1955 Alignment Toe-In & Caster

[ShellyB55]

Just getting the 55 back on the road. Toe-in was way off, corrected that, added some caster up to 1.7 degrees. Drives much better, but still not very stable.
All new front end components, new Coker wide whites. Thoughts?? Need more caster??

Is a 55-57 just not the best driving car?? My 66 XL and 68 LTD drive great.

 

[doug7740]

Please explain what you mean by it drives much better, but it still is not very stable. Does the vehicle pull to one side or does it wander? After making a turn does the steering easily return to the straight ahead position?

The alignment specifications for a 1955 Thunderbird are:

Caster - ½ to 1½ degree
Camber - ¼ to 1¼ degree
Tow-in - 1/16 to 1/8 inches

You said that the caster is set to 1.7 degrees, which is already beyond specifications, so I would not add any more caster. Is the caster set to 1.7 degrees on both front wheels, and what is the camber and tow-in set to?

Most road surfaces angle down from the center to keep rain water from collecting on the pavement. If the caster on both front wheels were the same, the road crown would make the car pull right. Since caster is a directional control angle and not a tire wearing angle, by setting the caster on the right front wheel slightly more positive then the left, this will counteract the forces caused by road crown and the car will travel straight ahead.

doug7740
1955 Thunderbird Blue

 

[jack-in-sac]

Please explain what you mean by it drives much better, but it still is not very stable. Does the vehicle pull to one side or does it wander? After making a turn does the steering easily return to the straight ahead position?

The alignment specifications for a 1955 Thunderbird are:

Caster - ½ to 1½ degree
Camber - ¼ to 1¼ degree
Tow-in - 1/16 to 1/8 inches

You said that the caster is set to 1.7 degrees, which is already beyond specifications, so I would not add any more caster. Is the caster set to 1.7 degrees on both front wheels, and what is the camber and tow-in set to?

Most road surfaces angle down from the center to keep rain water from collecting on the pavement. If the caster on both front wheels were the same, the road crown would make the car pull right. Since caster is a directional control angle and not a tire wearing angle, by setting the caster on the right front wheel slightly more positive then the left, this will counteract the forces caused by road crown and the car will travel straight ahead.

doug7740
1955 Thunderbird Blue

Dear Dug. Thank you for the description of alignment. This is one I am saving and would like to share in our club newsletter.

 

[doug7740]

If you would like to share it go right ahead, it's nice to know that someone appreciates the articles that I write. I used to put a monthly technical section in my club's newsletter, but only a couple of members ever commented on it.

doug7740
1955 Thunderbird Blue

 

[CSPIDY]

Just getting the 55 back on the road. Toe-in was way off, corrected that, added some caster up to 1.7 degrees. Drives much better, but still not very stable.
All new front end components, new Coker wide whites. Thoughts?? Need more caster??

Is a 55-57 just not the best driving car?? My 66 XL and 68 LTD drive great.

The new Coker wide whites you installed, are they a bias ply or a radial tire. The bias ply tires do not ride as well or track like a radial.

 

[ShellyB55]

Thnx for replies all. Toe at 1/8", radials, I had a local car savvy gent local drive this 55, he has a 56. Says this 55 drives as his 56 does for the most part, they both have some 'wander'. Character!!

 

[Harleyhoot]

my 55 has NO steering feedback to center, I have to constantly correct the steering. I live in the mountains so not many straight roads. Just put new Unisteer power rack with wider 15x8 wheels, spaced out 1 inch all around for tire clearance. The back is raised with flipped shackles. It also has modified upper control arms to provide more caster but still has no feedback to center. Current alignment specs are .03 camber, 3.0 and 3.4 caster and .18 degrees of total toe. I'm thinking of custom upper control arms for even more caster.....can anyone here offer more insight on making this car handle on mountain roads? Yhanks for any replies.