Do the readings on electronic scales stay constant unless you make a change? For instance, if the car is sitting on the scales, you've settled the suspension, and taken your readings. You then leave and enjoy a cold one on the patio for 1/2 hour or so. When you come back, do the scales still read exactly the same, or have they drifted by some significant degree - like 10 lbs or so? What if you settle the suspension again? Do your readings change by 10 lbs or more?

Why do I ask? I'm considering buying scales because I have trouble getting repeatable, consistent readings with the equipment that I have. What I have is an integrated alignment and weighing system that uses hydraulics to measure corner weight.

If your interested, this is the system:

http://sherline.com/alignsys.htm

I've had it since long before I had the SRF.

Ed: That system is creative, but I didn't see any accuracy claim for the scales. I have an 15+ year old set of Intercomp electronic scales that use load cells, and can't say that i have left them with the car on them for periods of time intentionally to check them, but have never noticed any variation in weight over time when scaling the car. In fact i am amazed at how repeatable the numbers are: i measured the perches, took the shocks off, sent them for rebuild, put them back on, and the car was just about exactly where it was previously. Made no adjustments. I think electronics are far better for this application that simple pressure gauges.

I also have Intercomp electronic scales. The total weight never vary by more than a pound or two, but the corner weights occasionally can change by ten or more pounds when rolling the car off and then back on with the total weight remaining the same. I'm guessing something is binding a little when that happens.

I have seen them change and need to be reserved when they experience temperature changes (ie. leaving them in the sun)

Rod

Thanks! That was what I was looking for. I would have hated to buy electronic scales only to face the same kind of issues that I'm having with the pressure gauges. The engineer in me tells me that if I bought 4 electronic pressure gauges that I'd "solve" the problem, but good electronic pressure gauges cost $300 a piece - easily enough to buy good, not great, scales.

Steve: you need to be careful, that post was helpful and completely lacking in abuse of any sort. I'm confident that you'll make-up for it later.

Ed Cavalier wrote:Steve: you need to be careful, that post was helpful and completely lacking in abuse of any sort. I'm confident that you'll make-up for it later.

Ed: I am speechless from that comment!

One thing that I noticed is that I need to make sure the tires are centered exactly the same on each scale and I do the fronts and backs separately. I do this by measuring the outside tire distance to the end of the pads and make sure they are the same on both sides. I also make sure the axle is centered in the middle of the pad. Believe it or not this works and you get repeatable measurements. One other item. Always and I mean always make sure you have the proper tire pressures. I use the target tire pressure I want after the run. One time I forgot to do that and my corners where way off when I had proper tire pressure.

goolsbey wrote:One thing that I noticed is that I need to make sure the tires are centered exactly the same on each scale and I do the fronts and backs separately.

For those of us that get our tires from the "trash pile", should I weigh with the flat spots up or down?

H.(some of us define "round" in relative terms)B.

Hal, Just make sure you have spots on both the top and bottom. You might not even notice them.

One thing I forgot to mention is that at one point I was having trouble getting accurate readings after I would adjust the springs. The way I was doing it was by jacking the car up and using my hands to make the changes and not by using the tool to adjust the ride height. It was easier to do it this way. If you do this remember after you let the car down to set the weight of the car. What I do for example on the front is to stand on the front support brace. If you don't do this your readings will be all over the place! I also do this if I am using the tool, just to be safe. When I first got my scales I was very frustrated as I wasn't able to repeat my results, when I rolled off the car then zero it out and rolled it back on. All the items I mentioned has take care of the problem. I now get very accurate results that are repeatable. It now takes me half the time!

We use different corner weights for every track depending on the track configuration. It was interesting to watch the NASCAR race this weekend at the Glen. They mentioned that on road courses it is imposable to get the car to work perfectly for all the corners. What they do is set it up in the best compromising manor for the most important trurns, perhaps those going onto long straights. We fought this problem for years at Mid Ohio and once we finally got it right our results improved.

Once you find the proper corner weights, I suggest you count the threads to the shock spring adjustment from the bottom. Record this for each corner and then the next time you are scaling the car for this same track you have a spot to start from. In most cases it is very accurate, as long as you haven't wrecked the car or bend the up-writes. One thing to remember is that no two cars are the same. We have two cars and the ride height settings for the two cars are quite different in order to get similar corner weights. Good Luck!

Great info, Pat.
Now if I could just get a set of scales...