My car is currently corner balanced on coilovers. I'd like to get a little more clearance and raise the suspension about 3/8". Obviously if I raise the spring perches by the same amount on all 4 shocks than nothing changes corner balance wise (alignment will change some).

Now my question is if the corner balance would change if I raise both the fronts by 1/4" and both the rears by 3/8". I believe that the corner balance will still be intact. Any opinions?

By the same token, the corner balance should NOT change if you adjusted both the LF and LR (or RF and RR) by the SAME amount. In other words, the height on one side of the car would be altered. Opinions?

My understanding is that the only way you would alter the corner balance is if you only adjusted one of your corners and left the other three intact or if you adjusted 2 cross corners and left the other 2 intact (LF and RR or vice versa).

 

Any change to the ride height will alter the corner balance. It's a more delicate balance than just equally raising everything.

 

Can you please expand of that from a simple physics standpoint? For simplicity sake, lets assume a chair with 4 legs is our "car with 4 wheels". If you have a chair that is balanced on 4 legs and you put an even thickness shim under each leg, how in the world would that change the balance distribution?

Let's assume this:

You take a chair and put a scale under each leg. Then you have a person sit in the chair and take readings on each scale:

LF= 45 lbs RF 45 lbs

LR= 55 lbs RR 55 lbs

You can see that the weight is biased towards the back of the chair (just like in our cars) The cross balance is 100 lbs /100 lbs (LF+RR/RF+LR) which is a 0% cross difference in weight. In other words ideal.

NOW, for the sake of argument, put an even thickness shim under each leg of the chair (between the leg and the scales) in the above example. This is the same as raising the spring perches on each corner by the same amount in our cars. Now what would the scales under the chair read? Nothing would change unless you can alter the laws of physics.

NOW, for the sake of argument, put an equal shim under the rear legs of the chair (LR and RR) while leaving the fronts as is. This will effectively shift the center of gravity slightly forward as the person sitting in the chair (and the chair) is tipped forward due to the shims under the rear legs. The reading on the scales should read something like this:

LF= 48 lbs RF= 48 lbs

LR= 52 lbs RR= 52 lbs

The cross balance is still 100 lbs/ 100 lbs which is still a 0% cross difference in weights. Still ideal.

NOW, for the sake of argument, put an equal shim under the left legs of the chair (LF and LR) while leaving the right side as is. This will effectively shift the center of gravity slightly to the right as the person sitting in the chair (and the chair) is tipped right due to the shims under the left legs. The reading on the scales should read something like this:


LF= 42 lbs RF= 48 lbs

LR= 52 lbs RR= 58 lbs

The cross balance is still 100 lbs/ 100 lbs which is still a 0% cross difference in weights. Still ideal....

NOW, for the sake of argument, put an equal shim under the LF and RR leg of the chair while leaving the others intact. This will effectively put more pressure on the LF and RR legs while unloading the LR and RF (the chair is now unbalanced and rocking from the LR to RF). The reading on the scales should read something like this:

LF= 48 lbs RF= 42 lbs

LR= 52 lbs RR= 58 lbs


The cross balance is now 106 lbs/ 94 lbs which is roughly a 10% cross difference in weights. Not good....

I am not a suspension expert but just using basic knowledge of physics. Am I completely wrong or do I not quite grasp the basics of corner balance?

 

If you google "corner balancing," Elephant Racing has a good technical article explaining the topic. I'd just give you the hyperlink, but the 6SO TOU doesn't allow that.

 

I don't think changing the height (same) of all four corners would affect the corner balancing; that's what my tech (well known in the Bay Area) told me when I wanted to raise the car a little higher.

 

I would think that if you adjusted each perch the exact same number of turns, that you would still be very close to balanced.

But unless you are seriously tracking the car at maximum capabilities, who cares?

A corner balance for the street is nice, but not really necessary.

 

I agree fully. I was just trying to understand the mechanics behind a corner balance from a physics standpoint. I think the term corner balance is a bit of a misnomer since our cars will NEVER be balanced front to rear and RARELY left to right but rather we are trying to achieve a "cross weigh balance" (LF+RR = LR+RF).

 

unfortunately, spring rates are different from front to rear and spring tension is not constant for the entire compression range of the spring..so your carefully thought out physics that adjusting all corners the same will not upset the corner balance does not work well in the real world..there is no substitute for putting it on the scales

 

The mass of the car is not centered that's why things change. Any change in height will effect your balance. In your first post you stated raise the fronts 1/4 and rears 3/8. That will change everything. Also make sure when you put the car on the scales the sway bars are disconnected as they will transfer weight.

 

Thanks for the input. Please explain how adjusting all 4 corners the SAME amount would have any effect on spring tension.

If all corners are adjusted up or down the SAME amount, the center of mass of the car will NOT change at all. The pressure that each spring sees is UNCHANGED since each spring perch is adjusted the same amount. It makes no difference what the spring rates are. If the pressure that each spring "sees" is unchanged, than how can the corner balance change? I am just using simple logic...

What is the difference in raising each spring perch the exact same amount (say 1/4") and driving all 4 wheels of your car onto a large 1/4 sheet of plywood? In each case the car body will be 1/4" higher and in each case the spring tension is unchanged. In other words, raising a spring perch by 1/4" has the exact same effect as sticking a 1/4" sheet of plywood under the tire.


Another question so that I understand this:
Is this car corner balanced?

LF= 770 lbs RF= 720 lbs

LR= 1020 lbs RR= 970 lbs

 

Is that number with the sway bars hooked up? Any car that is corner balanced will not have the same fender heights. also you move the perch so little to get the weighs right. setting up a car is anything but simple. Oh and don't forget to set your tire psi the way you run at the track, you guessed it that also changes things too.. as far as the car it 50lbs off one way the ground it was set up on or the one you are weighing it on can be out of level.

 

By changing the car height, you change the preload on the springs.

But, symmetrical changes cannot upset the balance IMO.

 

Sways are disconnected for the corner balance and then connected and adjusted afterwords. Ground is perfectly level and tire pressure is set correctly...

I'm not sure what you mean when you say:
"as far as the car it 50lbs off one way the ground it was set up on or the one you are weighing it on can be out of level".

So is the car corner balance in the previous post?

 

I agree 100% with the last sentence above. I do not understand what logic is used by those that say that a symmetrical change at all 4 corners will upset the balance.

 

Um, what? That's like saying driving uphill is synonymous with raising your ride height.