BS on changing tire alignment specs from stock.

[cap67]

My opinion for entertainment purposes only. My 67 RT with manual steering even if it had power steering. if you bought a new RT or GTX back in 1967 the car would handle better than most mid size cars back then. just think if they had radial tires and gas shocks handling would be a great deal better. fast forward today a lot of talk about changing alignment specs for better handling and changing parts and adding things for better handling but hurting the ride of the car and harder to steer with negative camber or positive caster. just putting my RT back to close to stock specs like camber from negative camber to near 0 camber the car rides a lot better not hitting the bumps as hard still handles very nice. I like my classic cars for the characteristics of what they were when I first started driving them. yes put on the radial tires and gas shocks but anything more If I want modern handling better gas mileage better brakes better AC more comfortable I will just hop in my new challenger.

Hi I'm sorry but I disagree. My 67 has carburetor still. No efi. But with that said I Love to Drive my Convertible. New disc brake swap, newer style m.c. front/rear sway bars, c body tierods & sleeveselec ing. Factory looking aluminum rad. Grant wood grain wheel. Kyb shocks & Just put in borgeson box. With that said All stock interior and body chrome. Please I'm Not here to say what's better or worse. Just my choice. More Safety & drive ability.

 

[Coelacanth]

This topic is a good read, thanks to all the contributors. I'll be going through this next spring. My '70 Charger had 195-75-14's on it when I bought it in 1986, and upgrading to 255-60-15's in the rear and 205-70-14's in the front made a very noticeable difference. I now have Cooper Cobra 275-60-15's on 9" rims for the rear, 235-60-15's on 8" rims for the front, planned for next spring. That alone will help even more, but I have the Moog offset bushings for the UCA's ready to install. At that point, I'll probably lower the front end at least an inch, then get an alignment. This could be considered Phase 1 of the handling mods as all of this is pretty affordable compared to the more radical, non-stock suspension upgrades.

Like Jamie from DDG says, these cars handle pretty good with the original torsion bar system, but some modern improvements make a big difference. I will probably consider fast-ratio Pitman & Idler arms for Phase 2, but that'll be a ways down the road.

 

[OldIron]

A lot of specs across the board went from 1/4 p caster to 3 p caster from the early 70s to late 70s. Probably as a result of radial tires?
But camber generally stayed at about 1/4 p. Probably because the new radial tires stayed relatively skinny?

I've come to the conclusion that fat tires need to be run flat on the ground. So, 0 to 1/4 n camber might be a thing to consider. But any p camber can cause rut following with fat tires, and maybe other negatives. Excess n camber can reduce kingpin inclination (about 7 degrees or its bent) induced recentering.

Too much p caster can allow the car to be blown around by the wind and follow bad crowns.

I'm having good success with 2 to 3 p caster and 1/4 p camber on all my A,B,C, and M Mopar's 1972 to 1987 with skinny 205/70 to 235/75 fifteen-inch tires.

But not on my 64 New Yorker with 255/60-15. It wants 0 (zero) camber and likes just 2 p caster.

The biggest Mopar problem is the reaction springs and reaction washers in the steering box. The ones that tell the centering valve on the top of the steering gearbox what to do.
Stiff springs call the power boost in early and reduce play at the steering wheel with a smooth boosted lead in to turning the tires. It happens almost undetected if everything's working right. And the car goes down the road straight and stable with no sawing on the steering wheel. And yes, it's the one finger steering presentation.

Soft reaction springs (crush factor) call for boost later, which imparts play (2 plus inches) at the steering wheel, and then requires inconsistently more effort at the steering wheel.
So, we go straight from lot of play to it gets stiff quick when it does start to turn the tires.

 

[Kern Dog]

A lot of specs across the board went from 1/4 p caster to 3 p caster from the early 70s to late 70s. Probably as a result of radial tires?
But camber generally stayed at about 1/4 p. Probably because the new radial tires stayed relatively skinny?

I've come to the conclusion that fat tires need to be run flat on the ground. So, 0 to 1/4 n camber might be a thing to consider. But any p camber can cause rut following with fat tires, and maybe other negatives. Excess n camber can reduce kingpin inclination (about 7 degrees or its bent) induced recentering.

Too much p caster can allow the car to be blown around by the wind and follow bad crowns.

Sorry, man....you are confused. NEW cars come with a LOT of caster and they are far more stable than our old stuff when aligned to original specs.
I run 8 degrees of caster and a full degree of negative camber in the red car and 6 degrees of caster and 3/4 degree of negative camber in the other one.

No, the cars don't follow ruts, they aren't blown around by the wind or any other such nonsense. They track straight and the tires don't wear irregularly. Your words seem like those from a factory engineer that knows theories but has never actually deviated from stock to know what really happens. Even Rick Ehrenberg, a man that is also a strong proponent of following most OEM guidelines, advised for alignment settings far different than stock:

Thanks for chiming in but positive camber and 0 caster went out of favor LONG ago.

 

[toolmanmike]

There is an alignment shop in town and the owner aligns cars at Indy every year. They align most of the old cars in town. They use their own alignment guidelines. They know what causes pull and tire wear. They no how to compensate for road crown. They know how much caster is needed. The shops that align to factory spec and turn the car loose regardless of how it drives, are not doing a proper alignment.

 

[j-c-c-62]

So I wonder, how many alignment shops test drive the vehicles pre or post?