I am thinking of setting up my home garage for corner balancing (and possibly alignment for adjusting camber and toe if I get camber plates) as I optimize my car on the skid pad. I intend to do this with the aid of a data acquisition system (DAS). How difficult is this is to do corner balancing?

My thought was that you could get 4 calibrated scales and then place them level on your floor using blocks as shims and level them using a laser level. This should work. Is this ridiculous or does it make sense?

What about doing my own alignment at least form the toe and camber stand point? My thoughts would be to set up gauges (long true bars and mark my floor from a known alignment position. Using some geometry, I could mark my floor and determine positions for camber and toe. OK, have I gone off the deep end and skip this crap or might it be fun and really worth while? Cary, I’m especially looking for your input.

 

Hi. My 2 cents: If you can get good calibrated scales under all four
corners, *at exactly the same height*, then you can safely
*measure* your corner weights. If everything is perfect with
your car, including identical tire pressures and tire wear etc,
then the cross weights should be equal. In other words, the
weight measuered at the right front wheel plus the weight at
the left rear wheel, should equal the sum of the other two.
If one thing is out of balance, such as one spring being weaker
than another, or shorter because of more preload, or one tire
over-inflated etc, then your cross weights will differ. The trick
is to find out what the problem is, not just to add a compensating
tweak. This is because as the car sits you can tweak it to balance,
but as soon as you sit in it or go around a corner, the chassis is
loaded differently and the two compensating tweaks will be
differently affected and you're out of balance in that condition.
In fact, there is a trick to be sure you really are A-OK: If you do
the math about cross weights, you will see why it is always true,
independent of car weight or center of gravity. Therefore if a car
*is* perfectly straight and has matched suspension components
etc, then the cross-weights will be equal with the car unloaded,
and also if you're sitting in it (or a bag of sand, which is more
stable )
Therefore, always take your corner weights with two suspension
loads, one with the car empty, and one with some static load
in the car. In fact, with the two separate sets of corner weights
you can probably figure out the rear problem.
Joe

 

You can check the rear toe-in by sighting horizontally along the outer tire edges. Have someone place an object on the ground about 30 feet from the tires in alignment with the tire edges. Repeat on the other side. If the toe-in is zero the objects will be the same distance apart as the width to the outer edges of the tires. You can calculate the toe-in by the difference between the distance the objects are apart and the width to the outer tire edges.
This only works if the tire edge stick out past the body.
This is the same as an alignment machine except you are using eyeball line of sight instead of a laser.
Turbo's have about 1100 pounds on each rear tire. Scales to support that weight may be too expensive to be practical.

 

You could also measure diagonal weights to verify scale precision and then reposition the car 180 degrees (rotate the car, backing the car onto the scales) to verify all 4 scales.

 

In my experience scalling and aligning pro race cars I can make a few suggestions for DIY:

1. If you are going to commit your self to a set of scales for home use, its well worth the extra expense to buy a set of ramps to go with them. Not only do they make leveling a million times easier, but yoy need to constantly roll the car on and off the scales with each change to unbind the the suspension and settle the weight. Ramps make this much more seamless and let you work in a more methodical and consistent manner = less mistakes and less frustrations. Cornerweighting is an art form that takes a long time to master

2. same with dit alignment. A Smart Camber gauge is a very nice tool that is easy to use and very accurate. For toe, there are lots of websites that will show you how to use strings and jackstands for a quick job. Just also be sure you square the car relative to centerline of the chassis and driveline, not just the 4 wheels in relation to eachother. There are many good books out there on the subject that should get you started.

3. find somebody with experience and learn all you can by watching and listening. There is far more to consider then meets the eye...

Most decent scales these days will calculate crossweight values and percentages for you and store a log of measurements for you...consider these features when pricing various models, the few $$ difference can save a lot of time and aggravation...

Hope that helps.
Dave w

 

As you know I’m not one to be shy about stepping up and giving my 2 cents but, these guys haven’t even left any crumbs on the table for me. You’ll hear different people talking about different cross weights … don’t listen to them. For the type of setups you’re going to be doing, Joe’s suggestion of 50/50 is EXACTLY right on. Dave makes another good point saying that it’s an art and it absolutely is but, that’s exactly why, in your case, I’d say go for it. From what I know of you, you seem to be a rather methodical guy and if you don’t mind spending the time to do the work and learn, I think you’ll do well. I can also assure you that once your confidence dialed, you’ll never let anyone else touch your car again. The concept of corner balancing is simple, however, the actual work is rather involved, tedious and ultimately time consuming. If someone tells you differently, I’d say that’s because they’ve never done it correctly. The nice thing about having your own equipment is that it becomes easy to check the stuff regularly and change it when needed. If you get sick of doing all this, scales and pads are generally easy to sell used.

Stuff to consider:

4 Electronic scales (Longacre, Intercomp, Tannner, etc.) Starting around ..$1100
Smart Products Camber gauge … $150
Smart Products stringer (eliminates using jack stands) … $395 ???

I’d also get some toe plates for quick checks and changes on the fly $60-$150
To help the car settle, you can make your own grease plates $30

You can get individual levelers and some drive up ramps. The problem with this is the pads aren’t tided together and start to move around as you drive on and off and eventually you will get false readings.

A set up pad is the best way to go, however, they start about $1800 without scales.

Remember, leave one step out or record it wrong and you’re whole setup with be wrong.

 

Can someone explain or provide a link to the "string and jackstand" method of setting toe-in?

 

Thanks everyone, and Cary, did you call me a constipated engineer? Yea, I guess you're right.

Since no one said it was a stupid idea, I'm going to continue. OK, what are my best books to really look into this? The basic idea of using lasers instead of stringers is easy. I would like to get the info from the best sources possible.

 

ART is the place that's well known for their laser alignment equipment. I believe Smart Racing sells there stuff. I'll see if I can find some sites and I'll list them

 

The basic concept behind "stringing" a car with string, lasers, or anything else, is that you draw a box around the vehicle that is square with the driveline and chassis and use this as a reference to square the wheels and then adjust toe angle accordingly. I'm sure a google search will uncover numerous links to follow.

For books, I would recomend anything by caroll smith, especially "tune to win", they are all a bit outdated having been written 25 years ago, but the concepts have not changed and his books have long been considered the standard on the topic.

a more recent book that i remember being usefull is Paul Van Valkenburg's Race Car Engineering and Mechanics...its about 10 years old.

-dave w