires simply can't take continuous qualifying style pace. I am more and more convinced the 295/355 F/R section width is too heavily rear biased.
For example I did 3 laps on MSR 3.1 mile configuration in 85 ambient and started all 4 corners 30 psi cold. I checked pressure and RF was at 42! Others were 36-37.
It just seems the car works the outside front tire too hard. I'd prefer a 315/335 F/R stagger and think the only way to drive hard for 30 min session is something like that.
Mind you the pace is blistering. Multiple seconds a lap qucker than any street car I've come across so far, on par with 997 Cup on slicks.
I am likely to get 18" wheels to open up tire choices a bit.
07-11-2016, 08:40 PM
#549
07-14-2016, 11:40 PM
#550
What I find disheartening is that the labor unions destroyed Chrysler (now purchased by Fiat after a bailout was taken (stolen) from the American tax payers). And GM stole billions from us as well. Yeah, quite disheartening....
I'm not spending the time to read through this entire thread, but did anyone ask for "CJ" to provide some history on his driving? Is he a real proven race car driver? Or, is he a "DE Champion" and/or a paid driver on some fancy race team and is really the "slower driver of the group."
Just saying...
And for the record, I was very close to buying an ACR. But I wasn't dumb enough to fall for the marketing hype - it's a RACE CAR that is (barely) street legal. And NO ONE should want to go that fast in ANY car that doesn't have a roll cage and full safety measures... Unless of course you're wanting to be a "DE Champion."
But, I guess when you know you're going out why not go out with a bang right? SRT division is getting the ax, so they created a race car in the new ACR. You could take a C7 Z06 or 991 GT3 and very easily make it hang all over the ACR. But, at that point you should be doing REAL racing not trying to be a DE champion which I suspect most people who purchased the ACR will be doing with the car...
With all that said, I'll be ready, willing and able to hurt the feelings of the unsuspecting ACR driver with my sh$t box 991 GT3. :-)
Cheers!
I'm not spending the time to read through this entire thread, but did anyone ask for "CJ" to provide some history on his driving? Is he a real proven race car driver? Or, is he a "DE Champion" and/or a paid driver on some fancy race team and is really the "slower driver of the group."
Just saying...
And for the record, I was very close to buying an ACR. But I wasn't dumb enough to fall for the marketing hype - it's a RACE CAR that is (barely) street legal. And NO ONE should want to go that fast in ANY car that doesn't have a roll cage and full safety measures... Unless of course you're wanting to be a "DE Champion."
But, I guess when you know you're going out why not go out with a bang right? SRT division is getting the ax, so they created a race car in the new ACR. You could take a C7 Z06 or 991 GT3 and very easily make it hang all over the ACR. But, at that point you should be doing REAL racing not trying to be a DE champion which I suspect most people who purchased the ACR will be doing with the car...
With all that said, I'll be ready, willing and able to hurt the feelings of the unsuspecting ACR driver with my sh$t box 991 GT3. :-)
Cheers!
This is typical....just look away from this....I apologize to the rennlist community....
07-29-2016, 10:37 PM
#551
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07-30-2016, 04:00 PM
#552
I had the incredible good fortune to meet Erich Hueschele who is both a 2-time SCCA Nationa Champ and therefore knows how to drive, but also Director of Vehicle Dynamics for SRT, and he had a few suggestions. First, he confirmed the front V720s are simply a very soft compound and it's expected they will wear 3x as fast as rears. That just a cost of the pace the car can run. Second, he confirmed to me that part of my problem may well be my home track, as it has lots of off camber slower stuff and a surface that can be abrasive. He said that it may be best to run the wing on the lowest setting, and that trying a bit of rear toe out is OK, too. He also suggested 2 clicks softer rebound rear and that's counterintuitive to me but putting it out there. He did not disagree with running the softer bar up front and I may take out the rear diffuser extensions, something he did consider tuning.
He also confirmed that SRT does honest hot weather testing with drivers of his caliber (including him personally) hammering the car and confirming it won't overheat even in 95+ ambient. They also carefully monitor and support the Bondurant cars.
This car is the real deal for the hard core, and all the adjustability is part of the joy of playing with it. Like any fast, 3000+ lb car it eats consumables, but so be it. Keep up with one in an RS and let me know how your tire and brake budget goes.
He also confirmed that SRT does honest hot weather testing with drivers of his caliber (including him personally) hammering the car and confirming it won't overheat even in 95+ ambient. They also carefully monitor and support the Bondurant cars.
This car is the real deal for the hard core, and all the adjustability is part of the joy of playing with it. Like any fast, 3000+ lb car it eats consumables, but so be it. Keep up with one in an RS and let me know how your tire and brake budget goes.
07-30-2016, 10:21 PM
#553
Burning Brakes
Scaled mine last week, 3383# with 1/2 tank. Add downforce at 100 MPH and your at 4000+. So a lot to accelerate, turn and slow. Base weight is 100# heavier than my T/A, mostly in wheels, tires and wing. Need to take about 300# out of it and it will a weapon "plus" on track. Allan
07-31-2016, 12:02 AM
#554
Scaled mine last week, 3383# with 1/2 tank. Add downforce at 100 MPH and your at 4000+. So a lot to accelerate, turn and slow. Base weight is 100# heavier than my T/A, mostly in wheels, tires and wing. Need to take about 300# out of it and it will a weapon "plus" on track. Allan
