I have heard that you use a different set of #'s for front end alignment on radial vs bias ties on the old chevelles when all the other supension parts or origianl. Is it true? Why the difference? What should be used for the caster, camber, & toe in for a 66 chevelle with all original suppension parts and bias tires? Thanks.

Every thing being stock, use the factory specs.
Tire design won't make any difference.
Radials do ride and handle a lot better though.

This has been gone over here before. Specs that work best for radials are slightly different from those for bias ply tires. Radials like as much caster as you can get.

Thanks, I will have to do a search regarding this unless you can point me to the post?

I have been trying to fing the answer to this with no luck, I'm in the process of alignment for my 64 chevelle, but it now has power steering, with larger radial tires and hot rod had this in the mag "for power steering cars running radials you can throw the book away for alignment" well what numbers do I use to get proper caster and toe where do you get this info from. I hope you have better luck then me, I posted the question here and never got a respond.

you want as much positive caster as you can get (stock parts limit you to 1 to 2 deg positive). Camber should be at 1/4 deg Negative. Toe should be about 1/8" in.

I had my 66 bbk changed from factory to these specs and it made all the difference in the world with radial tires. Handles much better in the curves. You can get more caster with tubular controls arms.

Caster doesn't wear tires. Positive caster has a dramatic effect on the steering return-to-center, which is to say it affects high-speed stability.

Camber can wear tires. Negative camber can improve cornering by angling the tires in the right direction to provide some tire lean (like a motorcycle) on the outside wheel in turns. Positive camber does nothing useful, and should be avoided. Of course, the camber changes as the suspension compresses. Because camber is a tire-wearing angle, you shouldn't get too nuts.

Toe wears tires quickly. No tire wants an excess of toe, wide tires especially. Toe is used to compensate for suspension looseness and deflection. Nice thing about stiff bushings and tight joints--toe can go to nearly nothing.

I understand why alignment specs for radial tires are what they are... what I don't understand is why bias tires would behave any differently, or require the screwed up specs that the factory aligned them to... Backwards camber, backwards caster, and too much toe. (OK, I understand the toe... to compensate for the backward caster)

Align a radial to the factory specs, and you'll wear the outside edges. Why would the result be any different on a bias tire?

I posted this Derek to see if we could get some feedback regarding why radial and bias tires behave differently. Looks like a little interest.

Schurkey; are your comments regarding bias, radial, or both?

Camber, caster, and toe have the same effect on bias tires as they have on radial tires.

What's important here is not the tire construction, it's the PHILOSOPHY that led GM to provide crappy alignment angles on the vehicles to begin with:

1. Cars were still ordered without power steering. Little Old Ladies couldn't parallel-park when the caster was adjusted for high-speed stability because the steering effort was too high. Even then, some vehicles suggested different caster for power steering vs. non-power steering.

2. GM wasn't TRYING to make the vehicle handle. They were deep into Unsafe At Any Speed; making the vehicle DELIBERATELY understeer off the road. Apparently, they weren't willing to trust that a North American had the driving skills to use "better" handling, and at least with massive understeer the correction needed is to turn the steering in the "natural" direction instead of reverse-lock. (Voice of Doc Hudson: "To turn left, you steer right...")

As a result of these items, the alignment angles (and suspension geometry!) specified were POORLY CHOSEN WHEN THE CAR WAS NEW. Using different angles would have helped the car on '60's bias rubber just as much as on today's rubber.

Remember Pontiac's "Radial Tuned Suspension"? It was 90% marketing bull****, and 10% engineering truth as related to the early radial tires. I won't go out on a limb and suggest that modern radial rubber has the identical characteristics as early radial tires, though.

That makes sense about the Caster and power-steering, but I would think the bad camber-curve would have been enough on the intentional understeer, that they could have given them a little negative camber to make the tires wear better.

What through me off was that I had heard "radial tires" so many times, and for so long, as reasoning for better specs, that I figured there had to be some sort of truth to it. :clonk:

So what does this all add up too? What should you shoot for? As much caster as possible up to 2 Degrees (car is 66 chevelle SS with power steering and bias ties)? A negative camber of say -.05 degrees? And a toe in of about 0.13 deg?

Currently car has:

Left camber 0.3deg right camber 0.4deg
Left caster -0.8deg right caster -0.4deg
left toe 0.21deg right toe 0.20deg

cross camber -0.1deg
cross caster -0.4deg
total toe 0.41deg

This is off the printout that I got after the alignment. The specified range according to the computer was:
Camber 0.0deg to 1.0deg
Caster -1.0deg to 0.0deg
Toe 0.13deg to 0.25deg