100GS Oil Filter Shim????

TaffyScouser · Dec 27, 2006

Have just dropped the oil on the bike and there was no shim in there. Many of the articles talk about the steel shim and it comes with the BMW filter kit. I know that there are spare parts not needed in the kit (copper washer, paper gasket etc) but can anyone shed some light on this one. have put the shim in there at moment as well as the white O ring and the black square sectioned ring. The order installed was
Hinged Oil Filter with attached rubber ring into oil cavity, metal shim on engine casing shelf, white o ring and then the Black o ring. All else was ok on the change. As the bike was stripped down, the oil cooler lines were not disturbed so I have not needed to use new crush washers on either side of the cooler take off unions.
The bike is a a May 1989 R100GS Bumble Bee with Oil cooler.

Sorry if this has been done to death but have phoned 2 BMW mechanics and there are differences of opinion as to the shim?????

Rob Farmer · Dec 27, 2006

The 80/81 G/s had a shim but all the later bikes didn't have one.

TaffyScouser · Dec 27, 2006

So I guess its oil out again and take the shim out. AAARRRGGGGHHHH

Thanks Rob ( again)

Graham W · Dec 27, 2006

ANDY MELTON said:
So I guess its oil out again and take the shim out. AAARRRGGGGHHHH

Thanks Rob ( again)

Just to throw another view into the ring - I'm new to GS's and by no means an expert, so I also worried about this when I did the first oil change on mine (1992 R100GS with oil cooler).

Mine DID have a shim, and the previous owner had noted its presence and position in the bikes handbook when he got the bike 15K miles before me. I therefore fitted a shim again, so it's done at least 20K miles, and possibly more, with one fitted and seems fine.

Later . . I've just looked at this: http://www.xmission.com/~wendell/GS/node22.html
which seems to show a shim (12 flat washer)

Maybe it doesn't matter too much? Or am I heading for a premature blow up? :confused:

Graham

Paradiso · Dec 27, 2006

Hi. There's a discussion of the issue here.
http://www.gunsmoke.com/motorcycling/r100gs/oil_filter/index.html

I've got a 1990 R100gs and I use the shim, but not the paper gasket.

Rob Farmer · Dec 27, 2006

It's a bit confusing isn't it?

The picture I posted earlier was from the BMW workshop manual. I do seem to remember having to fit the shim on my oil cooler on an old bike I had. The cover wouldn't pull down properly without it. I guess the best options to PM Steptoe.

This pictures from the BMW Mono G/S workshop manual and shows where the shims were used. The first bikes had a filter without the bonded washers on

Graham W · Dec 27, 2006

Ah, the link I posted was the BMW parts microfiche - so who knows!

Thinking about it more, I guess the big O ring needs to be compressed as you fasten the cover back down by enough to form a good seal, but not by so much that it is damaged in any way. Maybe there are variations in the oil filter housing and cover tolerances so some bikes need it and others don't? Maybe as Rob implies it's a question of 'feel' as you tighten the cover down on your particular bike as to how it is pulling in and compressing the ring?

If it was know to run as previously assembled with good oil pressure on one hand and no leaks or other problems on the other, I'd personally probably put it back the same way.

Eng · Dec 27, 2006

FILTER SHIM

Hi,
there are so many variations with airheads over the years, but if you want a definitive answer and an explanation as to why, then type in "snowbum" to google Robert Fleischers' website, and look under his tech articles. This should answer your concerns!

Regards

Eng

cookie · Dec 27, 2006

my 94 PD has always had the shim and it's been fitted first before the o ring.

steve at motobins told me it stops the o ring being sucked into the crankcase. ha said he'd seen plenty where that had happened (doesn't do any harm).

AliBaba · Dec 28, 2006

Graham W said:
Thinking about it more, I guess the big O ring needs to be compressed as you fasten the cover back down by enough to form a good seal, but not by so much that it is damaged in any way. Maybe there are variations in the oil filter housing and cover tolerances so some bikes need it and others don't? Maybe as Rob implies it's a question of 'feel' as you tighten the cover down on your particular bike as to how it is pulling in and compressing the ring?

---------------
Thinking about it more, I guess the big O ring needs to be compressed as you fasten the cover back down by enough to form a good seal, but not by so much that it is damaged in any way. Maybe there are variations in the oil filter housing and cover tolerances so some bikes need it and others don't? Maybe as Rob implies it's a question of 'feel' as you tighten the cover down on your particular bike as to how it is pulling in and compressing the ring?
---------------

Yes there are variations; the tube you put the oil filter into is inserted as various depths. The o-ring is 4mm so the space between the tube and the engine block has to be far less then 4mm to get the o-ring compressed. The depth of the tube can also change and it has a tendency to move on older bikes.

The o-ring has TWO purposes:
-It stops oil from leaking out of the cover
-It stops oil from leaking from the oil-filter pipe to you sump (which can cause a big drop in oil-pressure)
The first point is mostly cosmetic, the second point can be a total rebuild.

So if the distance between the pipe and the engine block is less then 3.6 mm you need the shim to compress the o-ring. The distance can increase over time. Mine was suddenly 4.6mm….

Rob Farmer · Dec 28, 2006

I've just retrieved the parts from my stash.

The outer cover doesn't rely on the taper on the shaft at all, just the interference fit between the shaft and the outer cover. As long as the shaft doesn't protude from the crankcase too far then the outer cover should pull down without any probem, if it does then you will need a shim. If you do shim the outer cover and the seal on the filter isn't tight then the filter will be bypassed.

As long as the shaft is screwed in fully then you shouldn't need a shim.

Hopefully that makes sense.

The cover in the photo is a later one with a large bypass hole, apparently, the ealier covers had a smaller hole and were prone to pressurising the oil cooler. There is a mod on one of the websites (just needs drilling out). it's worth checking while you have the cover off. I think the hole needs to be 6.5mm - worth checking out properly.

Paul Rochdale · Dec 28, 2006

"So I guess its oil out again and take the shim out. AAARRRGGGGHHHH"

Andy

You've misread the diagram. You have an R100GS so you need to install the steel shim (Part No.4).

Paul

Rob Farmer · Dec 28, 2006

I'd love to know the definitive answer. BMW have cocked things up by having different configurations in the Microfiche and the workshop manuals

Paul,

Part 4 on the 100 diagram is a rubber seal.

cookie · Dec 28, 2006

i don't fit the gasket on later bikes.

Timolgra · Dec 28, 2006

Where's that Kenny when you need him

Kenny · Dec 28, 2006

Staying out of this one...could result in engine rebuild if wrong advice given

On my G/S I put the shim in first

Cheers

Yoda · Dec 28, 2006

As well as compressing the O ring, the shim had an additional purpose on earlier bikes.

The outside facing edge of the oil filter cannister was quite sharp and the O ring would get cut and split. Pressured oil would then take the easy way straight back to the sump and disregard travelling round all those tiresome bearings. As stated above - Expensive (with a capital F).

I understand that later model airheads used a flatter edge to the cannister.

The general wisdom seesm to be to use the shim, but not the gasket. (If the O ring is compressed correctly then it seals the whole thing anyway and hence the gasket is redundant).

Just my 2c.

Rob Farmer · Dec 28, 2006

I can see this running for some time. Nobody really knows why their fitting a shim then apart from heresay and that their bikes had one fitted when they got them - which could realistically have been fitted because somebody bought a filter kit in the past and didn't know what to do with all the bits. The factory produced workshop manuals do not show them being fitted.

So we aren't any further on than when Andy asked the question in the first place

Rob Farmer · Dec 29, 2006

I mentioned a mod in the outer housing in an earlier post. I've just found a reference to it in the Haynes manual. Apparently bikes before April 1990 had a 2mm bypass hole in the outer cover, this causes excess pressure in the oil cooler when the engines cold, it was modified by BMW and should have been carried out as a modification to all bikes built prior to April 1990. The hole was enlarged to 4mm (not the 6.5mm I mentioned) A paint spot on the casting may have been used to indicate the mod had been carried out.

There's no reference to a shim on the 100GS/R in the haynes manual, it's specifically mentioned and shown for other models that need one.

TaffyScouser · Dec 29, 2006

Took the shim out as it was not fitted in the first place and the mech at BVM said it was not needed on the later models and by that I mean 89 as mine is. People say "later", "earlier" without mentioning dates and this just adds to the confusion. The pictures that Rob uploaded are very helpful and show the shim used with the non bonded older type oil filters with the small o rings that had to be used. The new bonded ones do not have the loose rings and have the inner ring bonded to the end of the filters inner surface and later BMW pics do not show the shim.

When I removed the shim it was easy to see how the pressure exerted by the cover when it was torqued down had left an imprint on the shim surface as well as slightly rounding its profile. When I put the cover back on with the shim removed and just the o ring in place there was plenty of resistance and you could feel the o ring being compressed by the cover as it went home.

Just my contribution to the muddied waters.

Andy

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