Pitman arm shorter than steering arm?

I'm working on selecting components for upgraded steering using a Saginaw gearbox.
I know that the pitman arm must match idler arms.
On one car I measured, the pitman arm was about 6 inches while the steering arm on the spindle is about 7 inches.
1) Does anyone know if it is this typical for the pitman arm to be slightly shorter than the steering arm?
Thanks

 

There's no "conventional" ratio for Pittman arm to steering arm length. It's all about what "feel" you want to achieve and the balance between steering quickness and ease of steering.

Bob

 

I would guess you can find them either way. It all depends on the ratios of the gearbox, and arm lengths, to get the desired movement vs effort and that can be achieved by varying combinations of those gear ratios and arm lengths.

Since you are replacing the steering box.......aside from using a more modern part, what are you trying to accomplish? Quicker steering? less effort? ???

The answer to those questions will point to what, if any, changes need to be made after installing the new gear box. Have you checked the number of turns lock to lock of both the original and replacement boxes? That would be a good place to start.

I didn't copy Bob ....honest...I was typing at the same time...just took longer

Ray

 

Thanks to both of you for the information.

 

Steering IMHO must be parallelogram configuration to function correctly and maintain OEM geometry. I adapted later GM steering to an early model Ozzie GM product and had to drop idler arm slightly to correct geometry with different pitman / idler arm & draglink.

 

The biggest issue a shorter pitman arm might cause is that your turning radius could be larger as it won't move the steering arm as far as a longer pitman arm would. In other words you could run out of pitman arm travel before the spindle hits the stops on the axle and not turn as tight.

 

>>>Does anyone know if it is this typical for the pitman arm to be slightly shorter than the steering arm?>>>

It's not uncommon. GM had several car models that had different Pitman arm lengths (power vs. manual steering for example) that used the same idler arm part number.

Doesn't make it "right" but it does happen........

Al in TN

 

Is your spindle arm a stock length unit? I'd begin by checking out the OEM length of the matching pitman arm. Mostly it is a second ratio/leverage effect, after the box value itself. I have changed/lengthened spindle arms, when they proved to be too quick.