And to think that in two months or so there will be someone else starting a Thread " Help Me With Bump Steer'', or ''School Me On Cowl Steer'' JW
Here's a couple of contrasting famous T roadsters. Schlemmer's T, the geometry looks bad. The pitman arm is well distanced from the wishbone. Frank Mack's T looks about as good as you can get. Mack's is a street roadster, Schlemmer's a compe***ion roadster. Was bump steer really a major issue for a car with 6:1 or 8:1 steering going flat out around a dirt track? I'm intending to find out. My own T roadster build will have geometry like Schlemmer's and a 6:1 steering box. Sometimes you find cool parts, and the parts dictate the build to some degree. I'm well aware I will have bump steer issues, but to what degree, and whether or not it is too much to drive safely I'll deal with later. I'm not intending to build a street roadster initially, but if I have to re-engineer it when it does go on the road, so be it. I like old hot rods the way they were. If we go down the track of engineering all the dangerous design features out of them, we will end up with either something so compromised it no longer resembles an early hot rod, or a belly ****on hot rod where everyone has basically the same thing. Might as well just buy a Jappa and not be on the HAMB. I might start a thread "Arguing About Cowl Steering - Just Stop It".
I disagree. These discussions serve a purpose and that purpose is to educate those who may not know any better or may not realize the geometry/physics/engineering that's going on with a certain aspect of their build. There are many steering designs that work, side steer similar to stock, cross steer, etc. Twenty five years ago I was a dumb hot rodder and built a '32 RPU with too much caster in the frontend. Didn't know any better but was told by those who did that one day I might try to make a turn and end up in a ditch. Well, it wasn't a ditch, but a tree in the median when I tried to make a turn after avoiding a Soccer Mom braking way harder than I could to avoid a red light camera. It was either end up under the SUV or go around and try to make the turn. The car plowed and went straight into a palm tree. So, there's nothing wrong with discussing proper build techniques, even if they hinge on the fringe. If it saves a mistake and a possible tragedy, then it's all worthwhile. Bumpsteer on a car at El Mirage where the lake is flat and smooth is not the same as entering an off-camber swooping freeway transition with a dip in the middle running 70 mph with a semi in the next lane. Every day is a school day and I'm here to learn!
My 29 Ford roadster has had "Bump Steer" for 64 years, I did ad a steering stabilizer to help keep it going straight down the road. Kind of keeps you on your toes.
You obviously have not driven ElMirage at speed in the last 10 years. My car has no bump-steer issues but has been turned at over 150 and not pointed down course in a heartbeat. J
What does this have to do with the discussion other than to point out that El Mirage isn't the best example of a smooth, flat surface? Subs***ute "El Mirage" with "Bonneville" or "Lake Gairdner" or "Giant Sheet of Gl***" if that works better for you.
The point is that any car will experience some direction change with or without bump steer geometry As you mentioned too much caster caused your mishap, a guess is there was another contributing factor Hot rods are notoriously twitchy especially with some of the modifications done Elmo and Bville are degrading it is just change and the SCTA along with others are doing everything in their powers to preserve them enjoy
The amount of effort to do that would be the same as mounting a Vega style box with cross steer, and will still have the same inherent issues. Get rid of that cast Chinese axle while you're at it.
I thought of a (maybe, probably) crazy idea to salvage your idea for maintaining cowl steering, but to make it work better. It would involve using a bellcrank at the front which converts the cowl steering to cross steer. In essence two drag llinks are used, one longitudinal going forward, and one transverse going across to other side. Since the bellcrank would be attached to the frame, it wont move with suspension travel to cause the bump steer with the longitudinal link from the cowl. Still needs to be set up right for the cross steer drag link to minimize bump steer there. The hard part is hiding the bellcrank so it does not look ugly, and of course a lot more connections for wear and slop. Hiding the ugly could be the tough part. But it could work, although it seems a lot easier to just use a different steering box, either stock style down at the frame near cowl, or cross steer style box mounted up front.
Brian, new Henry axle is suppose to be here today, finally. I am now back to the original pitman arm length and raised the steering arm 3 inches higher. Drove the car last week and it steers with much less effort than with the longer pitman previously used. It was stated earlier that this move would cancel each other out so I was expecting it to steer as hard as with the extra long pitman but in reality that is not the case. So, now we will change the axle and go from there. This has been an interesting excercise, anxious to see what effect the new dropped axle will provide in the overall scheme of things.
Also, when you get your axle check the perch bolt is a good snug fit in the axle bores and also chck that the perch bolt shoulder is long enough to to make full purchase in the axle. The canter lever spring radius rod is thicker on the top which holds the perch bolt higher. I extended mine by adding a tuned down nut with locking agent. JW
This is a better photo. There is a tremendous amount of force on these perch bolts from braking so they need to have full length contact or they will flog out. JW
Thanks 26T. Andy checked all the bores before he sent it out to me, but I will certainly heed your advice.
I think there are probably a hundred different ways to do it. That's one I didn't think of, and I'm sure there's potential there. First thought; not cowl steering, though: mount the steering box to the wishbone. Movement would have to be taken up via u-joints and telescoping splines in the steering column — and not a hell of a lot of movement that far back on the wishbone — but it would make the geometry of the drag link pretty much irrelevant for bump steer. It would allow the use of an "upside-down" steering box with the pitman arm pointing up, which would give a vague cowl-steeringish feel if you look quickly. Then: translate that idea to cowl steering. A big bracket inside the kick panel connected to the back of the wishbone would probably be impractical. It would have the steering box rock back and forth as the wishbone moves. The total travel at the steering box would be about 1.7" (43mm), which would be roughly but not entirely axial to the steering column. But how to get that bracket to work? You could have the steering box pivot on its own brackets, and construct a linkage to the wishbone. You just want the steering box to move with the wishbone. In fact, you only need the bottom end of the pitman arm to move with the wishbone, about 0.4" (10mm) forwards and 0.4" back. It doesn't matter if the steering box slides axially on the steering column or pivots about any other axis, as long as that is the case. So: steering box attached to steering column via one u-joint, and affixed to a bracket so that it pivots on a lateral axis through the centre of the u-joint. There is a diagonal link, perhaps inside the cowl, picking up a point on the wishbone ahead of its rear pivot, and a crank on the bracket behind the pivot axis. That way, when the wishbone rises, i.e. rotates clockwise in side elevation, the steering box rotates counterclockwise about the u-joint. The rotation over the entire suspension travel is in the order of 8°, which means that the pitman arm/steering box axis moves a mere 0.2" (5mm) up and 0.2" down to produce the required fore-aft movement at the bottom end of the pitman arm.
Glad you're ditching the axle. I'm a big fan of using cross steer (as you may have gathered from my comment), I've built three cars with it. From my limited anecdotal experience, they work great. I have no experience with cowl steering, so I'm no expert. It does require some acrobatics and U joints in the steering shaft to get around a V8 of any brand, but bits to do it are available from lots of different places. I happen to like the way it looks, but I'll give you that's it's not "traditional" from an appearance standpoint. It looks really cool (the Frank Mack car is the perfect example) and racy, but I think sometimes as hot-rodders we tend to overlook practicality and safety too often for appearances. I'm a perfect example of that, using this cast iron lump in my newest car is completely just for appearances. In my defense, it stops and steers great, with no bump steer...
I get the uncomfortable feeling of having been tarred with the same brush...... "Pretty much everyone" is a little over the top. Quite a few of us agree with your view.
So, after quite some time do you have your new Henry axle fitted and any other bits and do you have anything to report? JW
Finally, yes after many delays. first go with the axle and the new spring went well but the spring required a spacer as it was hitting the frame where it had been notched by the builder. Two spring leaf spacers fixed that. Then I had to make a longer pan hard bar and connecting link between the spindles. After that was all installed, I sat the axle at ride height to check the caster. It was just a hair over 10 degrees. Pulled the front end off again and removed the bones. I pie cut them to gain the lift required. After reinstalling them the caster at ride height was 5 1/2. Took the car out this week for the first time after all the changes. It steers remarkably better and with less effort. Still faced with the bump steer issue of course but it will get me thru the rest of driving season that is left. I am pulling the engine this winter to reface the flywheel and to check the ****** as it jumps out of 2nd gear. I will switch then to a cross steer box to rid myself of the bump steer.
I would for sure change to a cross steer. You can leave the cowl steering but take out the box internals. You would retain the look but get good steering. There is no way to make that cowl steering work right.
^^^Agreed....I am looking at boxes now. May use a Saginaw from a 85 Jeep. My friend has three of them in his coupes and loves them. They look like a 525, not sure though.
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