Rod ends Vs Bearing blocks.

[tauruck]

Guys. I designed my liner's suspension with plummer blocks in mind. I was going to bolt 4 front and four rear to hang the wishbone setup on. It's a pushrod activated system. The blocks have a bearing ID of 1". The problem is that these blocks need to come over from Germany and will only be here first week in November. I can't really wait that long and the easy option would be to replace the block setup with spherical rod ends. Instead of bolting I'd have to weld brackets onto the bulkheads. What advice can you give?. Thanks.

[Jon]

I would go for a bush type arrangement rather than a ball race, ball races are good for a rotating shaft not for something that reciprocates back and forth a small angle.

I would go the rod ends rather than Plummer blocks if I had them both on hand.

My opinion only.
jon

[Peter Jack]

Go for it Mikey. The rod ends are a better solution anyway. You could always design the mounting brackets to bolt in and thus have maximum flexibility for future changes.

Pete

[tauruck]

Thanks Pete, I was thinking the same thing. I could use the mounting points to change brackets to move the arms up or down. Pete, Jon said he didn't like a ball race for small increments. Just asking, there's not much of a duty cyle and there would be four of them on each end. I get what he's saying but what's your take on the subject?. Jon, thanks for your input as well. All the opinions help.

[Dean Los Angeles]

For very small radius movement, and all the beating and banging a suspension sees, the balls never move and wear into the races.

Bushings work fine and don't have that problem.

Spherical rod ends perform the same function as a Plummer block as long as they are sized properly.

[Peter Jack]

Dean explained it well. The rod ends are a much better choice for the job because they take the load over a much larger surface than a ball bearing and they're designed to take the load without travel as opposed to bearings which are designed to take continuous rotating loads rather than loads from a single direction. There, I know what I meant, I don't know if I said it as clearly as I intended. 

Pete

[Freud]

Dean.....for a kid you give good explanations.

Peter Jack knows but he forgets what he wrote.

FREUD

[tauruck]

Thanks. I think that's what Jon was getting at. The rod ends I have are 16mm ID but then I still have spherical bearings which are much larger on the ID that I was going to fit to some billet blocks I machined.

[Jon]

The weight bearing surface area on a 16mm rod end is much greater than the ball race Plummer blocks.
I have used a mixture of rod ends and spherical bearings in my suspension, depending on whether I am going to a rod on one component or a housing on both.
I've gone with sealed and greasable spherical bearings and will run Molly grease, a few slow pumps post meet will help get moisture out.

Roller bearings on suspension have two problems, a decent hit focuses a lot of pressure on very small contact points; the small arc of movement will wear a ball bearing unevenly similar to having a universal joint too straight.

jon

[tauruck]

Jon, I should have taken your advice yesterday. You were 100% right. Thanks. 

[manta22]

I had the same problem-- rather, Porsche had the same problem. They used caged needle bearings in the pivots of their G50 transaxle clutch release lever. This is a mis-application for an anti-friction bearing. They should rotate around 360 degrees. A small oscillating movement creates a channel in the grease and it eventually fails by fretting. A plain bearing (the ball in a rod end is a "plain bearing" does not fail due to small oscillating motion.

I discussed this in my "Mid-engine modified sports" build diary.

Regards, Neil  Tucson, AZ

[tauruck]

 I've taken the good advice you all gave and I'm organising the rod ends. My current stock has a 16mm ID. My sponsor has six available right now so I can carry on building. These are larger at 20mm ID. I figure they should be fine but are the type that need to be lubricated. Yes or no?.

[Peter Jack]

There should be no grease fitting in the body. The threaded hole causes a weak spot. The joints can be lubed if necessary before installation. Google "seals it" for seals that will protect the rod ends and keep them clean even if they are lubed.

Pete

[tauruck]

Thanks Pete, I have a long wait for components either way now. Should I stick with the 16mm I have right now or wait for 20mm versions?.

[kiwi belly tank]

I'd go for the 20's Mate.
  Sid.