Scales

Hi Sean,

Here are a couple of shots of me doing the corner weighting. I was fortunate enough to borrow a set of scales from the local sports car club. I had a bit of spring settling and so need to do it over again. I am not believing that they settled evenly or that i am still "even" after cranking everything up a couple of turns to clear the dam driveways.

One of my problems was a very uneven driveway, so i had to build a level surface with enough room to enable rolling the car forward and back to settle the car. Even with the torrington bearings between washers under the springs and a shot of lube, i still had to jack up the car to be able to turn the spring perch. Setting the car down put a tiny bit of bind in the tire to scale interface and it was necessary to roll foreward & backward to get that out. this required, as you can see in the pics, building ramps at the same height as the scale tops.

Next time i will find a friend with a flat piece of concrete. still a pita though.
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Borrow them if you can unless you expect to use them often. If you do use them often you will see the need for a decent platform and turntables. We often spend more time setting up the things than using them. Mark the scales and the floor once you have them setup the first time and it will make future use easier. A laser level is nice for setting up the scales and checking ride height. Front to back level is not as important as left to right, disconect the swaybars before taking any readings and roll the car back and forth and bounce up and down on it to settle the suspension before rolling it back on the scales. Make sure you are not preloading the suspension when you hook the swaybars up. There used to be a company that made something called a Ruggle scale that worked ok and was only a couple hundred bucks.

 

LOVE that color and wheel combination....

Jedi

 

http://www.longacreracing.com/catalog/item.asp?id=1407&catid=1

I do this all the time. Ask me if you got questions. Very technical

 

All of this assumes many things. Why are you doing this and for what gain? Most road cars never see a level and flat piece of the earth especially here in Indiana so corner weights can be fairly non-critical. Are you taking the readings with driver? As soon as you take on a passenger the weights will be off. Stock anti-roll bars are thin and even though non-adjustable mounted in unforgiving bushings. In fact all of the stock suspension (and aftermarket) bushings will distort to each heighth adjustment and prevent fine adjustments unless you reset them by loosening the bolts.

I run a 600hp track only Porsche 911 GT car with fully adjustable and rose jointed suspension for corporate days. The clients can be anywhere from 125lbs to 260lbder and the driver (normally Davey Hamilton) can feel the difference but the client has no idea even if they have their own track/racecar. I set the car up with emphasis on matching the diagonal using no driver or passenger weight. However, for a PCA racer we include driver weight when corner balancing.

Incidently, at ovals we often run as much as 75lbs front cross weight on a single seater (not Indy, 15lbs max there) along with 0.5" stagger and 0.6" chassis tilt. Hate to think what NASCRAP runs.

Brian

If you can drive around the block and repeat the numbers, then your good,

 

I paid a Porsche race shop $500 to do this on my track car. Unless I was going to change things every so often I can't imagine why you don't just take it to someone.
Unless you enjoy the work then OK.

Bob S.

 

If you lived in the area I'd offer to go in on a set with you. You might find someone out there that would be glad to go in on a set with you. Longacre makes a good product. Summit is probably the same unit as Longacre with a different name on them. I would consider getting the platforms for them as well. You can either get the rectangle ones with the four legs or the long ramps. You can do the same thing with wood but it's nice to just adjust the legs, mark the floor and then you just put them back in the same position on the floor every time and your ready to go.

 

Back to this original query. The basic set does just fine, you don't even need 4 scales, two work just fine (ask Mr Penske, they used just a 2 scale set up at the track for the longest time). My first set was 4 sack scales, I loved those wish I still had them. You don't need to see and read all 4 at once, just takes a little arithmetic. the total side to side or front/rear never changes so you just need the diags and cross weight figures.