Front Wheel Bearing confusion

[95BMWIC]

Did a little search but didn't find exactly what I need.

I need to order front wheel bearings for the IX..

REAL OEM states the part number is 31211132284 which is 42 x 75.05 x 37

BMA Autoparts lists that size as 545495ADW - and does not cross reference the number above.. When I google that number I get 42 x 75 x 37 for some and 42 x 75.05 for others. This number also corresponds to E30 325i (ic) rear...

AutohausAZ has the part number 33411468747 listed for the IX front.

http://www.autohausaz.com/pn/33411468747

Im looking for FAG bearings..


So what the hell is going on?


Second Question - Is the wheel hub the same as a rear E30 (non IX)? Part numbers are different but I thought someone stated they were the same..?

[95BMWIC]

FAG lists 2 different kits for the IX (front and rear)

http://webcat.schaeffler-aftermarket.com/web/schaeffler/en_US/PKW/16/290/36/192/713%206671%2050_654/applicationSearch.xhtml?result=1465530605736&csc=1

This is from the online catalog from FAG - (Scaeffler owns them).. 42x75x37

HOWEVER

Looking at the 325i E30 (nonIX) REAR kit, the OEM reference numbers list the Front IX wheel bearing # 31211132284

http://webcat.schaeffler-aftermarket.com/web/schaeffler/en_US/PKW/16/290/36/192/713%206492%2070_654/applicationSearch.xhtml?result=1465531480323&csc=1

[nando]

I used a rear bearing in my front struts. No issues yet.

Pretty sure all rear bearings are the same. The rear hub, however, is not.

[95BMWIC]

So don't worry eh?

OK

Ordered from BAVAUTO.. Thanks!

[erwendell]

I just ran into the same confusion myself. I'm assuming that extra .05mm (about 0.002 (2 thousandths) in.) on the OD makes for more of an interference fit between the bearing and the housing. I'm wondering if that has something to do with higher loads on the front wheels vs rear or a difference in thickness or type of metal used for the bore in the front upright vs the rear trailing arm.

I just checked the 2017 FAG catalog and it still lists different part numbers for front and rear. What confuses the issue is that these are wheel bearing "kits" that include hardware such as the axle nut and the locking ring, and the pictures show differing included hardware. No idea why as the assembly is the same. For reference, the front is p/n 713 6671 50 and the rear is 713 6492 70. See https://webcat.schaeffler.com/web/sc....xhtml?reset=1

Everyone else using the same FAG p/n bearing (actual bearing #) on the front and the rear?

I'm going to order a couple and then run them by a micrometer before I put them in. My curiosity has been piqued. Maybe they're all 75.05mm and they're just truncating the measurement in the catalog.

BTW, anyone have a problem with me reviving old threads like this? Seems like I'm doing it right by searching and adding to the info that's already been collected.

[D.Martijn]

I used the same FAG bearings on the front and rear. Has no issues installi them or running them for over a year now

[The Dark Side of Will]

0.05mm = 0.002"... if the dimension actually is different, that's mostly just a tighter press fit in the front knuckles than the rear trailing arms.

[nrubenstein]

I have had no issues running the much cheaper .05mm smaller standard bearings. I've done that for over a decade.

[The Dark Side of Will]

Has anyone actually measured the "right" front bearing to see if it really is 0.05mm larger than the rear bearing?

[nando]

I have had no issues running the much cheaper .05mm smaller standard bearings. I've done that for over a decade.

Same here. Lots of track/autox in there too.

I'm sure it's larger or it wouldn't have a different part # and listing in the ETK. Who knows the reasoning, but the rear bearings definitely work just fine.

[ForcedFirebird]

I installed Nando's bearings all those years ago, and remember they were still definitely a press fit (EDIT: To add, I always freeze the bearings, still needed the press).

[Kershaw]

This is an ix 75.05mm front wheel bearing that's been sitting on the back up parts shelf for 5 or 6 years. I accidentally pressed halfway into the hub before realizing I forgot to press it into the strut first. Lol. When I tried to pull it off, the bearing came apart. Not sure the 1 inner race missing would affect the OD. That's the disclaimer.

75.05mm = 2.954724"
75mm = 2.952756"

Doesn't even look like 75mm though, looks like 2.9504" ish. 74.94mm.

[ForcedFirebird]

SPI calipers are lucky to be .001" +/- at 3". Do you have a 1,2,3 block to check it's accuracy? Then you can set it to "0" at 3" and count backwards - will be far more accurate anyways. :(

[Kershaw]

I'm not a machinist and these tools are probably around my age, so the measurements are certainly to be taken with a grain of salt. Unfortunately I do not have a 3" block.

[The Dark Side of Will]

I wouldn't expect to be able to pick up a 0.002" difference with calipers.