Grease on axle nut - where did it come from

[steved0x]

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?

Thanks,

Steve

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?

[steved0x]

Aha - a related thread from Renntech on this issue with a possible theory:

http://www.renntech.org/forums/topic/23470-grease-coming-out-hole-in-rear-axle/

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...

[NewArt]

Vent hole? Who'd a thunk it?
Amazing what one can dig up on the net with a little perseverence!

[Deadeye]

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.

[steved0x]

Any ideas on an easy way to decrease or do you think I am looking at removing the axle?

[maytag]

Originally Posted by steved0x

Any ideas on an easy way to decrease or do you think I am looking at removing the axle?

Steve, I'm resurrecting this thread, maybe you can shed some light for me?

My new-to-me spec boxster was at the track for the very first time with me driving it yesterday, and after my 2 sessions I noticed some very light grease weeping out from where the center cap of the right/rear wheel would be. (no caps on the wheels presently).

Even 30 minutes after though, it was very liquid; like oil, not grease.

So now I'm reading these threads and I'm wondering.....

I overfilled the transmission on purpose, because I have a transmission cooler that needed to fill (but wouldn't until the lube warmed-up) and I didn't want the trans running low when that happened.

So now I'm reading these threads and wondering if there's a vent-hole that runs the length of the axle? Am I venting the transaxle from the ends of the axles? in which case, am I washing all the grease out of the CV with 75w90?

waddya know?

EDIT:
In retrospect, I know for a fact that on the 'S' trans, there is no vent through the output flange. I may assume the same is true of the 5-spd.
So have I simply melted the grease in a CV joint? or is this an indicator of a suspect wheel bearing?

[steved0x]

It is the CV grease, typically on the left rear wheel for clockwise tracks because I think that wheel gets more heat? And also the direction of the for corners forces the now liquified/overheated grease out that vent hole...

I removed both axles, removed the inner CV Joint, soaked it all in kerosene (or maybe diesel) and then rinsed it all out with acetone, and repacked with Redline CV-2 grease, put on new boots and clamps and put it all back together. 1 small tub was enough to do all 4 cv joints, and this totally resolved the issue for me

Edit: when it comes it, it is pretty liquidy and nasty...

I want to do the same thing on my Cayman, those axles don't have the vent hole, and they also use a different outer clamp style for the CV Boots and the grease typically oozes out under the outer edge of the cv boot/clamp... I had to add some new grease and a new clamp to the driver side axle some time back, and just this past weekend I had to do it on the passenger side. I want to remove both axles and do the same repacking, but just haven't gotten to it, and also since there is no vent hole, I am not sure how to get all the grease out of that outboard joint. With the vent hole I could just repeatedly dunk the axle in and out of the kerosene, and then the acetone to clean it. I guess I could shoot a lot of brakekleen in there after dunking in the kerosene

[maytag]

Originally Posted by steved0x

It is the CV grease, typically on the left rear wheel for clockwise tracks because I think that wheel gets more heat? And also the direction of the for corners forces the now liquified/overheated grease out that vent hole...

I removed both axles, removed the inner CV Joint, soaked it all in kerosene (or maybe diesel) and then rinsed it all out with acetone, and repacked with Redline CV-2 grease, put on new boots and clamps and put it all back together. 1 small tub was enough to do all 4 cv joints, and this totally resolved the issue for me

So, it begs the question; if there's a vent there, what's to stop me from tapping that and putting a grease zerk there? Does that cv joint really need to vent?

Sent from my SM-G970U using Tapatalk

[steved0x]

Originally Posted by maytag

So, it begs the question; if there's a vent there, what's to stop me from tapping that and putting a grease zerk there? Does that cv joint really need to vent?

Sent from my SM-G970U using Tapatalk

I don't know, I would guess porsche doesn't think so since they took it away on the Cayman and I know one boxster guy that tapped it and put in a small bolt to seal it. Car has been sold but I still see it on track every November when I go to VIR.

Since I repacked with CV-2 it has been totally solved for me though, no more oozing :-)

[husker boxster]

Last yr I had the oozing boot on the LR of my CSS. I had my Indy repack the joint and replace the boot. Prior to the work, I had a nice ring in my wheel where the grease had been flung.