'66 Biscayne- chassis adjustment for better traction-

[66cayne]

thanks for responses and ideas. Yes, unfortunately Southside Machine does not make the lower bars for our 65-70 b-body cars anymore. Thats why I started looking at lengthening the upper control arm rear mounts help make the needed change to the I/C. Dan Fahey- if you still have the bracket or a drawing you designed I would love to see it. 2" -2.5" is about right for setting that upper control arm at parallel. Also, I have do have brackets welded in support the upper control arm mounting frame cross-brace.

[Mark Yacavone]

A lot depends on what height springs you're using and what size tire and rim size you're stuffing under there. I've tried wagon springs.That will change the geometry somewhat.
Don't forget to gusset the lower arm front bracket. They'll tear off the frame too. ;-)

[66cayne]

Originally Posted by Mark Yacavone

A lot depends on what height springs you're using and what size tire and rim size you're stuffing under there. I've tried wagon springs.That will change the geometry somewhat.
Don't forget to gusset the lower arm front bracket. They'll tear off the frame too. ;-)

Using station wagon springs now. Hikes it up a little bit. 10.5x29/15 fits good on 8.5 rim with 4.25 backspace. Been running about 12-15lbs air pressure. I DO need to gusset those lower arms though.

[Marty Knox]

Originally Posted by Mark Yacavone

A lot depends on what height springs you're using and what size tire and rim size you're stuffing under there. I've tried wagon springs.That will change the geometry somewhat.
Don't forget to gusset the lower arm front bracket. They'll tear off the frame too. ;-)

I
I tore the lower arm front bracket on my 65' Bel Air with a 230 and a 3-speed!.

[Larry Merk]

66cayne,

Take the guesswork out of your change and use this spreadsheet. It explains how to make 8 simple measurements, then enter the numbers into the spreadsheet. The spreadsheet calculates the instant center and several other setup numbers. We used it to get the rear suspension set up properly on our 81 Malibu. It helps you get it right the first time without guessing. Good luck.

http://www.patooyee.com/calculators/4BarLinkV3.0c.xls

[66cayne]

Originally Posted by Larry Merk

66cayne,

Take the guesswork out of your change and use this spreadsheet. It explains how to make 8 simple measurements, then enter the numbers into the spreadsheet. The spreadsheet calculates the instant center and several other setup numbers. We used it to get the rear suspension set up properly on our 81 Malibu. It helps you get it right the first time without guessing. Good luck.

http://www.patooyee.com/calculators/4BarLinkV3.0c.xls

Ahh! the engineering approach. Thanks for the spreadsheet. I have a couple of questions about the variables. How do you calculate the vehicle center of gravity (is it half of the car's height?)? Also, the suspension geometry x, y, z, dimensions for control arm lengths. I know what the length is of each of my stock arms is but not sure how that converts to an x,y, z dimension.

[Larry Merk]

Originally Posted by 66cayne

Ahh! the engineering approach. Thanks for the spreadsheet. I have a couple of questions about the variables. How do you calculate the vehicle center of gravity (is it half of the car's height?)? Also, the suspension geometry x, y, z, dimensions for control arm lengths. I know what the length is of each of my stock arms is but not sure how that converts to an x,y, z dimension.

66cayne,

Put the car on jackstands, take off the rear wheels, and measure.

Open the spreadsheet and hover your mouse over the X, Y, and Z data entry cells. It will display a description of the measurement needed such as "height from ground" or "forward from rear axle center line." Enter the numbers in the appropriate cell and you will see a graphical depiction of your rear suspension with a top view and side view. It should be obvious from the plot if your numbers represent your suspension geometry. You can then modify mounting point locations to see how the change affects instant center and other dimensions.

Before using this spreadsheet we wondered why our car (and others) squat on acceleration. The spreadsheet showed us the stock instant center was behind the rear bumper.

Of course the final test is to run the car and see how it works at the track. We made a couple of adjustments and quickly found the sweet spot where the car really worked well. Good luck.

[66cayne]

Originally Posted by Larry Merk

66cayne,

Put the car on jackstands, take off the rear wheels, and measure.

Open the spreadsheet and hover your mouse over the X, Y, and Z data entry cells. It will display a description of the measurement needed such as "height from ground" or "forward from rear axle center line." Enter the numbers in the appropriate cell and you will see a graphical depiction of your rear suspension with a top view and side view. It should be obvious from the plot if your numbers represent your suspension geometry. You can then modify mounting point locations to see how the change affects instant center and other dimensions.

Before using this spreadsheet we wondered why our car (and others) squat on acceleration. The spreadsheet showed us the stock instant center was behind the rear bumper.

Of course the final test is to run the car and see how it works at the track. We made a couple of adjustments and quickly found the sweet spot where the car really worked well. Good luck.

Got it now, Thanks!

[300stw]

cant get the link for the suspension to work,, in the same boat as OP,


cant really get the tires to hit hard fighting traction, would like to see a pic of the original southside bars and a pic of raising the mounting points for upper control arms,

[Dan Fahey]

Originally Posted by 66cayne

thanks for responses and ideas. Yes, unfortunately Southside Machine does not make the lower bars for our 65-70 b-body cars anymore. Thats why I started looking at lengthening the upper control arm rear mounts help make the needed change to the I/C. Dan Fahey- if you still have the bracket or a drawing you designed I would love to see it. 2" -2.5" is about right for setting that upper control arm at parallel. Also, I have do have brackets welded in support the upper control arm mounting frame cross-brace.

Sheesh !!
The part is long lost.

Can Tell you how I did it.
Cut out several pieces of Cardboard.
Removed the Rear Bolt and raised the Control Arm about 2.5 inches.
Rules it had to be a Bolt On fixture.

Outside piece.
Cut two pieces of Card Board and taped them together.
Inside piece was the width of the Bushing.
That was for the out side of the Bracket.
Cut another piece for Inside Bracket.
Both inner and outer pieces matched the curve of the axle.

They were welded together to fit over the each side of the Bracket.
Cut another piece that curved around the axle.
Welded to the two inside Brackets pieces.

Intent was to use two grade 8 bolts for each bracket using existing hole.
Bolt Pinched the two plates to each side of the bracket.
Curved piece that wrapped the Axle would prevent the Control Arm Bracket from moving on Launch.

I then got my drafting board the made a drawing.
Worked with a Welder Friend also helped with the measurements.
For some reason did not follow my directions and went back forth until he got it right.
Then we had to move to Florida and never installed them other than for fitment.

Dan