Power Saginaw

Is that sitting at Ride Height or is the axle hanging? Not unusual to see the Drag Link dropped in from the top......using a flip bushing at the Pittman Arm........as long as your amount of droop doesn't pinch the Drag Link to Pittman Arm Tie rod end...............I set then up so the Drag link at Ride height is higher than the tie rod by say 3/4"-1" so that during compression & Dive under braking when bump steer can affect you most is less noticeable.

 

That is ride height. Axles are on jackstands. A flip bushing at the pitman might be the right approach. I expected more options would be available for pitman arms. Again, I should have got the pitman on hand, before I mounted the steering box.

 

All the weight in it?...........if so your now on the down-slope ( beyond center ) where bump steer will increase as braking / dive increase's due to weight transfer......Not saying it's a bad thing but in a leaf spring car there is no way to counter act that as compared to a 3-4 link suspension where you can add anti-dive to the bars which resists the diving action created by braking...........in any case that is why I opp to have the Drag link higher at RH so that when braking / compression acts on the suspension the Drag Link is starting above the point of Bump and hopefully finishing at near level and no Bump.........Everything is a compromise..

 

In the real world, here's how it looks.
I'm using a random, 27" radius to simulate a drag link. Yours may be longer, may be shorter. At perfectly level, the bar is touching the square.



At 1" of travel around the pivot (tie rod end), there is very little movement in the vertical plane (a hair under 1/32"). You will have no noticeable bump steer.



At 2", there is about 3/32" bump steer from a horizintal starting point. Still negligible, virtually unnoticeable.

With yours starting at less than 1" off of horizontal, and rarely will a bump or braking make you dive more than 1 to 1-1/2" in an old jeep, this is the range you most likely will be in.



At 3", were getting into the "noticeable" range. We're at a full 5/32" here, and numbers escalate quickly from there.



As you can see, as long as you're close to horizontal, the reality is that it comes down to what your idea of "good enough" is.

 

Thanks guys. I guess a few trips in it will tell the tale. I was hoping for a little different outcome, but this is what I got.

 

Here you clearly see the proper amount of drag link drop:

As the suspension is fully compressed the axle travels all the way up till axle bumpers hit.
At that point the drag link is an equidistant below the tie rod level instead of above as seen in pic.

When you upgrade from D25/27 with double knuckle to D30 , both the drag link and the pitman arms will be different.
D25/D27 will require longer pitman arm than a D30.

 

I actually thought this was the other way around. I thought the D30 would need a longer pitman because of more travel on the drag link to accommodate a tighter turning radius.
Does anyone know of a manufacturer that has a pitman with a 1in drop?

 

Time to look at and modify some pitman arms.
Here you see 3 different Saginaw pitman arms, right to left.
1) 5" long 1970's GM manual pitman with 1/2" of drop. (GM # 5693762)
2) 6-1/2" long Jeep manual pitman that has been shortened to 5-3/4".
The tie rod end looked exactly like #3 before I shortened it.
3) 6-1/2" long Jeep power pitman unmodified.
Note the larger spline diameter used for the power pitman arms.

1) This pitman arm will work unmodified with a Dana 25 axle and a manual box.
2) This pitman will work with a Dana 30 axle and a manual box.
3) This pitman must be shortened to 5-3/4" to work with a Dana 30 axle and a power box.
Note how long the flat area is. That flat area will allow one to shorten it by 3/4".

The up down position of the pitman effects the downward angle of the drag link relative to the horizontal tie rod.
Ideally the drag link should be horizontal to the tie rod with both front springs at full stuff.
With Jeep resting at normal spring position (ride height) there will be roughly 2" of drag link drop.
That is perfectly acceptable and normal .
2" or 3" of drag link drop will pose no notable "bump steer".
The up / down mounted height of the steering box has the greatest influence on drag link drop.
The drag link drop will also be effected by any up / down tilting of the Saginaw unit.

EDIT: The pitman arm lengths noted above are relative to the location of the saginaw box as it was properly positioned to a CJ-3 frame.

 

Pitman Arms and Tapering

 

Anything can be modified............I start with the 7" long "Blank" Saginaw Power Pittman arm on the right if I have a special need.......which has no key in the splines and then bore a taper to length.......they can also be dropped w/some with Heat and a large press.

 

Thanks a lot guys. I will try it when all the rest comes together. Engine, rad, electrical, etc. When I swap to a D30, I will be better capable of making the right moves, hopefully.

 

Didn't want to, but I had to mod the grill a little to accommodate the hose fittings. I'm getting closer.

 

You can always re-ream the pitman arm to put the TRE on top of the arm instead of under it.

Mike

 

thanks
I have considered that. I am getting fairly close to cranking it and hopefully driving it. I guess I will know more about it after that.