Axel Nut & wheel bearing Failure (Long)
12-29-2009, 06:54 PM
#1
Rennlist Member
Thread Starter
Axel Nut & wheel bearing Failure (Long)
(Non-catastrophic thank God)
Amendment to original post below in BLUE: {Here is a clue that your rear wheel bearing may be/is going out..prior to a catastrophe, God forbid}. You will get lots lights on the dash...ABS light, lights you didn't even know you had such as the ABD light. What the hell is ABD? Your speedometer will also be going whacko. If this happens, STOP driving and take a tow in. Inspect the heck out of your wheel bearings, be certain the left rear (Self loosening) is torqued to 300 Ft Lbs. You may have just lost a wheel sensor...this will give similar symptoms.
If you don't catch the problem you are looking potentially at:
Broken neck or broken car, or both...
New bearings,
New Axle
CV Joints
Wheel carrier
BTW, thanks for all the great feedback on my latest disaster...the only other disasters I have had would be broken drop links and failed brass synchros. The synchros are now steel!
A few weeks ago I was driving Laguna Seca with the Northern California Racing Club, great event by the way. I really pushed the car through the Corkscrew...in fact, the corner worker and I met up the following day at another track...he mentioned that I was really scooting down the Corkscrew. I was intentionally blasting though this part of the track to see how my FD Motorsports Platinum Rod and their Short Shift Kit worked under a side G load...where a shift from 2nd to third is necessary with a right sweeper coming out of the Corkscrew. This sort of turn must put a substantial load on the left side of the car. BTW, the FD Motorsports stuff worked great, and the Stage III Muffs passed 92 dB sound...but I digress....also note that I drove the car into town for gas. I noticed a little squeaking sound when I turned the car to the right, hmmm said I....noting that the car had been through Tech a few days earlier and the bearings were fine.
The next day I headed to to Willow Springs for the weekend. Ran two session, and note that the load on the car is on the left side, turn 8 and 9, as well as Turn 2. For the third session, I mounted up some sticker Hoosiers, ready to rumble!
After torquing down the wheels, the last being the left rear, I noticed that after the lug nuts were torqued do spec, the left rear had a definite wobble...I concluded I had just lost a wheel bearing and my weekend was toast..took the car to the shop for repairs.
Today I get a call from the shop that the axle nut was gone and the end of the axle sheared off. There was a wee bit of thread remaining. They think the bearing went and the wobbling wheel may have contributed to the shearing of the axle.
I realize that the wheel is held to the rear upright by lug nuts, but the thought that the left rear wheel was wobbling around under right turn G loads is a bit terrifying in retrospect.
I was on original axles, with about 75,000 miles on them. The car sees about 7 track days a year, or about 63 events over the past 9 years. I was on my third set of wheel bearings....here is what the shop and I plan to do for the future. Every 2 years we are changing out the rear wheel bearings, maybe the front as well. The fronts don't seem so problematic, noting that the fronts don't carry nearly the load of the rears with 60/40 weight distribution, and the rears sport larger tires, 285 rear compared to 235 front. Also note that I usually run Nitto NT-01 tires or RA-1s if I can get them. They don't have near the bite of the Hoosiers....I have only run 1 set of Hoosiers the past nine years. At $1,200 a set, a bit on the spendy side.
In conclusion, whenever you have your car up in the air during a track weekend, take a second and check the wheel bearings but putting pressure on the top of the tire and attempting to move it back and forth. If there is noticeable movement, have an expert examine the wheel. Also, don't be afraid to peek into the hub to be certain the axle nut is secure. You may have just had the car tech'd, but the bearings don't know that...they fail when they feel like it.
Amendment to original post below in BLUE: {Here is a clue that your rear wheel bearing may be/is going out..prior to a catastrophe, God forbid}. You will get lots lights on the dash...ABS light, lights you didn't even know you had such as the ABD light. What the hell is ABD? Your speedometer will also be going whacko. If this happens, STOP driving and take a tow in. Inspect the heck out of your wheel bearings, be certain the left rear (Self loosening) is torqued to 300 Ft Lbs. You may have just lost a wheel sensor...this will give similar symptoms.
If you don't catch the problem you are looking potentially at:
Broken neck or broken car, or both...
New bearings,
New Axle
CV Joints
Wheel carrier
BTW, thanks for all the great feedback on my latest disaster...the only other disasters I have had would be broken drop links and failed brass synchros. The synchros are now steel!
A few weeks ago I was driving Laguna Seca with the Northern California Racing Club, great event by the way. I really pushed the car through the Corkscrew...in fact, the corner worker and I met up the following day at another track...he mentioned that I was really scooting down the Corkscrew. I was intentionally blasting though this part of the track to see how my FD Motorsports Platinum Rod and their Short Shift Kit worked under a side G load...where a shift from 2nd to third is necessary with a right sweeper coming out of the Corkscrew. This sort of turn must put a substantial load on the left side of the car. BTW, the FD Motorsports stuff worked great, and the Stage III Muffs passed 92 dB sound...but I digress....also note that I drove the car into town for gas. I noticed a little squeaking sound when I turned the car to the right, hmmm said I....noting that the car had been through Tech a few days earlier and the bearings were fine.
The next day I headed to to Willow Springs for the weekend. Ran two session, and note that the load on the car is on the left side, turn 8 and 9, as well as Turn 2. For the third session, I mounted up some sticker Hoosiers, ready to rumble!
After torquing down the wheels, the last being the left rear, I noticed that after the lug nuts were torqued do spec, the left rear had a definite wobble...I concluded I had just lost a wheel bearing and my weekend was toast..took the car to the shop for repairs.
Today I get a call from the shop that the axle nut was gone and the end of the axle sheared off. There was a wee bit of thread remaining. They think the bearing went and the wobbling wheel may have contributed to the shearing of the axle.
I realize that the wheel is held to the rear upright by lug nuts, but the thought that the left rear wheel was wobbling around under right turn G loads is a bit terrifying in retrospect.
I was on original axles, with about 75,000 miles on them. The car sees about 7 track days a year, or about 63 events over the past 9 years. I was on my third set of wheel bearings....here is what the shop and I plan to do for the future. Every 2 years we are changing out the rear wheel bearings, maybe the front as well. The fronts don't seem so problematic, noting that the fronts don't carry nearly the load of the rears with 60/40 weight distribution, and the rears sport larger tires, 285 rear compared to 235 front. Also note that I usually run Nitto NT-01 tires or RA-1s if I can get them. They don't have near the bite of the Hoosiers....I have only run 1 set of Hoosiers the past nine years. At $1,200 a set, a bit on the spendy side.
In conclusion, whenever you have your car up in the air during a track weekend, take a second and check the wheel bearings but putting pressure on the top of the tire and attempting to move it back and forth. If there is noticeable movement, have an expert examine the wheel. Also, don't be afraid to peek into the hub to be certain the axle nut is secure. You may have just had the car tech'd, but the bearings don't know that...they fail when they feel like it.
Last edited by Martin S.; 12-31-2009 at 05:25 PM. Reason: New Info
12-29-2009, 08:56 PM
#3
Rennlist Member
Thread Starter
The cost?
I am replacing both axles, just to be sure...List price for a 993 axle is about $700...lots of labor to replace the bearings...replacing both sides as well. I see the $2,000 to $2,500 figure coming up, wifey will not be thrilled!
12-29-2009, 11:12 PM
#5
Addict
Rennlist Member
Rennlist Member
Wait until you find out it's actually the hub, then spend it all again plus the hub.
The way I noticed the axle nut was sheared was that my wheel crest was gone. The brake calipers do a great job of holding the rotor and axle on
The way I noticed the axle nut was sheared was that my wheel crest was gone. The brake calipers do a great job of holding the rotor and axle on
12-29-2009, 11:18 PM
#6
Rennlist Member
Thread Starter
I am lucky.....
"The brake calipers do a great job of holding the rotor and axle on". Yup, that's what holds it together. I am very thankful that the damage was purely mechanical...let's hope I didn't ruin the wheel carrier.
The five (5) stages of mechanical failure (Works for job loss, divorce, any major life calamity) {Note below in extremely poor taste}
1-Denial-"this can't be happening to me", No crying. Not accepting or even acknowledging the loss.
2-Anger-"why me?", feelings of wanting to fight back or get even with ???
3-Bargaining-bargaining often takes place , or attempting to make deals with God to stop or change the loss. Begging, wishing, praying...
4-Depression-overwhelming feelings of hopelessness, frustration, bitterness, self pity, mourning ....
5-Acceptance-better figure out a way to pay for it....now let's see if I sell my ????, Then.....
The five (5) stages of mechanical failure (Works for job loss, divorce, any major life calamity) {Note below in extremely poor taste}
1-Denial-"this can't be happening to me", No crying. Not accepting or even acknowledging the loss.
2-Anger-"why me?", feelings of wanting to fight back or get even with ???
3-Bargaining-bargaining often takes place , or attempting to make deals with God to stop or change the loss. Begging, wishing, praying...
4-Depression-overwhelming feelings of hopelessness, frustration, bitterness, self pity, mourning ....
5-Acceptance-better figure out a way to pay for it....now let's see if I sell my ????, Then.....
12-30-2009, 10:22 AM
#7
Rennlist Member
Lots of perfectly good used axels (IMHO) around for $100-150ea: add 4 boot kits w. moly lube & clamps for $60, and rebuild to new in <2hrs.
Any shop can drift out the bearing .... or buy the press for home use. Bearing is ~$65 ...
Any shop can drift out the bearing .... or buy the press for home use. Bearing is ~$65 ...
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12-30-2009, 12:15 PM
#11
Burning Brakes
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Sounds expensive for the axle. I paid 500 for a new one reciently and installed my self. Changing a bearing is not that hard once you know how. I change my own. Worth buying the tools if you are going to track a lot. If your not mechanically inclined then pay a pro but fixing this stuff is half the fun for me.
Plus, put a locking nut setup on your new axles. If you are going to track a lot, consider pulling the boots, putting some better, high temp grease in the CVs, new stock axles dont come with much and Ive even seen stock ones with the greas pretty dried up in there.
On my race axles we had them machined apart to be servicable and had them REMMED/ micro polished. Well see how long these last under race conditions but so far so good. Ive even seen cooling setups to cool the inner CV joint.
With that much wobble, check your brakes and rear carrier to be sure they are straight.
Good luck...
Plus, put a locking nut setup on your new axles. If you are going to track a lot, consider pulling the boots, putting some better, high temp grease in the CVs, new stock axles dont come with much and Ive even seen stock ones with the greas pretty dried up in there.
On my race axles we had them machined apart to be servicable and had them REMMED/ micro polished. Well see how long these last under race conditions but so far so good. Ive even seen cooling setups to cool the inner CV joint.
With that much wobble, check your brakes and rear carrier to be sure they are straight.
Good luck...
12-30-2009, 03:31 PM
#12
Instructor
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Do you have more info on how the outer CV was machined to make it serviceable? I have taken one apart and they appear to be friction welded to the stub axle.
12-30-2009, 04:01 PM
#13
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Thread Starter
The word from an expert (Not me!) (A must read?)
This note was sent to me by a Porsche Expert...it has some very pertinent info:
"The point of a Tech Inspection is not to fill out the form, it is to prevent catastrophe, and catch maintenance lapses, which it failed to do in your case. Don't drive the car from failure to failure. The left side axle nuts are self-loosening because of the direction of driving. The right side are self-tightening. Every year, minimum, TORQUE ALL FOUR AXLE NUTS. Not the lug bolts, I mean the big 330 foot-pound center nut on all four axle stub ends. The left rear was probably not tight, which leads to premature wheel bearing failure. We use a tool we call the BFT, the Big Fockin Torque wrench, it is a huge torque wrench about 4 feet long. An impact gun is not accurate."
I am henceforth to torque my axel nuts with a Big Fockin Torque wrench. These big wrenches cost about $800 new...they are the ones you see the GT3 Cub Car guys using after they change a wheel.
"The point of a Tech Inspection is not to fill out the form, it is to prevent catastrophe, and catch maintenance lapses, which it failed to do in your case. Don't drive the car from failure to failure. The left side axle nuts are self-loosening because of the direction of driving. The right side are self-tightening. Every year, minimum, TORQUE ALL FOUR AXLE NUTS. Not the lug bolts, I mean the big 330 foot-pound center nut on all four axle stub ends. The left rear was probably not tight, which leads to premature wheel bearing failure. We use a tool we call the BFT, the Big Fockin Torque wrench, it is a huge torque wrench about 4 feet long. An impact gun is not accurate."
I am henceforth to torque my axel nuts with a Big Fockin Torque wrench. These big wrenches cost about $800 new...they are the ones you see the GT3 Cub Car guys using after they change a wheel.
12-30-2009, 05:34 PM
#14
Rennlist Member
This note was sent to me by a Porsche Expert...it has some very pertinent info:
I am henceforth to torque my axel nuts with a Big Fockin Torque wrench. These big wrenches cost about $800 new...they are the ones you see the GT3 Cub Car guys using after they change a wheel.
I am henceforth to torque my axel nuts with a Big Fockin Torque wrench. These big wrenches cost about $800 new...they are the ones you see the GT3 Cub Car guys using after they change a wheel.
12-30-2009, 05:56 PM
#15
This note was sent to me by a Porsche Expert...it has some very pertinent info:
"The point of a Tech Inspection is not to fill out the form, it is to prevent catastrophe, and catch maintenance lapses, which it failed to do in your case. Don't drive the car from failure to failure. The left side axle nuts are self-loosening because of the direction of driving. The right side are self-tightening. Every year, minimum, TORQUE ALL FOUR AXLE NUTS. Not the lug bolts, I mean the big 330 foot-pound center nut on all four axle stub ends. The left rear was probably not tight, which leads to premature wheel bearing failure. We use a tool we call the BFT, the Big Fockin Torque wrench, it is a huge torque wrench about 4 feet long. An impact gun is not accurate."
I am henceforth to torque my axel nuts with a Big Fockin Torque wrench. These big wrenches cost about $800 new...they are the ones you see the GT3 Cub Car guys using after they change a wheel.
"The point of a Tech Inspection is not to fill out the form, it is to prevent catastrophe, and catch maintenance lapses, which it failed to do in your case. Don't drive the car from failure to failure. The left side axle nuts are self-loosening because of the direction of driving. The right side are self-tightening. Every year, minimum, TORQUE ALL FOUR AXLE NUTS. Not the lug bolts, I mean the big 330 foot-pound center nut on all four axle stub ends. The left rear was probably not tight, which leads to premature wheel bearing failure. We use a tool we call the BFT, the Big Fockin Torque wrench, it is a huge torque wrench about 4 feet long. An impact gun is not accurate."
I am henceforth to torque my axel nuts with a Big Fockin Torque wrench. These big wrenches cost about $800 new...they are the ones you see the GT3 Cub Car guys using after they change a wheel.
Your source is correct about the self loosening property of the left side axle and lug nuts. Mopars are the only ones that I have seen that use( or at least used to use) the correct reversed threads on those items