[JonDaddy82]

2018 ZL1 M6 on stock GY SC3's.

Car currently has:

BMR Upper Control Arms
BMR Upper Trailing Arms
BMR Lower Trailing Arms
BMR Chassis Brace Front of Rear Cradle
BMR Driveshaft Tunnel Brace
BMR Rear Cradle Lockout Kit

I do about 3-4 track days a rear and am looking for more grip off the corners. I seem to have zero problems late braking the P-cars, but they leave me by a few car lengths on exit every time because I'm back there trying to manage wheelspin. I know 100TW tires would help, but I need my tires to last for at least that years "event season".

What say you?

[5.M0NSTER]

No magic formula here, as you are comparing your front engine car with mid-engine or even rear engine Porsches. They will have an inherent traction advantage just past the apex on throttle, all the way down to the exit and past.

If you're willing to compromise some body roll, you could try a softer sway bar in the back. Or a stiffer one up front, but I wouldn't do that as it would add understeer

[weemus]

Wider GY SC3s (feel ya on the 100TW). You can fit a ZLE tire setup on a ZL1. 305 front/325 rear. That's 20mm wider at all corners so lateral grip goes up as well as some more meat for throttle application.

[sr71bb]

Originally Posted by JonDaddy82

2018 ZL1 M6 on stock GY SC3's.

Car currently has:

BMR Upper Control Arms
BMR Upper Trailing Arms
BMR Lower Trailing Arms
BMR Chassis Brace Front of Rear Cradle
BMR Driveshaft Tunnel Brace
BMR Rear Cradle Lockout Kit

I do about 3-4 track days a rear and am looking for more grip off the corners. I seem to have zero problems late braking the P-cars, but they leave me by a few car lengths on exit every time because I'm back there trying to manage wheelspin. I know 100TW tires would help, but I need my tires to last for at least that years "event season".

What say you?

OK there are several ways to get there. One is with AERO. I assume you are NOT a ZL1 1LE??? The ZL1 1LE wing will create MORE downforce on the REAR of the car. There is also a company called TRACKWING www.trackwing.com that makes an even BIGGER wing setup that is REMOVABLE when you are NOT at the track and is even BIGGER and TALLER than a factory ZL1 1LE wing. Below is a picture of one mounted on my car. I will be trying it out tomorrow at EAGLES CANYON but typical GAINS ARE 1-1.5 second quicker lap times (will see). I will post up tomorrow evening.

The SECOND way is get a stiffer SWAY BAR relative to what you are running now on your Zl1. I personally am running BMR adjustable BMR rear and rear sway bars. The FRONT bar is on the middle setting and the REAR bar is on the stiffest setting. You MUST use SBB010 billet bearing holder and Delrin bearing if you use the BMR bar up front because the stock set up is too weak and will split under extreme conditions.

The THIRD way is to run MORE negatiive camber on the REAR of the car. I would try -2.4 degrees. To get there you may need to install SPL toe rods .PUT toe in toe out at neutral position on BOTH front and rear. Run -3.6 camber on front.

[khcoaching]

Pay attention to how well the car is pointed for the exit as well as your initial throttle inputs. These have a massive effect on wheel spin and when you can get to wide open throttle. My SS 1LE on 3SCs has a wheel spin issues off the low speed corners and being more deliberate with exit driving technique works wonders.

Ken

[gbeaty]

I don't have a Camaro, but I've studied this pretty extensively in other makes.

Adding rear grip is pretty easy: wider rear tires, more front roll stiffness or less rear roll stiffness, more rear downforce, etc. Downforcing having the biggest impact. The trouble is all these things will also increase understeer everywhere else.

I've had a C5Z and C6Z which were both too loose. The C5Z was the worst, and it picked up measurable corner exit speed with better balanced sway bars. However it picked up more corner entry, since it could now be trail braked.

The C6Z's corner exit benefited from a softer rear bar but it was barely measurable with 10Hz GPS daq.

i.e. increasing relative front / rear roll stiffness only goes so far. You're limited by the weight on the rear tires under acceleration, which cannot be improved with suspension tuning (unless you raise the ride height I guess). You can only change the distribution of that weight across the rear tires. In a street car your options on improving weight balance are limited. A Porsche is just in a better position to power out of a corner with its rear engine. The lower the grip level, the more static weight on the drive wheels matters.

One day I'd like to try an active aero wing which can provide more rear downforce on accel and less at other times.

[Msquared]

Originally Posted by gbeaty

Adding rear grip is pretty easy: wider rear tires, more front roll stiffness or less rear roll stiffness, more rear downforce, etc. Downforcing having the biggest impact. The trouble is all these things will also increase understeer everywhere else.

I agree with your whole post. I just want to point out that of the list you wrote about above, adding wider rear tires (wheels probably need to get wider also) actually adds to the total grip of the car with no other tradeoffs.

OP, I notice you have BMR rear suspension links. Are they the ones with poly bushings and no rod ends (nonadjustable)? If so, this is one source of your problems. You've added a bunch of bind because the rear links have to move in more than one plane. IOW, you have a nonlinear, rising-rate rear wheel rate in roll that will cause unpredictable rear grip. You either need links with stock rubber bushings or with rod ends so they have all the required degrees of freedom. Honestly, I'd return the car to stock and start doing controlled trials of the other parts, too. There's no telling what all those parts are doing to the car, and lots of these packages make cars worse, not better. A stock ZL1 should not have lots of trouble hooking up out of road course corners.

[gbeaty]

Originally Posted by Msquared

I agree with your whole post. I just want to point out that of the list you wrote about above, adding wider rear tires (wheels probably need to get wider also) actually adds to the total grip of the car with no other tradeoffs.

True, I was mostly talking about suspension tuning. If he's got 305 rears, 325s should help a bit.

My first thought was 'wing'. The drag increase should be pretty meaningless on a road course, and the small increase in front lift is usually well worth the extra rear grip on a powerful, traction-limited car.

I've bolted on a wing at a track day and picked up 1.5 seconds.

[Mountain]

Some good suggestions here.

Another to consider: the bonded bushings on the factory sway bars. I can tell you that moving from the factory FE4 or FE3 (both coupe) rear bars to the Hotchkis rear bar, the rear suspension of the car is able to move more freely.

[DaveC113]

Originally Posted by sr71bb

OK there are several ways to get there. One is with AERO. I assume you are NOT a ZL1 1LE??? The ZL1 1LE wing will create MORE downforce on the REAR of the car. There is also a company called TRACKWING www.trackwing.com that makes an even BIGGER wing setup that is REMOVABLE when you are NOT at the track and is even BIGGER and TALLER than a factory ZL1 1LE wing. Below is a picture of one mounted on my car. I will be trying it out tomorrow at EAGLES CANYON but typical GAINS ARE 1-1.5 second quicker lap times (will see). I will post up tomorrow evening.

The SECOND way is get a stiffer SWAY BAR relative to what you are running now on your Zl1. I personally am running BMR adjustable BMR rear and rear sway bars. The FRONT bar is on the middle setting and the REAR bar is on the stiffest setting. You MUST use SBB010 billet bearing holder and Delrin bearing if you use the BMR bar up front because the stock set up is too weak and will split under extreme conditions.

The THIRD way is to run MORE negatiive camber on the REAR of the car. I would try -2.4 degrees. To get there you may need to install SPL toe rods .PUT toe in toe out at neutral position on BOTH front and rear. Run -3.6 camber on front.

Nice car!

If it's not too late I'd consider putting something between the trunk lid and rear bumper cover, another member here added a wing and it forced the trunk lid down into the bumper and did some damage to the paint.

[JonDaddy82]

Thanks for the info everyone! Some more info from me. I use the car in many different ways, from a Grand Touring car with the wife to airstrip attack events and drag racing. That aspect eliminates spherical rod ends as they simply are too harsh for a plesant driving experince. I know it's hard to have a perfect "jack of all trades master of none" setup but I'm working on it! My car is also about 50 RWHP up from a stock one, so that doesn't necessarily help with traction. On to the suggestions:

1. Big rear wing: Not doing a big rear wing. Not that it wouldn't help, but I guess I just don't want grip THAT bad to install that on my car.

2. Wider tires: Maybe! I was actually planing on getting a set of APEX ARC-8's for next year, and I was thinking of going 19x11 all around so I could run on of the super 200's in 305/30/19. I don't know if using basically the same tires (SC3's) in a 325 will really add that much grip, but if you're telling it does then I can change my plans to run a square setup and do the ZLE fittment with regular SC3's.

3. Swaybars: Yes! I see many people saying the front Hotchkis is the one. Is it just that simple? Do I also run the rear bar? Stock endlinks? Just need a little more info so I can make sure to get the right stuff.

I had already planned on getting Vorschlag camber plates and BMR adjustable toe rods so I can dial in the track alignment and let me run the ZLE front fitment and track alignment without grinding the MRC strut assembly.