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914World.com _ 914World Garage _ Rear Wheel Bearing Difference
Posted by: 914Sixer Jan 15 2017, 03:50 PM
For months now I have maintained there is a big difference in the quality of the new rear bearings verses the original ones. Today I had time to compare an original FAG (Germany)and a new SKF (Italy) bearing shells. MY conclusion is what I suspected, the new ones are NOT the same. I took pictures and measurements to document what I saw. I hope the pictures let you see the difference. Guess which one is the original German one!
Attached image(s)
Posted by: Krieger Jan 15 2017, 06:35 PM
I am new to this discussion, but may be a victim. There is an obvious visual and measurable difference in the two parts your measuring, but overall don't they go by OD/ID and some sort of load rating? I had heard that these are the same bearings they use in Boxster. If so, is the bearing held in the same way?
Posted by: Perry Kiehl Jan 15 2017, 07:26 PM
I wonder what the age cut off for these are. I've got a stash of several sets.
Posted by: ConeDodger Jan 15 2017, 08:08 PM
I am new to this discussion, but may be a victim. There is an obvious visual and measurable difference in the two parts your measuring, but overall don't they go by OD/ID and some sort of load rating? I had heard that these are the same bearings they use in Boxster. If so, is the bearing held in the same way?
That's what Brad Roberts tells me. It's a Boxster part so it should be a Porsche parts counter part.
Posted by: Krieger Jan 15 2017, 08:36 PM
The Boxster is about 800lbs heavier too. About 200 each corner. Maybe the grease vs no grease or crappy grease is the real issue?
Posted by: 914Sixer Jan 15 2017, 09:57 PM
Yes, the Boxster bearing is the same item. The SKF was factory greased when I installed it. The FAG had smaller bearings than the SKF. Not sure if that made any difference.
Posted by: mbseto Jan 16 2017, 09:01 AM
And those Boxster guys know how to pick a bearing...
Posted by: falcor75 Jan 16 2017, 01:22 PM
Just as a heads up. I live in Sweden and have a friend from uni that now works for SKF. Apparently fake bearings are an increasing problem. They have 6 people spread worldwide that work with nothing but tracking down and siezing counterfit bearings.
http://www.skf.com/binary/21-252392/Counterfeiting%2Bbrochure%2B-%2B6940_1%2BEN_tcm_12-252392.pdf
Posted by: Krieger Jan 16 2017, 01:28 PM
Mats. Thank you for this information. Crappy to hear, but it may explain some of the problems...
Posted by: altitude411 Jan 17 2017, 12:43 PM
Just as a heads up. I live in Sweden and have a friend from uni that now works for SKF. Apparently fake bearings are an increasing problem. They have 6 people spread worldwide that work with nothing but tracking down and siezing counterfit bearings.
http://www.skf.com/binary/21-252392/Counterfeiting%2Bbrochure%2B-%2B6940_1%2BEN_tcm_12-252392.pdf
(knock knock) Open the door...BEA!!!
*Bearing enforcement agency...
Posted by: jd74914 Jan 17 2017, 12:57 PM
Interesting. It looks like they are trying to save some material cost in the races.
Do they have the same number of balls? If they do I would expect the newer ones to be stronger given larger balls.
What's the failure mechanism? I assume people notice slop, but are the balls or races failing?
Perhaps there is some surface hardness issue? Or a preload mismatch? Do Boxsters have the same loading a 914's? I feel like grease shouldn't be an issue since they are pre-greased and the fact that the bearing world should have a pretty good handle on greases...
Posted by: worn Jan 17 2017, 05:28 PM
I would expect the newer ones to be stronger given larger balls.
Yeah - the young get all the credit in this country...
Posted by: 914Sixer Jan 17 2017, 07:31 PM
Sloppy bearing after installation. Varying degrees deflection from center. Using SIR tool kit to install.
Posted by: 914_teener Jan 17 2017, 08:38 PM
Sloppy bearing after installation. Varying degrees deflection from center. Using SIR tool kit to install.
Bigger and less balls does not equal stronger bearing.
It means more bearing deflection as noted above and the same force distributed as point loads on the race, meaning it most probably will wear out faster.....so they can sell more bearings.
Think less cereal.....same size box.
Or...just like longer is not better...bigger balls is not stronger.......more balls is better.
Posted by: mb911 Jan 17 2017, 09:21 PM
I am surprised no one has turned this into a cottage industry. I have a manufacturing background and can see the need but I have no background in bearings.
Someone out there should make a quality part.
Posted by: jd74914 Jan 18 2017, 06:54 AM
Bigger and less balls does not equal stronger bearing.
It means more bearing deflection as noted above and the same force distributed as point loads on the race, meaning it most probably will wear out faster.....so they can sell more bearings.
Or...just like longer is not better...bigger balls is not stronger.......more balls is better.
That's why I'm curious as to the count. If they did go the less balls route to save money the faster wearing makes perfect sense. The race dimensions don't do anything for me-pretty sure it's probably plenty stiff and the actual failure is because of increased point loading.
I am surprised no one has turned this into a cottage industry. I have a manufacturing background and can see the need but I have no background in bearings.
Someone out there should make a quality part.
Pretty specialized manufacturing though. I would imagine their is quite a bit of development into the surface finish, hardness,, etc-not to mentioning the machines. Now a smaller bearing company (like an RBC, Enduro, etc. might do well to reproduce though the market is quite small).
Posted by: 6freak Jan 18 2017, 09:04 AM
I wonder what the age cut off for these are. I've got a stash of several sets.
bearings do have a shelf life beleave it or not and your supposed to turn them over every year... because the earth has a constant vibration
and the ball train has a harmonic point (vibration) at a set speed which cause`s premature failure ,change the amount of balls and the harmonics change and mass dampens vibration....... 
Posted by: JoeDees Jan 18 2017, 09:45 AM
Just as a heads up. I live in Sweden and have a friend from uni that now works for SKF. Apparently fake bearings are an increasing problem. They have 6 people spread worldwide that work with nothing but tracking down and siezing counterfit bearings.
http://www.skf.com/binary/21-252392/Counterfeiting%2Bbrochure%2B-%2B6940_1%2BEN_tcm_12-252392.pdf
I heard a report on BBC or NPR about that. They said that auto parts are counterfeited even more than designer clothes/purses. The report also said that the fakes even end up in reputable parts stores who have no idea they they're fake.
Posted by: SixerJ Jan 18 2017, 11:56 AM
Does anyone know the old FAG part number and dims of the bearing, does 75x42x37 sound right or... Perry are your NOS in boxes still, any ID info?
Think I might have found a NOS set and figuring that even though they have a shelf life they may just be just fine or possibly still better than the POS new stuff floating around
Posted by: 914_teener Jan 18 2017, 01:10 PM
I wonder what the age cut off for these are. I've got a stash of several sets.
bearings do have a shelf life beleave it or not and your supposed to turn them over every year... because the earth has a constant vibration
and the ball train has a harmonic point (vibration) at a set speed which cause`s premature failure ,change the amount of balls and the harmonics change and mass dampens vibration....... At that point....your swing arm droops.
I think you.ve lost your bearing.
Posted by: 6freak Jan 18 2017, 04:24 PM
I wonder what the age cut off for these are. I've got a stash of several sets.
bearings do have a shelf life beleave it or not and your supposed to turn them over every year... because the earth has a constant vibration
and the ball train has a harmonic point (vibration) at a set speed which cause`s premature failure ,change the amount of balls and the harmonics change and mass dampens vibration....... At that point....your swing arm droops.
I think you.ve lost your bearing.
look it up then get back to me
Posted by: 914_teener Jan 18 2017, 08:18 PM
I wonder what the age cut off for these are. I've got a stash of several sets.
bearings do have a shelf life beleave it or not and your supposed to turn them over every year... because the earth has a constant vibration
and the ball train has a harmonic point (vibration) at a set speed which cause`s premature failure ,change the amount of balls and the harmonics change and mass dampens vibration....... At that point....your swing arm droops.
I think you.ve lost your bearing.
look it up then get back to me
Nothing to look up.
Attempted double entendre.
Posted by: mepstein Jan 18 2017, 09:05 PM
Bearings have a shelf life due to the grease aging out. That's an easy fix. Replace the grease. You have to grease the front wheel bearings anyway and the boxter spec racers are replacing the grease on the rear bearings with new and more before installation. There's a video or two on how to repack a rear hub bearing.
Posted by: 6freak Jan 19 2017, 08:18 AM
storage
The conditions under which bearings and seals are stored can have an adverse effect on their performance. Inventory control can also play an important role in performance, particularly if seals are involved. Therefore, SKF recommends a "first in, first out" inventory policy. .
Storage conditions
To maximize the service life of bearings, SKF recommends the following basic housekeeping practices: Store bearings flat, in a vibration-free, dry area with a cool, steady temperature.
Control and limit the relative humidity of the storage area as follows: 75% at 20 °C (68 °F)
60% at 22 °C (72 °F)
50% at 25 °C (77 °F)
Keep bearings in their original unopened packages until immediately prior to mounting to prevent the ingress of contaminants and corrosion.
Bearings that are not stored in their original packaging should be well protected against corrosion and contaminants.
.
Shelf life of open bearings
SKF bearings are coated with a rust-inhibiting compound and suitably packaged before distribution. For open bearings, the preservative provides protection against corrosion for approximately three years, provided the storage conditions are appropriate. .
Shelf life of sealed bearings
The maximum storage interval for sealed SKF bearings is dictated by the lubricant inside the bearings. Lubricant deteriorates over time as a result of ageing, condensation, and separation of the oil and thickener. Therefore, sealed bearings should not be stored for more than three years. .
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Posted by: mepstein Jan 19 2017, 11:58 AM
What's funny is once the bearing is in our car, we might let it go for 20+ years. Heat, cold, humidity, whatever.
Posted by: 914_teener Jan 19 2017, 12:11 PM
What's funny is once the bearing is in our car, we might let it go for 20+ years. Heat, cold, humidity, whatever.
What was posted has more to do with legal and liability than engineering.
Most distributors at our level don.t have means to track FIFO and when they go back to try and warranty a lot they have such a small claim it.s not worth it.
While it.s worth noting about care of bearings in storage, once they are in the car the grease is being distributed and iron oxide (rust) which will permantly f up the bearing is less likely to form if you drive your car regularly. One more reason to get out and drive your car.
If it fails in the car after a few years....they can always claim abuse or road damage. I think the OP makes a good point about the differences in the two manuf. of the bearings. When I replaced them in my car.....now a few years back I used FAG.s
Posted by: 6freak Jan 19 2017, 03:29 PM
What's funny is once the bearing is in our car, we might let it go for 20+ years. Heat, cold, humidity, whatever.
because its not sitting static and the lube moves around.. remember earth vibrates at a constant? and the bearing dont roll on the shelf but they do vibrate.. and yes theres alot to do with what type of grease in the bearings, but bearings with no lube have a short shelf life! because no grease film between the balls and races...the stuff gets deep hahahah the microscopic film of grease is what the bearings ride on not the race
Posted by: 914Sixer Jan 19 2017, 08:29 PM
See tygaboys post. His picture of the bearing all over the place is what I am complaining about. Mine was not that loose but even when tightened up to spec both sides wiggled more than they should have.
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