This is a documentation thread.
There are some definate differences in both the Manual Steering (MS) & Power Steering (PS) parts related to the centerlink and the pitman arms. In the factory setup these shape differences are obviously required for the installation of the large PSCV and all of it's hoses.
But does it matter what parts combo you use on a Borgeson install?

I am doing a Borgeson install on my MS 72, and I have heard that sometimes one of the grease fittings touches or gets closer to one of the A-Arms.
Does anyone know why?
Or found a combination that clears?


72 MS centerlink (top), and PS centerlink (bottom) this has with a Borgeson adapter, not a control valve assy

Issue #1:
The PS centerlink is angled more sharply by the left hand ball stud and may (or may not) move it 1/8 to 1/4" further away to the rear as pictured. Very tough to measure on the bench.
If this is true, it may move the left hand tie rod joint/grease fitting closer to the a-arm.
I will document as installed on the car, unless someone has already done so.
I will also check left to right dimensions later as well.

 

Issue #2

The PS and MS pitman arms are different as well.
I only have one version of these, so I am relying on pictures, for now.

Pitman arm part numbers, MS on top.


Side view of both pitman arms. PS on left.


Side view of pitman arms

I apparently have two 383A pitman arms. The PS one.
Can anyone confirm this is the PS arm?
It came installed on my 72 MS car.
Does anyone have a 451 pitman arm?
I would like to at least borrow one for measurements and documentation.
The shape may or may not affect the location of the ball stud.

But just based on the pictures, it does look like the PS arm drops the ball stud location a little bit.
If true, this would lower the centerlink on one side only, which is a comment I have have read.

 

OK mystery #1 solved. My MS car did come with the incorrect 383 PS pitman arm installed.
Big surprise, it had a lot of incorrect date parts on it.


Now the real question is, does the shape difference affect any of the critical dimensions of the ball stud location?

 

Hi leigh,
The top arm I am holding in the picture is the 383 PS arm, the bottom one is the 451. You can see the offset on the PS 383 arm clears the Ram cylinder rod. You can use a PS arm on a manual car but you can't use a Manual arm on a PS car since the arm will hit the rod. Those were the only arms used, 451 & 383- the last three digits cast into the arm part number.

 

Yes Gary I think one of those pictures are yours.

I know the extra bends are required to clear the large PSCV unit.
But I also believe those same bends cause some minor issues with a Borgeson box install.
And possibly geometry differences.



Looking at this image closely, and measuring the drop between the two sets of lines, I see a difference between the two pitman arms.
My arm is 6.0" long, ctr to ctr.
The pic shows the MS arm (bottom) drops the ball stud about ~0.9".
The PS arm (top) drops the ball stud more, about ~1.1"

If true, this 0.2" difference may work OK, and clear everything, but it will lower one inner tie rod link ball joint, and cause a difference in the bump steer.

I will obtain a MS arm, and actually measure the differences.

Because I'm curious, and curious minds want to know.
Also I am an old racer, and I want to eliminate as much bump steer as possible.

 

I have a Borgeson conversion with all the MS parts. I don't have any issues but the right side Tie rod zerk fitting is hard to get the grease gun on.

I had it jacked up yesterday. I should have taken a picture.

 

I received my MS pitman arm in the mail today.

I checked the MS & the PS pitman arm together, and took some measurements.

Basically there is ZERO difference, except for the big S-curve the PS arm has, that it needs for PSCV clearance.
Rotational difference - none.
Length difference - none.
Drop difference - virtually none. PS one may have .040-.060" more drop. Nothing at all like the above picture indicated. That must have been a perspective thing. Or too much cropping in Photoshop.

So in a Borgeson conversion, either pitman arm will work, it makes no difference.
But for a factory PSCV clearance, you will need the PS pitman arm, 3741383.

Centerlink comparisons next.
I will need to do those on the car.

 

When I converted from power steering to Manual steering, I purchased a NOS center link, also know as center sections or drag links.
One thing I found was there is a difference in the diameter between the early center links and the later model year center links.
The later model links are larger in diameter than the early model year links.
If there are any other differences in length or shape I’m not aware.

When I made the decision to swap to manual steering I called Borgeson who told me that it was completely possible to convert back to a Borgeson steering system if I decided I wanted to swap back to power steering and I would not need to swap out my manual center link.

As part of my swap, Gary rebuilt my steering box.
Gary installed a manual steering pitman arm onto my steering box and there was a big difference in the shape between the two.

 

Thanks OCB!

I had heard that also about early and late MS centerlinks being thinner or thicker.
But I do not have any specific info as to when that change occured.

As far as the pitman arm, yes there is a huge difference in the shape.
But the two joint link locations are exactly the same.

 

OK I found a problem.

The Borgeson conversion box is 1.2" taller than a std C3 box.
As measured from the input shaft centerline, to the lower end of the cross-shaft, by the pitman arm.

I lined up the two boxes in this photo, and you can see how much lower it will drop the Pitman arm.
But notice how the three mounting holes do not line up.

Borgeson "split the difference" top & bottom.

In this 2nd photo I lined up the 3 mounting holes.
Borgeson split the 1.2" difference between the top & the bottom, by where they welded on the plate locating the mounting holes.

The input shaft is .6" higher than the original, and the Pitman Arm is .6" lower than the original.
This will make you re-adjust the steering column upward at the rag joint, by .6", to line up. That apparently works out fine.

It will also lower the pitman arm by 0.6" from it's original location.
This will cause the centerlink to now be .6" low, but only on the left side.
This will affect the bumpsteer, and on the left side only. The car will now respond to bumps differently on right and left wheels.

There was a comment by a borgeson owner that said his centerlink was not "flat" anymore. Now we know why.

This is all fixable, but you have to know what's wrong, to know what to fix.

There is no issue at all with using either the MS or PS Pitman arms or centerlinks, when doing a Borgeson install. Those all measure the same.

For a normal driver, bumpsteer may not even be an issue. Whatever self-steering issue it may cause may just be attributed to old classic car syndrome. But we can do better.

I'll be measuring bumpsteer next. Then I will correct these issues. And show you how to.

 

I am convinced there are not enough differences in the two Pitman arms, or the two centerlinks, to be a problem swapping them back-n-forth.
With respect to alignment issues.

The Borgeson box itself is another story however.

This thread is basically finished.
I will continue the Bump Steer testing here.