slipper diagnosis

[BK_856er]

I put 3-4 track days on my SBK slipper since I last overhauled it.  Probably overdue for some maintenance.  The last two events it was squealing pretty good coming into certain turns when the slipping action would taper off.  Otherwise it was functioning well.

Taking it out yesterday I found the two hub pieces tough to separate.  Lots of metal-metal wear and galling between the two parts!  I sanded/smoothed it down best I could and found an orientation where it operates smoothly.

What causes this, and can I get some more miles out of this slipper unit?  Would it be a bad idea to apply a light coating of lubricant to the hub mating surface to allow the two parts to slide against each other more easily?

BTW, this is an older Bucci/MW unit.

BK

[BK_856er]

After thinking about this for a few days, I think the source of the problem is revealed in the last pic above.  The balls have widened the groove in the ramp towards the inside.  The top part of the ramp is the location of the ball under back-torque or slipping conditions.  At the top of the travel, the balls/ramps no longer keep the two parts of the hub perfectly concentric and the two parts can make contact.  I can feel the extra movement at the top vs. the bottom.  When back-torque is removed, the hub parts can slide and eat each other.

I haven't been into enough slippers to know if this is common.  It's probably accelerated by infrequent lubrication of the balls/ramps.

Some of the metal in the ramps where the balls ride was pushed around to create ridges.  Like the balls were sliding and not rolling.  You can sort of see one in the last pic running left to right at an angle.  I very carefully cleaned all these up with small files and polished smooth to get back good bearing action in a good path.  Hopefully that will help.  When I put it back together I'm going to apply a very thin film of synthetic caliper grease (moly + teflon + hi-temp grease product) to the worn hub parts and hope for the best.  I'll now relube after each track day.

Looks like I need to start saving for a replacement slipper!

BK