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Question - Improved Camber Curve

Shocks, Springs, Brakes, Frame, Body Work, etc

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enigma57
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Question - Improved Camber Curve

Post by enigma57 »

Had a question...... I am setting up my '57 Chevy's suspension (its a road car) to handle better. Have done this with several '55s and one '56 Chevy many years ago. The usual mods...... Lower car a few inches, stiffen springs, firmer shocks, front and rear anti-sway bars, set camber at 0 degrees, 7" wide wheels, radial tires with 8.5" tread width front and rear.

However, I had an idea this evening...... Improve camber curve. I recall the A-body GM cars and F-body cars using taller spindles from the full sized B-body cars both to improve the camber curve for better cornering and to mount larger disc brakes.

So here is my question...... Remember the upper ball joint spacers that were used on '55 - '57 Chevys in the '60s when it was fashionable to use longer (usually early '60s 409 station wagon springs) to raise the front end (rather than install a straight axle) for the 'gasser look'?

Well it occurred to me this evening that if the front of the car was at or near stock ride height rather than being raised...... Upper ball joint spacers would have the same effect as having taller spindles and should have a beneficial effect on cornering (better camber curve)......

Image

Does that sound right to y'all? Or am I just getting old?

Your input and ideas greatly appreciated,

Harry
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Re: Question - Improved Camber Curve

Post by dannobee »

The actual camber curve is dictated by the length of the upper control arm. Or more accurately, the ratio of upper and lower control arm lengths.
Moving the ball joint up or down changes the front roll center, not the camber curve.
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Re: Question - Improved Camber Curve

Post by enigma57 »

Thanks for the explanation, danno! I can see that I need to gain a much better understanding of this before making any changes beyond what I have done in the past.

Much obliged,

Harry
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Re: Question - Improved Camber Curve

Post by BigBlockMopar »

For (street)handling you would want about -.50° to -1° camber, and a healthy 2-4° of caster.
This makes the front tires 'lean in' into the curve and direction you going to. Giving the tires a bit more bite on the road.
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Re: Question - Improved Camber Curve

Post by Kenova »

If the upper control arms are close to level at ride height then the spacers will increase you camber gain. You could also use extended upper ball joints.
Increasing you caster will also help, but is sometimes difficult to get any significant gains on these older cars.

There is the "Guldstrand" mod for early F and X body cars (Camaro, Nova). It moves the mounting point of the upper control arm down and rearward. Moving the mounting point down has the same effect as using a longer ball joint or spacer. Moving it rearward increases caster. I used this mod on my '71 Nova and it made a great improvement in the way it handles. I'm not aware of any similar mod for the Tri-Fives.

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Re: Question - Improved Camber Curve

Post by enigma57 »

Many thanks, BigBlockMopar! I have made a note of that. In years past, I have stiffened springing considerably and set camber on these cars at - 0.5 degrees to 0 degrees.

One of the issues with alignment on the '55 - '57 Chevy suspension is that caster is limited to around + 1-1/2 degrees. The car will be more stable at speed with additional caster as you say. There are aftermarket upper control arms made as are the originals, but with the upper ball joints positioned farther to the rear in order to increase caster to around 5 degrees positive.

This works well with power steering, but adds a bit of effort with a manual steering box. I seriously considered these upper control arms but they are made in communist China for the vendor (I won't name them here except to say they sell quite a few suspension parts for these cars) and frankly, there have been instances of other parts for these cars from the same vendor either wearing prematurely or failing. So I will retain my original upper control arms.

One of the changes I am making involves adapting the larger drum type brakes from the full sized '59 - '64 Chevy to my car. To do this, I will be adapting the entire '59 - '64 spindles and brakes on the front. Upper ball joints are the same as the '55 - '57 cars, but the later year lower ball joints are a bit larger / stronger and mount differently to the lower control arms. So when I modify the lower control arms to accept the '59 - '64 lower ball joints, I will see if I can reposition the lower lower ball joints a short distance farther forward on the lower control arms to give another degree or so of positive caster.

I will probably retain the original manual steering box and (for the added leverage), the 15" original steering wheel, as well...... But will use shorter steering arms to speed up the steering a bit. If you've ever driven one of these 60+ year old American cars with original steering and wider wheels and radial tires through tight turns and switchbacks at speed, you will find that turning the 15" steering wheel lock to lock not only requires additional effort but is much like turning a ship's wheel...... 'Aye, Captain....... Hard a-port!'

Best regards,

Harry
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Re: Question - Improved Camber Curve

Post by enigma57 »

Yes, Ken...... I was hoping to have a similar camber improvement in turns similar to that provided by the Guldstrand mods which move the upper control arm mounting points downward and rearward as well. That was my thought in possibly adding upper ball joint spacers to the Chevy. To move the ball joint upwards whilst leaving the upper control arm pivot / mounting points in their original position to accomplish the same vertical repositioning. And not being able to reposition the upper control arm mounting points to gain additional positive caster...... I will see if I can reposition the lower ball joints a small distance forward.

'55 - '57 Chevy front suspension looks like this......

Image

Image

Image

When at standard ride height or a couple inches lower, the lower control arms are level and the upper control arms as you can see, have a bit of a curvature built into them.

Best regards,

Harry
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Re: Question - Improved Camber Curve

Post by Rick! »

SLA suspensions won't have parallel arms at ride height.
Their ball joint center coupled with the chassis points create a line that is extended into space a ways.
Do this with both the control arms and they intersect at what is called their instant center (IC).
Doing the same with the other set of control arms and now you get a picture of what your camber will do as the wheel center rotates around their respective IC.
This is half of the picture of the front view swing arm angle and height (FVSA).
Now draw a line from the tire patch to the IC for each side. The lines will intersect with each other at the center longitudinal plane of the car. This will be what's known as the front roll center. In a turn, the car CG will want to go laterally outward and applies a moment at the roll center. IF the roll center is above the wheel center, it will compress the outboard spring. If the roll center is below the hub center and at or below ground level, it will actually jack the spring up.

If you want to improve the camber curve, as in minimize camber change throughout the wheel center vertical travel, moving the IC further away from the center plane is one way to do it. At the same time, lengthening the LCA also helps with this.

This gets a bit involved and usually requires measuring all the hard points of the front suspension and entering them into any one of several suspension programs and playing around. Then you can play with Akerman, SVSA, anti dive and learn how the interactions are between each characteristic.

The other way to do this is apply the Herb Adams method of handling: use the biggest diameter sway bar you can find and use the softest coil springs that prevent bottoming. Set it up at -1° to -1.5°camber at all corners, as little toe as possible and have fun. You can install camber in a solid axle housing by running a weld bead down the top of the axle tube. Shaved tires work really well, if that is done any more.
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Re: Question - Improved Camber Curve

Post by BigBlockMopar »

Rick! wrote: Mon Aug 17, 2020 7:33 am ... You can install camber in a solid axle housing by running a weld bead down the top of the axle tube.
Rick, how are you envisioning this?
IMO, the only thing that gets 'cocked' is the brake-assembly. The axle shafts are a solid part with gears in the center, and the axle flanges will always keep the wheel/tires at 90°, so 0 camber.



As for front camber/caster, I'm using 'offset' UCA bushings in my '73 Dart.
These are the MOOG "problem solver bushings", originally ment to fix alignment-issues on damage-tweaked cars. But when installed opposite of what the instructions say, you can add about 2 - 2.5 degrees of caster on a factory setup.
I'm running with around 4 degrees of caster on the Dart and about 1° of camber. It handles very nice during cornering.


Image

Image
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Re: Question - Improved Camber Curve

Post by dannobee »

Rick has it right, even the welding part. Think of an old VW swing axle, if you bend the axles up, there will be a slight camber change. In nascar we run cambered rear snouts on the end of the axle tubes and a full floating axle hobbed on the wheel side is used with a drive plate. Rear camber is dictated by rule, but "around" -3 degrees on the right side and +2 degrees on the left side.

What we're ultimately changing when changing the angle of the upper control arms is the front roll center, NOT the camber curve. The Instant Center that Rick speaks of is another critical dimension if you want the car to handle. Too short and the suspension will "jack up" like an old VW or Corvair rear suspension. Longer IC is usually a good thing, all else considered.

The camber curve is dictated by the length of the upper control arm. Shorter arm will give you more negative camber gain (outside wheel when going around a corner).

Since altering the upper control arm pickup points was mentioned, be aware that you will also change the "anti-dive" along with the front roll center. And if you're making changes in caster, it WILL affect the bump steer.

Obviously, there's a lot more going on than what most people think when we're talking suspension.
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Re: Question - Improved Camber Curve

Post by enigma57 »

Thanks for the info! That helps me to gain a better understanding of this. Much appreciated.

I may have mentioned in another thread that one of the mods I am doing on my '57 is adding the wider '59 - '64 front and rear drum brakes.

By swapping '59 - '64 Chevy drum brakes onto my '57 Chevy (going from 11" X 2.0" wide front brakes and 11" X 1-3/4" rear brakes to 11" X 2.75" wide front brakes and 11" X 2.0" rear brakes)...... I will increase swept area of front brakes by 37.5% and swept area of rear brakes by 14.28%. By way of comparison, the increased front brake swept area will be equivalent to that of an 11" diameter disc brake rotor. Of course, that doesn't take other factors into account such as coefficients of friction and applied pressure, but I will be using a high quality ceramic brake shoe and fitting one of the large remote Bendix power boosters that were used on '57 - '58 series 62 Cadillacs and larger GM trucks of the period. These are said to put out the equivalent of 500 lb. of pedal pressure when brakes are applied, so will have to use a light touch on brakes in normal driving, I would think.

I have adapted these larger drum brakes to a '56 spindle 48 years ago (1972), but doing it that way requires shortening both the anchor bolt and the threaded receiving boss on the '55 -'57 spindle. And that in turn, reduces thread engagement of the anchor bolt to around 3 threads. I never had an issue with the '56 spindles I modified but in the back of my mind, I always worried that one day one of the anchor bolts might pull out (that car had Lakewood Velvetouch metalic brake linings).

So this time round, I have decided to swap the entire '59 - '64 front spindles (and front brakes) onto my '57. Upper ball joint is same, but lower ball joint is larger / stronger and mounts to the lower control arm differently. So I scrounged up a set of lower control arms from a '62 Impala and will cut the outer ends off and weld them to my '57 lower control arms to adapt the '59 - '64 spindles and brakes. Will also reinforce (strengthen) the lower control arms as was done with the dirt track cars and moon cars of the late 1950s when doing this.

I looked up front alignment specs for a '62 Impala this evening and they are not all that different from my '57 except that steering axis inclination for my '56 is 3° to 4° whilst the '62 Impala steering axis inclination is 7-1/4°. When I can get out to the garage again, I'll see if I can dig out the '62 spindles and measure them to see if they are same height (or 1" taller) than my '57 spindles (as C-3 Corvette spindles were).

Probably a dumb question but as I am trying to gain a better understanding of this, I will ask it anyway...... If it turns out the '62 Impala spindles I have here not only have the same 7-1/4° steering axis inclination as C-3 'Vette spindles, but are taller than my '57 spindles as well...... Will existing ball joint pivot locations work well or will I need to shorten my upper control arms? Or as an alternative (for I will be welding the '62 lower control arm ends to my '57 control arms to adapt the '62 lower ball joints anyway)...... Could I accomplish the same thing by lengthening my lower control arms (measured from pivot point to center of lower ball joint) by the necessary amount in lieu of shortening the upper control arms?

Thanks,

Harry
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Re: Question - Improved Camber Curve

Post by BigBlockMopar »

Why not upgrade to disc brakes?
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Re: Question - Improved Camber Curve

Post by enigma57 »

I could do that BigBlockMopar, but as I am old and this is my last build, I thought I would build this car much as I built the '55 and '56 Chevys I had 50 years ago. No cookie cutter bolt-on disc brake kits nor small block crate engine/700 R4 automatic transmission combo. Every non-stock part used to upgrade steering, brakes, suspension and drivetrain...... Adapted (and hand fitted) from other cars (and trucks). With the exception of the NOS early '80s MSD ignition box and speed rated radial tires, no parts newer than mid-'60s.

Regarding my retaining drum brakes...... I have done this big brake swap before and it works well. This is a road car and will occasionally pull a boat and trailer up in the Texas hill country. Some grades in the 35% range extending for over a mile to crest of hill. The larger drum brakes work well with a car this weight (3,300 lb.) and I have had no brake fade issues when running this setup in the past. This car will have a Borg Warner T-85N 3-speed overdrive transmission from a mid '60s Ford truck adapted to my Chevy bellhousing using a T-85 gear case from a '62 Pontiac Super Duty car and I can always lock out overdrive and gear down to assist braking when descending steep grades. Drove semis before going into heavy construction so that's just 2nd nature. :D

Best regards,

Harry
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Re: Question - Improved Camber Curve

Post by pdq67 »

enigma57 wrote: Mon Aug 17, 2020 6:29 pm I could do that BigBlockMopar, but as I am old and this is my last build, I thought I would build this car much as I built the '55 and '56 Chevys I had 50 years ago. No cookie cutter bolt-on disc brake kits nor small block crate engine/700 R4 automatic transmission combo. Every non-stock part used to upgrade steering, brakes, suspension and drivetrain...... Adapted (and hand fitted) from other cars (and trucks). With the exception of the NOS early '80s MSD ignition box and speed rated radial tires, no parts newer than mid-'60s.

Regarding my retaining drum brakes...... I have done this big brake swap before and it works well. This is a road car and will occasionally pull a boat and trailer up in the Texas hill country. Some grades in the 35% range extending for over a mile to crest of hill. The larger drum brakes work well with a car this weight (3,300 lb.) and I have had no brake fade issues when running this setup in the past. This car will have a Borg Warner T-85N 3-speed overdrive transmission from a mid '60s Ford truck adapted to my Chevy bellhousing using a T-85 gear case from a '62 Pontiac Super Duty car and I can always lock out overdrive and gear down to assist braking when descending steep grades. Drove semis before going into heavy construction so that's just 2nd nature. :D

Best regards,

Harry
Harry,

Have you bothered to read my posts on my, "pdqCBB", conversion?

I used homemade caliper brackets and '79 and '80 rotors so it falls right in line with your 1980 date.

Front, 2-15/16" big single piston calipers, 13", '79/'80 Vette front rotors and homemade caliper brackets. Oh, about forgot, for my '67 Camaro, I used 2-piece hubs. Hubs can also be made from 1-piece rotor hubs by just machining the rotor off. This does increase the front track by something like an inch, I forget but check it for front tire fender lip clearance.

Rear, small '80 or so Cad. Seville e-brake calipers, '79 Camaro rear 11.75" rotors and again homemade caliper brackets.

I hope i am not that far off on the rotor dates because it's been years since i installed all this on my car so I am going by memory???

pdq67
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Re: Question - Improved Camber Curve

Post by enigma57 »

:D Hi, Paul! Thanks for the info. Yes, I read your post. Much appreciated. Might end up machining one piece rotor off hubs I have here as you suggest, as I will be running 15" X 7" 9C1 cop car rims with the large cooling slots (5 on 5" big car wheel pattern) on the '57. These rims have quite a bit of negative offset so that should compensate for the added distance outboard the new hubs will provide. I am planning on going with the big drum brake conversion rather than disc brakes on this car, though.

Best regards,

Harry
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