Cowl steering questions

Hey everyone,
I am running a cowl steering set up on my 1934 Hanomag and have come across a problem. Wile mocking up my drag link I realized that the drank link will hit the tire when i turn. Its not even at drastic turns just about halfway. What is the accepted policy when it comes to bending a drag link? Also how much will messing with the upper steering arm height and length help me out? Also how big of a difference will putting more nostalgic skinny wheels and tires on the front help me out, what are their offsets like?

Here are a few pictures.
From the cowl looking forward at the front driver side wheel.


Here is my pitman arm set up. Kinda weird, but i like it.


Here is just an overall view of my car, with half way finished headers. I finished up my headers last weekend ill try and put a picture up of that when i can.

 

I'm no expert on this stuff, but this looks like it could use a bump, anyway.

I'd say NO to bending the arm , and yes, I think that a slightly longer steering bracket on the spindle and a taller, skinnier tire with little or no inset on the backside would help.


Hanomag? Heard of it, don't think I've ever seen one on here. What engine & trans are you running, and do you have a picture of the car before you started work on it?

Good luck, this looks like a cool project. Kinky6

 

Well, i didnt start off with a stock car. i bought it from someone that tried to built a hotrod out of it but i just took the body and build new everything else, so it didnt look drastically different. The engine and transmission are out of a '88 BMW 750i. Its a 5 liter v12 with a 4 speed transmission. The rear end is an IRS set up out of a jaguar.

Anyone else know anything about bending the drag link?

 

Don't bend the Drag Link, definite Mickey Mouse.

Instead, make a longer steering arm for the left front spindle to get clearance.

 

You didn't state whether you were mounting the drag link to the inside of the pitman arm or the outside? Mount it on the inside of the arm and use a longer steering arm on the spindle, more than say an inch or 25 mm in your case and it will start to slow down your steering to where you notice it.

 

Please get those lawn roller front tires off and go for something skinny. Could be all you need to solve your problem. By the way, do you have stops on your spindles?

 

Here's a bent and extended steering arm that was done 10 years ago and still on the road.

 

Well the thing is that since my pitman arm sticks out of the cowl like it does, the heim joint wont clear the cowl. I dont want to cut anymore into the cowl so im gonna have to keep it on the outside.

Also how would you guys suggest going about extending and bending the steering arm?

haha and yes i am definitely planning on getting rid of those front rims and tires. Being a highschooler without a full time job tends to make it hard to just go buy everything i want. Im keeping an eye out for parts that i can get a deal on. Just haven't come across a set of skinny rims and tires yet.

 

On some dragsters with LONG distances to front spindles, they use a relay rod system. In your case you could run the pitman arm on the outside to a relay,then transfer to inside of relay to tuck in closer to frame. So you end up with 2 short arms instead of 1 long one.

Does all this make sense?

 

Killer car and I like the Bimmer wheels and tires. I can picture that thing cycle type fenders all the way around. Can we say dirt tracker that made it to the street?

Good call on the relay arm KENDEUCE. Tying the first drag link (one from the pitman arm) into it the same distance from the pivot as it is on the pitman arm, and tying the second drag link in the same distance out from the first that you extend the steering arm will give you the same steering ratio as you have currently.

 

You could do something along the lines of a belcrank and have 2 arms a distance apart to really tuck it in.

Just think outside the box. It is a HOTROD.

 

Right, I've seen steering arms like that with a bend in them that are stiff enough to do the job; its the DRAG LINK that you don't want to have a bend in. That's the red-orange piece in the upper left of 4x4's photo that attaches to the steering arm.

And now, back to the real experts.


Later, Kinky6

 

The idea of putting an idler arm as a relay mechanism has its limitations.
If the idler is mounted too far away from the wishbone mount then you will build in bump steer due to the mismatch in the length of the front piece of the drag link and the wishbone length. Appearance wise it wouldn't matter on a full fendered arrangement but if not then the appearance might not be great.

You might try to sculpt a relief in the cowl to allow for the draglink to attach on the inside of the pitman arm. A longer steering arm is a good idea also. Try and achieve the needed clearance via these methods first.

I note the comments about the drag link not to be bent. I understand that concern. You do not bend a tubular rod like that. I have seen draglinks on some light trucks over the years with slight bends in them. These were however not of a tubular construction they were solid bar and high grade steel. They tended to be shorter bars as well. I have a similar arrangement on my car and its been that way for 25 years and no problems.

Make sure you have steering stops on the stub axles on each side. And a big yes to swapping to narrower tyres. Not so much for clearance issues but those fat tyres will produce a large scrub radius and consequential poor tracking. For me,not really a good look on a beam axle.

 

Where do the steering stops mount at?

 

My question is, can you get enough turning radius with the setup you have now before the rod hits the tire?

If so you could build stops that either attach to the kingpin retaining bolt under the nut or on the backing plate. The idea is a positive stop so that the .spindle will only turn so far

 

Since it isn't that far along have you considered changing pitman arms so that the drag link exits straight out through the firewall instead of through the side of the cowl? More in line with the radius rods. It would look a bit funky maybe but it would work and you could fill that hacked out cut in the side of the cowl back in. even if you moved it in a bit and put some sort of scoop on the side to cover things .

 

Putting cosmetic considerations aside, the actuality is "fat" tires add drag as well as provide much greater adhesion (less drag for radials), but of themselves do NOT have anything to do with scrub radius. ANY tire NOT centered on the ground point of the king pin axis will produce scrub. The farther the tire centerline is from this point, the greater the amount of scrub will be. Wide, skinny, short, tall, radial, bias, belted bias, race tire, street tire, treaded or slick, it just doesn't matter, center the tire centerline on the king pin axis and you minimize scrub.

What should be of greater concern here is the conflicting geometries of this cowl steering setup and the split wishbones (hairpin in this case).

Pick the wheel tire combo of your dreams.

Install/adjust steering stops to keep the tires off the hairpins.

Dummy in a steering arm thats clears your chosen tire/wheel while allowing the drag link to run back to approximate location of your steering box sector shaft.

Now the most important part to minimize bumpsteer;
Move the steering box and/or lengthen the pitman arm to allow the arc of the drag link eye in the pitman arm to intersect the centerline (line splitting it in half between the legs and running through the mounting eye) of the hairpin. This might mean moving the box outside the firewall and down on the frame or simply running a longer, straight pitman arm (not likely, sorry) and blasting away whatever sheetmetal is in the way.

If you are determined to use a cowl steering setup, a far easier solution would be to convert the hairpin setup to a four bar allowing you to run the drag link parallel to the four bar legs. You will still need to abandon the "bent" pitman arm and use a straight pitman arm (90 degrees to the sector) and probably still be lengthening the steering arms (both of them) to clear the tires at full lock. No doubt this means modifying the cowl sheetmetal as necessary.

Don't forget, the ratio between the lengths of the pitman arm and the steering arm you finally use can (and most likely will) change your steering ratio regardless of the internal box ratio, and you will still need to know the internal ratio of your box to calculate the final overall ratio.

This "ain't" rocket science as they say (who ever they are), but it does require much study to get it right. It is, however, easier and cheaper to get right on paper, before you start mucking up the hardware. You've done a good thing asking those here that have been down this road before you, to help lead you in the right direction.