rfn026

Here's an article I did for Vintage Motorsport magazine a few years back. It's a basic guide to corner balancing. You really can't believe the difference this makes.

Richard Newton

rithsleeper

I read the whole thing and its very interesting and informative. I wouldnt mind trying it myself. However, you claim "you can't believe the difference this makes" but not once is there any data or reference to lap numbers etc..... so what are we talking here. If im running a gran prix in my ferrari gt car then yes, I would like to do this. However if im just podunking around in an ITA civic then are we cutting 1 sec off a normally 2 min lap times or are we talking 3 seconds? What if my car is open wheeled and is already pretty close and only weighs 2000 lbs to begin with? I doubt it would have the same effect as a corvette that is front heavy and ovee 3k lbs. I would love some data if even hypothetical.

rfn026

Quantifying this is not easy since most folks have already done it. They actually did it before the car went to the track for the first time. They usually check it constantly at the track.

As you gain sophistication you can play with different things. In the beginning you want a square car. As you gain experience (and data) you can play with the settings. Sebring is mostly right hand corners. The really fast guy are set up for this. They aren't about to share information with you about this. Actually for most of us it doesn't make much difference.

I don't think of this as a speed secret. It's just something you do. The guys in the front are doing it. They see corner balancing about the way most of regard putting oil in the motor. You just do it.

Now on your test days you can change the weight balance and see what happens to your segment times. Just start here with the basics. That's a lot of effort in and of itself.

Richard Newton

63Corvette

Excellent article. Thanks for posting

Bill32

We corner weight the open wheel car to within 5 lbs side to side and cross weights. And that's on a 1,250 lb. car.

The difference is - do you want to run mid-pack or at the front?

Bill32

Before every event.

Crepitus

I would change that a little to; you cant predict the difference this makes. As Richard says, I would expect a profound difference on a car that has never been balanced. Most of my experience is on short ovals but cross weight is critical. if you have a lot of cross weight there is gonna be a lot of hard to predict handling problems. If you need to turn left and right, oh man! basically a lot of rf/lr weight I would expect to push in and center turning left and loose turning right with unnessary heat & wear rf/lr. With a production car there is a lot of other stuff that will pile on and make life miserable and unpredictable. with out scaling the car I dont see how adjustments would be much more than swinging in the dark. neutral cross weight will provide a repeatable starting point and remove unnecessary variables. With the C4 there are handy little weight jacks on the rear spring.

rfn026

Actually you have the little weight jacks (ride height adjustors) on the C2, C3 and C4. The problem is they only allow you a limited amount of weight jacking. You still end up doing things like moving the battery or adding weight to a given corner.

You guys with coil-overs or C5 through C7 don't understand how rough we have it with the older cars.

Actually one of the design goals for the C5 was to make ride height easily adjustable. The Bowling Green plant went crazy getting ride height correct on the C4 Corvette.

Richard Newton

fatbillybob

A few things I have noted over the years of racing the C5 vette. First the factory had 50/50 cross on my Z06 without driver right from the factory! Very nice good starting point. Second I think the lighter the car the more CW is an issue. In our 3200lb pigs not so much. Third there is so much stichion in our suspensions even with free delrin, that you can change the CW between 1/4 and 1/2% just by how you bounce and settle the suspension. Despite the drawbacks of CW a C5 I still do it. In my new SCCA T2 class we have to weigh a whopping 3300lb min.! Honestly, even when my weights are off 1% I feel no difference. How many percent off do you need to be able to feel it? I don't know. Also putting the battery in the right rear pocket behind the RR wheel is not the best place for the weight. Don't believe me. Believe the scales.

Rob31

I scaled my C4 last fall . I was able to even the cross weight pretty close " Looking for my notes right now " But I lost some ride height on the drivers side .
I still have the stock swaybar links ...I scaled it with those connected .

fatbillybob

Experts say scale without bars connected! But I say scale the car without bars connected if you have at least one side with an adjustable endlink. If you car has non-adjustable endlinks then scale with the bars attached because your bars may add wheel rate statically at rideheight and you want to zero that. It is just another compromise that I don't think you can feel on a 3000bl pig.

Rob31

Last time I drove it 51.5% cross I could not tell a differance . even with a 270# passenger I could not notice any differance between rt / lt turns . Barely felt a differance on braking , on marginal pads .At a trackday ACC full course. running around at a 75-80 % pace

MarkDFW

I would love to know if anyone has before and after lap times with the only variable being the car was corner weighted. Wile I am sure this can vary from track to track, a meaningful difference would help me justify the expense.

davidfarmer

there is no way to do a comparison, except on YOUR car under YOUR conditions. I've had cars with stock settings, stock bars, have nearly perfect balance, and I've seen cars with over 200lbs of cross-weight jacked in. It's a total crapshoot, although most cars come from the factory in pretty good shape, assuming no one has tried to lower or muck around with them!

rfn026

Once you start lowering the car it's a whole new ballgame. Lower it and you go back to square 1. You get to start all over again.

Richard Newton

Solofast

On my C4 I had a very reputable shop rebuild my diff, which of course required removing the spring in the back. When they put it back in, contrary to my instructions, they wound both rear spring bolts fully tight. The proper setup was the RR bolt to be as loose as possible and still get the cotter key in, and the LR bolt was to be max tight.

When I got the car back it felt ok on the street, but it pushed like a pig in right turns... Drove it like that for three weekends and couldn't figure it out, the car never behaved like that before and I wasn't used to runnin mid pack.

I finally decided to look at things and found the error and it only took 5 minutes to fix it. After that it was amazing how much better the car worked. Since the front end wasn't plowing I had much better grip and the difference in autocross times was more than two seconds a run.

Since it isn't hard to do and it makes the car handle so much sweeter, most folks just get it done and never do a back to back. As noted above also, some cars are pretty well balanced from the factory, and others are way the heck out.

If you don't corner weight it, and you to notice that it handles differently turning in one direction or the other, then corner weighting will help a lot. That's been my experience.

MarkDFW

Thanks everyone for the feedback. I'll look to get this done soon.

SG4206