Forking leaking forks

[79beem]

 Hi again,

Forgot to mention in my last post this little issue.

Right fork lower allen screw sprung a leak after a 350km day trip

Almost empty less than 24hrs after parking her up.

Removed wheel, checked allen screw, not tight but not loose.

Aluminium washer intact.

Should i replace washer and re-torque, or as i read in a previous post ( sorry cant remember ) also use thread sealer and blue loctite?

I figured i'd change the left fork oil whilst i was at it but discovered PO
( GRRRRRRRR ) had stripped the female fork drain thread, not the plug.

Any advice b4 i go out and buy a tap and die set?

Should i stick with aluminium washers or is there something better?

 Copper ?

I've been warned off helicoils by an aviation engineer friend.

Finally, what weight / quantity oil 7.5, 10 ? 190,200,230,280,300cc.?

I've seen all these figures floating around, i'am 75kg and will eventually get a tank bag and panniers.

Regards

Ian

[darrylri]

Better get some Helicoils for those drain screws.  Sounds like you're going to need them on both sides.  Fixing that will give you the "opportunity" to replace the fork seals if they need it.

[Bob_Roller]

Try tightening up the bolt first, if it still leaks, then you need to replace the aluminum crush washer .

Thread sealer shouldn't be necessary, but if you want to use it, no harm will be done .

You'll probably need to enlarge the stripped hole to the next size and then re-thread it, there's not a lot of metal there to get a thread repair insert in there, that's why they strip out the threads so easily .

The OEM washers are copper, seeing as you can't get any real torque on the drain plug without stripping it, I would try to stay with copper .

Original OEM fork oil is 7.5 wt, BMW now has a 10 wt oil, I don't think I'd go too much heavier than that .

For an oil change on the forks, 190 cc is the recommended amount, if you take the forks apart, then around 220 cc is required .

You can also adjust the oil level to suit your riding style if you don't like the 'feel' of the front forks .

Fork springs are probably due for replacement, if the bike has accumulated a fair amount of usage .

[Barry]

If you don't have new ones to hand the aluminium drain screw washers can be annealed and re-used. Of course being so small even with the "soap temperature indicator" aluminium is easy to overheat and you can ruin them ... which I did.  

So not having anything else suitable and not about to put a mail order in for 2 washers I used  small O rings and while they wouldn't be a first choice they have worked fine for several years now. Never come loose and leaked and it's near impossible to over torque the screws as the O ring just distorts.

As I said not ideal but maybe something in between like a fibre washer would be a good substitute for aluminium and might also offer some protection against over torquing.

The large bottom Allen screw washers I did manage to anneal OK but wonder if a dowty washer would be a better engineering solution.
  

[Rob Valdez 79 R65]

Ian, are you in the U.S.?  If so, Hucky's can be a good source for copper washers.

Several years ago, Sue in Canada stripped one of her drain hole threads by using a small torque wrench and "going by the numbers", instead of "feel".

On fasteners this small you cannot depend on a torque wrench from saving you.  It is best done with a small wrench and a light touch.  The oil pan fasteners are another place this philosophy works best.
It is the price we pay for the light weight of an aluminum block.

[nhmaf]

You're talking about the crush washers under the large allen bolt that is "inside" to bottom of the fork lower, correct (you indicated that you had to remove the wheel/axle to get to it ?).  If this is the case, I've found that trying to re-use those aluminum crush washers- which cost eleven cents in my area- is truly a false economy.  They often leak/don't seal right if re-used, even if one flips them round.    One has about a 50/50 chance that they will work OK on re-use, better to just get new ones each time.   I have also, in a pinch, used a copper washer from the hardware store with success.   One may have to insert a long extension and socket into the fork leg from teh top to hold the top of the damper assembly to permit "snugging" that allen bolt up a little more tightly, too.

[Rob Valdez 79 R65]

One may have to insert a long extension and socket into the fork leg from the top to hold the top of the damper assembly to permit "snugging" that allen bolt up a little more tightly, too.

I think that is a "given".

[79beem]

Thanks all for the info,

Nhmaf, yep allen screws inside fork sliders. Looking for new washers, i agree its not worth the risk. Everyday off the road is driveing me nuts.....

[nhmaf]

The last time I re-used one of those washers, it didn't leak on me until I was riding some nice twisty -and very bumpy- backroads.  All was fine until about 15 miles into the ride I discovered that I had almost no front brakes -> fork oil leaked out the bottom, ran along the axle and dripped onto the rotors & carriers, that then evenly distributed a nice film all around and wet the disc pads.   ARgh!  For want of a nail....