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Old 03-02-2016, 05:57 AM   #1
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Grease on axle nut - where did it come from

This is a picture after I wiped away the grease but you can still see some. Before I wiped it away the center cavity was filled and the surface around the center cavity was covered with a thin film of the grease. This is my driver side rear hub. I noticed it when I took my wheels off to clean and there is some grease on the inside of the wheel where the center cap goes.

Odd/interesting factors:

The wheel that had grease was mounted on the passenger side of the car, where that area above the axle nut was bone dry. That wheel got moved there in October/November last year after I flipped my Hankook R-S3 tires on the rim and moved them to the other side. So if the grease was ejected from the axle nut, it appeared to have happened before October?

But I feel like I would have noticed the grease since I have had my wheels off 3 or 4 times since then for brake bleeds and checks? Although maybe not, it was a very thin coating and looked "normalish"?

I have 2 other sets of wheels that I have been running (street and r-comp) - I haven't checked them to see if they have any grease behind the wheel cap but will do so at lunch today and update this thread. Update: I checked and none of my other back wheels has that grease. So it seems like it may have been a one time event that grease came from the end of the axle?

These extra things may provide more info, or may not....

So does anyone know when or why grease would come out of the center of the axle nut (axle? the nut is actually threaded down and not on the very end where the grease was)? Is it a sign of doom?



Edit: I have not crawled under there to see if there is any grease coming out of the back side? CV Boot issue? If it was leaking behind the wheel would it come through the end of the axle and out that little hole?

Last edited by steved0x; 03-02-2016 at 09:05 AM.
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Old 03-02-2016, 10:44 AM   #2
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Aha - a related thread from Renntech on this issue with a possible theory:


Sounds like the left side got hot one time and some grease vented out the vent hole. So I guess I need to get under there and check my boots to make sure they have enough grease?

Left rear tire makes kind of sense - I have TC and I was at Roebling in October when I think this happened and had 6 hot sessions that weekend, and picked up a lot of speed, taking 2.1 seconds off my previous fastest laps. I bet the TC was going off and braking that left rear wheel and heating it up?

One of these days I am going to turn off that TC... but I am not there yet... Every time I turn it off at autocross it seems like I spin...
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Old 03-03-2016, 08:13 AM   #3
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Vent hole? Who'd a thunk it?
Amazing what one can dig up on the net with a little perseverence!
2004 986 S
987 air intake TB and plenum, Mantissport 2 litre sump, UDP, Bilstein B6 with H&R lowering spings, re71-rs for track, other stuff.
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Old 03-04-2016, 10:15 AM   #4
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Yes, there is a small hole in the center of the axle that vents the CV joint. If the grease got hot enough to get pushed out of that hole, probably a good idea to re grease.
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Old 03-06-2016, 06:28 PM   #5
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Any ideas on an easy way to decrease or do you think I am looking at removing the axle?

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