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> Rear Wheel Bearing Difference, Comparison that may have caused my failures
914Sixer
post Jan 15 2017, 03:50 PM
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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!


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Krieger
post Jan 15 2017, 06:35 PM
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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?
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IronHillRestorations
post Jan 15 2017, 07:26 PM
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I wonder what the age cut off for these are. I've got a stash of several sets.
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ConeDodger
post Jan 15 2017, 08:08 PM
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QUOTE(Krieger @ Jan 15 2017, 09:35 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?


That's what Brad Roberts tells me. It's a Boxster part so it should be a Porsche parts counter part.
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Krieger
post Jan 15 2017, 08:36 PM
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The Boxster is about 800lbs heavier too. About 200 each corner. Maybe the grease vs no grease or crappy grease is the real issue?
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914Sixer
post Jan 15 2017, 09:57 PM
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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.
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mbseto
post Jan 16 2017, 09:01 AM
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And those Boxster guys know how to pick a bearing...
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falcor75
post Jan 16 2017, 01:22 PM
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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/Counte...m_12-252392.pdf
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Krieger
post Jan 16 2017, 01:28 PM
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Mats. Thank you for this information. Crappy to hear, but it may explain some of the problems...
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altitude411
post Jan 17 2017, 12:43 PM
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QUOTE(falcor75 @ Jan 16 2017, 12:22 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/Counte...m_12-252392.pdf


(knock knock) Open the door...BEA!!! (IMG:style_emoticons/default/ar15.gif) (IMG:style_emoticons/default/hide.gif)

*Bearing enforcement agency...
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jd74914
post Jan 17 2017, 12:57 PM
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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...
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worn
post Jan 17 2017, 05:28 PM
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QUOTE(jd74914 @ Jan 17 2017, 10:57 AM) *

I would expect the newer ones to be stronger given larger balls.


Yeah - the young get all the credit in this country...
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914Sixer
post Jan 17 2017, 07:31 PM
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Sloppy bearing after installation. Varying degrees deflection from center. Using SIR tool kit to install.
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914_teener
post Jan 17 2017, 08:38 PM
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QUOTE(914Sixer @ Jan 17 2017, 05:31 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. (IMG:style_emoticons/default/shades.gif)
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mb911
post Jan 17 2017, 09:21 PM
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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.
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jd74914
post Jan 18 2017, 06:54 AM
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QUOTE(914_teener @ Jan 17 2017, 09:38 PM) *

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. (IMG:style_emoticons/default/shades.gif)


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.

QUOTE(mb911 @ Jan 17 2017, 10:21 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.


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).
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6freak
post Jan 18 2017, 09:04 AM
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QUOTE(Perry Kiehl @ Jan 15 2017, 05:26 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 (IMG:style_emoticons/default/wacko.gif) 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....... (IMG:style_emoticons/default/smile.gif)
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JoeDees
post Jan 18 2017, 09:45 AM
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QUOTE(falcor75 @ Jan 16 2017, 02:22 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/Counte...m_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.
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SixerJ
post Jan 18 2017, 11:56 AM
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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
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914_teener
post Jan 18 2017, 01:10 PM
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QUOTE(6freak @ Jan 18 2017, 07:04 AM) *

QUOTE(Perry Kiehl @ Jan 15 2017, 05:26 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 (IMG:style_emoticons/default/wacko.gif) 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....... (IMG:style_emoticons/default/smile.gif)



At that point....your swing arm droops.

I think you.ve lost your bearing.
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