motoTrooper
True Classic
Very clear and well articulated, thanks Steve!
Very clear and well articulated, thanks Steve!
I've always thought it would be nice to have a "spherical" type joint (allowing movement in multiple planes) with a vibration absorbing material within it (something similar to urethane). Therefore the best of both words; free movement in all desired directions, with better control of the movement, but no metal-to-metal contact to transmit the vibration/harshness. The challenge of the concept would be having a special material strong enough to hold up to the loads and wear, yet soft enough to offer the needed compliance. One thought might be to make the overall size of the joint larger than typical metal heims to distribute the load to a greater area. But even better would be a different design of joint all together that is better suited to this. Much in the way the CV-joint replaced the U-joint.
I would think there must be a joint design of some type that is akin to the CV joint (but not literally the same), offering the movement without all the "play" and yet smooth/quiet. It might be easy to say, "if there was then the car makers would be using it". However that may not necessarily be true. It could just be impractical or too costly for mass production, but still good for limited custom installations. Race car designers do not need such a joint because the metal heim/spherical ones are best for that application. But for a performance street vehicle...
I would say that Steve's setup probably took a great deal of consideration and expertise on his part to setup correctly, that he may not be emphasizing. Most heims do not allow for a high degree of misalignment- think about it - you have a rod passing through the center that will hit the “hub” - allowing more or less movement depending on size of said bolt/rod and the cross section of the Heim center. Some joints require offset spacers which allow for a greater degree of misalignment. I think your average ball joint has greater degree of axial (correct term here?) movement simply because the “bolt” only comes out one side.
I think heims are often used simply because of the increased adjustment flexibility they offer for varying conditions, no?
But keep in mind, the primary direction of movement is along the pivot axis of the joint. The off-axis movement is not that much, so a spherical joint can easily handle it. Its not like we are asking it to go 90 degrees in two dimensions. Plus there are some tricks to allow a heim joint to handle quite a bit of misalignment (relatively speaking).Most heims do not allow for a high degree of misalignment
Just to throw in another idea regarding NVH
Manufacturers of carbon road bike frames have over the years experimented with frame inserts tuned to absorb the most common vibration and ‘noise’ frequencies. They’ve been used in everything from chainstays to bike seats to forks. My point is that all your vibration damping doesnt have to come from the bushings but rather (I dont know how you would configure this on a car) could be handled ‘upstream’ of the suspensions movement, maybe incorporated into the body mount tabs or control arms themselves. Many people think these are a form of suspension for stiff road bikes but really they are designed to absorb road frequencies. I believe Zertz (a common marketing nomer) is a play on words between Hertz and inserts. The word is out if they actually work but Specialized has incorporated them for years and still does on thier top of the line bikes.
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Another common location for these is brake calipers.Auto makers have used NVH counter weights and dampeners for years in all kinds of applications.
Like the way modern medicine targets symptoms rather than the actual cause of the disease.