Alignment Woes - 72 Fury

[Analog Kid]

Update here - I was able to adjust the ride height. The car felt much better and I felt there was more control. I'm still on the fence about the steering though. I feel like it could use some improvement but I don't feel like I'm losing control of the car. I wiggled all the connections to the steering box and everything seems tight. I am also not hearing any clunking which I would assume would mean a bad box. So after I feel confident about the alignment I might try to make some adjustments on the steering box and see how that feels.

Back to the alignment - I am a little confused on the specs for the camber. The FSM calls for a positive camber (Left side one quarter, right side one-half) but what I'm reading online (Mopar Action Alignment specs) states that you should have a negative camber. CBODY67 - you mentioned it should be around zero. I had put the cam bolts back in the same way they came out and if I check it with a level it looks like it is slightly negative. So I am wondering if I should ignore the FSM specs since they were based on bias ply tires and not radials. It sounds like having a negative camber might be better.

 

[rapidtrans]

That car will never feel like a current vehicle does. Mine definitely felt tighter after the front end was rebuilt. The steering box adjustment might tighten the slop in the steering wheel a little bit. These cars steer very easily with the power assist and big steering wheel.

 

[CBODY67]

The "camber spread" in the factory settings takes into consideration the weight of the driver upon the camber settings. Plus, possibly, "road crown" (when many roads were less flat, center to edge, and generally two-lane). On caster, the wheel with the greatest caster will be the side the car will tend to "pull" toward (steering wheel centered and on really flat roads). Caster will be more oriented toward crowned roads than camber might be, but to a possibly greater degree. Consider that ALL roads have a certain amount of "slant" toward the right (from the center, in the direction you're driving), so the rain water will drain away from the roadway onto the shoulder and grassy areas adjacent to that.

THE PROBLEM is that once you start to key on certain things, they really become "obvious" and "issues". A lot more roads are flatter than they were when the alignment specs were first formulated for even a '70s car. Tires are different, too, which affects toe-in actual amounts that work with modern tire construction (generally radial with less rolling resistance AND less rolling load upon steering linkage components).

THE REASON the car now feels better is that all of the alignment specs are based upon a certain positioning of the control arms to each other, which will vary with ride height. The OTHER thing is that actual caster (at the more-correct ride height) approaches the "design caster" geometric adjustment spec. You can have the geometric caster adjustment "to spec" (as it will relate to the body's rocker panel (in absence of a chassis "frame" to gauge off of), but the actual line between the ball joints will actually be "negative" (behind the centerline of the tire's contact patch, which also relates to easier steering, which is why many '50-'60s manual steering cars had different caster specs for manual and power steering vehicles) rather than "positive" (with that "line" will be in front of the centerline of the tire's contact patch. There's a Chrysler MasterTech video on this.

So, when you put the car back to approx. factory ride height, you effectively put more caster in to the mix, which stabilizes the car and can add enough "load" into the steering linkage to better compress any pivot points where some "compliance" might exist. And that is probably where the "feel of control" comes from. Plus possibly a stronger "self-return" of the steering after a turn. This is why it's better to use drop spindles for a lower front end ride height rather than just to crank the bars down! With positive caster, the car is more stable, too. Think "bicycle or motorcycle front fork angle", for a visual of actual caster.

So, you can use the Chrysler factory setting, especially is you are running bias or bias-belted tires (which were common at the time the car was designed/produced). Radials need less toe-in for best wear, so "min-spec" would be best for that. Camber can be minimized, too, but the flexible sidewall of radials can tolerate more or less camber than a stiffer-sidewall bias or bias-belted tire would. Caster can be in the factory range.

The "toe-in" setting is a static setting that should result in an actual "rolling toe" of close to "0". The rolling resistance of the tires puts forces against the steering linkage joints, which are designed for this to happen. Some alignment shops in the '70s could do a "rolling toe" front end alignment, putting the front wheels on rollers that simulated "road driving". More pricey for the alignment rack and few were known to exist. Now, we've got electronics with greater precision, but still "electronic rulers and such".

CBODY67

 

[CBODY67]

In the MasterTech item I mentioned above, it has graphics of how the Chrysler suspension system design differs from others. In a turn, the outside wheels goes into negative camber, as the inside wheel goes into positive camber. As the illustration indicates, when the car leans in the corner, the tires are more perpendicular to the road surface, which better braces the sidewall against the turn for better ultimate cornering performance.

Contrast that with what GM and Ford did, where their geometry did just the opposite. The car leans, the tires lean with it, which puts the edges of the tread as the main load-bearing part of the tread, rather than otherwise.

With rear sway bars, GM vehicles became good handling vehicles, as the car didn't lean as much, so the tires stayed more perpendicular to the road surface, yet deflected. Adding more positive caster to their specs will get closer to what Chrysler's geometry is. Contrast the handling of the '69 Camaro against that of the '70 Z/28, same with Firebirds), for example.

Having a "rear steer" linkage (as Chryslers and Corvettes were back then) keeps the Ackerman angles more correct, but "front steer" generally does not. That should be in the MasterTech article,too.

With "front steer", when the wheels turn side-to-side, the Ackerman angles are not the same as with "rear steer", which is why GM cars of that era make tire noises on smooth and finished concrete shop floors, as Chryslers made much less. Front Steer can also mean better transient response in auto-cross situations AS the tires are already in "slip mode" so they are already generating cornering forces, whereas if the Ackerman angles are more correct, there can be a slight millisecond lag before full cornering forces are generated.

Only thing is that with positive/max caster and wider tires, the turn angles can result in enough camber change to accelerate wear on the outside tread ribs in a mix of straight and curvy driving, over time, on the GM geometry and stiff sway bars (f/r).

In any event, start with the factory setting range and ago from there, depending upon the intended use of the vehicle.

CBODY67

 

[Knebel]

i did a "rough" alignment in my garage... then took it to les schwab and oh did they mess it up. I gave them exact numbers where i wanted it to be and from the printout (before/after) my garage alignment was closer to equal on both sides than what they did. After lits of arguing back and forth (they tried selling me the "we know better") they redid and oh behold they got it right. Their mechanic first only touched one side, that was evident from the printout too. I don't give my car to any shops anymore, if I want it done correctly, I do it myself.

 

[Analog Kid]

I ended up finding a place near me through a local Mopar club that did the alignment. The mechanic there has a '67 Buick so he knows the deal with old cars. They charged me $100 like I was expecting and it turned out good. Car feels great now.

On the printout the caster came out slightly under the 1 degree spec and I probably should have asked them why but I was in a hurry that day so I forgot to.

 

[tbm3fan]

Congratulations. It is getting harder. My Dodge was done 7 years ago and the first place ignored my settings. That job was free. The next place got it right but took 90 minutes. Just this past February no place wanted to touch the 67 Park Lane. Even the place recommended by everybody as he did older cars, mostly Mopars they said, said no. The guy looked my car over, knew all the components were replaced and declined. Had to do set camber, caster and toe-in myself.