The stock suspension alignments (for any marque) are determined with an overall view towards the intended use and users. Typically, they are a compromise between performance (grip, responsiveness, and balance), steadiness on the road, steering effort and tire life. Finally, they are tweaked towards the safest mode – a little (sometimes, a lot) of understeer. Of course, every maker picks their own compromise between handling and ride.
In my opinion, Alfa does a particularly good job of striking this compromise. For production cars, they are at the performance end of the spectrum and are a great pleasure to drive. However, for many drivers, an increase in performance – cornering speeds, handling balance, turn in, etc. are of more importance than some of the other factors mentioned. These drivers want to shift the compromise more towards the performance side.
The deDion chassis front end is fairly weak in roll and softly sprung in general. This was a typical design philosophy at the time these cars were built. Unfortunately, this approach allows a lot of camber change at the front wheels, to the detriment of tire contact with the road surface. Reduction of tire contact patch works against grip, handling, and balance.
The following alignment recommendations are biased towards performance. Please bear in mind that they are not definitive for your car. The car will perform better than with stock alignment, but these settings will most likely not be optimized for your car, your usual tracks, and your style of driving. However, they will be good point to start from. You will no doubt need to experiment to find your own best settings.
Ride height and tire pressure also have a lot to do with overall grip.
Ride height effects roll & weight distribution (both statically and dynamically) – which effects handling and overall grip.
Ideally, you would get the car scaled, and ride heights adjusted to get diagonal corner weights as close to even as possible. This allows all four tires to share the workload as evenly as they can, thereby maximizing overall grip.
Tire pressure is especially important to grip as well. The more extreme the tires are in construction (width, sidewall height) and specification (DOT-R & slicks), the more important pressure is. It is worthwhile talking to your tire maker to get their recommendations on tire pressures. You’ll have to experiment to determine what is best for your car. Tire temperatures and wear patterns are the best indicators of contact and therefore grip.
After the torsion bars and springs have been replaced, the front end will need to be aligned. This of course, raises questions on what sort of alignment you want for the car. Please bear in mind that these are only starting points – you will probably have to fine tune the alignment to match your car, your driving style and your “comfort” level.
Generally speaking, the object of the front-end alignment exercise is to keep the front tire contact patch as flat to the road surface as possible in order to maximize grip. Because of the “short upper arm, long lower arm” suspension, as the chassis leans, the outside tire top (the one doing most of the work) pushes to the outside. This motion also tends to pick the tire tread up off the road surface – which reduces the amount of tire in contact with the road, reducing grip. This is viewed as a bad thing. To counteract the wheel’s motion when the car leans during turns, static camber is set negative (top of the wheel leans in toward the engine). Now, as the car leans in a turn, this causes the outside wheel to move to perpendicular and hopefully, the tread ends up flat on the road – better for cornering. It is however, important to remember that the car does more than corner and cornering performance has to be balanced against the other behaviors of the car in straight line running – stability, acceleration, braking, and of course, tire life. Most makers of radial track tires recommend camber of Negative 2.5’ as a good start point (with more likely). Most radial tires are pretty similar, but it is a worthwhile effort to ask your tire maker for their recommendations for static camber settings. This much negative camber can be hard on tire life, and if you go much beyond this point, can affect straight line stability, especially under heavy braking.
For cars that live most of their life on the street, with the occasional track stint, something less aggressive is a better choice. This will give significantly better performance than the stock settings, tire life will hardly be affected, and you will see no deterioration in straight line stability.
Putting a lot of caster into the system does not have much effect on straight line running or tire life. It does give the outside wheel a lot of dynamic gain in negative camber when the wheel is turned into the turn – but only when turned. This aids grip during the turn and is neutral when the wheel is straight ahead. The only negative effect is that adding caster makes the steering heavier than normal. The more caster you add, the heavier the steering gets and the harder the wheel fights to come back to straight ahead.
Toe effects how the car runs in a straight line and how willing it is to turn. Toe in will make the car very stable, and lots of toe in can even make it hard to turn the car. Toe out makes the car very “eager” to change directions, and lots of toe out can even make it hard to drive in a straight line. This effect will be even more pronounced in braking and acceleration. Toe can have significant effects on tire life. Beware! Slight changes in Toe can make substantial changes in behavior. For performance driving, most prefer to see some toe out. This gives immediate steering response for turn in.
For the street use, zero with any error to very slight toe out is usually best.
Set the alignment with your weight in driver seat and floor.
Track alignment with Radial tires:
Camber = – 2.5’, Caster = as much as you can get before the shock hits the upper control arm.
Toe = approx. 1/16” toe out > or more
Street alignment with Radial tires:
Camber = – 1.5’, Caster = as much as you can get before the shock hits the upper control arm.
Toe = as close to 0 as you can get. Try not to end up with any toe in.
As to ride height, in general, lower is better for handling and grip. Of course, this lowering must be balanced with other needs – proper ground clearance and proper front end geometry, tire clearance, etc.
If you are not scaling the car, you will have to resort to a rule of thumb sort of approach. Generally speaking, you should strive to set front ride height roughly ½” to 1” lower than the rear. Measure from the bottom of the rocker panels to the ground. Pick a point just behind the front wheel and just ahead of the rear wheel.
If you are using a non-adjustable rear springs – put them in first and then adjust the front ride height to match as listed above.
If you are using springs with adjustable rear seats, then you can lower the front ride height moderately to great benefit. With 205/50/15 tires – you can lower the front to measure 4.5” from the “frame rail” where the steering arm comes out of the body, to the ground.
With different tires, you will have to figure the OD difference from 205/50/15 and adjust the final ride height accordingly. The only caveat, is that unless you are planning on modifying the front end drastically, try to keep the lower control arms parallel to the ground – in other words, do not lower the car so much that the ball joint end is higher than the chassis end.
As in all of this, you can go a little lower than this without noticeable negative effect, but doing so drastically will affect suspension and handling behavior negatively.