Fork Seal Replacement... Tips?

[montmil]

The right fork leg on my latest purchased R65 has puked its contents down my lower leg... rather, the bike's lower leg.  

Got a pair of seals heading this way. Have the Haynes manual and have read the section on seal replacement. Got the basic idea but would appreciate any tips from those that done been there - done that. No T-shirt, yet.

Thanks for any and all guidance. Lemme see... got my 'Justin' shift linkage ordered, fork seals, going with the NGK plug caps and stuff. Whew. Big fun. Lottsa help 'round these parts. Cheers!  [smiley=1drink.gif]

[airhead]

You may also be needing the upper bump bush as they can pound to pieces with age:



Some other consumables may also be needed, such as O rings etc.

Do only one leg at a time and check with a good exploded view, I did some forks once and the PO had assembled one fork wrong, so don't take for granted that that's how it was meant to go.

The 65 forks and mounting are pretty straightforward, so should offer no particular difficulty.

Bill.....................;-)

[nhmaf]

montmill - I don't recall the year of your R65, but some general tips I/we've learned about this fork maintenance task:

1.  While the soft metal "crush" or "wave" washers can fairly often be reused, they are supposed to be replaced with new ones, and they are inexpensive to order along with the seals.   These washers are on the drain bolts on the back of the sliders and there are also similar (but different size) washers used on the allen bolts in the bottom of the sliders.  I've reused these washers numerous times, but sometimes they decided that they don't quite want to hold oil anymore.  They usually make this decision while you are out exploring a twisty back road and dump fork oil onto your front brake rotors just when you might need some front wheel braking power.   Also, note how far the tubes are inserted into the upper triple clamp before you remove them - you can put a mark with a felt pen or something on each to help get you back to close to the right spot and even/equal on both sides when reassembling.

2.  The small 10mm drain bolts on the back of the sliders thread into soft alloy - DO NOT TORQUE THEM very tight.  The manuals state approx 10 ft-lbs, I think, which I think we'd all agree is an absolute upper limit.  It is VERY easy to strip the threads on these buggers, so use a small wrench and use your "delicate" touch when doing this.

3.  When reassembling - and sometimes when disassembling the slider from the tube one has to tighten/loosen and allen-bolt through the bottom of the sliders that screws up into the damper in the slider.    Sometimes one gets lucky, but sometimes one needs to get a looooong extension for a socket wrench to also reach down in from the top of fork tube to hold the bolt on top of the damper and keep things from turning inside the assembly - otherwise you might think that the lower allen bolt has stripped or not mating, but in fact the whole inner mechanism is turning.

4.  When you remove the top cap and or nut in the top of the fork tube, you need to press down against the tube's spring about an inch or so to gain access to the spring wire "clip" ring that is in a grrove in the top of the tube and which retains the assembly.  A small screwdriver or needle nose pliers can be used to pry out the spring - be carefuly not to gouge up the inside of the fork tube and SLOOWLY release the pressure from the spring so you don't get any parts popping up into your face.   This can be done by one person, but it is what is often called a "3-handed job", so if you have someone to assist you, it can go much easier.

5.   When you put the fork tubes back together and have them mounted in the triple clamps, I will put the fender brace, fender, wheel and axle on but leave the bolts/nuts for the fender, brace and axle pinch bolts a bit loose. I'll then push down on the handlebars and let it bounce back up
and repeat this a couple times to set the axle and sliders into their natural alignment before final tightening of all the fasteners.   This ideally enables you to get everything tightened up properly in proper alignment, so as to avoid undue stiction and allow smooth, unstressed action of the suspension.

This is a maintenance task that you can do and save yourself some $$$ over going to a shop.  Just be methodical and take your time and you'll do fine.   IF you get into a jam (but you won't !) there are plenty here who can help.

[montmil]

You may also be needing the upper bump bush as they can pound to pieces with age:

Thanks for the photo and tip, Bill. My R65 in a 1981 model.

And just where does this upper bump bush go? Is it necessary to pull the upper fork legs for replacement?  I'll check the micro fiche for location of the O-rings. Would like to get all the pieces on one order.

Thanks, again.   Monte

[azcycle]

montmill - I don't recall the year of your R65, but some general tips I/we've learned about this fork maintenance task:

4.  When you remove the top cap and or nut in the top of the fork tube, you need to press down against the tube's spring about an inch or so to gain access to the spring wire "clip" ring that is in a groove in the top of the tube and which retains the assembly.  A small screwdriver or needle nose pliers can be used to pry out the spring - be carefuly not to gouge up the inside of the fork tube and SLOOWLY release the pressure from the spring so you don't get any parts popping up into your face.   This can be done by one person, but it is what is often called a "3-handed job", so if you have someone to assist you, it can go much easier.

I'm about to tackle this project for the first time this weekend.  I finally purchased the Clymer manual and read it through, and I've read pretty much all the "fork seal" threads here that I can find.

I'm still in a bit of a confused state about #4 above.  I don't plan on dropping the upper fork tubes out of the triple clamps...they're going to stay attached to the bike.  So if this is the case, can I still remove the circlips myself? I guess what I'm saying is I don't quite understand how to "press down on the tube spring..." Using what?  

It might be easy once I see it myself... I'm a very visual person and just reading instructions without seeing it myself is a bit difficult. Can someone clarify this one mystery step for me?  I'm thinking I might document the entire process with pictures and add it to our technical wiki for future newbies.

[Bob_Roller]

The top cap on the R65 fork tubes, is held in by a wire circlip, to get access to the clip, you need to press down on the cap to expose the circlip .

You can use an Allen wrench that fits the fill port bolt that threads into the cap .

It sounds a lot easier than it is, after you've been working on it for a while and you still don't have it out yet .

I devised a method that works for me,  I take a portion of an old inner tube, wrap it around the top of the fork tube, then use a 3 jaw puller over the top of the tube with the jaws of the swapped around, so they are up against the fork tube, use a couple of radiator clamps threaded into each other, or if you have one long enough .

Tighten the radiator clamp  to hold the puller in place, then screw the center bolt down to push the top plug down to gain access to the wire circlip, remove the clip with an awl or scribe, thread the bolt back out to relieve the spring tension .

I remove the entire fork from the bike and work on it in a vise with a couple of pieces of wood to prevent the vise jaws from touching the fork tube .

[azcycle]

Thanks, Bob... I understand your process.  I just don't have the tools (no three-jaw puller, no vice...not even a work bench) so I'll have to wing it.  I expect quite a bit of frustration and some creative word-usage.

Last question... the 13mm socket that goes on the long extension: Is that a regular 13mm socket for bolts or a hex socket? I read somewhere here that it is a hex-socket, but only one mention...

[Barry]

Is it necessary to pull the upper fork legs for replacement?

No it isn't but it can be a bit fiddly to remove the damper valve body with the stanchion in place because unless you have a bike lift you are going to be lying on your back.  However there might be one good reason not to remove the stanchions and that is if you don't  want to disturb the fork alignment.

Azcycle,
It's possible to replace the bumper ring which fits between the valve plate and piston while leaving the damper valve in place by removing and replacing  the damper rod and piston through the top of the stanchion. I prefer to do it that way because the tapered section at the top of the stanchion eases the piston rings in nicely.  On the other hand if the forks haven't been overhauled recently you might still want to remove the damper valve to give everything a good clean.

And it's a regular socket but I've always been able to shock the bottom allen screw free and to tighten it the same way so never needed to use one.

[Ed Miller]

Last question... the 13mm socket that goes on the long extension: Is that a regular 13mm socket for bolts or a hex socket? I read somewhere here that it is a hex-socket, but only one mention...

Are you changing the seals?  

One person can get that top cap out, at least I did it by myself.  I do it before even removing the front tire.  Put the bike on the centerstand, stand on the foot pegs so that you can use your weight to force down the top plug, hold it steady down with one hand (I sort of cock it a little in the bore and that helps keep it from popping back out) and pry the wire clip out with a little screwdriver or something.  Try not to let it fly across the room.  Then you can ease the plug out, the spring will push it.

The 13 mm socket that goes on the long extension is just a normal socket, not an allen type tool like these bikes use so many of.  I think the little bolt on the bottom end is an allen bolt though, but I can't remember what size.  

[azcycle]

Yep, just replacing the seals.  I'll try standing on the foot pegs... great idea!

[Rob Valdez 79 R65]

I used my impact screwdriver handle for extra weight when pushing down on the cap:





You also might find this thread of mine from last Sept. useful:
http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1254093089/0

[azcycle]

Alright guys... need help.  Pressing down the top cap was a pain but not as difficult as I thought. Got them out in about 20 minutes or so.

But here is where I'm at. Both legs broke loose just fine, but the internal "guts" of the right side (facing the bike) stayed upside the fork tube.  On the left, the main shaft slid down... see pic:



Now, I have these three bits that I assume came from the leg that dropped.  I know the bottom "cap" piece is obvious... but what are the two spacers and were do they go? The smaller one slides down inside the "T" shaped piece but I"m not sure if that is where it goes.  The larger spacer piece ... I have NO idea where that goes. It had quite a bit of road grit on it so maybe it's a wheel spacer or something? I don't remember it coming off the wheel, but it certainly doesn't look like it goes inside the fork.  

[azcycle]

Update... I got the innards out of the lower leg and confirmed that the "T" shaped piece sits alone at the bottom of the shaft.  I am pretty sure (looking at the Clymer wheel diagram) that the larger spacer is actually for the front axle.

But I still don't know what that smaller spacer is for.

[Rob Valdez 79 R65]

Are you sure the piece on the left is not your axle spacer?  See if it fits around your axle.
Is this the first time you have had the front wheel off?  Did you not see the spacer fall when you removed the axle?

Never mind - here is one of my pictures:



The "road grit" was probably the disintegrated vinyl washer.

See the pictures in the link I provided just above.  I don't know if there are any differences in the '79 forks and the '81's.

I don't remember seeing a small one like in the center, on my assembly.

[azcycle]

Rob, the only problem I see is that I haven't completely disassembled the forks... see the photos. The only thing I have outside the uppers is the piece on the far left in your photo.  The retaining circlip/ring and everything to the right of it in your picture is still up inside the fork uppers.

Left upper (facing the bike):


Right upper (facing the bike):


This is what I have "loose"


And here is the spacer on the axle. Fits perfectly.


So I think it is the axle spacer. It truly felt like road crud and not the remains of any bumper stop.  When I was removing the front wheel (first time doing it), it dropped suddenly and I didn't see how everything was assembled (stupid.)