You Can Run, but You Can't Hide

I learned something yesterday. If you spend 150 bucks at the beer store, you get a free T-shirt. I guess I went a little overboard. If anyone is in Charlotte and is jonesing for some good beers, check out Brawley's Beverage on South Blvd. (http://www.brawleysbeverage.com/) They have a superb selection (don't go there to buy Bud Light Lime, OK...they have it, but don't waste their time), and since my family is coming down next week, I wanted to make sure they drank well. So now you know where the rest of the THP store money is going..hehe..

It's winter time in the Carolinas, and the smell of the crisp air means that RG is switching manufacturers. To be fair, it seems obvious that Dodge is looking for an exit strategy, so moving to Toyota is probably a smart move. Good motors, good team support, and I'm sure I'll be bouncing some of thier cars on the 7 post in the coming year. I guess I couldn't avoid the 7 car forever.

Before I take a week off from the blog for Christmas, I wanted to shed some light on the work that needs to be done when you change manufacturers. The most obvious thing that needs to be changed (other than the sticker on the side of the hauler) is the body work. With the COT this is relatively easy. There are 2 nose peices that need to be switched out as well as the tail cover. The rest of the COT bodies are the same between makes, so all the side panels and roof can stay. In fact, all the tail peices are the same between makes too, but for some reason NASCAR insists that all the manufacturers have their own part number for it, so you have to switch that too. If you ever get close to a Cup car, you will see that there are 2 unpainted areas of the nose underneith the LF headlight, and one underneith the RR tail light. This is where the part numbers are stamped into the molds and NASCAR mandates that they be left unpainted so they can be teched. See blue circled region below.

When you switched manufacturers with the old car, the bodies were trickier. The noses were offset and bent around so bad that you usually had to replace alot more peices. Sometimes the amount that the nose was offset from center for maximum downforce was different between models, and then you really had to change alot of the guts. Now that the body shapes are the same it is no big deal.

The other big change is the motor. Obviously the general architecture of Cup motors is the same between makes. However, motor mounting and plumbing will be different. This usually means that each chassis has to go to hard-fab to get new motor mounts put in them. All of the oil lines need to be rerouted, and the cooling strategy and fittings might all be different as well. So each car will need atleast a few new oil and water lines made just to get the cars to fire up again. Basically it's alot of hours and headaches for the mechanics to sort out all the little issues.

From the engineering side, all of the simulation and analysis tools will be different, so there is some effort on that end to get calibrated to the support documentation from Toyota. From what I can tell, the Toyota tools are pretty good and there is a fair amount of sharing between teams. That is not to say that RG will get Kyle Busch's setup every week, but Toyota tries to share car info in a non-offensive way to get all the teams to run better.

It will be a challenge to get the cars sorted out for Daytona, but not as bad as last year with the change a week before the truck left. I look forward to seeing the 7 guys at my shop, and hopefully the change will be for the better.

Camber Tuna

I am proud to report 2 major achievements that were attained just today. The first was that I took tuna sandwiches to a whole new level. For lunch today I mixed cucumbers, onions, and feta cheese into my tuna with some mayo and plastered it on an onion bun with some muenster cheese...Brilliant...The other achievement of the day is probably more profound, but less tasty. I am pleased to announce that TheHotPass.com has taken $100 from THP store sales and donated it to the Jamie McMurray foundation that does work with Autism. So, again, I thank all of the current and former THP customers for making it such a success, and I hope to continue the spirit of giving in the future. I would have given to a Robby Gordon Foundation if one existed since it was mostly his shirts that allowed us to do this, but alas there is none. When he does, I will be one of the first to sign up. The only reason that I picked McMurrays is that he seemed like a nice guy when I met him at a test a couple of years ago, and since Robby punted him in one of the last couple of races, I thought he deserved it. I've heard Kyle Petty is a dick, and the Victory Junction Gang gets more money than god anyway, so I went a different route.

In today's techinical discussion, I want to talk about camber and its significance. Camber is the angle of the tires that you see when you look at a car from the front. If the tires are angled with the tires toward the middle of the car, this is negative camber and is referred to as "top in" in Cup lingo. If the tires are angled with the tops of the tires away from the car, the camber is positive or "top out". Here is a figure to help out with the definition.

Camber is a double edged sword. Dialling camber into the car gets the tires to generate lateral force which helps the car to turn better. However, when you run camber, the tire runs on a thinner contact patch and this can generate too much heat and cause the tires to wear out quicker or to fail. In general, for any random oval track, cup cars will run close to 8 degrees of positive camber on the LF (top towards the infield) and about 2-3 degrees of negative camber on the RF. In the rear, positive 2 on the LR and negative 2 on the RR is pretty normal. NASCAR rules say you can't run more than 8 degrees of camber on either of the front tires and no more than 2 on the rears. So, you can see that on all but the RF, the cars are maxed out. Also note that the tops of all the tires are pointed towards the infield to get the car to pull to the left. Now, it is less important where the camber starts and more important where it ends when the car is traveling in the corners. In cornering the RF will gain negative camber, so now instead of -2 degrees we might have -6 in the corner. On the LF the tire will lose camber in the corner and instead of 8 we might have 3 in the middle of the corner. The exact numbers depend on the geometry of the suspension. Even at full car travel all of the tires are still pointed toward the infield. Engineers on the teams spend alot of time looking at tire data to figure out the optimum camber to run for a given race, and they use this data to chose a suspension setup that will achieve the desired camber in the middle of the corner. Alot of times the RF tire will only want about 5-6 degrees in the middle of the corner before the contact patch becomes so small that it starts to lose grip.

Up until 1991 no one really paid attention to camber. Then Harry Gant started running a ton of rear camber and won 4 races in a row and almost a 5th when his brakes failed. Then the rest of the garage cought on and started bending camber into their rear axles too. Eventuallt the teams were taking it too far and there were axle failures every week due to the stress of too much camber in the drive train. NASCAR then came down with the 2 degree rule for the rear axle. The front is not so sensitive to camber induced failure so they still let them start with 8 degrees now.

It's Going to be a Bumpy Ride

I am pretty sure that I am finally getting caught back up in life after the Thanksgiving 30 hour driving weekend last week. What a nitemare. Two years ago I said I would never travel again for Thanksgiving, so i guess I lied to myself.

Anyway...Here are the final 2 weeks of the 25 Days of Robby Items. We'll get that wrapped up by the 19th so everyone can get their Christmas gifts.

It's the middle of the offseason now, and plans for 2009 are starting to be executed. All the teams are hard at work figuring out sponsorship (still) and trying to get a good peice for Daytona. The testing ban will be a releif for the mechanics as the Daytona testing in years past was so boring it was stupid. There were only 2 drafting sessions in the 3 days and in those you just crossed your fingers that you didn't get your car wadded up. Even though the banquet was boring (I heard) and there are no races, teams are still pounding away behind the scenes.

A couple of weeks ago I wrote about how a cup team goes about deciding what spring to use, and I want to revisit that topic a little bit. Before I talked about just the spring choice, and now I want to talk about how the bumpstops come into the equation.

In the early days of the COT, there were a few different configurations of bumpstops that people tried. Many of the teams at the first COT race ran chassis mounted bumpstops. These were a piece of rubber on the end of a screw to adjust the height. When the lower control arm of the suspension moved up it would hit it and stop the car from traveling. The other way was to mount some foam or rubber or whatever on the shock shaft. When I worked for RG, we were one of the only teams at the Bristol race with the shock mounted stops, and now everyone mounts them this way.

The purpose of the bumpstop is to stiffen the suspension in the last fraction of an inch of travel, so that you can run as soft of spring as possible and still keep the car from hitting the ground. For example, running a 400 lb spring in the RF would be desireable at say Chicago to keep the car low and the aero attitude right, but is too soft to keep the splitter from eating the track. So you put a bumpstop on that will make the RF spring feel like a 1500 lb spring for the last 1/4 inch of travel, and now you are good to go (theoretically). So you try to get all of the good benefits of running soft springs without hitting the ground.

Now...There are alot of ways to try to achieve this, and alot that I can't talk about. Speaking in general terms, probably the most common bumpstop is some kind of foam rubber that is stacked in some sort of aluminum can. There are hard plastic "packers" that can be slid in and out to adjust your "packer gap" which will determine at what shock travel the bumpstops engage and how far the car will travel. In 2007 people started coming out with aluminum canisters that could be charged with pressurized air to make a sort of airspring for the car to ride on. I think these were legal for all of about 7-8 races before NASCAR put an end to that. So there are always people that are pushing the envelope with bumpstop designs. The teams have had alot of time to work on them now, so they are becomign more and more refined. Here is a picture of some different foam/rubber peices that are sold for use as bumpstops.

I hope that helps demystify bumpstops somewhat. You can ask many of the smartest NASCAR people around what the best bumpstop curve looks like, and they can't tell you. In the end you just have to test stuff out at the track and see what feels good to the driver. Of course 7-posting can help get it sortof close (maybe) before you hit the track too.