Dear Bill –
Recently purchased 79 Lincoln Continental town car took to Firestone for steering wheel shimmy and tire bounce balanced tires OK, alignment was good on rear but front camber was way off. Adjusted front camber but ran out of adjustment, now sets at -1.0 degree right on right front tire toe and caster are almost perfect. Passenger side adjustment extremely close to perfect. At this time measured height of car at front wheel centers and rear ground to chrome on fender wells drivers side was approximately 3/4 to 1 inch higher front and rear wheel areas, off enough to see visually. I was told to change coil springs and possibly shocks. Changed all 4 shocks and coil springs (new MOOG springs and sensatrack shocks), installed new rear isolators and reused front upper isolators (very good shape). Still unable to align front end. Measured car same as before 3/4 to 1 inch difference, drivers side high. Tires are inflated to within 1 psi , same size tires on all 4 , tires are all same age by date on tires, parked on level ground check with 6 foot level approximately 1/8 inch down slope from front to rear . Tires are very old but height measurement pretty close at center line of wheel. Checked coil spring measurement prior to install- identical. Tire bounce corrected with wheel balance, car still shimmy’s at over 50 MPH. AT A LOSS WHAT ARE WE MISSING. ANYTHING LEFT TO CHECK? I have a shop manual on order.
Some of these problems that you are experiencing could have been with the car for some time and may be difficult to diagnose and correct. Assuming that your present repair shop has performed all of the usual suspension inspections thoroughly and that their adjustments etc. are correct your comments regarding the left to right height measurement differences and “running out of adjustment” for camber adjustment cause me to want to know the history of the vehicle as to any previous body and or frame repair. To pursue this further you may need to visit a specialty shop capable of performing frame and body measurements properly to determine the structural integrity. Larger cities have Body and or Frame shops having this capability as well as the ability to do a good job of front end alignments.
As for the shimmy above 50mph, is this actually a shimmy or a vibration? A shimmy is usually felt at much lower speeds. In any case I would advise an inspection of the driveshaft and the u-joints. Any looseness here can cause several types of vibrations at lower and upper speeds. The driveshaft may then need to be balanced. You also state that the tires are all the same size and age. What exactly is the age and size of these tires? Even though the tires seem to balance o/k they can because of age still be separating and causing a shimmy and vibration once the vehicle is underway and at speed on the road. I should add that old unknown tires can sometimes be dangerous and costly as a result.