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TECH TIPS FROM THE
“OLE KOOTER”
The Panhard Bar
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What is a Panhard Rod? I really do get asked that from time to time.
It is mounted in the rear of the car. One end is connected to a bracket on the frame on one side & the other end is connected to a bracket on the axle housing as far over on the other side of the car as possible. The Panhard Rod is then adjusted so that it is horizontal when the car is half full of fuel and at normal ride height. The panhard rod serves several purposes. But let’s stick to basics.
1. Lateral locator of rear leaf springs. We have always run with a panhard rod. And since we went to 1¾ inch wide springs, from the original 2½ inch wide Mustang springs, we have found it is even more important.
2. It also serves as a handling-tuning device. The total height can be changed to effect the roll center. One side can be raised relative to the other to get a jacking effect in one direction. We haven’t tried that yet, so will report on it later.
Our design has gone through a number of changes through the 13 years that we have been developing the Panhard Rod from the original design of the 60’s. We found that the floor was cracking on our 1965 A Sedan Mustang from the tremendous stresses on the subframe. The fix for this was a brace that went from the subframe bracket across the car to the subframe on the other side. This is called a Bolis bar. It is named for a previous employee that did the first brace, Joe Bolis. The next change was to strengthen the Panhard Bar and the spherical joints at each end.
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"Yes, Walt, but when the car goes up & down, the Panhard Rod goes through an arc that causes the rear axle to move laterally back & forth across the car. If you used a Watt’s link, the housing could only move vertically. So, why don’t you use a Watt’s link?"
Let’s address the lateral movement of our 36-inch long Panhard Rod first. From the horizontal, as the rear of the car rises and falls, here are the results:
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+ & -
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Axle
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vertical
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lateral
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travel
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travel
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5.02 inches
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.0878 inches
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7.52 inches
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.1973 inches
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12.50 inches
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.5468 inches
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If the bar was longer, the side movement would be even less and visa versa.
Now let’s look at watts link. For the price of no lateral movement, the installation is much more complicated and heavier. And it is much more difficult to use it as a tuning device. Look under a NASCAR racecar sometime. You will see a Panhard Rod. They use them as a tuning device.
The goal in our cars is to have a very smooth transition when entering a corner, so that the driver doesn’t have to make rapid unwanted corrections. Our Panhard Rod setup is one of the factors that allow this.
I guess, in comparing the Panhard Rod and Watt’s link, "if it ain’t broke, don’t fix it". Or, don’t make it complicated if it doesn’t have to be. One thing we engineers have to be careful about is not making our setups unnecessarily complicated. This applies to the entire car. It is a balancing act. The question is: what are the benefits versus the draw backs, such as cost, complexity and weight, just to name a few.
Walt Hane
Tech Tips-3
12/00
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For more information:
E.P.S., Inc.
P.O. Box 1043
Evergreen, CO 80437-1043 US
Email: epswalth@aol.com
303-674-6017
© Copyright 2009 This website was created by SNetSolutions
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