Pulling, cleaning, using #1 moly grease
may help. Drill a very small hole in cover plate
will fix.
My rear propeller shaft cap plate loosened under pressure, so grease & air are passes at plate freely, which solved the clunk problem. Front shaft grease passes seal without excessive force, after removing & cleaning.
Grease zerk goes through rear cap plate. Drilling small hole in plate makes servicing each 5K miles with greasing less effective, as grease escapes out hole. But this is what Lexus shops do, after replacement shaft fail to stop clunk.
We have two possible issues causing clunk:
- One stiction (Stiction is the static friction that needs to be overcome to enable relative motion of stationary objects in contact. The term is a portmanteau of the term "static friction", perhaps also influenced by the verb "stick".) If you every pulled apart the shaft from yoke, you'll see fine teeth/threads on the spline of the yoke. There is a GM lube made to overcome this stiction, which is believe accentuated by the ridges on the yoke. I used a grease with moly to fill ridges and #1 which is thinner to pass seals. The problem with this, moly may make it more difficult for grease to passing seal.
- Seals are so tight the grease can't passes, which builds excessive hydraulic pressure in cavity of propeller shafts. It's been suggested that not servicing regularly dries seal creating this issue. This does not explain why properly service relatively new LX, had this issue. I use LX as example, only because it was the most senor Lexus mechanic in Co that told me how they solved the clunk by drilling the small hole.
Here is test to see if small hole will be usefully. Does grease escape passed seal without excessive force while greasing. If no, then drilling a small hole will fix clunk. Note: Excessive force is when greasing through zerk extends propeller-shaft more than a few milometers, while rear wheels on ground.
Tip: Grease propeller shaft while rear wheels on ground keeps shaft in neutral position, this avoids over greasing.
If I ever remove shaft again, I'll tighten plate. Then drill and tap a small hole, so I can put in a check valve or removable plug in plate. The extra weight of plug/check valve could cause a balance issue. Hopefully if this accrues, vibration will move grease in shaft around until it effectively balances. But it's been trouble free for ~65K miles now, so I've not worried about it. My hope has been a small amount of grease is circulating during my servicing's, so no excessive wear has been accruing.