OK, straight axles were obviously designed for skinny bias tires. The alignment specs were a compromise to allow good tracking, decent tire wear and ease in steering effort. Does anyone change their specs to facilitate fat, radial modern tires? The caster is a function of tracking straight, but excessive + caster makes you lift the car over center when turning, making it harder to steer. The camber is a function of compensating for tire deformation when cornring , thereby keeping the tire flat. For instance: I have a problem with that whole positive camber deal and the excessive positive caster. I'm thinking that on , say, a 7" wheel width, better/modern tube shocks, 3" back spacing (decreased scrub radius) and power steering on a 104" WB car- the specs would look closer to: caster=+4 deg. camber=-1.5 deg. toe= 1/16"- 1/8" Anyone care to share their specs and the reason for them? Thanks in advance. MIZ
I've always tried to stay between 5-7 degrees of caster. camber I never really checked. and toe I've always done 0-1/8" toe'd in
My caster on my 31 is 5 degrees while the camber is about 1/2 degree positive and 1/8th toe in. The wheels are 7 inch chromies with fat radials that are 7 inch wide, nice stability at all speeds and mot too hardto turn at a stand still, no power steering
How about the specs for a straight axle on a '53 Chevy pickup? And, does anybody know of a good alignment shop in Dallas area that knows the in-and-outs of straight axles on rods?
straight axles don't need any more than a tape measure to align them. at most if you have a 4 bar you need an angle finder. the toe measurements are taken at the OD of the tires.
I've never aligned a vehicle Mine wanders the road a bit when I catch a rut and I keep being told that I can remedy some of that by adjusting the caster/camber??
depending on the amount of slop/wear in your front end you may not be able to get rid of it. the way I've always checked my toe in/out was to measure the treads on the tires at the mid point from the ground. just make sure you use the same treads when you measure the front and rear, and pulled straight into a nice flat smooth place when you do it. car must be parked and on the ground. measure front of tires at mid point then measure the backs. the front should be about 1/8" smaller. if the front is bigger than the back (toed out) the car will want to wander all over the place. if it is more than an 1/8" toed in you will get alot of front tire wear. caster/camber should be measured at the hub or spindle with a good angle finder.
I think your specs are good except for the negative camber, it's used in circle track and road racing to flatten out the tread when cornering but not so much for highway driving where the positive camber compensates for the crown of the road. The only straight axle specs I have handy are: caster= +5.5 to 6.5 deg. camber= +1.5 deg. toe= 1/8" I think you can get by with less caster, especially with power steering (I know nobody on here uses that ****), and camber any where from +1/4 to 1.5 deg. will work fine. 1/16 to 1/8" toe in usually works fine if tie rod ends are tight (they should be) - Toe out will make the car "dart" when you move the steering wheel a little left or right (so will lose rod ends etc.)
If you can't run the tape measure accross the back of the tires, I've used 2 carpenters framing squares w/the short leg placed vertically on the back side of tire tread ctr, and measured across the bottom square legs, outside edge to outside edge.
Here's what my old "Motors" Auto Repair Manual book that covers back to 1935 lists for Ford wheel alignment data: 1935 through 1948, all models: preferred caster degrees +6-3/4 preferred camber degrees 5/8 kingpin inclination degrees 8 For 1935 and 1936, they list toe in as 3/32" For 1937 through 1948, they list toe in as 1/16"
I've always heard that if you take it to a shop that you ask for it to be aligned like a Ford twin I-beam truck.
2many: I never knew that positive camber would stabilize road crown, but makes sense. You got me there...im a retired crew chief. Did both roundy-round and road race...heh I am running a split wishbone and have not yet welded the anchor points to the frame. So, i'm all set. After reading all of the specs the guys sent me, I think ill do this: 5 Deg caster, camber is at +2 now-ill leave it, Toe 1/16" to start-everything is new. If I have any tire issues, I can always rebend to change the camber, but I wanted to get the caster close the first time without it being excessve. This car will not usually go on long distance, 400+ mile runs. THX again to all. I can get all of this done tomorrow. MIZ
On a fenderless car 1.5 degrees of camber is noticeable, with the tires tipped either in or out at the top. That's why I go for pretty close to zero camber.
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