Hot Rods Cowl Steering . . . just stop !

@twenty8 , my reference to track bars was when used on a pre 35 or so straight axle with a proper length transverse spring correctly installed . I should have been more specific .
Not trying to argue , just define.

 

The way the early transverse spring was set up does do a fair job of lateral axle location. The addition of a Panhard bar will still be an improvement. People's reluctance comes from two issues - space restraints and aesthetics. The fact remains that adding one will improve the performance of the suspension/steering, whether it looks good or not.

 

Does the axle shift ( a panhard swings in an arc) the panhard introduces worse/ more movement than the " shift" that occurs with the stock setup ? And , I would think that the "shift" would only occur under high lateral loads where it would be very gradual ?
If you're talking cross steering , then the panhard is required.

 

2OLD2FAST, points out"I'm not saying don't make every attempt to limit
Bumpsteer , just that the amount should be considered ."*

Very right ,in a number of ways. But also one not talked about,the way it matters,also*,except saying like he said ""Are you going to feel it "; Hummmm
Most drivers don;t even feel it,when it's kind of bad,they really don't know how to"Feel it",even some so called race car drivers don't.
*Put that all a side a bit and lets talk about what the tire to road grip dose<We'll call it,"What you don't feel" mostly. Tire dose feel!
Your control,depends a lot on tire grip to the road/or track.
The tires every vibration* affects it's grip { your ability to control car},the vibrations come from a lot of things good designers try to limit as much as they can.
Bumpsteer,even when you can't feel it,but there is some left,dose add too removing grip.
The magic small bit of grip ,that you don't feel ,may be what saves the car an you!
That all comes back too*"How much",,,=Do as much as you can,often that means learning more about,vs dismissing engineering that seems to be too much of a waste time.
Lots of other vib's,yet we fix as many as we can,,tire balance,round,straight,shocks an bumpsteer that dose brake grip by it's twist of tread. The road is never smooth,an tire max bit only happens when it can follow the ups n down of road/track.

You can see real bad bumpsteer,with car standing still,just find a way to jump up an down on the front of a car,an watch to see the steering wheel wiggles with each jump.
Some drivers can't feel that.

 

How many small compromises does it take to create a large detrimental effect. It is unlikely that people who accept mediocre results in one area are going to get everything else spot on. A little fudging here, a bit more there, and a tad elsewhere as well, and then the excuse of "that's just how hot rods are". Well, that's how some hot rods are, but it isn't how it has to be. It can be better........ much better.

 

Being realistic in your expectations is generally helpful .

 

That's very true. You will only achieve the level that you set the bar at. I guess some just set it higher than others.......

The real kicker is when people want to argue a principle that is a proven concept. There are none so blind as those who refuse to see.

 

Pete is there a chance you could draw the optimum setup you are describing here...without cowl steering. I am of the impression that for proper function even with cowl steering that aft wishbone connect point to steering arm connect point, drag link/pitman connect point, to pitman arm steering arm connect point with steering centered are the areas the lines are drawn to do the arcing so if one chooses to do one or the other they will have a visual reference from a source that truly understands something so hard to separate from so many other issues in steering and driving...

Thanks in advance...if I missed a correct diagram just share the post...

 

Yea, what Stogy said.

 

I like drawings...verbal works for many but I like to see visual backup with it...pin it up on the wall in the shop...

 

Everyone should read the first few pages of the Pete & Jake's catalog.
The best I know how to do, is to use the drawings from the Pete & Jake's catalog. Jake did these drawings 40 years ago. Lucky for us, geometry hasn't changed in the last 5,000 years.
The " Mustang steering " will be a satisfactory substitute for cowl steering.
The " Mustang with wishbone" best represents what is going on with most " Cowl steering " set ups.
Although most of the popular methods of cowl steering usually react worse than what is shown with the "Mustang with wishbone " drawing.
I hope this will answer your questions.

 

^^^ thanks to your dedication to the hobby you and P&J have helped a lot of people solve some problems!! People like me get to enjoy the benefits of good and safe steering.................

 

I so frequently recommend people do this.

Another point is, it doesn't matter how many 'z' shapes you bend in a bar to make something out of alignment look right, the operating angle is always a straight line between point A and point B.
You see this often, if for instance the tie rod at the pitman arm on a cowl is say, 6 inches higher than the steering arm end on the spindle. Also panhard bars.

 

I feel the need to comment on these statements. While theoretically it is true that the end points will determine the action of the drag link (or tie rod, or other steering strut) the act of putting a bend or an offest in a control rod will greatly affect its column bending strength and it could lead to column buckling for hard and quick maneuvers, or just a "spongy" response to a steering wheel input.
For example, a pushrod in the shape of an "S" bend may theoretically transmit the same linear motion from a lifter to a rocker arm but the "springyness" of the "S" pushrod will not transmit the same response as the rigidity of a straight tubular pushrod.

Putting bends in drag links and tie rods should be avoided.

 

You don't see this setup often.

 

I just saw this. Neither @Pete Eastwood or myself are suggesting anything other than the use of straight rods/bars etc.
We were simply pointing out that bent or dog-leg bars are not a solution for misalignment.

 

True.
And yet I have seen it on even professionally built cars. My old altered had a two-piece drag link and one section has a slight kink in it. As far as I can tell this was done mainly for the aesthetics of keeping the link parallel to the upper frame rail and to keep the heim connecting rod end in axial alignment. Many FEDs of the HAMB era had similar kinks. Of course with lightweight front ends, minimal suspension travel, and using chrome moly tubing the risks of failure are minimal.

 

The link gets subjected to a bending moment it wouldn't be subjected to otherwise. That is calculable: the moment arm being the distance of the end of the shorter straight portion measured perpendicular to the longer straight portion, in the case of a single bend, for instance. That can be designed for. In severer cases the penalty could be in weight rather than safety.

 

This issue keeps coming up. It has recently cropped up here: https://www.jalopyjournal.com/forum/threads/schroeder-steering.1292102/

What I gather from what a lot of people are saying is that part of the problem is that a split wishbone looks like a link, even though it isn't a link but part of a complex rotating assembly. That is why "parallel to the wishbone" doesn't mean anything in a geometric sense, and supposing that the drag link ought to be so isn't even wrong. How do you define "the line of the wishbone"? The rear defining point is simple enough: it's where the wishbone pivots on the frame; but what about the front? Where it bolts to the axle? There is no hinge with an identifiable axis there.

I got to thinking about this again this morning, and it occurred to me that taking a thing to extremes can sometimes make it more understandable. Hopefully it doesn't make it more confusing:

What I've tried to do here was to give the axle/spindles/wishbone assembly a shape that doesn't look anything like a link. I made it duck-shaped to point out that the concept "parallel to the wishbone" is as nonsensical as "parallel to a duck". The penny should drop, if it hasn't already, once you see that the entire duck, including the pink line, the random point near the back of its head, and the inner end of the steering arm on the spindle all rotate together about the frame pivot.

Because the real error here is to imagine that there is any geometric difference between having the drag link "parallel to the wishbone" and having it anywhere or any way else. There is no point in changing the steering arm on the spindle to get the drag link closer to "parallel to the wishbone": doing that accomplishes exactly nothing. It makes zero change to the steering geometry. It makes as little sense as supposing that, if you had a kart with drag-link steering, there is some drag link orientation which is better that any other. Because a kart has rigid suspension, it doesn't matter where or how the drag link would run.

There are several reasons why people might experience steering geometry with high-mounted cowl steering as "just fine": one is certainly that they are for all intents and purposes dealing with a kart, because they are running wheel rates which allow precious little suspension movement in ordinary driving. Another is that they've grown used to the bump steer and unconsciously allow for it; or perhaps they never do the sort of driving in which it could be an issue.

Another misconception is that the problem is cowl steering as such, the attached-to-the-cowlness of the steering gear, and thus we get all kinds of examples of successful cowl steering in competition contexts. But one thing which jumps out with all those early sprint cars etc. is that the split bones attached to the car much higher up than they do on a typical Deuce or Model A: more often than not just below the drag link. You don't see a foot of air between the drag link and the back of the wishbone. And that would certainly be a valid way to do cowl steering on a hot rod, to pivot the split bones high up on the frame, above the tops of the rails, with an undropped axle well ahead of the radiator. I wonder if there is precedent for that?

 

I had an extremely Ned Ludd thought this week. Are there any circumstances where cowl steering "parallel to the wishbone"(!) would be not only harmless but actually beneficial? I could think of one instance:

If you had separate cowl steering on both sides of the car, like on a tractor, it might just be possible. How to get contrarotating outputs out of the steering box would be another matter (what are tractor steering boxes like?*) but supposing that's the case, what would result wouldn't be bump steer strictly, but similar toe changes in the front wheels. Because these would ordinarily cancel out, it wouldn't manifest as a reaction at the steering wheel, but just as momentary increases in toe-in or toe-out. And that might be beneficial, if the height of the drag links above the wishbone pivots isn't too extreme.

If the car is set up to carry the front end a tiny bit on launch, it would result in a tiny bit of extra toe-in under acceleration, improving straight-line stability. If the car is set up for a tiny bit of benign pro-dive under braking, it would result in a tiny bit of toe-out under braking, improving steering response and possibly even delaying the onset of front wheel traction loss.

But note all the tiny bits. Huge chunks might prove stupid.

*Edit: The outputs appear to be staggered:

 

I wonder what it would be like to drive a Ford 8N tractor at 70 MPH?

 

I think if a tie rod was attached to each spindle you run the risk of "overly constraining" the steering mechanism, i.e., Two drag links will almost assuredly not move in perfect unison with the two hairpins inducing stress on the spindles and tie rod, etc. Removing the tie rod from the car would relieve the stress but what would be the advantage of a system like this? Just as complex as a single drag link and tierod.

As a fearless teen I had to drive our 8N down a 1/4 mile long steep hill so I just figured I'd slip 'er into neutral and get down faster. BoyHowdy I didn't bargain for how that thing picked up speed. Plus, I was afraid to try to use the one-wheeled cutting brakes because it probably would have flipped me into the ditch. Hung on with white knuckles - somehow made it down doing at least 45 mph. Never tried that again. Never told my dad. Scarry

 

Chip foose built A 32 years back that had dual cowl steering like a tractor.

 

Seems there is a rod roaming around somewhere with a sign on the dash that reads "position steering to full left before opening door".....

 

Harry Miller had that setup on the Golden Submarine, but it was a four spring chassis, so the bump steer deal didn't come into play.

 

Slightly besides the point, but yes, I'd presume no tie rod. And now that you mention it, with conventional drag link steering the tie rod is mechanically in series with the drag link, so all the lost motion adds up by the time it gets to the passenger side front wheel. Dual drag links are mechanically in parallel, so lost motion on one side simply mirrors lost motion on the other. That's an advantage right there, albeit a small one.

IIRC that had dual drag links, but not cowl steering. I seem to recall there being a tie rod of sorts roughly below the firewall.