This is fairly interesting... seems like a new thing. Spohn has the Delrin joint. UMI has the roto joint, there's probably other ones that are the same basic idea too.






Im thinking about getting some new LCA's. I've got some tubular LCA's already but tehy have big poly bushings on both ends and I'm concerneda bout how they limit rotation of the rear end over bumps due to the way the bushings work.

So I was thinking about getting some single-rod ended LCA's. Not sure how there'd be much of a benefit going to a double rod end from a single rod end, but I did notice these new "roto-joints". I was vaguely familiar with them, but this is the first time I've seen a mainstream company offer them for our cars.

Which is superior? How do rod ends hold up over time? I've got a used panhard rod that had a crapped out rod end (The whole joint could slide almost all the way out of the eyelet) and I'm replacing that, but I'm wondering if the unsealed nature of rod end joints just lends itself to rapid (relatively) degradation over time.

The "roto joint" is slightly more expensive, but I figure if it allows rod-end style movement it should be superior... right? And how bad is the ride difference between poly and rod ends?

 

Looks like a johnny joint to me. Been around for ages. They are nice for street cars compared to full spherical ends, they can easily be greased transmit less vibrations and don't wear out as fast because they are sealed and greasable.

For spherical ends you can use seals it seals to seal them from dirt and then use a snall needle w. grease to grease them under the seal. The johnny joint/rotojoint whatever works better. They offer about the same misalignment angle so no big difference there.

What I don't get is why only on one side of the LCA. Misalignment angles are at both ends.

 

Its quite a bit cheaper, and I intuitively get the feeling that as long as one end can rotate, you get most of the benefit of having rod ends. I'm sure it's not quite as good, but maybe I'm wrong about how much.

 

Think about it like a driveshaft, angle the shaft and you get opposing misalignment angles on both ends. Same here, you will retain a parallelogram so both ends must provide misalignment and this way the poly end must deform where the other end is free to rotate.

 

A pivot joint should be superior to a rod end due to the rebuild-ability of the pivot joint.

The Spohn pivot joint can be torn down and rebuilt if it ever wears out. Can't do that with a rod end. The Spohn pivot joint is also preload adjustable, can't do that with a rod end. Also, the Spohn pivot joint sealed so dirt shouldn't be able to get in the joint and fowl it up. Can't do that on a rod end unless as stated above. Plus, the pivot joint has bushings on it, so it'll be quieter and transmit less vibrations to the car.