Vetterman 4 pipe system on RV-8

Am doing condition inspection and found ball joints seized although it appears they do move in operation as they are a little shiny at joint.

I called Curt and asked if it was necessary to get the joints freed up cold.

He responded, concurring with my feeling, it is not necessary.

The system is like a solid pipe system except there is wiggle room at the joints when hot, no need to be free cold. There is no cracking and ball joints are more for adjusting at install to get them in right position exiting lower cowl.

Under temperatures in flight, lub will not stay in the joints.
The pipes must be at least 400-500 degrees at the balls.

One time, I mouse milked my ball joints eek right before firing up the engine. Didn't take very long until light smoke came wafting in through the air vent. I'm sure that mouse milk was gone in a flash. I was wondering about this and how you could possibly keep them freed up. I'm glad to hear that it's not expected when the engine is running.

Ball joint lube

Here is the thing on mouse milk. It was originally used for keeping turbo waste gates from freezing up so it does have some lube properties. The main thing that I was always amazed by was it dissolves carbon build up. Over the years I got many systems back with frozen ball joints, I mean really frozen. A few drops of mouse milk applied then let set over nite, and bingo, not frozen up anymore. Wiggling the pipe back and forth, wiping away the goo on the ball joint, applying more mouse milk did the trick. I would then apply a mixture of mouse milk and a high temperature anti-seize. There are two uses for ball joints depending on the system its on. On the 4 pipe system, the weld in style of ball joint, they are typically used for alignment of the pipes. On a crossover with the triangle mount using springs and bolts they are designed to constantly flex as needed. Hope this helps a little. Vetterman

I've had a couple of exhaust stacks crack at the end flange. I suspect the likely cause was stresses due to engine movement, especially at start up etc. Those stresses would be relieved by accommodation in the ball joints and slip joints.

I now give a squirt of mouse milk on all the joints every time the cowls come off. I know some people use anti-seize paste too, but you would need to unhitch the ends to work it into the joint.