Delrin ball?
 

When should I replace the delrin ball on the clutch?

Uniball
 

The Uniball should be replaced when the ball shows a wear ring around the center where it contacts the fan hub. As long as the ball is round, it can be reused. I find that if the dampers are replaced before they are totally ruined, the uniball is usually still workable but if I have ANY doubt about the ball, I replace it as if it is worn, it can detroy the dampers and the start shaft bearings, costing way more than replacing the ball.

Delrin ball?
 

It's a press fit right?

Delrin ball?
 

It's a press fit with a catch.

There is a little lip machined into the clutch that that ball snaps over. I used to cuss taking the uniballs off. Now it's easy because I just use the heat of a small soldering iron to cut a groove in the ball. You don't even have to go all the way through. Just make a cut deep enough to insert a screwdriver blade and twist; the plastic is pretty brittle.

I make it a practice to replace the ball whenever the wear line on the ball is over a mm or few wide. That ball is critical to having the clutch run concentric with the fan. Gordie is surely correct; it isn't worth the cost savings to skip replacement when it's needed.

Ben Minor

Delrin ball?
 

So, what's a ballpark figure for replacing the ball? Given a sedate (non-3F) flying style, minor aerobatics but hardly any stress on the drive train at all- other than normal running.

The ship has approximately 100 flights of 10-12 minutes duration each. Good alignment, no shakes or buzzes, etc.

This is only my second uni-ball X-Cell; I murdered the other one at 35 flights, so I have no idea how long htis thing is supposed to last...

Steve

Delrin ball?
 

Steve,

If the bearings in the clutch assembly/bearing block aren't causing problems and the dampers are otherwise OK, I see no real need to pull down the drive train just to replace the ball. Assuming reasonable drivetrain alignment, the longevity of the uniball should be at least as good as the bearings and the dampers. It's more an issue of replacing the ball if you are otherwise pulling down the drivetrain for service of some other components - we swap out the ball while we're in there.

Make sense?


Ben Minor

Delrin ball?
 

Yup.

And I'm glad we agree; because everything is still sweet, and I wasn't about to disturb it just to check that delrin ball...<G>

Steve