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Gone but never forgetten
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Discussion Starter · #1 ·
Why did the '65/'66 manual steering cars have the 19.9:1 box while the PS cars have the 16:1? I know this has to do with gearing and such (and I've never been to good with that sort of thing), but could someone explain in dummy language what the advantages/disadvantages of each are.

We're going to convert my son's '65 coupe to PS. It has the 19.9:1 box in it, and I have a 16:1 box in the garage that I plan to swap into it. That'd be the right thing to do, yes?

If you always do what you've always done,
You'll always get what you've always got

http://www.classic-mustang.net/johnpro
 
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The G.T. option gave you the 16 to 1 ratio with manual steering. The car steers
quicker but with considerable more effort. I think Ford felt for the average Joe
20 to 1 was as hard as they could make it and not affect sales in a negative way.
Yes use the 16/1 box with p.s. If you don't the car will drive like a chevy
jimbo
M.C.A.# 50000
http://albums.photopoint.com/j/View?u=1575692&a=11979479&p=43517165.jpg<P ID="edit"><FONT SIZE=-1>Edited by eljimb0 on 03/19/01 00:48 AM (server time).</FONT></P>
 

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Allow me to beat this subject like a dead horse (wow, I really ramble on in this one):

The higher the gear ratio, the easier it is to turn the steering wheel. However, it also takes more revolutions of the steering wheel to make the tires turn a given distance. (Just like the gears on your bicycle. If you're in first gear on your bike, you can climb a steep hill without too much trouble... you go really slow up the hill, and you have to turn the pedals a bunch of times, but it's REALLY easier to turn the pedal. This is the same concept as the 19:1 ratio box. If you're in 18th gear on your bike, it hard to turn the pedals around, but when you do, your bike goes a greater distance).

If you use the 16:1 ratio box without power steering, you get a "tighter" feel around corners, because you don't have to turn the wheel as far to make the car go around the corner. But since the ratio is lower, it's harder to turn, making parking lots a bitch. Turning at low speeds is likely an arm crunching activity. The reason why 16:1 ratios are used in Power Steering cars, is because the extra force needed to turn the steering wheel is provided by the power ram. Since the non-power steering cars obviously didn't have this power ram helping out, they had to use the 19:1 ratio gear box to allow people to turn the wheel at low speed without requiring 18" biceps.

Think about driving a school bus. Ever watch the driver turn a sharp 90 degree turn? They have to spin the damn steering wheel around a billion times. That's because (generally speaking) the gear box ratio is really high because the load is so great in the front and the tires are enormous. The huge tires and heavy load create a great amount of friction up front, making the higher gear boxes more logical for the application.

If you use the 19:1 ratio box with the power steering setup, the steering wheel would be unusually easy to turn, and you wouldn't get the added effect created by the "quick steering" 16:1 box.

Thespazardman
 

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Boils down to torque effort needed to turn the wheels. Manual cars needed more torque to move the linkage whereas power-assisted cars didn't, hence manual boxes had a higher "gear ratio" to make it (marginally) easier on the driver. Internally, the difference between the two boxes is restricted the groove on the worm shaft and corresponding ball nut. The tighter the machined grooves, the slower the box. For more info, check my website at http://moostangjoe.tripod.com/steering_gear.htm

Vintage Burgundy 1966 Mustang GT Fastback
MCA member #46447
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Okay, I learned something there. Guess I can go back to bed. If I keep reading the forum long enough, maybe someday I can contribute something.

James

1965 convertible "White Pony", my own lesson in mechanical humility
 
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