Join Date: Aug 2011
Location: Saginaw, Michigan
Modern fast ratio power steering gears have either 12.7:1 or 14:1 straight ratios (i.e. The same gear ratio from on-center all the way to full lock.) These gears typically have heavier effort valves in the gear.
Older Chevrolet B-car power gears (1965 - 1969) had ratios around 17.5:1 - and had "pinky finger" light effort steering. Around 1969 variable ratio gears began appearing in Chevrolet B-cars. The variable ratio gears were still quite slow right on center (16:1) but quickened as you turned the steering wheel to full lock (12:1). The faster ratio at near full lock reduced the total number of steering wheel turns but the steering was still pretty slow and doggy right on center. These gears also tended to be "pinky finger" light effort.
One thing else to remember, your older B-cars had gears that were "full travel". In other words the pitman shaft would rotate something like 86 degrees in order to move the linkage and steering knuckle to full lock. Some people make the mistake of trying to install a Camaro or Firebird fast ratio gears into their B-cars. The F-car gears have restricted travel to match the Camaro/Firebird suspension geometry. The F-car pitman shaft rotates roughly 70 degrees compared to the 86 degrees in a B-car. If you install a restriced travel F-car gear into a full travel B-car you will find that your turning circle begins to approach that of a Greyhound bus.
That is why you need to obtain a fast ratio (12.7:1), full travel gears from the following vehicles in order to upgrade the steering in older B-cars:
1885-88 Monte Carlo SS (not quite full travel but close)
1988-94 Chev B-car with F41 or FE2 suspension
1992-94 Chev B-car police
1995-96 Chev B-car with police, FE, FE2, or FE3 suspension
1985-87 Buick A-car Grand National
1992 1/2 - 1998 Jeep Grand Cherokee