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Discussion Starter · #1 ·
Good day all.

I've been doing some research into front hub/bearing replacement for my F30, but it has thrown up a more general topic on the thread pitch of the hub to knuckle bolts. The bearings are the same for many 1/2/3/4 series F models so I've posted this in the general forum.

The bolts are 80nm + 90 degree stretch bolts (I think), and pre-2016 they had a M12 bolt with a 1.5mm thread pitch. In 2016, the bearing part was replaced with a new version which is exactly the same except with a M12 1.25mm thread pitch. The 'new' parts are exchangeable retrospectively to all models, and I don't think BMW sell the 1.5mm pitch version anymore.

Can anyone comment on the 'benefits' of moving from a 1.5mm thread pitch to a 1.25mm thread pitch on these stretch bolts? I haven't seen any information on these bolts failing. Could it just be that the OEM supplier was changed?

I note that SKF sell both versions, with the 'old' 1.5mm version being available to purchase direct from SKF, but the 1.25mm version is only available to buy through stockists. I'm tempted to buy the ones available direct from SKF, but I'm aware BMW don't sell this type anymore...
 

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A finer thread bolt will,by design, have less stretch during the 90 degree tightening phase than the courser one, however I am sure the ultimate tensile strength of both bolts in their fully tightened and stretched condition should outweigh their design strength requirements significantly with suitable safety margins when taking into consideration their service life and any reduction in strength overtime due to corrosion, fatigue etc.

Unless there have been any service bulletins issued by BMW to state the finer course bolts should be retrofitted due to failures of the old ones then I’m in agreement with you fit the old ones if you can get them from the OEM supplier.


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Or just get OEM bearings = F_A_G (the bloody auto correction will delete the manufacturer written correctly).
 

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Discussion Starter · #4 ·
Or just get OEM bearings = F_A_G (the bloody auto correction will delete the manufacturer written correctly).
My review of the Schaeffler product catalog didn't yield any front bearing parts made by F_A_G. Neither the 'new' 1.25mm pitched version or the 'old' 1.5mm pitched version.

Can I find the OEM suppliers listed somewhere?
 

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I normally go on realoem and find the proper BMW on then put that into Google and le tit give you the OEM manufacturers for that PN … you can normally work out from that which ones are the original al equipment and which are the patterned parts


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Discussion Starter · #7 ·
Is this not the correct part?

I think you're right - it is.

Thank you very much for doing a bit of leg work there on my behalf - it wasn't expected and I appreciate it. For some reason, searching via my car's VIN takes me directly to that part - whereas when I tried yesterday I must have made a mistake which only got me to rear bearings.

I will research that bearing as you say, if that is the underlying supplier, it will undoubtedly be a more comfortable choice for me.

Thanks agin.
 
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