Camaro Z/28 Engineers Get a Grip on Wheel Slip [Video Added]

[Tran]

Camaro Z/28 Engineers Get a Grip on Wheel Slip
Tire grip, braking capability require action to prevent wheels rotating in tires

2014-03-13

DETROIT – While running fast laps at several of the country’s most challenging tracks, Camaro Z/28 engineers noticed the tires were providing so much traction and the brakes so much stopping force that the wheels rotated inside the tire – an unexpected challenge that required fast thinking.

“We were told to build a fast car – period,” said Mark Stielow, Camaro Z/28 program manager and pro-touring expert. “We knew on Day One we’d need to bring some of the best suppliers onboard to make it happen.”

The suppliers included Pirelli and its P Zero™ Trofeo R tires and Brembo for carbon-ceramic brake rotors. The Trofeo R tires have a track-oriented tread design and compound that, together with the carbon-ceramic rotors, help the Z/28 achieve up to 1.5 g in deceleration force.

It was a perfect combination, but engineers quickly found that when the Z/28’s capability was tested, the wheels were rotating – slipping – inside the tires. They sought the root of the problem by marking one of the Pirelli P Zero™ Trofeo R tires at the beginning of a lap with a chalk line relative to the valve stem on the wheel. At the end of the lap, they recorded where the chalk line ended up and noticed the tire had rotated at least a full 360 degrees from where they started.

Racers use an abrasive paint around the bead of the wheel, where the tire meets the rim, to combat the problem on race cars. The Z/28’s engineers tried it, but it wasn’t strong enough to prevent the slippage, so other approaches were tried. Finally, they tried media blasting, which involves shooting a gritty material through an air gun at the wheel's surface, adding texture to the paint for the tire to grip.

“Media-blasting the wheel created an extremely aggressive grit on the rim, which finally got the tire to hold,” said Stielow.

Along with the tires and brakes, some of the tire slip can also be attributed to the 7.0L LS7 engine helping spin the wheels with an SAE-certified 505 horsepower (376 kW) and 481 lb-ft of torque (652 Nm). While going around corners, the helical-gear limited-slip rear differential also sends power to the wheels so well that differences in tire slip can be observed from side to side on the rear axle.

The 2014 Camaro Z/28 arrives in dealerships this spring.

[Camaro_Corvette]

Wow that's interesting! I wonder how many vehicles run into that issue..

[vroomapunk]

Didnt even know that happened lol. Awesome.

[Bhobbs]

I thought they knurled the wheels to help prevent slipping?

[LAWMAN]

That's some power right there,

[paul44]

Further proof that the Z/28 will be one hell of a machine!

[daveagogo1]

Common problem in racing and drag racing. Big time drags screw the rim right to the bead of the tire lol.

[Zfatuated]

Originally Posted by Bhobbs

I thought they knurled the wheels to help prevent slipping?

I used Rays (Volk Racing) wheels because they had very grippy knurled bead seats. No rotating on the rim with those bad boys.

Knurling is a cost-adding production process though, and I can see where abrasive blasting the bead seat would accomplish the same result at lower cost.

Just another detail that trackers will appreciate. Aggravating to lose your wheel balance after the first session and then be running on "square" wheels. Once again kudos to GM from a person who understands and appreciates what they did with the Z/28.

[AlohaBR]

Originally Posted by daveagogo1

Common problem in racing and drag racing. Big time drags screw the rim right to the bead of the tire lol.

I was waiting to see f that was how the fixed the issue!

[Todd in Vancouver]

Wow, those tires must be like glue. They are UTQG= 60. Depending on where you race these are not class legit in a lot of the events that are out there.

But, that's a stunning accomplishment by GM. From the way it's been happening I'm guessing we are going to get a feature a week until it arrives at dealerships.

[Zfatuated]

Originally Posted by Todd in Vancouver

Depending on where you race these are not class legit in a lot of the events that are out there.

Specifically, what events?

The Z/28 is not a race car so your comment perplexes me. There are no limits on tires used at any DE/HPDE/PDX I attend other than minimum tread depth. The Trofeo is a street legal, DOT tire meant for use on street cars, it is not used in any "racing" series that I am aware of as it is not a racing slick.

Please explain with details.

[Bhobbs]

Originally Posted by Zfatuated

I used Rays (Volk Racing) wheels because they had very grippy knurled bead seats. No rotating on the rim with those bad boys.

Knurling is a cost-adding production process though, and I can see where abrasive blasting the bead seat would accomplish the same result at lower cost.

Just another detail that trackers will appreciate. Aggravating to lose your wheel balance after the first session and then be running on "square" wheels. Once again kudos to GM from a person who understands and appreciates what they did with the Z/28.

I know what you're saying but I remember reading something about the Z/28 wheels being knurled. It was posted here a while back. I guess they could have changed from knurling to blasting if it was cheaper.

[Dropspeed]

Originally Posted by Bhobbs

I know what you're saying but I remember reading something about the Z/28 wheels being knurled. It was posted here a while back. I guess they could have changed from knurling to blasting if it was cheaper.

I recall seeing the same thing with a picture of the inside of the wheel.

[Mikebrinda]

So much for the "just drop a ___ motor in a 1LE Camaro, it's way overpriced, put a blower in it, etc., etc." comments. It's never as easy as it looks or sounds.