Rear panhard - straight or bent?

I'm about to start fabricating a rear panhard bar for my '34 Chev project but was wondering if it can be a bent tube or does it have to be straight.

If ok to bend (obviously not a very sharp bend) then I can mount it lower on the ch***is to have it more level with the axle mounting point at ride height and it would then be able to clear the diff center when the springs are fully compressed.

Or would there be too much tendency for it to flex when cornering?

 

Panhard bars are often bent or kinked just as the drag links on early Fords to clear obstructions or movement of suspension components.
Do not forget to use jam nuts on each end if both are adjustable. Also be sure to check all possible rub points when ***ghtening up the rod ends.

 

I've seen bent panhard bars in some oval track type cars. I think they're usually made of a little beefier DOM tubing than they would be for a straight one.

I always wondered why they would want a bent panhard bar in a race car, and all I could think of is that if a race car slides sideways into the wall, that a bent panhard bar would just bend up more and possibly save the frame or rear suspension from further abuse. But I've also seen bent panhard bars that have gussets in them to reinforce them so they won't bend too easily.

Depending on what type of ends you use on the panhard bar, you might have problems with the ends coming loose and the panhard bar flopping over crooked and banging around.

Even if the bar is bent, the actual transmission of force is between the two ends of the bar. So even if the bar looks level through the straight part, it will still act like a bar that's sitting crooked if you draw an imaginary line between the two ends.

 

Volvo use a bent panhard rod on all the 240 series cars It's pretty hefty tubing though, bigger than you'd need for a straight one.
Mart.

 

Thanks for all the replies.

The "best" I've got currently is 1.5" x .160 and the next best is 1.3" x .120

 

Most race cars that have bent bars have them to clear things like quick change rear covers or the drive shaft up front, or whatever. When you hit the wall, the rear end housing gets bent AND the panard bar gets bent or broken, shape is pretty much irrelevant at that point.

Your roll center will be located at the mid-point of a straight line projected between the two mount points, so you can bend the bar any which way you like, and still not change the roll center if the mount points stay the same. Obviously, for a street car, it's best to keep the roll center located in the center of the track width.

 

really makes no difference. either way it's still a "locating device". The main idea here is to get a solid roll center. Where it crosses your 3rd member, or pumpkin, is your roll center. I will try to find the article that I read going in depth a bit more on the subject.

 

As told by "BioMax" of Bio Kustoms

"You can use a pannard bar to tune the way a vehicle handles. Where the pannard bar crosses the center of the rearend is the roll-center and by lowering or raising the roll-center you can "dial" in the vehicle. You probably won't ever be in a situation where you can properly tune your suspension, but taking what steps you can to make it handle better will help.

To properly set up a pannard bar, you will need to do some drawings on the ground or something big enough for you to cycle the pannard bar on.

First, figure out how long your bar is going to be, don't worry about making it as long as possible, just run from the frame to the other side of the rearend to a point that is convienient.

Second, draw a line on the ground and mark that length out. On one end of the drawing, use a square to draw as close to a perpendicular line as possible up and down from the first line long enough in each direction to cycle your total travel. You should now have a "T" laying on it's side.

Now mark on the lines that you just made 1/2 of your travel up and half of your travel down. This represents your total USEABLE travel. Be realistic, if are trying to use a pannard bar with a 20" travel system it's not going to work very well. Keep it around 12" max.

Now using the point at the opposite end from the perpendicular line as a pivot, draw an arc that would represent the pannard bar through its travel, all the way from top to bottom. Now, you should have a "T" with a curve under it.

At the top and bottom travel points is the amount of pulling or pushing that the pannard bar is going to generate. Both the top and bottom points should be the same distance, if they are not, then you did something wrong. Let's ***ume that you came up with 3/4" the rearend IS going to move from side to side the full 3/4" but you are going to split the difference in half so that it is never more than 3/8" from center.

When you actually set up the pannard bar on the truck, do it at half travel and push the rearend over, so that the pannard bar would be pushing the rearend housing, half of the distance that you figured out on your drawing.

Make sense?
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