RacePro Engineering

The venerable A.J. Foyt once quipped, "Somewhere around the second weekend in May each year, we arrive in Indy with a pretty nicely balanced racecar. And in only 3 short weeks, we ADJUST it into a pile of junk!"

I am certain the quote is not word-for-word. but (like corner weights!) it is close enough.

Ed

drivinhard

that's worthy of a shop poster

ErnieN85

The hardest part of any job is knowing when to quit

RacePro Engineering

What you wrote is fine. When estimating, we like to place 50 pounds or so in the driver footwell, and the rest on the seat.

Here's another trick we like real well, assuming the driver of the car will be the same each time: The first time, it requires two people, and only one thereafter -

[1] Adjust and set corner weights with "average" amount of fuel, and driver, with equipment, in position. Permanently CAPTURE on paper.

[2] Now, with driver and his equipment out of car, permanently CAPTURE weights on paper.

[3] At this point, with a little bit of elementary math, one can see exactly how the driver's weight is distributed on all four corners. We like to use percentages, so when the driver gains 25 pounds over the long winter, the math still works. EXAMPLE: 35% of driver weight settles on LR; 15% settles on RF, etc.

[4] Thereafter, whenever doing corner weights, one does not need the driver, because one can simply "add back in" his percentage of (then current) weight to the various corners.

Now, couple this little routine with SoloFast's knowledge of how many pounds of weight are shifted when one takes a single turn off (say) the LR spring bolt, and your handy bag of setup tricks just got a little - "heavier" - to continue the metaphor.

Ed

travisnd

This stuff makes my head hurt... which is why I just eyeballed my ride height, got an allignment and went and drove as hard as I could

I'm going to a local road race shop run by a fellow competitor in two weeks to do a proper setup on my car. I'll probably be opening Pandora's box.

redtopz

I use my fingers to set ride height and tape measure and level for alignment. It's close enough not to make any difference at my level anyway.

Solofast

You can have a lot of fun that way, but you are leaving a lot on the table compared to a properly set up car.

A long time ago I had my RX-7 and offered a ride to friend (who wasn't known to be a stellar driver, in fact he was about to give up the sport because he was doing poorly), to "go down to OVR and kick some butt" at a local regional solo event with my car.

To make a long story short he ran within a few tenths of a second of me (and I was coming off a second place at nationals just before this). He was giddy he was having so much fun, he came out the car beeming after each run.. He said... "it just goes where ever you want it to go!!!!"

A really well set up car will make you a much better driver. Having a car that does EVERYTHING that you ask it to is really amazing, and if you experience a car that is just flat HOOKED and really well balanced, it will make you realize how important the car is in the equation.

This is just my opinion, but when you get to the top levels of the sport, everybody is good, some are a bit better than others, but if the car isn't there I don't know anybody that could win at the national level on drivers skill alone. I haven't been at that level for a good while, but I've always thought that.....

"cars win races, drivers are just spectators too, but they get a lot better view of action"

I had a good friend who was a FV runoffs champion... He said "they call it motor racing because motors win races, a driver is just required ballast", so I'm not alone in that thought.

JMHO and qualified as such.

And I agree that that it's a waste to spend a bunch of money looking for speed in the car if you aren't capable of getting everything out of the car that it has. But really, setup is not the most expensive part of the sport. On a relative basis, since usually once you have it set up there isn't much maintenance cost, making sure that the car is working right is actually the biggest bang for the buck that you can get in the sport.

For someone who is a novice a good basic setup is needed until you learn what you want and what the car needs, and after that you will progress to where fatbillybob is and find those last few tenths of a second of lap time.

travisnd

I held the TTA record at VIR all year with a 2:04.6 until Mr. Drivinhard took it with a 2:03.9 in October.

I went to Summit Point for the first time in my life this past November and beat the old TTA track record by 2.5 seconds which was set by a very capable driver. The old record was. 1:20.3 and I ran a 1:17.8... faster than the 570 rwhp TTU car I was chasing on that lap.

Unless you have a pitcrew sometimes close-enough and turning the "don't give a damn" **** to 11 works just fine

drivinhard

But had you had 250 lbs of ballast where you want it, lower Cg, and additional set up, it might have been a 1:16.8

travisnd

Not debating that

redtopz

Yeah, I agree that taking the time to set your car up is very important. And I do take more time now than I used to. However, my point is that with very simple methods and getting it "close enough" my car will handle very well. Well enough that I have no desire to take it to a pro shop. I don't bother corner weighing my T1 car, I just make sure the fenders are approximately equally gapped over the tires side to side and I have forward rake and a good alignment. It works.

CP Thunder

Unfortunately, this was without driver...........done with borrowed scales on our lift. My first attempt at corner weighting. It was easy.

froggy47

Braggin

fatbillybob

I sit on 2 of my scales. Feet on one butt on another. The weights on each are what I put on the floor of my car and on my seat.

fatbillybob

This is at the green flag. There is a left bias 32lbs at the nose and 35lbs at the tail. I wonder at what point running with ballast on the right side makes a better handling car to make up for the extra weight? Does that ever happen?

Solofast

I had an old RX7 with an open diff. In that case 25 lbs in the RR quarterpanel really helped put power down coming out of RH corners. It killed the onewheelerpeeler effect and I could accelerate a lot faster off of slow corners.

For a road race car I don't think you can get enough back. There is too much time spent on the straights and any ballast is going to really slow you down all the way down the straights. Remember that SCCA generally hits people with 50 lbs of ballast to make things "more equal", so that's your benchmark.

If you are running to a weight limit, and can move some weight to the RR corner of the car, then that's a good thing and you should. Taking weight off of the RF should be a priority for any weight transfer efforts, and that means moving as much to the RR quarter panel area as you can.

RacePro Engineering

No!

RX-Ben

Obviously it depends on your setup, but S. Perkins said he ran faster with full tanks than nearly empty (i.e. 100+lb extra ballast in a good location).

RacePro Engineering

Ben,

You are absolutely correct, that it depends upon setup; and frequently it depends upon what one is allowed by class rules, or has available (adjustable) for setup.

With those limitations in mind, (voluntarily) adding ballast simply to counter-balance the car, whether on the R side or in the rear, is sort of like putting on front tires with significantly less grip, just to "balance" an oversteering condition - now one has poor grip on both ends!

Not knowing the circumstances, but being somewhat familiar with Mr. S. Perkins otherwise intelligent approach, I would guess that this was either a "last resort", or a "quick fix" to an understeering condition. And such conditions point to problems in the car's basic setup.

LoPresti's Adjustment Rule #7: It is NEVER advisable to diminish the capability on one end of the car, or one side of the car, to have it match the (less capable) other end, or other side. And this is where knowing when, and precisely how, to make suspension adjustments, comes into play.

With due apologies to those who know this stuff already:
From our road racing experience, and that of thousands of others, here is how one makes corner weights effective:
[1] Remove absolutely everthing that you are allowed, and that does not make the car go faster (with the exception of safety equipment).
[2] Of the items remaining, physically move stuff around within the car, with the goal of placing equal static weights on all four corners. Keep weighted items as LOW as possible in the chassis.
[3] Keep items "within the wheels", even though placing something in front of the front axle, or behind the rear, might APPEAR to help weight distribution.
[4] Prep for the scales with a suitable alignment. Set ride height and rake. Adjust tire pressures to match typical HOT pressures. Average level of fuel. Disconnect drop-link anti-roll bars (one side only is fine). Driver and his gear in position. Jounce and settle suspension.
[5] On the scales, adjust to get EITHER wedge close to 50%, OR front corner weights approximately equal, as we have already discussed.

Once the chassis is as statically balanced as is possible, future handling deficiencies need to be addressed with suspension ADJUSTMENTS.

In the scheme of things, it is all a huge matrix of compromises and trade-offs, but this particular path to setting up a production or GT car has shown to be the most fruitful

Ed

redtopz

How did you do that Carl? For the first time, I'm making an effort to corner balance my T1 car with leaf springs. The right rear is about 100 lbs lighter than the other 3 corners. After about 6 iterations of changing heights, driving around the block, and re-scaling I have the front 2 wheels about equal in weight. The left rear is also about the same as the front 2. But the right rear is about 100 lbs lighter. So my corner balance is 51.4%. Good enough or can I somehow get it to 50%? BTW, fuel level is about 3/8ths of a tank so I assume most or all of the gas is on the driver's side?