1955 Wheel Alignment Specs

[radar]

I have a 55 TBird.
Installed a 2” spring drop from stock specs and gas shocks on front, New leafs and gas shocks on rear @ stock height.
Radial tires.
I have the factory specs as;
Caster - ½ to 1½ degree -
And Possibly:
1 1/4 degree Right, 1 degree Left
Camber - ¼ to 1¼ degree -
And Possibly:
3/4 degree Right, 1/2 degree Left
Tow-in - 1/16 to 1/8 inches
King Pin Inclination: 7.1°
Turning Radius:
Outer Wheel: 20
Inner Wheel: 24.5
Questions:
1) What does the lowered front end stance do to these numbers?
2) Do the left and right sides have to be different if I’m not driving on very crowned roads?
Or in other words, shouldn’t both sides be the same?

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[jimntempe]

I would think you'd use the same specs lowered or not. I agree that you probably would use the same spec on both sides, esp with radial tires. What might be a bit different is the best settings with radials on it instead of the old bias tires but I think people overthink that aspect.

 

[jimntempe]

I have a 55 TBird.
Installed a 2” spring drop from stock specs and gas shocks on front, New leafs and gas shocks on rear @ stock height.
Radial tires.
I have the factory specs as;
Caster - ½ to 1½ degree -
And Possibly:
1 1/4 degree Right, 1 degree Left
Camber - ¼ to 1¼ degree -
And Possibly:
3/4 degree Right, 1/2 degree Left
Tow-in - 1/16 to 1/8 inches
King Pin Inclination: 7.1°
Turning Radius:
Outer Wheel: 20
Inner Wheel: 24.5
Questions:
1) What does the lowered front end stance do to these numbers?
2) Do the left and right sides have to be different if I’m not driving on very crowned roads?
Or in other words, shouldn’t both sides be the same?

Check out this thread too... https://forums.fordthunderbirdforum.com/threads/1957-wheel-alignment-problems.8897/

 

[paul5456]

I person that restores Tbirds suggest these for car with radials

Castor 3/4 to 1 degree
Camber 3/4 to 1 degree
Toe In ) to slightly toed in.

 

[radar]

Thanks for this info.
Can you tell me if this
Turning Radius:
Outer Wheel: 20
Inner Wheel: 24.5
Is important to set and if this is the correct setting?
Also, should both sides be identical in this setting as well as the castor and cabbie as jmntempe has suggested?

 

[55blacktie]

A competent alignment shop that knows these old cars will do a better job getting it right than we can suggest/recommend. You can't use stock specs, because your car isn't stock. I'll have the same concerns when I'm ready to put my car back on the road. The suspension and steering are new/rebuilt/w Aerostar coil springs, Granada 1 1/2-inch drop spindles, Bilstein shocks, and Hotchkis tubular sway bar, and Wilwood Dynalite disc brakes, and 15 x 7 10-spoke alloys/w 3.875" backspacing and 215/70R15 radial tires. In the rear, new springs, re-arched to increase height 1 1/2 ", Bilstein shocks, and Hotchkis rear sway bar. Stock drum brakes on back.

 

[paul5456]

Thanks for this info.
Can you tell me if this
Turning Radius:
Outer Wheel: 20
Inner Wheel: 24.5
Is important to set and if this is the correct setting?
Also, should both sides be identical in this setting as well as the castor and cabbie as jmntempe has suggested?

Both sides the same. On the other question, I don't know.

 

[radar]

After speaking to several people who are experts, I think the correct answer is that since the car was lowered by shortening the spring rather than lowering the body by changing the spring mounts, nothing changes. That is, the geometry relative to the frame and wheel are not altered.
Both sides should be identical in terms of castor, camber, toe in, turning radius.
Radial Ties and power steering, results in:
Castor 1.5°
Camber 0.5°
Toe In 1/16
If anybody has any different opinions, please post.
Thanks All

 

[55blacktie]

Shorter springs alter geometry, drop spindles do not.