Oil Filters: To hinge or not to hinge

[AnnapolisAirhead]

I innocently asked for a couple of oil filters for my '83 R100 and '76 R90/6 at my local BMW dealer (Bob's BMW in Jessup, MD). I was given a couple hinged filters with the explanation that it makes it simpler to install on bikes with crash bars. Since they both do, I thought that sounded reasonable.

Upon a recent read of one Oak's articles he was addressing the subject of 'O Ring Compression' on oil filters. Excellent information and it got me wondering if I've done mine right. I have crash bars, that were a pain to move (but worth it), but no oil cooler.

I've only run the bike for 3-4 minutes at a time, and one 1/4 mile test ride since being it out of an 8 year coma. So, if I have the wrong filter in, I'm really hoping I haven't done any damage to the bike. The old filter I removed was a straight through one, but the dealer told me they are harder to get anymore--I know Fram makes them, but I opted for a trip to the dealer.

Is there any difference between the compression on a hinged filter versus a straight one?

NEVERMIND: I re-read the other posts and am going for straight filters from http://www.beemerboneyard.com/oicrwaairfi.html

[20774]

Is there any difference between the compression on a hinged filter versus a straight one?

No...provided you get the comparable filter. One can measure the length of the straight one and find it to be exactly the length of the hinged one. And yes, the straight ones are supposed NLA but they're out there.

Also, supposedly, the hinged filters are stronger than the straight ones because of the metal rings that in the middle...they reduce the unsupported length. However, you give up some filter area, but I think the amount of filter area is probably over designed anyway.

I suspect Oak's discussion about o-ring compression is the large white o-ring which you need on the '83 but don't believe you need on the /6. Doesn't your /6 have another bolted cap inside the filter housing? This was the superior arrangement until they came up with the system started (IIRC) with the /7 machines. Provided you get the correct length hinged filter, it will make no difference on the large white o-ring compression ('83) one way or another. What does affect the o-ring compression is the depth of the filter canister that sits inside the engine block. If the canister is deeper than normal (greater than 3-3.5mm), then you might not get enough compression if you use the wrong number of shims and/or the cover gasket. If the canister depth is less than 3mm, then too many shims or leaving off the gasket could result in too much o-ring compression.

Rule of thumb - 3-3.5mm canister depth, use one shim no gasket. Deeper than 3.5mm, use multiple shims. Less than 3mm, use one shim and one paper gasket. YMMV...