Centerlock pin sticking-- significant, or just annoying?
10-21-2012, 09:40 AM
#46
The wheel can't move. For it to move all drive pins should be broken. The drive pins are on the disc, and that is held into place with 2 screws so that can't move either.
10-21-2012, 01:33 PM
#48
Same as when you squeeze brake pads against the brake disc, yes? Squeeze brake pads hard enough you lock the wheel against rotation.
The drive pins are there to position everything together during installation with very little tolerance (they locate the hat to the hub flange as much as locate wheel to hat). As the hub would do (hubcentric, yes?) on non-centerlock.
The drive pins and the two screws holding the hat to the hub axle flange should never be subject to a rotational load. That is why the drive pins are your honest witness to a loose CL nut, they get damaged on their sides. The two small screws in the hat are there for only one purpose- hold the rotor/hat assembly on to the hub flange when the wheel is off.
10-21-2012, 08:34 PM
#50
Rennlist Member
This is becoming a pet peeve of mine... it's not about the whole wheel rotating relative to the hub. It's about the CL nut+spline mechanism rotating relative to the hub. There's a HUGE difference.
No one's arguing that the wheel should remain largely stationary rel. to the wheel hub. Agree that's what the 5 drive pins are for.
A failing wheel hub/CL nut doesn't hold torque and allows the CL nut to rotate under stress. Anti-clockwise in the RR corner, clockwise in the LR. Heck, we have a picture in this very thread so there's no debate around this point--the nut is well capable of rotating WITH SPLINES PROPERLY ENGAGED. I've seen it myself countless times at the track.
As the hub wears and the CL nut rotates, the splines are designed to stop the rotation within a 10-15 degree range. But it's an awfully big load on a small part. Over time you see deep scoring marks on the inner half of the spline assembly.
What happens beyond that is anybody's guess. We've seen too many pictures of wheel loss around here.
No one's arguing that the wheel should remain largely stationary rel. to the wheel hub. Agree that's what the 5 drive pins are for.
A failing wheel hub/CL nut doesn't hold torque and allows the CL nut to rotate under stress. Anti-clockwise in the RR corner, clockwise in the LR. Heck, we have a picture in this very thread so there's no debate around this point--the nut is well capable of rotating WITH SPLINES PROPERLY ENGAGED. I've seen it myself countless times at the track.
As the hub wears and the CL nut rotates, the splines are designed to stop the rotation within a 10-15 degree range. But it's an awfully big load on a small part. Over time you see deep scoring marks on the inner half of the spline assembly.
What happens beyond that is anybody's guess. We've seen too many pictures of wheel loss around here.
The hub/hat/wheel is locked together by the clamping force of a the torqued CL nut transmitted from the flange area of the wheel -> flange area of hat -> flange area of hub.
Same as when you squeeze brake pads against the brake disc, yes? Squeeze brake pads hard enough you lock the wheel against rotation.
The drive pins are there to position everything together during installation with very little tolerance (they locate the hat to the hub flange as much as locate wheel to hat). As the hub would do (hubcentric, yes?) on non-centerlock.
The drive pins and the two screws holding the hat to the hub axle flange should never be subject to a rotational load. That is why the drive pins are your honest witness to a loose CL nut, they get damaged on their sides. The two small screws in the hat are there for only one purpose- hold the rotor/hat assembly on to the hub flange when the wheel is off.
Same as when you squeeze brake pads against the brake disc, yes? Squeeze brake pads hard enough you lock the wheel against rotation.
The drive pins are there to position everything together during installation with very little tolerance (they locate the hat to the hub flange as much as locate wheel to hat). As the hub would do (hubcentric, yes?) on non-centerlock.
The drive pins and the two screws holding the hat to the hub axle flange should never be subject to a rotational load. That is why the drive pins are your honest witness to a loose CL nut, they get damaged on their sides. The two small screws in the hat are there for only one purpose- hold the rotor/hat assembly on to the hub flange when the wheel is off.
10-21-2012, 09:11 PM
#51
Race Director
10-21-2012, 09:18 PM
#52
Race Director
I finally got around to swapping my track wheels and brake pads back to stock today. My RR CL nut was not still with in torque spec!...my LR CL nut was really tight. My Precision Tool Torque Wrench torques in both directions.
The LR CL nut clicked the torque wrench once and then loosened. Pretty much as tight, maybe slightly tighter than the fronts. The RR CL did not click the torque wretch at all when I went to loosen it.
This was on a 95 mile drive to Sebring, 1 day track day and 95 miles back home.
Thoughts?
The LR CL nut clicked the torque wrench once and then loosened. Pretty much as tight, maybe slightly tighter than the fronts. The RR CL did not click the torque wretch at all when I went to loosen it.
This was on a 95 mile drive to Sebring, 1 day track day and 95 miles back home.
Thoughts?
10-21-2012, 10:19 PM
#53
Rennlist Member
I finally got around to swapping my track wheels and brake pads back to stock today. My RR CL nut was not still with in torque spec!...my LR CL nut was really tight. My Precision Tool Torque Wrench torques in both directions.
The LR CL nut clicked the torque wrench once and then loosened. Pretty much as tight, maybe slightly tighter than the fronts. The RR CL did not click the torque wretch at all when I went to loosen it.
The LR CL nut clicked the torque wrench once and then loosened. Pretty much as tight, maybe slightly tighter than the fronts. The RR CL did not click the torque wretch at all when I went to loosen it.
Re-test RR torque specs before each session. If it gets to the point where it gets loose every time I'll replace wheel hub and CL nut.
This is strictly MY OWN interpretation in the absence of proper guidance from Porsche. It's a shame we have to resort to such couch-engineer techniques. I'm all ears if anyone has a more educated view.
10-21-2012, 10:27 PM
#54
Rennlist Member
Have you ever seen the nut move on a torque check?
My buddy helped me change wheels ar the track recently. He torqued a couple with his wrench, and then i retorqued with my wrench cause i'm ****. The nut moved a significant amount before my wrench clicked. Point being: keep those wrenches calibrated!
My buddy helped me change wheels ar the track recently. He torqued a couple with his wrench, and then i retorqued with my wrench cause i'm ****. The nut moved a significant amount before my wrench clicked. Point being: keep those wrenches calibrated!
10-21-2012, 11:28 PM
#55
Intermediate
Join Date: Aug 2010
Posts: 26
Likes: 0
Received 0 Likes
on
0 Posts
During acceleration the wt of the nut will creat a force in the CCW direction in the RR. Thats why bike pedal has a reverse thread on one side to keep it tight. When I drive on track I slide a lot and from rolling to sliding I can hear my rpm goes up faster than any no sliding accelerations. This I believe creates the force necessary to break the nut loose and bind up the spine. I have Hankook rs3 tires and I try to have a little fun at the corners whenever I can. This is the reason that I am willing to bet that the RR has the most tendency to bind and potential failure. Under calibrated torque wrench does help either (i did that; but the spine still bound with my friends torque wrench) I suppose someone could jack the rear up and try to spine the wheel or just the hub to test this theory. Check the nut. Then do the same again, but brake really hard--this action could loosen LR and tighten the RR.
10-21-2012, 11:34 PM
#56
Intermediate
Join Date: Aug 2010
Posts: 26
Likes: 0
Received 0 Likes
on
0 Posts
Don't try the test I suggested. Too dangerous without proper equipment. From rolling to sliding the transmission is under stored energy and create more acceleration than anticipated and it's difficult to duplicate that with wheel up in the air.
10-21-2012, 11:46 PM
#57
Intermediate
Join Date: Aug 2010
Posts: 26
Likes: 0
Received 0 Likes
on
0 Posts
To Ir-fuel
The tapes were two piece and there were no overlap at time of torquing Then they moved and overlap each other. The nut tape is om top. Then I re-torqued it with nut removal and regrease with my friends properly calibrated torque wrench. At this time there was some overlap but I found a little notch on the tape that is on the nut. The tale notch lines up with the upper side of the wheel tape. After that session the nut moved CCW to the degree shown. Always easier to loosen the RR after the spine binding as compared to the other side.
The tapes were two piece and there were no overlap at time of torquing Then they moved and overlap each other. The nut tape is om top. Then I re-torqued it with nut removal and regrease with my friends properly calibrated torque wrench. At this time there was some overlap but I found a little notch on the tape that is on the nut. The tale notch lines up with the upper side of the wheel tape. After that session the nut moved CCW to the degree shown. Always easier to loosen the RR after the spine binding as compared to the other side.
10-22-2012, 12:47 AM
#58
Rennlist Member
This is becoming a pet peeve of mine... it's not about the whole wheel rotating relative to the hub. It's about the CL nut+spline mechanism rotating relative to the hub. There's a HUGE difference.
No one's arguing that the wheel should remain largely stationary rel. to the wheel hub. Agree that's what the 5 drive pins are for.
A failing wheel hub/CL nut doesn't hold torque and allows the CL nut to rotate under stress. Anti-clockwise in the RR corner, clockwise in the LR. Heck, we have a picture in this very thread so there's no debate around this point--the nut is well capable of rotating WITH SPLINES PROPERLY ENGAGED. I've seen it myself countless times at the track.
As the hub wears and the CL nut rotates, the splines are designed to stop the rotation within a 10-15 degree range. But it's an awfully big load on a small part. Over time you see deep scoring marks on the inner half of the spline assembly.
What happens beyond that is anybody's guess. We've seen too many pictures of wheel loss around here.
No one's arguing that the wheel should remain largely stationary rel. to the wheel hub. Agree that's what the 5 drive pins are for.
A failing wheel hub/CL nut doesn't hold torque and allows the CL nut to rotate under stress. Anti-clockwise in the RR corner, clockwise in the LR. Heck, we have a picture in this very thread so there's no debate around this point--the nut is well capable of rotating WITH SPLINES PROPERLY ENGAGED. I've seen it myself countless times at the track.
As the hub wears and the CL nut rotates, the splines are designed to stop the rotation within a 10-15 degree range. But it's an awfully big load on a small part. Over time you see deep scoring marks on the inner half of the spline assembly.
What happens beyond that is anybody's guess. We've seen too many pictures of wheel loss around here.
Join the club!!
Re-test RR torque specs before each session. If it gets to the point where it gets loose every time I'll replace wheel hub and CL nut.
This is strictly MY OWN interpretation in the absence of proper guidance from Porsche. It's a shame we have to resort to such couch-engineer techniques. I'm all ears if anyone has a more educated view.
Re-test RR torque specs before each session. If it gets to the point where it gets loose every time I'll replace wheel hub and CL nut.
This is strictly MY OWN interpretation in the absence of proper guidance from Porsche. It's a shame we have to resort to such couch-engineer techniques. I'm all ears if anyone has a more educated view.
IMO, if a CL bolt can't hold torque for a track day and is becoming lose between sessions, there has got to be a major issue (assuming the wrench is calibrated and the insallation procedure as been followed)..
And as for your question about the secondary spline mechanism, if it were my car and there had been enough rotation to goudge the seconadaries against the hub, i'd be timing out that hub and replacing...
I think we all need to be reporting these type of incidents you, mdrums and others have raised above and make it Porsche's responsibility to make a call on cause and solution...
10-22-2012, 09:43 PM
#59
Rennlist Member
Fact is, Porsche DOES NOT have a guideline on this particular issue.
There's the CL inspection tech bulletin that's been shared around. The present CL-losing-torque issue is a precursor to those ills, to which there is no official answer.
Most dealers remain oblivious to CL issues and can't even change wheels according to specs (off the ground, torque, loosen, retorque, splines out). That's certainly the case with Jebsen over here. Told them the whole deal, showed them the tech bulletin, and the best they can do is "sorry this loosening situation is currently undocumented... can't do anything until your hub looks shot up like those pictures in the bulletin..."
That's what they said. What they didn't say was their "warranty" won't cover one bit if my hub and drive pins eventually get all banged up. "Wear and tear" and "track use" is just on the tip of their heathen tongues.
We're very much alone on this issue. Not that I ever expected Porsche to watch the backs of their customers.
There's the CL inspection tech bulletin that's been shared around. The present CL-losing-torque issue is a precursor to those ills, to which there is no official answer.
Most dealers remain oblivious to CL issues and can't even change wheels according to specs (off the ground, torque, loosen, retorque, splines out). That's certainly the case with Jebsen over here. Told them the whole deal, showed them the tech bulletin, and the best they can do is "sorry this loosening situation is currently undocumented... can't do anything until your hub looks shot up like those pictures in the bulletin..."
That's what they said. What they didn't say was their "warranty" won't cover one bit if my hub and drive pins eventually get all banged up. "Wear and tear" and "track use" is just on the tip of their heathen tongues.
We're very much alone on this issue. Not that I ever expected Porsche to watch the backs of their customers.
Crex have you approached Porsche regarding you CL bolts coming lose? Did they have any light to shed on this?
IMO, if a CL bolt can't hold torque for a track day and is becoming lose between sessions, there has got to be a major issue (assuming the wrench is calibrated and the insallation procedure as been followed)..
And as for your question about the secondary spline mechanism, if it were my car and there had been enough rotation to goudge the seconadaries against the hub, i'd be timing out that hub and replacing...
I think we all need to be reporting these type of incidents you, mdrums and others have raised above and make it Porsche's responsibility to make a call on cause and solution...
IMO, if a CL bolt can't hold torque for a track day and is becoming lose between sessions, there has got to be a major issue (assuming the wrench is calibrated and the insallation procedure as been followed)..
And as for your question about the secondary spline mechanism, if it were my car and there had been enough rotation to goudge the seconadaries against the hub, i'd be timing out that hub and replacing...
I think we all need to be reporting these type of incidents you, mdrums and others have raised above and make it Porsche's responsibility to make a call on cause and solution...
03-21-2013, 04:56 AM
#60
Intermediate
Join Date: Aug 2010
Posts: 26
Likes: 0
Received 0 Likes
on
0 Posts
I am happy to report that after the recent hub recall/replacement the rear nuts stayed tight after 4--25 min track driving at the tires adhesion limits (michellin pilot super sports). The pins were loose and easy to push in and out. So, get them replaced if u have issues of binding pins. Will do another track day soon and report back later.