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Old 05-25-2019, 06:36 PM   #1
66cayne
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Default '66 Biscayne- chassis adjustment for better traction-

I have a '66 Biscayne, 496BBC, 4 speed, 12 bolt, M/T 10.5/29/15 slicks. I am trying to improve traction when I launch this thing. She is running 11.60s s with a 1.70 60 ft.. I have fiddled with slick air pressure, an airbag in the passenger side rear spring and different spring and shock combinations. I am now trying to adjust the instant center( where the 2 upper and 2 lower control arms would theoretically intersect if they ran through the entire car) more towards the center of the car instead of slightly in front of it (by my calculation, hard to do with the body on the frame). I understand this change in I/C will benefit planting of the rear tires and hopefully improve my launch/60 ft times. My plan is to change the angle of the two upper control arms so they will intersect with the projected line of the lower control arms more towards the center of the car. I believe by adjusting the angle downward on the two upper bars by about two inches it will get me there. I suppose this could also be done by lowering the rear mounting point of the lower control arms to achieve the same effect. Just want to hear from those with more chassis experience if I'm on the right track for attempting this change. Thanks
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Old 05-25-2019, 09:46 PM   #2
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Default Re: '66 Biscayne- chassis adjustment for better traction-

I ran a 1968 Impala with a 396/325HP I/S 2003-2005 Jerico 4 speed, McCloed Sof-Lok clutch, 14 lb flywheel, (you make enough HP to run a Aluminum flywheel too) 4:88 w spool. Rear suspension was a set of Southside Machine lower control arms, they are no longer around, but the bars lowered the mounting point of the back of the bar changing the IC I have them on my 65 Impala stocker now, but with automatic. I also run adjustable upper control arm with Heim joints. The crossmember they bolt too was also braced and I run a X frame off my roll bar to it, these tend too pull out without any bracing. I ran 11.70's , 115 MPH with it. I never really sorted out the clutch, but I remember running only like 600 lb clutch base pressure. My best 60 ft times i believe were high 1.50's , this was at 4095 lb
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Old 05-25-2019, 10:31 PM   #3
Dan Fahey
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Default Re: '66 Biscayne- chassis adjustment for better traction-

Have a 1969 Impala that ran in M/SA.
Used airbags and glued on a piece of 2by4 on axle housing.
On launch this would hit the Pinion Snubber.

Doing a full restoration on the car.
The new chassis set up will have the Southside Machine lower control arm.
Chassis was restored and reinforced by Steve Yeagle.
Including the Crossmember that the Upper Control arm attaches to.
Every year hope to finish the car.

Years ago designed a bracket raising Upper Control Arm at the Axle 2.5 inches.
Made it and never installed it.
That is when we started having kids.

All said and done.
Gluing the piece of wood on the top of the Axle worked well.
At rest was 1.5 inches from the Snubber.
Car squatted smoothly, launched hard pulled left front tire.
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Old 05-27-2019, 09:05 AM   #4
Lee Valentine
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Default Re: '66 Biscayne- chassis adjustment for better traction-

Have a friend with 66 Biscayne running low 10's with reinforced crossmember and an air bag
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Old 05-27-2019, 11:55 AM   #5
Mark Yacavone
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Default Re: '66 Biscayne- chassis adjustment for better traction-

That type suspension is one of the easiest to raise the rear of the uppers on .
You need some flat stock , a few extra short bolts, and a welder..and. oh yes , the ability to use it properly.
I don't think I'd go up 2, 1/2 inches though.
Solid lower bushings help those cars immensely . There is very little binding, with the uppers running straight ahead.
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Old 05-27-2019, 01:38 PM   #6
66cayne
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Default Re: '66 Biscayne- chassis adjustment for better traction-

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.
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Old 05-27-2019, 03:17 PM   #7
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Default Re: '66 Biscayne- chassis adjustment for better traction-

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. ;-)
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Old 05-27-2019, 03:21 PM   #8
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Default Re: '66 Biscayne- chassis adjustment for better traction-

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
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Old 05-27-2019, 04:57 PM   #9
66cayne
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Default Re: '66 Biscayne- chassis adjustment for better traction-

Quote:
Originally Posted by Mark Yacavone View Post
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.
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Old 05-27-2019, 05:14 PM   #10
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Default Re: '66 Biscayne- chassis adjustment for better traction-

Quote:
Originally Posted by 66cayne View Post
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

Last edited by Dan Fahey; 05-27-2019 at 05:30 PM.
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