|Alfa Romeo GTV6 Site:
European Car Magazine - GTV6 Project
European Car Magazine - August 1995
Author - Paul Mitchell
Photos by the author and Peter Wu
|You've performed all the suspension
modifications on your GTV-6 or Milano that you thought were possible - new shocks, lower
ride height, higher rate rear springs, larger diameter sway bars, performance bushings and
a good alignment. The handling is superb, but you find that the front tires are
wearing unevenly. The inside of each tire is wearing more than the outside.
There are no other signs of uneven wear; the car tracks straight, there's just this bald
strip on the inside of your front tires. Upon returning to the alignment shop, you're
informed that the wear is caused by excessive camber, several degrees of it, the result of
low lowering your car.
On the cars spun-off of the 116 Alfetta chassis-the GTV-6 and Milano, Alfa Romeo provided for camber adjustment, a first for Alfa for some time: Through the simple method of adding or subtracting shims from the lower A-arm at the subframe, a range of adjustment of several degrees is available. Sounds like just what you need at this point. Unfortunately, now that you've lowered your car, you've changed the geometry slightly - just enough to not allow you to dial out the negative camber.
Now at this point many assumed that there was nothing that could be done to remedy the situation and allow them to enjoy their newfound performance to the fullest. Few things are as discouraging as knowing that when it's time to replace your front tires, they will have 70% of the tread remaining on the outer half and be almost to the cord on the inside edge. To further torture you, the front tires will certainly need replacement more often than the rear tires under these conditions. It's difficulties such as these that can cast doubt as to the wisdom of the decision to modify your car, thereby ruining an otherwise enjoyable experience.
Luckily, the solution was always right under your nose - under your car, actually. After a thorough examination of the front suspension, you'll find two spacers between each lower A-arm and the subframe. It is at these spacers where the adjustment shims are placed to correct the camber when at stock ride height. You dont need a degree in engineering (though this shouldn't be deemed an excuse not to get one) to see that by reducing the thickness of the spacers, you can recover the lost camber adjustability.
This modification was brought to our attention by the proprietor of Omega Motorsports, Rex Chalmers. After patiently listening to our complaints of tire wear (and complain we did, as we have also another car; a 3.0 Milano suffering from this problem), he suggested this as the solution.
After going home and getting up the nerve to undertake minor surgery on the front suspension and assembling the proper tools, we found that the job was far easier than it first seemed. The only special tool required is the lower ball joint separator; # ST 60, available through AR Ricambi for approximately $38. The rest of the tools are just simple hand tools that you'll find listed in the Tech Procedures. The entire procedure should require no more than three hours to complete. Afterward, the car will require a front alignment to set the correct camber, and this should be the last one youll need for a while.
Having completed the modification, I can say that our tire
wear is now normal and that the procedure was well worth the effort. Should you
choose to have the procedure done by a garage, the labor expense will easily be offset by
the extended tire wear you'll receive after this modification.
Alignment Specs - Alfa GTV-6, Milano
Notes on Suspension
Judging by the questions in the Tech Letters we've received, apparently our readers have been giving great thought to what's been previously written regarding suspensions and their modification. Hopefully this will help put to rest some misconceptions and illuminate the difficult process of setting up a performance suspension.
A debate still rages over what the preferred suspension "hot set-up." One camp believes that increasing spring rates 1.5 to 2 times the stock rates and substantially increasing the dampening rates of the shocks is the correct method for controlling body roll. The other group insists that the preferred way to control body roll is with stock or close to stock spring rates and dampening rates, and substantially larger Sway bars. Both methods usually involve lowering the car to some degree, and we'll discuss that later
Keep in mind that the purpose of having a suspension is to keep the tires in contact with the road surface when that surface is less than smooth. Most engineers involved in racing will agree that the first setup - the one composed of essentially stiffer springs and shocks - is basically a step backward in design and will markedly affect the handling negatively in real-world driving. As we all know, the real world is full of bumps and potholes, figurative and literal. When encountering these bumps and such at high speed while cornering, a too stiff suspension can cause the tire affected to lose contact, with possibly disastrous results.
The other system to control body roll - relying primarily
on sway bars - allows the suspension the compliance to follow the irregularities in the
road. This is crucial in cars with MacPherson-strut suspensions, and less so on cars with
well-designed un-equal length A-arm front suspensions.
The one potentially significant drawback to sway bars will
not become a factor if the sway-bars are properly designed and employed. If the bars
chosen by a hypothetical, misinformed owner are so large (more is better, right?), the
advantages of independent suspension are lost. In this Situation, when only one
wheel encounters a bump, the force compressing the suspension at that wheel will be
transferred by this
When considering lowering a car, the goal most of us are trying to achieve is simply a lower center of gravity. Unfortunately, often you can end up changing the geometry of the suspension to the degree that you introduce new problems that are far more difficult to remedy than correcting body roll with a reduced center of gravity. I won't go into roll center geometry theory here, but some cars are so designed that their roll center is close to the margin already, and any change in ride height will be detrimental. Correcting this requires major suspension surgery, so it follows that the best method for avoiding this situation is to calculate the roll center of your car before it's lowered. Then only lower to a point within the range of proper roll center geometry, leaving a margin for maintaining correct geometry under full jounce. As with all modifications, planning, and moderation are called for.
Of course, for the average owner, all of this may be
moot. Alfa Romeos are renowned for delivering outstanding cornering, while still
exhibiting substantial body roll. They have been able to accomplish these seemingly
mutually exclusive feats by having extremely well located rear axles (live axles,
surprisingly) and a properly designed un-equal length A-arm front suspension. So,
for some, this debate holds no personal significance; they find the body roll
entertaining. For myself, I prefer less body roll and so was drawn into the fray.
Thoughts on alignment
Once your Alfas suspension as been improved through all of the modifications listed in this series, including the camber modification, you'll need a wheel alignment. To skip this last step is to throw all of your effort and money away. Youll continue to throw away money as your tires wear unevenly. What specifications do you align the suspension to? Obviously the original factory specifications were for an unaltered car.
The alignment, will not only affect the tire wear but will also have a significant effect on the feel of the car and the handling, particularly turn-in and transitional handling.
These specifications were determined through use and testing and will fall within those that are generally accepted for performance street use. If aligned to these specifications, tire wear will be within acceptable limits as long as the car's bushings are in good repair and there is no previous frame damage.
First let's look at camber. Some would have you
believe that a negative camber setting of from 2 to 3 degrees is preferable for a
performance car. Not only, is tire wear going to be excessive, but a condition known
as camber thrust occurs. This will cause the tire to turn in the direction it's
leaned, just as a bicycle will turn in the direction it's leaned. To correct for
this extreme camber, the toe setting must be adjusted to toe out, again causing another
situation for excessive tire wear. The camber should never be set over 1 degree for
a street performance car, and the preferred setting is ¼ degree negative for the GTV6
Caster is another adjustment that has a significant impact
on the feel and handling of the car, but usually has little influence on tire wear.
Most overlook the caster setting and its ability to fine tune their car's handling.
Caster can be used to increase or decrease the low-speed steering effort, high-speed
stability (the willingness of the steering wheel to stav centered at speed) and turn-in
characteristics. More caster will increase steering effort and high-speed stability,
and less caster will provide lighter turn-in effort and easier transition when
cornering. The caster can be adjusted to within a small degree to fine-tune your
suspension to suit your driving style and the conditions of use-all of this while having
essentially no effect
Lastly, there's the toe setting, which can significantly affect both feel and tire wear. Generally, on rear-wheel-drive cars, the toe is set very slightly in to compensate for the tendency of the bushings to give, allowing the wheels to shift rearward and outward under the friction created by the vehicle moving forward over the road surface. Setting the toe-out slightly will result in quicker turn in and faster transitional handling, but will also result in increased tire wear. With the GTV6, and its already quick turn-in, the toe should be set at 0.04 in to the inside. Tire wear at this setting will be acceptable and the suspension design allows for very little longitudinal compliance within the bushings, so the amount of toe-in is minimal.
When considering a shop to perform the alignment, care should be taken to ensure that the shop be capable of performing the Job properly. Since it's most likely that you won't be receiving any parts back, youll just have to take the mechanics word that it's done right. If it wasn't, you went know it until the tires start showing uneven wear at which point it will be too late to recover, the lost tread wear. All that can be done is re-align the car and hope it is done properly.
Don't even bother trying to get the shop to pro-rate the
tires for the tread lost between the alignments; they went do it. Maybe I'm just
cynical, but its been my experience that they will find every excuse not to pay
up. The best course of action is to have it done right the first time.
Dont be swayed by a shop's latest whiz-ban, laser liner alignment rack - the job can
be just as accurately done by for -year-old equipment, which is what we used on our
project car. The most important thing is to have a technician you can trust to do
the job right. An easy way to gain piece of mind is to have him show you the
readings on the equipment as each adjustment is made.