Corner Balancing ????

[cary]

Lee and I were discussing this last weekend.

I thought I knew. But when we started getting down the details. It didn't all come together.

I know that the load at all four corners. Is adjusted to compenstate for the drivers weight.

But how is this done ?????

[sammyg2]

You can't intentionally shift weight from the left side to the right side and keep it even. Corner balancing just tries to make the difference between the L&R front wheels equal to the difference between the L&R rear wheels.
Example (numbers are not necessarily real world):
Let's say LF tire has 525#, RF tire has 500. Difference is 25#, probably in part cause by the weight of the driver.
Now to the back:
If the LR tire has 625#, then you would want the RR tire to have around 600, to maintain the 25# difference left to right.
The whole idea is to try to eliminate the 4 legged stool wobble.
You do not want extra weight on opposite corners.

Of course, that was over-simplified. Other factors that determine preset on race cars can enter into the equation such as torque transfer and chassis flex, but that is for the experts and usually not necessary in my little realm and is way too complicated for me :-)

[Chuck Moreland]

The car does not weigh the same left and right. And that's just fine.

The goal of corner balancing is to have the same ratio of weight, front to rear, for both sides.

That is to say:

LF/LR = RF/RR

The front is easy to adjust, just turn the tbar adjuster screws.

The rear is easy if have adjustable spring plates ('77 on). You turn the eccentric bolt to dial in the weight.

If you have an early car without adjustable rear, the easy way to do the job is .....get the newer spring plates. But if you insist on making work, you need to pull the spring plates and re-index the tbars.

The reason that is such a pain is that you are likely to have to do it several times before you get it right.

This is an iterative process because ajusting any one wheel weight affects every other wheel weight.

You need a scale. A cheap home scale ($150) is available from speedway motors. The pro scales are expensive.

Good luck.

[goldrench]

I hate assuming things, but would it safe to say the proper procedure could be summed up by:
1. Put the car on the alignment rack and adjust front and rear heights to equal balance difference.
2. Align to desired alignment specs.
3. Test drive and repeat.

What'd I miss?
(Beisbarth Machine...4 scales.)

[goldrench]

I hate assuming things, but would it safe to say the proper procedure could be summed up by:
1. Put the car on the alignment rack and adjust front and rear heights to equal balance difference.
2. Align to desired alignment specs.
3. Test drive and repeat.

What'd I miss?
(Beisbarth Machine...4 scales.)

[vash]

ok, i was just asking this;

is it only our beloved 911's that need corner balancing? honestly, with our cars, it is the first time hearing about it.

[goldrench]

I'll leave that one to the experts.

[imcarthur]

Corner balancing threads:

What is corner balancing?

Home ride height and corner balance success story

And the grandaddy of threads:

CORNER balanced - numbers from this...and the weight

Ian

[jluetjen]

Originally posted by vash
ok, i was just asking this;

is it only our beloved 911's that need corner balancing? honestly, with our cars, it is the first time hearing about it.

Yes and No.

Most cars (including 911's) go through their life and never get corner balanced. They get set at the factory based on the presumption of a square chassis (based on the assembly tooling), and some standards (ie: Install both rear spring plates with an angle of ...") and then spend the rest of their life happily like that.

But a lot of 911's get tracked. When you are driving a car on track -- any car, not just 911's -- corner balancing becomes more important because often the cars are lowered (upsetting the initial settings). Also, when you have the car in the last 5% of it's handling performance, as a driver -- you'll be able to notice small inbalances like a slight push in left hand corners and a slight looseness in right hand corners. Properly corner balancing a car will ensure that the handling is consistent in both left and right hand turns. It will also ensure that all 4 wheels are doing their share when braking in a straight line. It will not change a weight bias (usually to the left side for US cars as a result of the driver) which results in the car having a slightly higher cornering potential in left hand turns.

[javadog]

Vash,

In theory, all cars should be corner balanced. In reality, most do not have the means to easily adjust the height of each corner independently, so they don't get done, as a matter of practicality.

If your car has never been done, you ought to do it. After the car has settled on it's suspension over the years and the bushings have worn, I can pretty much guarantee it will be off. Sometimes the error can be substantial. On a street car, you may not notice an imbalance of cornering ability but you may notice a tendency to lock one of the front brakes fairly early. This will obviously limit your braking ability, sometimes to the point that the car has only 70-80% of the braking capability it should.

JR

[vash]

thanks for the answers!

mine has been done, but will get it again because i am raising my ride height a bit tomorrow. beside, i got bit by the track bug...

[Chuck Moreland]

Corner balance is much more important for a stiffly sprung car. This because a small difference in height of a stiff spring yields a big change in corner weight.

Most production cars are softly sprung, and therefor minor differences in height make relatively small corner weight differences. In short, soft springs are forgiving of corner weight errors.

Also, if you have no provision to adjust spring height - you can't really screw up the spring height. Our 911s have adjustable height, it is therefore up to the mechanic to get the height and corner weight correct - they've been given the means to set it right, but also to screw it up!