Misc. / General Technical Questions
My speedometer is fluttering. What could be causing this?
The most obvious check should be on the speedometer cable itself. More than likely it's binding and just needs to be lubricated. Also, if your car is equipped with cruise control, it's possible the servo unit can introduce some flutter if it's worn out.
Sometimes the flutter is in the speedo head itself. A speedometer is actually a small electric generator, though there's no wiring to it. The cable drives an input shaft that spins a small magnet inside a metal cage. As the magnet spins, it induces a voltage and current that starts the cage spinning. The spinning cage is what drives the speedometer needle. If a speedometer is way off calibration or flutters and bounces around, the magnetic field may have gotten weak. A good speedometer repair shop can remagnetize the speedometer head to where it will be dead on the money accurate and no more bounce and flutter. A friend had this done to correct a 20 mph error on a '69 Toronado, and in the process found out the tolerances the local cop car speedometers are set to. His is on the money, zero error...theirs aren't. +/- 3 mph is acceptable for their purposes.
Are there any special considerations for balancing my SSI wheels?
The biggest problem will be finding a tire shop that can balance them. They have to be balanced by the lug holes, NOT the center hole. This requires an adapter on the balancing machine that not a lot of tire shops still have.
Another alternative to using an adapter on a computer spin balancer is to find an old shop that will balance them on the car. Your best bet is a chassis shop, one that works on commercial vehicles, too.
The advantage of balancing wheels ON the car is that they can do it at speed (70 mph), and the wheel is mounted exactly as it will be while driving, so they're in effect balancing the drums/disks and trim, too. Make sure they mark the stud closes to the valve stem so you can put the wheel back in the right position if you remove it.
Once you get your car done this way you'll never let a tire shop computer spin-balance your wheels again. I will admit, though, that it's a little un-nerving to see your car with the back end up on jack stands, with the wheels spinning 70 mph, and picturing what would happen if it fell off the stands ....