modified hot rod F-1 steering box

[Init1]

Anybody found a way to modify a F-1 or F-100 steering box
So the Pittman arm is pointing up instead of down on a side
Steer install for a Model A to eliminate the sharp steering rod angle? Or is there another box that works?

[Bruce Lancaster]

'37-48 passenger steering can be mounted thus. It is the same basic design as the F1.

[rotorwrench]

Folks on the HAMB have used cowl mounted boxes like the old race cars used to use. Some folks just shorten the pitman arm a bit and use a dropped hairpin type steering arm on the spindle. This levels things out a lot without going to crazy with modifications. It works OK.

You just want to make sure the car turns the same way as the steering wheel. A right hand drive worm might work but it sounds risky to me. One way will be a little low and the other way likely too high for good geometry.

[Ronnieroadster]

I always use the F-1 box on the Hot Rods I build. To eliminate the sharp angle I just put two opposite bends in the steering rod between the box and backing plate picture the letter Z for shape but just drawn out. The steering rod is shaped so its level to the ground this eliminates any bump steer. For the last 43 years that's how the steering on my roadster has been it works perfectly.

[Init1]

Thought about that. Should be easy enough
To do too.

[Fortunateson]

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Originally Posted by Ronnieroadster

I always use the F-1 box on the Hot Rods I build. To eliminate the sharp angle I just put two opposite bends in the steering rod between the box and backing plate picture the letter Z for shape but just drawn out. The steering rod is shaped so its level to the ground this eliminates any bump steer. For the last 43 years that's how the steering on my roadster has been it works perfectly.

Any chance of a photo?

[JSeery]

The shape of the steering rod (drag link) should not be a factor, the steering arm has no idea what shape the drag link is. It is the relative position of the pitman arm end and the steering arm end that is important and that would be determined by a straight line between them. The big factor in bump steer is the relative position of the radius rod end and the pitman arm end, if the drag link rotates in a different arc than the radius rod it can push or pull the steering arm as the wheel move up and down. This can be because of the angle between a line between the pitman end and the steering arm end and the radius rods or the length of the drag link and the radius rods.

[32phil]

An easy way to make the pitman arm point straight up is to use a 32-34 steering box with 35-36 internals. If you google my son's (Phil Migliore 29RPU ) car, a black 29 Model A RPU with a Cragar Overhead conversion, you will see the set up I described. Depending on the car you are working on this may work for you.

[Fordors]

Originally Posted by JSeery

The shape of the steering rod (drag link) should not be a factor, the steering arm has no idea what shape the drag link is. It is the relative position of the pitman arm end and the steering arm end that is important and that would be determined by a straight line between them. The big factor in bump steer is the relative position of the radius rod end and the pitman arm end, if the drag link rotates in a different arc than the radius rod it can push or pull the steering arm as the wheel move up and down. This can be because of the angle between a line between the pitman end and the steering arm end and the radius rods or the length of the drag link and the radius rods.

You are right, the steering arm does not know what shape the drag link is, nor does it care. That is why Ronnie's method works. What is important is having the drag link and radius rods move in the same plane and bending the d/l with a dogleg in the middle can accomplish that. You are "tricking" the d/l into operating as if there were no difference in the angles.

[John R]

Reshaping the drag link has no effect on steering geometry. The steering geometry is set by the relative locations of the pitman arm end and the steering arm end.

[NealinCA]

Originally Posted by Fordors

You are right, the steering arm does not know what shape the drag link is, nor does it care. That is why Ronnie's method works. What is important is having the drag link and radius rods move in the same plane and bending the d/l with a dogleg in the middle can accomplish that. You are "tricking" the d/l into operating as if there were no difference in the angles.

Does it help if you hipnotize the draglink first?

John R is correct in saying that reshaping the draglink does nothing to correct steering geometry.

The draglink does not necessarily want to be parallel with the wishbone. It does want to intersect with the pivot point, so they both move through the same arc with suspension travel. One thing that helps mask steering geometry problems on hot rods is limited suspension travel. With a fairly flat front spring, you may only see 1-2" of suspension travel, which greatly reduces the chance of experiencing bump steer.

Neal

[Tim Ayers]

Originally Posted by Fortunateson

Any chance of a photo?

Me too. A picture would be great. Having a hard time coming up with a mental image of gradual Z bend.

OP, in your set-up, can you bend the hairpin or spindle mount to help the drag link positioning?

[Ronnieroadster]

Here's a driver side view of the car. My thought as a kid doing this so long ago was it looks better than a straight rod going up hill from the steering box plus I thought having the rod going up hill would end up binding on a left turn. The geometry factor never came into consideration but no matter I got it right from the start.

[FlatheadTed]

I may be wrong but I think you would get more chance of bump steer with the parallel tie rod /drag link as in 1935 to 48 ,if the spring shackles swing side ways then it will self steer.Ted

[NealinCA]

Here's a pic showing the draglink angle on my 32 pickup...



You can see it has a fairly steep angle, but I have 3 cars set up similarly and none have bump steer symptoms. They also have limited suspension travel.

Your mileage may vary.

Neal

[JSeery]

Originally Posted by Fordors

You are right, the steering arm does not know what shape the drag link is, nor does it care. That is why Ronnie's method works. What is important is having the drag link and radius rods move in the same plane and bending the d/l with a dogleg in the middle can accomplish that. You are "tricking" the d/l into operating as if there were no difference in the angles.

It don't work that way.

[V8COOPMAN]

Originally Posted by Fordors

......bending the d/l with a dogleg in the middle, you are "tricking" the d/l into operating as if there were no difference in the angles.

Originally Posted by JSeery

It don't work that way.

JSeery is absolutely correct. Ya can't fool physics and forces with backyard trickery and supposition. DD

[Init1]

Thanks Neal for the pic. That set up looks about like mine. I'm using a 40 Ford Pittman arm bent a little to clear the split wishbone and an aftermarket loop at the front with the tie rod end pointing down. It can't go up because of interference with the spring hanger. Just looking for ways to improve the steering and so far a dampner has been the best addition.

[Andy]

Originally Posted by 32phil

An easy way to make the pitman arm point straight up is to use a 32-34 steering box with 35-36 internals. If you google my son's (Phil Migliore 29RPU ) car, a black 29 Model A RPU with a Cragar Overhead conversion, you will see the set up I described. Depending on the car you are working on this may work for you.

I found that the 35-36 sector shafts are too short to be used in the 32-34 housings. What was done to make this work?

[Kahuna]

Andy
I found the same thing when trying to get a better steering ratio (better than 15:1) on my car.
Something had to be modified to do what 32 Phil is talking about