1930s Era Champ Car - new project

Cowel steering is often miss understood ,about how it makes bumpsteer as seen in most designs!
Your putting some thought in it,but your still not understanding it! Making only small gain.
Older race cars an bumpsteer,even some new dirt cars get away with having bumpsteer built in{not deliberate},some had a lot of bump steer an still won races"Why"=Race cars are often driven more*> With set-up* and throttle/gas pedal* =high % of control ! The steering wheel is being moved around a lot anyway!!.= Is why!!
That is not at all ,how a street car is driven every day*,were bumpsteer in the cars steering makes it dart from bumps an even brake poorly. < So if building a cool looking hotrod,that looks like a old race car,that will be driven on the street every day,with other reg. cars. < It will be far better controlled if it dose have minimum bump steer.
You do need to look an reread this note n drawings,take a hard look at how things work. What I see your doing is nice work,but missing the why!!engineering of it. This drawing is not for 4 bar type front ends,but is right for wishbone.
One other factor in steering is,every added joint and amount of added length to a pitman arm,also adds play.
Hope that helps. Love the hole build anyway,as I do love old race cars. I built 100's an had a ball driving many of them and witching other win as will with my builds on both dirt n black top. Hope this helps,may even help some others.

 

Thanks for the insight dana barlow. The whole point of eliminating bump steer was not lost on me as I read the "cowl steering - just stop" thread. I recognize that my setup is not optimum, as were many old race cars. Having the hairpin arc and draglink arc to be co-linear would be a worthy goal. A 4-link would go a long way to that, but not as traditional.
I'm working with my current cowl steer and making it better.
Not perfect.
Better.

By making the drag link two piece the swing arcs of the hairpin and front link will be close to the same length, reducing the parallelogram effect. Not eliminating it. Reducing it.
Likewise I have observed dragsters with a single long drag link. Some would start to visibly oscillate up and down in resonance like a bass guitar string as it ran down the strip. I've even seen a couple of old photos where the builder triangulated it with trusses to stop that. Making the link two-piece will raise the natural frequency of both shorter pieces out of the resonance range.
I too encourage other builders to read the bump steer thread and design a more perfect system than mine.

 

Today I have other fish to fry. I'm doing a half marathon bike TT this Saturday. Last year I did it and used a gravel bike. Not optimum. This year I borrowed a TT rocket ship from my son and will try to improve on my past performance. I need to set it up and try it out.




I did make a couple of temporary bushings to insert in the boss so I can finalize the design of the drag link. I also welded in the pivot bolt. Incremental progress...

 

Having a hard time understanding front panhard bar mount with spring causing change of panhard location. Could u rough out draw layout & 2nd draw when spring moves. Seems almost like panhard bar becomes torsion bar force on axle end?

 

AmishMike, I'm not very proficient at computer drawing skills so let me see if I can explain how it works better with a marked up pic.
A bump or increased cornering loading is going to flatten out the arch in the front spring. When this happens the C-C distance of the main spring leaf eyes is going to increase - the eye will move away from the centerline of the car. Since the shackle distance on the axle perch is fixed on the front axle, that outward movement will make the shackle pictured rotate clockwise as viewed from the rear. That tilts the end of the Panhard Bar downward as the axle is rising upward relative to the frame, thereby negating the effect of the bar's tendency to rotate upward with the axle.
I hope this helps. If not, I hope somebody can generate an animation to demo this, to clear things up.

 

Got it - tks much for detail. On bump, panhard normally swings in arc, causing slight sideway movement of axle & thus some bump steer. You did away with fixed end of panhard on axle, spring causes mount to swing clockwise down eliminate ( hopefully ) panhard arc & thus eliminate bump steer. Will only work with a bump on that end of axle I think but very interesting attempt. Really look forward to results. Working on four bar front + panhard. Hope to keep cross steer same length as panhard to avoid bump steer. At least I think that will help. Following closely, nice build

 

That is what I used when I built a '33 Willys coupe. It works famously well on both strip and street.

 

A silly little project completed today, before I head out to beat myself up on a bicycle. These exhaust pipe heat shield stand-off mounting tabs are made from stainless steel, like the rest of the exhaust. Instead of drilling the mounting holes in them I pierced them with an Ingersol Rand piercing tool.. Pierced holes offer about 50% more holding strength in sheet metal than do drilled pilot holes. I may add French washers on assembly.

 

That is interesting would you show us the process and tool needed for that?

 

jim32, The tool is shown in the above photo of the stand-off tabs. It is basically an Ingersol Rand riveter with a piercing point attached to the end. To use it you literally point and shoot. On thin metals <16 gauge you merely have to press the tool tip against the metal surface and pull the trigger. It blasts an extruded hole into the metal. Screw a sheet metal screw into it and it will pull the conical extruded metal into the screw and lock it down. On thicker metals I prefer to drill a small pilot hole to let the pierce point push the metal aside as it penetrates.
If you look at bare sheet metal surfaces on late model car's floor pans, firewalls, and bulkheads you may see little dimples scattered about. There are used as a guide for pierced holes to attach optional equipment, consoles, wiring harness hold-downs, and the like.
I worked in the Body Engineering Department at FoMoCo Dearborn where pierced holes were used in abundance for mostly non critical component attachment to body sheet metal panels. That is where I picked up on this technique.
For more critical attachment of parts that must withstand high shock and vibration loads, sure, I'll use Rivnuts, weld nuts, caged nuts, and reinforcing plates.
On the heat shield mounting I took the pierced holes a step further and tapped the raw hole for a 10-32 flat head machine screws. That should give even more secure attachment.
I'll take a better pic of the tool and post.

 

Thank you very much! I like the look and the benefits of this process. I can see this as a very useful process for sheet metal work. many thanks to you Sir. I am following your builds.

 

Thanks Jim
Here are photos of the piercing tool.
One has to be careful not to apply too much pressure. The tool has enough zotz to blast its way completely through a panel if you are not careful, as illustrated.

I like your avatar roadster too.

 

I made the seat pan. It is .045" steel with flanges and beads for stiffness. It gets fastened by four Dzus buttons in back and two up front. I still need to put two "bun depressions" in the pan between the beads to cradle my butt and give a bit more support. I'll make a wood forming buck for that. Also needs a notch for the crotch belt.

 

The additional Heim ends arrived today so I drilled out the link attachment holes. I may add lightening holes to the steering arm sometime.



I also made a buck for the butt socket depressions. It is much more comfortable to sit in with these dimples and the lateral support it gives my body is noticeable. Instead of sitting on what amounts to a two-point seat I get cradled into the seat. It reminds me of the seats on old farm tractors and farm implements. The machinery may have been relatively crude but there was a lot of thought put into the ergonomics of the cast iron seating. And many were beautifully embellished with pretty designs too.

 

When I was a mechanical designer working in diagnostic imaging, our MRI prototype breast coil started out looking very similar to your recesses, although it was used just to prove the concept.

 

Double DDs?

 

I wasn't kept abreast of the ergonomic research, but if mammary serves me correctly, the Industrial Designer/Ergonomic Engineer just grabbed what was hanging around our department to model and felt the 95 percentiles standard was well in hand.
I Digress.

 

Garment for Zena, Warrior Princess?

 

My first thought on the seat dimples was that they were for clearance for other manly parts. It took real balls to drive those old Champ cars. Brass ones might have been required.

 

I don't know if I will ever drive it like the old timers did. A hot lap or two, 4th of July parade, cruise nights, or maybe sashay down into town for a milkshake will make me a happy guy.

 

I'd like to see it make a lap or two at Flat Rock. Maybe on dirt too, Dixie or Auto City.

 

After the cycling TT last weekend (broke 40 minutes; averaged 20.14 mph; finished 5th of twelve entries in the Male/Over 70 age bracket) I turned again to the champ car. My Heim ends arrived so I chopped the steering arm apart to measure the wall thickness and order rod end bungs. Then I fitted up the idler arm. It needed clearancing to the hairpin end so I put it in a rotary table and whacked away. I also added a few lightening holes mostly for looks.
This two piece drag link not only will reduce any bump steer but it will also allow me to vary the steering ratio and thus speed.
Once the steering rod is completed the real estate devoted to the tank pump and the hand brake handle must be addressed. Space is tight on the left side. The air pump is decorative; the hand brake, on the other hand, is to be functional. They both want to occupy nearly the same space. I'll place them in the car next.

 

Here is my dilemma regarding pump and handbrake placement. In order for the hand brake and pump knob to be accessible to the driver the space they take up conflicts with the steering.
One possible solution is to mount the pump on the other side above the exhaust pipe. If you were a left handed driver that would be OK. I have seen photos of at least one car that had the pump on the right side.
Another solution that was more common was to bend up the hand brake lever with a big WowWoose to fit around the pump on the outside. Not real crazy about how that handle might look, but many cars were done that way. The hand brake must be functional. It is to actuate the rear brakes only. Most sprinters had only rear brakes. Mine gets 4-wheel brakes to be street legal. Rear only brakes are useful to toss the car sideways going into a corner. I'm leaning toward putting the pump on the right side over the exhaust pipe.
...or leave it out entirely???

 

Can you mount it higher on the cowl like this one?

 

YES!
I'll have to clock the pump mounting tabs to conform to the compound curvature of the cowl but I do believe it will look OK above the steering arm nacelle, even though my steering arm is higher than the pic you posted.

See Mike - this is why I keep you on the payroll, for all your good solutions.
That is a nice eclectic car collection BTW. I'm not too crazy about the flame job they did on that sprint car though.

 

My steering rod end bungs arrived so I cut and welded the links up. Now with the two-piece drag link in combination with the multiple holes in the steering arm I will have a total of nine possible steering ratios, just by juggling the mounting hole locations of the drag links.



middle point:


for quicker steering:


for slower steering:

 

I determined the best location to put a sleeve through the frame to hold the hand brake handle. Plans are to weld the pivot shaft on to the handle. Everything south of the pivot will get cut off and the handle itself will get further ground down for a better look and glove fit. I turned down a grade 8 5/8 bolt leaving a shoulder to press onto the handle and weld permanently. The shaft will then slip in the welded in sleeve and get a bell crank on the inside of the frame to pull on the e-brake cables. That means the bell crank needs to be removeable but it must withstand the force applied by the driver on the handle. Splines on the shaft would be good but I do not have the means to make male splines on the shaft nor spline the hole in the bell crank. So I decided to put a square section on the shaft and slice a piece of a 1/2" socket off to slide on the square shaft. A crank arm will then get welded on the socket disc to apply force to the cables. The 5/8" shaft was machined for a 1/2" square drive crank arm and a 3/8-NF retainer nut.

 

Liking the work you’re doing.

 

Doing a little something every day.
That's what I am trying for.
I ground down the handle grip, removed the clevis end, and welded up the no-longer-needed lever holes. Thinking the GM part number on the handle may be useful to the next caretaker some day I decided not to grind the part number off it. Then a trip through the sandblast cabinet and a metal prep wash.
I laid out the components needed so far. Still need a 1/2" socket to finish the bell crank. I have a blanked-out piece to use, along with a cable equalizer bar.

 

After supper I went out to the garage to have a conversation with the car and make plans. Before long I was laying out the hole location for the brake handle and then proceeded to drill out the frame for the sleeve. Bonus time this evening.