Gen V ACR E suspension and Wing settings

[Racingswh]

There is another post like this in the test area but I am not sure if anyone sees it so I wanted to repost the question.

We have the starting points as found in the manual but what has everyone been finding works the best? I am suspect of the #7 compression and 5 rebound setting. I would expect that to be the opposite? Just for clarification 1 is the softest setting and 10 is the stiffest.

Too much compression pops the car upwards unsettling it and then the rebound setting at a lower point is then trying to control the chassis. I always have run it just the opposite. As soft as I can on the compression side and stiff enough on the rebound side to control chassis movement.

Secondly I was curious if anyone has varied the angle of attack on the rear wing and noticed an appreciable difference either that the car is more planted or starts to push excessively when the angle of attack is increased?

Does anyone have any input they can share?

[ACR Steve]

Factory race setting makes the car veryyyy neutral on track. Try using it as base and then go from there according to what you feel. Not sure what you normally drive on track but its safe to assume it has no where near the down force our cars have. We are getting lots of compression just from aero so it has to be dealt with.

Wing setting from factory is more then enough wing and actually maybe to much. I am going to try and take a little out .

[VENOM V]

The recommendations in the ACR manual are spot on. Those settings were confirmed by Erich Heuschele and Tom O'Dell and I've had good success with them. Start there. I'm still at those settings.

Ride height is critical too. 4" front and 5.5" rear to the frame (not to the belly pan) per the manual. I'm going to try 3.75" front and 5.5" rear and will report back.

I recommend setting the wing to position 1 (least downforce). It reduces understeer and balances the car. It has worked well at all tracks I've been on.

As for alignment, I tried ACR specs but with -3.0 deg front camber and found tire wear on the front insides excessive. I've just realigned it at -2.8 degrees and will see how the Kumhos hold up. Rotate tires side to side every other session for longevity.

As for tire pressure, aim for 33psi hot. That means about 24psi cold for me. Make sure to do a medium pace warm up lap to bring tires up to temp before going hard or you may chunk the fronts.

[Racingswh]

Factory race setting makes the car veryyyy neutral on track. Try using it as base and then go from there according to what you feel. Not sure what you normally drive on track but its safe to assume it has no where near the down force our cars have. We are getting lots of compression just from aero so it has to be dealt with.

Wing setting from factory is more then enough wing and actually maybe to much. I am going to try and take a little out .

I was going to put the Wing in the first setting and see how it feels.

Does the ACR-E have adjustable sway bar end links? I haven't looked and do not know the answer. I just assumed that it did. If no then how is everyone properly cornerweighting the car?

I went with 2.6 negative with 0 toe in the front and hoping the tires last a full 3 day weekend. The rest of the settings are as recommended.



The other track car is my Wife's car and it does not have nearly as much downforce but a little. Wing is mounted to the chassis.

http://i10.photobucket.com/albums/a126/Racingswh/Corvette%20Wing%20Mount%201_zps1xdyn8qj.jpg (http://s10.photobucket.com/user/Racingswh/media/Corvette%20Wing%20Mount%201_zps1xdyn8qj.jpg.html)

http://i10.photobucket.com/albums/a126/Racingswh/20160610_142929_zpssw4joyej.jpg (http://s10.photobucket.com/user/Racingswh/media/20160610_142929_zpssw4joyej.jpg.html)

[ACR Steve]

Not sure how fast you are but good luck getting them to last 12 sessions (3 days) I would be happy with 1 day. My advice... Bring spares and know where the best tire installer closest to track is

[Racingswh]

Not sure how fast you are but good luck getting them to last 12 sessions (3 days) I would be happy with 1 day. My advice... Bring spares and know where the best tire installer closest to track is

Not that fast but if I am not going sub 1:10's at NJMP Lightning I will be disappointed. Well driven I figure it to be a 1:06-07 car there. 1 day? Wow.

I have the ACR-X Michelin slicks. I just need the wheels to get here. I thought I had ordered them with plenty of advance notice. It's always this way. I bet they will arrive Thursday afternoon. Luckily the installer is close by.

[ViperGeorge]

Not that fast but if I am not going sub 1:10's at NJMP Lightning I will be disappointed. Well driven I figure it to be a 1:06-07 car there. 1 day? Wow.

I have the ACR-X Michelin slicks. I just need the wheels to get here. I thought I had ordered them with plenty of advance notice. It's always this way. I bet they will arrive Thursday afternoon. Luckily the installer is close by.

Guy at the Viper Rendezvous in Hastings was running Michelins on his ACR with 18 inch aftermarket wheels. Didn't last for shit. He was running the 9L compound. I was running Hoosiers (315/30/18 Front and 345/30/19 Rear) on my TA and after 8 heat cycles they are still good to go. Now the ESC was kicking in just driving to the local gas station but on the track with ESC in "Track" mode it was fine.

[Nambo]

Not sure if your Michelins are older construction or made in 2016, if older great, if this years tire then not so great. Michelin changed the construction (not the compound) and they wore as poorly as the Kumho's. I corded the outside edge of drivers front after 5 sessions. Before then they spanked the hell out of the Kumho's and the Hoosier's, grip was consistent the entire 25 minute session. Kumho's get hot after a few laps requiring some cool down laps before you push them again or you'll just overdrive and ruin the tire. Hoosier's just get greasy when hot and stay that way. Keep in mind air temps were in the mid to upper 90's and the track surface was baking hot and is basically exposed aggregate. Most folks went through at least one set of fronts during the event regardless of what brand they were using. My alignment and ride height was the recommended ACR specs. Mark and I discussed adjustments and I would recommend trying 1 hole less wing and would swap at least the fronts after every 2 sessions to try to extend tire life. I have been in contact with Michelin engineering and they are supposed to be getting back to me on solutions to extend the tire life (alignment, pressures, etc.) as they were very surprised at the durability or lack thereof on the slick.

[ViperGeorge]

Not sure if your Michelins are older construction or made in 2016, if older great, if this years tire then not so great. Michelin changed the construction (not the compound) and they wore as poorly as the Kumho's. I corded the outside edge of drivers front after 5 sessions. Before then they spanked the hell out of the Kumho's and the Hoosier's, grip was consistent the entire 25 minute session. Kumho's get hot after a few laps requiring some cool down laps before you push them again or you'll just overdrive and ruin the tire. Hoosier's just get greasy when hot and stay that way. Keep in mind air temps were in the mid to upper 90's and the track surface was baking hot and is basically exposed aggregate. Most folks went through at least one set of fronts during the event regardless of what brand they were using. My alignment and ride height was the recommended ACR specs. Mark and I discussed adjustments and I would recommend trying 1 hole less wing and would swap at least the fronts after every 2 sessions to try to extend tire life. I have been in contact with Michelin engineering and they are supposed to be getting back to me on solutions to extend the tire life (alignment, pressures, etc.) as they were very surprised at the durability or lack thereof on the slick.

JD, that you?

[VENOM V]

Luke McGrew is having some success with Pirelli slicks, DH formula. That is what I'm thinking about trying, on 18" front / 19" rear Forgelines. However before spending more money on wheels, first I want to try the Kumhos with -2.8 degree front camber. I previously had -3.0 degrees and the front Kumhos would last between 1 and 1-1/2 days.

[Nambo]

I have always ran the 2.8 with Kumho's. They will last 10 to 15 sessions IF you back off when the get hot and the car starts to push. If you don't back off a few laps and let them cool they blister then cord within a lap or two.

[VENOM V]

I have always ran the 2.8 with Kumho's. They will last 10 to 15 sessions IF you back off when the get hot and the car starts to push. If you don't back off a few laps and let them cool they blister then cord within a lap or two.

That's good to hear, we haven't had that level of success here in CA. I get 5 to 8 sessions out of them, and I drive very hard but I do back off a few laps when they get too warm. I haven't had any blistering, just wear out. My Kumhos are lasting longer than some of the guys here but haven't gotten 10+ out of the fronts yet. It may have to do with the tracks that we run as well.

[Nambo]

I think you are spot on in regards to track surface. The Kumho's might as well be competition slicks with grooves cut in them and the rougher surfaces greatly increase the wear rate. May be worth trying to rotate fronts after every session. May be the only way to keep them alive and not have to carry a truck full of spares. I am going to keep working on other tires as well as I firmly believe that Kumho will stop production of this tire when the ACR goes out of production.

[Racingswh]

Is anyone taking tire temps?

It sounds like the Kumho's need less camber and the slicks need more. Makes taking both types of tires a challenge. Meaning shortly I will have 3 sets of wheels, two sets with Slicks or Hoosiers mounted and the 1 set that came with the car running Kumho's. I will eventually set the car up for the slicks and if it destroys the Kumho's so be it. They will be a last resort tire anyway after the slicks are gone. I have to hope that 3 sets of tires get me through a 3 day weekend. If not we will need a support trailer.

I have just resigned myself to the fact that there is lot's to learn in addition to learning to drive the car. I am looking forward to it and just want to get on with it at this point.

Because we are waiting for the rear wheel metal to arrive what size would you go with 19" diameter or 18" diameter? Michelins come in an 18" or 19" diameter. Hoosier SLICKS come ONLY in 18" that can fit the back, and I believe the Yoko's and Pirelli's come in 18" as well. Make me lean towards the 18's for the rear as well. I just AM NOT a fan of the giant sidewall on the 31/71/18 slick.

[VENOM V]

I haven't taken tire temps yet.

I think slicks and Kumhos need similar camber. Luke had premature wear on the front inside of both Kumhos and Pirelli slicks. He backed off to -2.7 deg front camber and wear improved on both. However it's important to maintain rake and ride height. If your slicks have similar heights to the Kumhos then you should be ok. Most front slicks are too tall.

I'm going to try Pirelli DH 305/640-18 front and 325/705-19 rear on Forgelines that will clear the CCM brakes. They are approximately the same height and rake as the Kumhos so I shouldn't need any adjustments as I swap between the two.

As was suggested, frequent rotation side to side is important. I rotate every two sessions. I use two floor jacks and two Jack stands. You can rotate really quickly with this setup. Not that bad.

[Nambo]

I liked the 18"/19" setup with the Michelins. ABS and the traction control (I ran with it off but I did turn it on long enough to see what would happen) were happy with this setup. Just need to figure out a way to make the fronts last longer. I am hoping more frequent rotation, less wing, and maybe lower air pressure will help. Going back to COTA in September to test it out.

[VENOM V]

I liked the 18"/19" setup with the Michelins. ABS and the traction control (I ran with it off but I did turn it on long enough to see what would happen) were happy with this setup. Just need to figure out a way to make the fronts last longer. I am hoping more frequent rotation, less wing, and maybe lower air pressure will help. Going back to COTA in September to test it out.

Great, keep us posted. I'm taking a break from tracking until October for a shoulder surgery so hopefully you guys will have done some testing by then. I have two sets of factory 19s, not totally sure I'll spring for 18/19s unless really worth it.

[Racingswh]

So it was interesting. Wheels came too late to have my mounting guy get a crack at them. Took the tires and wheels to Mavis Tire right around the corner and their machine COULD NOT get the Michelins over the barrel of the wheel. Over the initial lip YES but it would not slide down over the barrel. Had to mount some Hoosiers I had in 315/30/18. Didn't run them. Ended up mounting the 295/30/19 R7's on the front factory wheels and running the Kumho's on the rear and they worked great all weekend.

So we are going to lay the Michelins in the hot sun and keep the wheels in the air conditioning before we mount them. Should help. If anyone has any other tips or tricks I am all ears.

I did test fit the 18" fronts and they fit perfectly over the brake calipers. Still waiting on the rears but we have 3 sets of front wheels now. I am considering running the A7's in the front and R's in the rear. I just want to give the front more stick if possible.

I am going to see how the car feels to me up into the esses at Watkins Glen in a couple weeks but I think I will be taking wing out of the car. It's unbelievable to me how much grip the rear has.

NJMP Lightning

Viper 1:10.43

Corvette 1:10.68

Both in traffic and high temps. Corvette time was set chasing a new friend in his ACR-E. Had to pedal it once on the straight as the Corvette got sucked right up behind his car. Made me laugh right out loud. These ACR's punch a huge hole in the air. Could NOT catch him in the slow stuff. I was having to feather the throttle and he was just going away from me. Cars make similar power. We were never on track in the same car at the same time. I am 3 or 4 seconds off the pace in either car. Lots of work to be done.

http://i10.photobucket.com/albums/a126/Racingswh/Viper%20and%20Corvette%20NJMP%20Lightning_zps8d4vn 3jz.jpg (http://s10.photobucket.com/user/Racingswh/media/Viper%20and%20Corvette%20NJMP%20Lightning_zps8d4vn 3jz.jpg.html)

[ACR Steve]

I would think the ACR, should be running around 1:03's or less at Lightning (Lap record in a 996 Cup is 1:05 our cars are faster)

My 996 Cup runs 1:23's on Thunderbolt and my ACR is faster by a good amount :)

[Racingswh]

I would think the ACR, should be running around 1:03's or less at Lightning (Lap record in a 996 Cup is 1:05 our cars are faster)

My 996 Cup runs 1:23's on Thunderbolt and my ACR is faster by a good amount :)

That kind of time at Lightning is far, far beyond my abilities as a driver. I have a ton of work to do but even after that work is done I will never be that fast in anything I will ever drive there.

If I can get into the 1:06's at some point I will be happy.