Oh no! Another corner balancing thread!

[widebody911]

Ok, I have my car up on the scales right now. I have 1/2 tank of gas. Tire pressures 31 rear, 30 front. Sway bars disconnected.

Fully laden (spare, tools, etc), no ballast.

http://vintagebus.com/cgi-bin/balance.cgi?name=Thom&car=77+911+cab&notes=no+ballast%2C+1%2F2+tank%2C+fully+laden&LF=137&RF=124&LR=205&RR=220&multiply=on

Unladen, no ballast

http://vintagebus.com/cgi-bin/balance.cgi?name=Thom&car=77+911+cab&notes=no+ballast%2C+1%2F2+tank%2C+unladen&LF=116&RF=120&LR=207&RR=210&multiply=on

Unladen, appros 235lbs ballast (track trim)

http://vintagebus.com/cgi-bin/balance.cgi?name=Thom&car=77+911+cab&notes=unladen%2C+approx+235lbs+balast&LF=141&RF=126&LR=228&RR=217&multiply=on



So, what would I adjust and why?

I'd really like to reduce this to something I could code into the corner balance calculator, and have it make suggestions, as is "raise FR" or "lower RR"

[Chuck Moreland]

Assuming it is #3 that you are trying to optimize...... you are pretty damn good right now. If you want to get better, tighten the right front 1/4 turn and loosen left front 1/4 turn.

This assumes you are also happy with the existing ride height.

[Joe911]

Is the ballast the driver? Decide which situation you want to optimize. From my experience (corner balanced my car 4-5 times after various projects) - you want to raise each pair (RF - LR or LF - RR) for the light diagonal and lower each pair for a heavy diagonal. Which pair would depend on ride height considerations. Although not much change in ride height occurs when fine-tuning corner weights so get the height set as close to optimal before you start with the balance.

[msailer]

Is there a chart that describes the ideal weights for each corner?
Why don't we try when Corner Balance to get the car closer to 50/50?

Alot of what I have read puzzles me.
Such as why should the nose of the car be higher than the rear, by 1/2"?

Can anyone enlighten me?

TNX

[Chuck Moreland]

Mark

Total weight on an axle cannot be changed via corner balancing. You can lighten one wheel of an axle, but the opposite wheel on the same axle will get heavier by the same amount. So no way to approach 50/50.

Height is a function of where you measure it. The commonly quoted 25.5 inch front, 25 inch rear is to the highest point of the wheel arch. But the wheel arches are not the same shape.

If you look at a car setup this way, you will clearly see the door sill angles down in the front. Of course, the door sill is not an absolute frame of reference either.

[widebody911]

Yes, the 3rd scenario is the one I want to optimize; I put the others there just out of curiosity.

The ride height now is OK, maybe a tad low in the front; I didn't take any measurements before I put it on the scales.

[widebody911]

Originally posted by Chuck Moreland
Assuming it is #3 that you are trying to optimize...... you are pretty damn good right now. If you want to get better, tighten the right front 1/4 turn and loosen left front 1/4 turn.

Ok, I did that:

http://vintagebus.com/cgi-bin/balance.cgi?name=Thom&car=77+911+cab&notes=unladen%2C+approx+235lbs+balast&LF=139&RF=127&LR=228&RR=218&multiply=on

I'm within 8lbs; will he quit while he's ahead, or will he screw it up?

[Chuck Moreland]

What do you figure the accuracy / repeatability of those scales to be?

I believe you are now being limited by your tools. You can adjust all day, and never get it better.

[widebody911]

Originally posted by Chuck Moreland
What do you figure the accuracy / repeatability of those scales to be?

I believe you are now being limited by your tools. You can adjust all day, and never get it better.

You're 100% correct, sir. I figure there's a 5lb margin of error per corner, between the Ruggles multipliers, cheap bathroom scales, and suspension friction. Case in point: I discovered
that I'd left the spacer on the LR wheel. After removing the wheel, removing the spacer, and re-installing the wheel, the car shows 8lbs lighter. The spacer does not weigh 8lbs!

FWIW, I can hear the suspension creak and groan several minutes after I've made an adjustment; sounds like an excuse to go to bronze bushings...

He's the final number, for better or for worse:
http://vintagebus.com/cgi-bin/balance.cgi?name=Thom&car=77+911+cab&notes=235lbs+ballast%2C+half-tank%2C+no+tools+or+spare&LF=552&RF=532&LR=884&RR=872

I think this is "close enough for government work"

Even better: when I was re-attaching the sway bar drop links, I found that the LR drop-link was loose - I figure another couple weeks of driving and I would have lost the clamp bolt. That might explain my squirrely handling (which is why I was corner balancing in the first place)