All right Guys and Gals I have a question about lateral location of a tube axle. I have got myself in a corner, I do not have room for a panhard bar on the front suspension and I will be using cross steering. The drawing is not to scale or equal from side to side the car is. The suspension is parallel torsion bars, the torsion arms go into the bat wings which have parallel plates with three bolt holes. The holes are used to stiffen or soften the bar rate. The furthest out being the softest and the ones closet in being the stiffest. The arms ride on a roller, no direct or hard connection between the roller and arm. What I am thinking about doing is remaking one of the torsion arms so that the bolt on the bat wing will go through the arm which now becomes my lateral or side to side locating device. If one side is free to slide on the roller and the other side is located by the bolt through the arm will this work? As always thanks in advance.
That's going to make a very short panhard bar. The axle will move side to side with travel causing bump steer. With cross steer, you want the panhard the same length as, and parallel to, the drag link.
x2 on the very short panhard and likely effects if there's anything more than minimal suspension travel. You could use one of those verical sliders / bearings in the center of the axle and crossmember to achieve your aim. Various designs around. Dunno the term though. The Doanne Spencer roadster has a fork type arrangement. Sure someone with a good link will chime in soon. Chris
Running the drop links from the axle at 45% angles and will make the system act like a buggy spring setup (where the shackle angle holds the axle centered). How effective this is depends on how much weight you have on the front end and how hard you try to corner it. I'm assuming you'll have a pretty limited range of travel, so the Spencer fork would probably be a good, simple solution (and it's traditional...).
Why can't you use a panard rod, you can use a simple 3/4" diameter tube with 3/8" x heim ends going from the bottom of the batwing to an opposing bracket off the frame rail tucked right tight up to the axle. Even if your axle is in front of the frame a bracket and rod positioned just inside the torsion bar span will still be in the area of 16-20" long and only produce around 1/16" lateral deflection on a 4" travel. Shoot a better overall picture of your construction and it will be easier to come up with a solution.
Photos of front of car. The wooden square behind the grille shell is approximating a 1965 mustang radiator. The axle is in front of the grille shell which is causing the lack of space for the panhard bar. I had a bad experience with a panhard bar below the axle. In a prior life a ran a micro midget and had the panhard below the axle which caused the car to bicycle. That is why I am shying away from the bar under the axle. Again Thanks for your replies and advice.
In theory what you describe should work. Not saying whats good for race cars is always good for the street but when Wally Meskowski converted his cross spring sprint car to parallel bars he did kinda what you decribe. Dead perched the left arm and pivoted the right. Food for thought anyway.
I made this little thing to get the actual movement of the torsion arm. The three holes are the correct distance from the pivot to represent the torsion arm. The far end is the same distance from the pivot to the center of the wheel. The far end has three (3) inches of travel up and down.
Having the pan bar below the axle in this case will likely not be a problem unless you get on a heavy dirt track... It looks like you tried a bracket on there and changed your mind, or was that for something else? It looks like you would still have room to attach one to the batwing between the torsion arm and axle. Does the rad shroud come out that far?
Thanks for the pictures. You bicycle issue was not due to the panard rod below the axle so you can discount that as a problem source. exwest has a good suggestion about opposed link shackles but that limits the travel. The simplest set in my approach would be to pivot off the center of one of the torsion bars to a stud on the axle tube. If you have hollow torsion bars just drill and tap the tube so you can install a stud or bolt in the center and choose a length over to the opposite side and weld a stud on the axle, make up a panard rod and whala your done. If your torsion bars not hollow you can drill it or just tig weld a bolt on the end for a stud. Dont waste much time trying to move roller pins on the batwing to change spring rate, I think the arms are way to short for you to see any significant change of rate. You can calculate the rate by using one of the torsion bar calculator charts if you know the original rate of your bar. Choose the longest span and go with that.
If one end of a torsion bar is "free" to slide parallel to the front axle, and the other torsion bar arm is fixed (dead perch) to it's respective bat wing, will you need a panard bar? Gary I'm no engineer, just guessing the best I can.
ex yes the bracket was for the panhard bar. If you look at the radiator shell i want to have it between the front crossmember and the axle. Placing the bottom half of the shell takes up all that space. Mr. Spadaro the bars are out of a 1/2 ton Toyota pu. I have already moved the roller pin and it does make a difference. Schroders bar chart shows about a 20% change for every inch of increase or decrease in arm length. gnichols what my original question was could I leave one side on the roller and capture the bolt in the other arm, basically a dead perch. The wooden jig shows the three bolt holes in the bat wing and the modified arm, the amount of movement side to side would not exceed 1/4". I guess I should make another jig to see how much side to side movement a panhard bar has. I know I am a little hard headed but I do appreciate all the help. Duane
In a prior life a ran a micro midget and had the panhard below the axle which caused the car to bicycle. That is why I am shying away from the bar under the axle. Just don't back er in on the cushion you'll be ok
Some pictures on here http://www.jalopyjournal.com/forum/showthread.php?t=685236 showing how I did mine. I used spherical joints both sides. Right hand side is fixed and acting as a panhard and left side knuckle is free to move about. Longer arms than yours may make a difference, and I have steering from cowl with draglink to minimise steering issues.
Racer 5C great comment, about choked laughing hard. Wood box / fleet master I always tell people that when my modified grows up it wants to be a sprint car. It appears you guys are building race cars, both are very NICE. WOODBOX I only got to page seven, have you driven your car yet and how did it handle bump steer wise? What you did is very similar to what I want to do. Only difference is my left side would ride on a roller with no direct hook up. Thanks to all.Duane
On early dirt cars the dead perch or fixed torsion arm was on the LH side to be under tension during cornering [ this also helped "carry" the inside front ] They always used "Side Steer" so there wasn't any bump steer [by design] If you dead perch a cross steer set up the dead perch should always arc the same way as the drag link [ LH steering boxes require the dead perch on the RH side ] The same applies to a panhard bar, it should never arc the opposite to the drag link. A panhard bar doesn't need to be straight [it is just an imaginary line between 2 pivot points] Having the panhard bar as low as possible is very desirable because it lowers the roll center. Bicycling is usually caused by too much scrub radius and sometimes too much positive caster. This problem is worse when the car carries one of the front wheels while the other is in the ruts
Skip to the last couple of pages! No I have not driven it yet.....other things keep getting in the way! I have had the car through a full range of movements and there appears to be no bump steer at all......I guess only time and miles will tell.
Confusion reigns supreme. I have not made any decision on what to do. As my friend says it is time to sit and stare. Really appreciate all of the comments and suggestions to solve this problem. Will post what I finally do. Thanks to all duane
To all that offered thoughts or suggestions thank you. I borrowed a 1965 mustang radiator, it will not work. I decided to use a regular panhard bar. The pictures show a bracket that is attached to the batwing on one side and a bracket attached to the frame on the drivers side. Welds are pretty bad will be cleaned up on final frame prep.
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