I have a complete stock power steering unit from a 6 cylinder car. I have upgraded the rest of the car with Z/28 parts. I have a new pitman arm which measures 5 & 7/8's vs the original which is 5 & 3/8's. Does this mean using the 5 & 7/8's will give me a slower steering ratio?

You've got is bass ackwards mate.

The steering box converts rotary motion of the steering wheel to rotary motion of the steering box output shaft at some given ratio. For example the "fast ratio" modern box with a 12.7:1 ratio, if you turn the input shaft (steering wheel) 127 degrees, the output shaft would turn 10 degrees (127/10 == 12.7) For a 16.0:1 steering box, you'd have to turn the steering wheel 160 degrees to get the same output shaft movement....

The pitman arm converts the rotary motion into a linear (sort of) motion of the drag link. In this case -- the longer the pitman arm, the greater the side/side motion for a given angle. Continuing the maths, 10 degrees of output shaft movement would be ~ 1.02" of drag link movement with the 5.875" pitman and ~0.93" with the 5.375" pitman.

The outer steering arms then convert the linear (sort of) movement of the drag link back into a rotary movement at the wheels. In this case the longer the steering arm, the lower the rotary motion of the wheels for a given change in angle...

Steering Box Ratio:
-- lower ratio (12.7) == faster steering, higher effort

Pitman arm:
-- longer pitman == faster steering, higher effort

Steering arms:
-- shorter arms == faster steering, higher effort

David has some great info over on his site:
http://www.pozziracing.com/camaro_steering.htm#Steering box and ratio info

 

Thanks "T" that is great info. Now I get it. I will check out the link you attached to see if I can get the comparison between the steering set up I have and the Z/28 steering assembly.

When I got my steering box rebuilt I asked the guy about making my steering box a fast ratio steering box and he said the only difference between my current box and upgrading to a Z/28 style unit is about a 16th of a turn. I am assuming that he is referring to the worm gear only. Obviously the steering arms and pitman arm would contribute to that equation as well.

Sounds like what you are saying is that the Z/28 would have shorter steering arms and a longer pitman arm, with a faster turn worm gear.

Would it make sense to run my current set up with the longer pitman arm or keep everything matched stock.

Thanks

 

Here are a few more pics of the pitman arms.

 

Here are my steering arms.

 

According to the Dave Pozzi Steering info my pitman arm is a MANUAL SHORT 5.25", 3953217 (on part 3953219). Even though my car has power steering. Very interesting.

Also according to Dave my car has these short steering arms. SHORT 5.25" LH-3954875 RH-3954876 Used on power steer, and Z/28 fast ratio manual.

So now I am confused. Now I need to know if I should use the HBC longer pitman arm with my steering arms.

It also sounds like all of the drag links on the 69 are the same if I am reading the article correctly.

 

That would be correct Mike. From what David and T had stated for my combo I will be running. The short arms with a long pitman arm will be faster feedback . But in my case I have long steering arms with a long pitman arm will be medium feedback. And it really depends on your steering box. What I stated above is for a fast ratio box 12.7.1. I am not sure what ratio your box is. But if your wanting a little faster ratio/feedback on your car the short steering arm/long pitman is what you want.
If I have posted the info wrong please correct me as I am a little green on this subject as well. Hope this helps Mike..
Thanks Jonathon,

 

Thanks Johathon. I have whatever the stock power steering box is on a 6 cylinder car. I will investigate a bit more. I am green on the subject as well. The Dave Pozzi Article is great learning material.

 

Does anyone know where I can buy a set of steering arms LH-3954875 and RH-3954876 my number is 770-366-2475 thanks

 

Hey Shannon I have one if that helps.

 

Yes thanks how much would you take for it

 

Can you call me when you get time 770-366-2475

 

Hey Mike, I thought I might add my two-cents:

1) Longer Pitman and Idler Arms make faster steering.
2) Shorter Steering Arms make faster steering.
3) Closer ratio steering boxes (less turns lock-to-lock) make faster steering.

By closer ratio steering box, I mean 12.7:1 would be "closer." A 16:1 steering box ratio is a "wider" ratio.

The steering box gear ratio not only means "faster" steering but also fewer turns lock-to-lock. Its really the same thing. When setting up my '68, my first concern was fewer turns lock-to-lock because driving a 3.5 to 4 turns lock-to-lock car is down right annoying.

Having said all that, I have heard from a few people that if you pick all of the "fastest" steering components - long pitman arm, short steering arms and 1980s style IROC steering box with the 12.7 ratio, the steering can be very twitchy. More specifically, the comment I heard (but have not experienced) is that a "twitchy" car can be a handful when cruising at freeway speeds just trying to keep the car straight.

So for my car (which I have not driven yet), I chose the long moog pitman arm, short steering arms (they are the ones I had on hand) and a '60s era rebuilt 2.5 turns lock-to-lock steering box with a reported 14:1 ratio. I hope it isn't twitchy. I also am putting on 235-60-15 radials and a 1-1/8-inch sway bar so with the good tires I don't expect it to track but the suspension should be pretty tight with the big sway bar. I'm actually most concern about under steer. By the way, all of the above is with a power steering box.

I hope that helps but as I said, its just my two-cents.

 

Hey Mike is that the left or right side you have

 

Hey Mike I was trying see witch one you have I found a left hand and I was trying to see if the one you have is for a right hand side thanks!!!

 

Charlie, the fast linkage with a 14:1 box should be fine.
Mike, I had a manual short pitman arm, so I listed the forging number. I later learned the short power pitman uses the same forging but has a larger shaft hole broached into it.
GM mixed the pitman & outer arms to vary the steering ratio for various steering options.

 

Hey Mike I have the 3954876 I'm looking for the 3954875 thanks