Thread: And more questions: Front suspension & clearance

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Mr. Techinspector, I thank you for your explanation of your opinion about the Panhard bar. Maybe I did come on too strong in my question. I didn't intend to be offensive, but only wanted to have some facts to back up your opinion. Peace?

You are right . . . a panhard should be as long as is practical in the car, and it needs to be level. Otherwise it will push the front end of the car a little sideways as the suspension moves up and down, and this will cause the car to wander around, rather than going straight down the highway (bumpsteer).

This is why I don't like a "dead perch". The dead perch connects one end of the spring directly to one of the perch bolts, without using a shackle, so half of the spring acts like a panhard. The advantage of this arrangement is that it's simple . . . no extra parts. The disadvantage is that this "panhard substitute" is very short, and it's not level. Two of the primary requirements for a good panhard.

The drag link should also be level with the ground for the same reason. As the suspension moves up and down, the arc that the right end (passenger side) of the drag link moves vertically, so it doesn't try to push or pull on the right steering arm. If both the drag link and the panhard aren't level, you'll get that dreaded bumpsteer problem.

Originally Posted by Hot Rod Roy

The drag link should also be level with the ground for the same reason. As the suspension moves up and down, the arc that the right end (passenger side) of the drag link moves vertically, so it doesn't try to push or pull on the right steering arm. If both the drag link and the panhard aren't level, you'll get that dreaded bumpsteer problem.

All above points have been well noted. However I am now confused I thought the panhard bar was supposed to REMOVE the bump steer I currently have? But you guys are saying if not set up right it will cause bumpsteer? More bumpsteer than I currently have WITHOUT the Panhard bar?? (if that's humanly possible ).

I don't think you can entirely eliminate bump steer with either a panhard bar or a deadperch because they both swing on a long arc which changes the effective length with the up and down motion. However, I would think either would GREATLY REDUCE bump steer compared to none at all. I think you can see in my picture a page or so back that the panhard bar on my '29 is parallel to both rods of the cross steer setup and the up and down motion is probably not more than an inch. Probably a dead perch has a slightly greater effective length but then don't forget that the spring changes length as it flexes as well, so all in all I think a panhard bar is much better than none at all!

Don Shillady
Retired Scientist/teen rodder

Originally Posted by HiboyGal

All above points have been well noted. However I am now confused I thought the panhard bar was supposed to REMOVE the bump steer I currently have? But you guys are saying if not set up right it will cause bumpsteer? More bumpsteer than I currently have WITHOUT the Panhard bar?? (if that's humanly possible ).

Faith, that is why I have been so opposed to them in the past, because nobody takes the time to research the geometry and make them and install them correctly. This monkey-see, monkey-do business just irritates me to no end.