NASCAR Rear Steer Rules

Looks like my technical assesment of what the teams were doing was fairly accurate. From what I read the front trailing arm bushing will now be limited to allow 1/4" of wheelbase change at the rear axle. Policing the rubber compliance (hardness/softness), the placement of the voids in the bushings, etc. will be hard to police. Perhaps they plan to do it by bushing part #. The only way we could measuremovement when I did this work was to anchor the car and physically pull on the suspension components while the wheel/tires were suspended on floating air bearing plates. A time consuming, expensiveand complicated process I doubt NASCAR will tech cars to this extent, even at their Charlotte R&D facility.

Here's what I posted Aug 30th.

Reply by Frank Hager on August 30, 2012 at 8:39am Delete

Great explanation, Frank. I was having trouble understanding exactly what they were doing. Just curious...how much of a void would be necessary to affect the wheelbase to thattolerance of 1/4". I can imagine how hard this is going to be to police...unless as you stated they require a specific p/n.

Poor ole Brad has really gained some notoriety over this deal, hasn't he?

Keselowski talks as well as he drives

By: Paul Woody | Richmond Times-Dispatch
Published: September 07, 2012

RICHMOND, Va. --

The only thing Brad Keselowski might do better than drive a Sprint Cup car is talk.

The young driver, 28, is affable, outgoing and unafraid to say what is on his mind.

Recently, he said some Sprint Cup cars were finding more speed than others. That was interpreted as Keselowski accusing Hendrick Motorsports of bending the rules.

"My comments were an observation on what was being seen and that was turned around into an accusation of cheating," Keselowski said. "There is a misconception that since we drive stock cars, they're all the same and anybody who drives a car that is different is cheating.

"That's baffling to me. I made it a point not to call out specific teams. I said half a dozen to a dozen cars ... I don't think there's anyone out there who doesn't believe Hendrick cars are one of those groups. But I respect them and their ability to be innovators."

Somehow, the HMS drivers didn't get the message. They must not follow Keselowski on Twitter.

"I think you need to have your facts straight and understand what's going on," said Hendrick driver Jimmie Johnson.

Keselowski once drove for the Nationwide team owned by another HMS driver, Dale Earnhardt Jr.

"Brad is a really good guy," Earnhardt said. "He has a pretty good heart. He's a really great race car driver, and I wish he would concentrate on that.

"I think he likes to talk a lot, but I think his true skills shine on the race track, not really behind the microphone."

Earnhardt offers thoughtful answers, and his insight is instructive.

But it's hard to agree with him on Keselowski.

NASCAR is a much tamer place than it once was. Drivers are more buttoned down, far more aware of sponsors and the corporate image they need to maintain.

Keselowski is with an owner, Roger Penske, and sponsor, Miller Lite, that have a tolerance for drivers who speak their minds.

Rusty Wallace, never shy with his opinions, won 55 races in the same car, the No. 2 Blue Deuce, for Penske and Miller Lite.

"He's doing it his way, and his way is similar to my way," Wallace said. "Brad is a fantastic driver. He's different. He's now. He's new age.

"He's fun to watch. He's confident. He's aggressive and can still bring the car home to victory lane. A lot of guys are aggressive, and they wreck the car."

Keselowski, who has qualified for the Chase for the Sprint Cup, caught on quickly that driving a race car would be an important part of his life.

"Racing excited me," he said. "It got me out of bed every morning when few things did. I respected it and wanted to do my best."

So far, so good. If you doubt that, just ask him. Thankfully, Keselowski isn't shy about answering.

Thanks Dave.......Brad Keslowski did notseeJimmy Johnson's axle move (as he claimed) at Indy....or anywhere else. Nope, alreadyknewor suspected the suspension enhancements that were aboard the #48. Brad was calling as much attention, with as much drama as he possibly could, with his team-radio outburst at Indy. For a moment, though, it was exciting to think NASCAR teams were truly working with a new suspension concept.

Jeff, That's a question I can't answer. The voids in the Mustang bushings were about 1/4" and located at 3 and 9 o'clock when installed(remember, this is searching my memory from over 30 years ago).

Until just recently, I thought all front mounts onNASCAR truck arm suspension systems were done with a solid spherical bearing. I have a couple of sets in my shop I bought, on the cheap,at the racer auctions. Maybethey were cheap because they're obsolete!! But now with the mention of rubber bushings, I can see what I think they are doing

Now these NASCAR guys are pretty smart, so if they installed a bushing with a single void on the drivers side to the front and passcar side to the rear, you could get a significant amount of movement. AND, because the mounts are close together in front and the tires in the rear far apart, I think the total axle movement would be larger than the amount of movement at the void.

But, I can tell you that the voids in the Mustang bushing were small compared to those of a comfort cruiser. The more plush the comfort levels, the more rubber and voids used in the suspension bushings. Some cars had oval shaped bushings on the lower front control arms and others had a huge rubber donut front strut. The car company engineers would experiment with durometer changes in the rubber. I remember doing back to back rides in a Lincoln Town Car after changing justbody to frame bushings. BIG difference in comfort levels just by isolating the car body from the frame. AND they also have to accommodate extreme temperature changes from the frozen north to desert southwest.

High end luxury cars can easily have 1"+ momentary longitudinal compliance (movement) to help absorbthe shock of hitting a road obstacle. Todays low profile tires make the suspension components work even harder to absorb shock. With that in mind, the 1"+ might be conservative today.

I tend to get lengthy with a technical explanation, so I apologize for that.

Also notice the absence of ????????? marks in my response? None needed here, if you get my drift.

As more info is coming forward on this topic, I'm not so sure............is all this rear steer stuff aTrojan horse?. The very limited movement than can be realized from a compressing bushing does not explain the total domination the 48 displayed at Indy.....and that run away performance at Michigan (only foiled by engine failure). Johnson/Knaus may have thrown every Chase competitor off their game with all this rear-steer smoke-screen. The Hendrick R&D dept. may have turned up it up a notch.....but the Hendrick intelligence strategy dept. may havereallyturned it up. Knowing his command of the social media and all things hi-tech, did the Hendrick group deliberately divulge the rear suspension saga to Brad?

Ok everyone be sure to tune in Monday night at 6pm and we will get the answers to some of these questions. Our Crew Chief Skip Eyler will be here to explain away some of our questions.

The switches are for fans.

Thanks Frank! Good stuff.

Have always loved this game in racing, Bobby. If your theory is correct...the biggest gain factor maybe located on the front end.

Billy, The way I understand the rear end geometry with truck arms, the Panhard bar (track bar) only controls lateral movement. And it operates in an arc which will change the rear end position relative to the centerline of the car. The longer the Panhard bar, the less position change, the shorter will produce more movement.

Dirt and asphalt bar locations are usually different, and this might be what you did years ago. Usually the frame mount for asphalt will be on the right side. Pretty sure that's where it is on a CUP car with that sliding adjuster. The dirt crowd usually have the frame mount on the left side. There's a technical explanation for that which involves the rear roll center you mention, but all that "stuff" is over my head. I read about it and about 10% of it registered, the rest blew me away.

See ya' at the Charlotte Auto Fair? When ya' see my tenant Doug, come next door and pay a visit.

Bobby, I like the way you're thinking. Keep the other teams focused on the rear while the other "stuff" is what they should be looking for.

BUT, I have a comment about Johnson. I think he really is better than the other guys. The other that's close is Stewart. That off-road, Johnson, and dirt oval, Stewart, experience pays off.

Those off-road races are long and grueling events requiring a tremendous amount of driver concentration. Something that Johnson has, especially near the end of the race.

I always remember Bud Moore telling me that if he had a really good, new cheating deal, he made sure he had at least three other more obvious things for inspectors to find that he would then jump up and down about while what he really wanted to get through inspection slid by.

I also, like Slick, thought those were fan switches Jimmie was switching on and off.

Now that the limit is 1/4"......how much deflection / rear steer were they achieving before it was limited, how much were they deflecting. All my analysis leads me to beleive that 1/4" is about the most you would need to deflect.

Any thoughts or inside on how much they were actually deflecting?