82 R65LS Fork Oil Change

[jgp1854]

Members,

A glorious fall day in northern Michigan.  

I'm in the process of draining and re-filling the fork oil in my LS.  Specs call for 7.5 wgt, 190 cc per tube.  I've drained the forks, and when I removed the "fill" plugs I noticed what appeared to be a brownish paper type material gasket on each of the fill plugs.  The gaskets  are deteriored and breaking apart, no longer useable.  I called the local BMW dealer, and he advises, metal gaskets are now being used?  Can anyone confirm that?  I checked MAX's BMW fiche and couldn't find the plugs nor the gaskets listed??  Also, the fill plugs were TIGHT, let me be clear, they were REALLY TIGHT.  Can anyone advise the torgue value for the refill plugs?

thanks

73516

[Bob_Roller]

I had the same thing, it looked more like some sort of liquid 'gasket' material, rather than a paper gasket .

I believe copper crush washers are used now, I'll check when I get home from work today, but if I remember correctly I got them at the local BMW dealer .

Here's a link to the RealOEM page, disregard the prices, I don't think they are any where near current, but the part numbers are good .


http://www.realoem.com/bmw/showparts.do?model=0364&mospid=51897&btnr=31_0296&hg=31&fg=10

Item # 4 .

If you click on the camera icon at the right, it will give you a picture of the washer .

[Barry]

The Allen socket filler plug screws have a fibre washer seal. It's nothing special. Any correctly sized fibre or crush washer from your local autoparts supplier  would be fine. It just has to be oil and air tight.  As for torque there is no reason on earth to over tighten them. The listed torque value is 6.5 lbft. I've never used a torque wrench and just fit them hand tight using a screwdriver handled bit holder. Can't be above a couple of lbft and they never leak.

Don't put too much trust in every published torque value. As an illustration the figure for the tiny fork oil drain screws is 6 lbft.  I think that's madness and an invitation to strip the threads. The object is to keep the oil in and not have the screw fall out and nothing more.  Gentle screwdriver tightness is all that's needed. If that doesn't make them seal then it's new washers that are needed rather than more torque.

[jgp1854]

Bob,

You are right on, they look like paper gasket material.  I revisited MAX's fiche and found the gasket.  It obviously gives the PN, but doesn't indicate what it is made from.

Barry,

I used a 3/8" ratchet, short extension and 8mm hex head, and couldn't break it loose.  I convinced it loose adding a 22mm open end/box end wrench to the handle of the ratchet, and then I think I pulled a groin muscle in doing so.  It was ridiculously TIGHT.

The fluid drained measured out to 150 cc per side, is that normal?  Nothing leaking whatsoever.  I suspect it was the OEM oil, what are the odds?  When I refilled each side with 190 cc, I think I heard someone in the fork tube holler up to me, its about time!  (Note) I've owned the LS the past two summers.

Thanks

Jim

[Barry]

Forks do get neglected don't they and in more ways than one. !90cc is the correct drain/refill volume. A completely dry fill needs a little over 200cc's. Can't imagine 150cc would have been enough to cover the damper piston top. So not normal. I bet it came out mucky looking too.

My preference is always to measure the oil level with a dipstick. Prescribed depth of oil is between 20mm and 50mm above the top of the damper piston. You have some control over fork feel and dive by variation of the level between those limits.

[Bob_Roller]

If you go back to the MAX BMW parts page, it gives the description of the part as : Gasket Ring-A10x13,5-CU .

The last two letters, CU, is the abbreviation in the Periodic Table of Elements for copper .

The washers on the fill and  drain plugs for engine, transmission, shaft and final drive will have the letters AL, for aluminum .

[jgp1854]

Once again the membership has been most helpful, thank you.  Just waiting on the new gaskets to arrive Sunday, and putting things back together.

The look of the oil drained, and the condition of the gasket (deteriorated) likely proves it was the OEM.  Should I expect any affects on handling etc?

Again thanks

Jim

[Barry]

Should I expect any affects on handling etc?
 

It depends what state the fork insides are in. If they function OK with no clonks I would think not.

After all this time the original oil will have left some gum and sludge in there and also there is a rubber topping out bush which tends to perish and add to the muck. Then there's no alternative to a strip and clean up with new bushes. If the forks seem OK you might consider draining the oil after a few months to see if it comes out clean. If it does just put it back in again. If not replace it and if it keeps coming out full of muck consider planning for a fork overhaul.


If you want to test the damping function then with the wheel, mudguard and brace off and with the spring out exercise each individual fork leg by hand. You should feel very little resistance on the compression stroke but significantly more on rebound with a further substantial increase over the last 20mm of travel. Forks always have several times more damping on rebound than they do on compression. The big increase in rebound damping over the last bit of travel is effectively an hydraulic bump stop.

[jgp1854]

Well got the new gasket and put things back together yesterday all seems good to go.  Took the LS for a ride and handle fine.  

A question if I may:  the end cap that spins around, and has to be held while removing/installing the fill plug, what is it, and does it matter if it moved (rotated) during the procecess?

thanks

jgp

[Barry]

The cap or plug retains the fork spring. It has an O ring seal so you will do no harm by allowing it to rotate. It's held in place by a wire circlip which locates in a groove cut into the stanchion bore. If you press down hard on the plug compressing the spring by 20 - 30mm the circlip becomes visible. Removal of the circlip and plug is one of the few 3 handed jobs on the bike but it's easy enough when you've done it once.

[jgp1854]

Barry

Thanks

Jim

[Barry]

No worries Jim.

I should have mentioned that this method of retaining the fork spring is unique to the R45/R65 range, so every new owner of an R65 almost to a man has pondered the same question when faced with that rotating plug - me included.