Fork seal leaking

[Rockosmith]

Has anyone had to replace fork seals in a ‘15 RT?  Mine started leaking today at 87000 miles.

[RecentConvert]

not on a '15,  but three times on right fork of a '14.  The left side just started weeping at 48000 miles.  Take the fork tube out, don't try without removal.  It is possible, but removal is easier.  AllBalls seals this time after factory seals.

[PadG]

. . . . why not try to re-seat the seal first?

 

[dirtrider]

On 12/28/2019 at 7:13 PM, Rockosmith said:

Has anyone had to replace fork seals in a ‘15 RT?  Mine started leaking today at 87000 miles.

 

Morning   Rockosmith

 

As rule it isn't a bad or worn seal but just soap scum & road dirt that has worked it's way through the dust excluder lips (top seal)  then ended up  between the lower (main oil seal) & inner fork tube, therefore you get a seal seep.

 

If you haven't lost much fork oil (usually  not as a little oil looks like a lot), then you can gently pry the dust excluder up (top seal) as they usually come off pretty easily, then slide the dust excluder up the fork tube out of the way.

 

Then using a piece of thin plastic or acrylic "old 35mm film negative works great",  (or just but a $7.00 seal cleaner online), then  work some power steering stop leak (seal conditioner) between the main  seal lips & the fork tube. Work enough in to totally wet the inner seal lips & get between the full seal & fork tube. I use an old hypodermic syringe with small needle to  squirt the stop leak in between the seal lips & fork tube (caution: don't damage the seal lips). Maybe do the above a couple times,  a day or so apart.

 

Then gently tap the dust excluder back on.

 

As a rule that will fully stop your seal seeping & restore the seal function to like new. (I have had a very high  success rate at stopping the seal seep using this method). 

 

 

[Rockosmith]

Thanks for the replies.  I have had some success in years past with the method dirtrider proposed although it never occurred to me to work stop leak into the seal.  As you know, the seals on an RT live up pretty far inside the fairing so working space is very limited.  As a result, they are fairly well protected from general road grime and bugs.  That said, I already have seals coming so will most likely change them out when I receive them.  

[BamaJohn]

I'll bring the beer and moral support, old Friend......and of course, go along for the test ride! 

 

[Boxflyer]

My New Year's Eve day in the cold garage...

I had a RH leaking fork seal on my '08RT while up in AK on a trip in 2014 that I cleaned out with a DIY seal cleaner that I carry in my tool kit to this day.  I tried several times to clean out my current '16RT RH fork seal, but could not get it to stop weeping.  The bike currently has 67k miles.

.

I had ordered the OEM seals and have had them for a couple of months and finally got around to putting them in today.

  

The service manual is nice and clear as to the process and it only took about 2hrs from start to finish with the bike up on my lift.

I tried cleaning up the original seal to find a cut or some crud on the lips of the seal, but it just looked a little more worn on one side vs the other...I don't remember if it was the leading edge or trailing edge, so just replaced both the inner seal and the wiper.

   

I poured out the fork oil into a graduated cup and it was about 500ml.  The manual calls for 545ml as well as measuring it during reassembly to be 90 +/-2mm from the top of the lower fork tube.  The original fork oil was not contaminated/dirty, so I topped up the volume to 545ml in my pitcher and poured it in the lower tube. With this volume, it measured from the upper lip of the tube about 75mm, so I kept pouring it out until the measurement was at 90mm...which just about equaled the 45ml I added in the first place...so almost no measurable loss of fork oil.  A couple of drops of oil can look like a mess over time.

 

I used the Motion Pro 08-0551 bearing driver to drive the lower seal squarely to the spacer ring in the lower fork.  It only took about 4 light hits with a hammer to drive it home.  The new OEM seal comes pre lubed and the wiper seal just presses into the top of the lower fork tube.

Sliding the upper shiny tube into the new seals is simple and needs no tools or special procedure with the vent screw still out.  When the upper fork slider is up in the top fork bracket next to the handle bar, you install a new top nut holding the slider to a torque of 40Nm, then you replace the vent screw with a new O ring.

Since I only was working on the RH fork, the LH fork tube is the alignment reference with the Quick Release Axle shaft between the 2 for setting the position in the lower clamp. 

The instructions are VERY specific about torquing the 2 main pinch bolts in an alternating fashion 3 times each to 19Nm.

 

There was never any degraded performance with the annoying small oil leak on this fork tube, but I was tired of seeing some oil and not knowing if it was a drop or a more serious leak.

 

This was a couple of hours well spent, I'd had enough of wiping down the fork at the end of each day of riding to see if it was getting worse...because I knew it was not going to get better on it's own. 

 

[BamaJohn]

Good job on your posting!  I'll figure on about 4 hrs if I have to do it....2 hrs will be for gathering tools and materials, and walking back and forth to get the RIGHT tools..... 

[gary45]

If the seal is worn on one side, it pays to replace the bronze bushing below the seal, I ended up doing my K1100 seals twice, replacing the bushings second time.

[Boxflyer]

7 hours ago, gary45 said:

If the seal is worn on one side, it pays to replace the bronze bushing below the seal, I ended up doing my K1100 seals twice, replacing the bushings second time.

Hi Gary,

Nothing as simple as bronze bushings...completely new setup...now they are called "Guide Elements", something unique to BMW, and come in a set of 4.  2 for the lower end and 2 for the upper end (1 set per side/tube) Part number 31428532724.

They probably do the same thing as what was used in other BMW series, but I think these are some space age coating on the ring shown here from yesterday's process.

The black ring is the "guide element" and shows no wear or scratches in my case.

 

When I made the decision to replace my seals, I based that on wiping down the inner seal surfaces to see if there was something obvious.  Too hard to for me to tell while still installed...so I replace them since I had the new parts.

Today, I was able to really clean them and see that in fact there are NO perceptible wear marks, scratches, pits, junk, anything, kind of marks on the existing removed seals...

Whatever was allowing my tiny amount of oil to seep out must have been just some debris between the slider and seal lips, and in my opinion is now cleaned up and no longer an issue...although I have new OEM seals installed, I wouldn't hesitate to reinstall these.

[gary45]

The ones for the K1100 are called guide bush in realoem and if I remember correctly they came with a coating on the friction surface, they are not expensive and keep stanchion centered in the slider, my previous comment is just a caution because it never occurred to me when I was doing seals that they could fail from more than just age and could have a mechanical reason for failing.

 

[AndyS]

20 hours ago, gary45 said:

If the seal is worn on one side, it pays to replace the bronze bushing below the seal, I ended up doing my K1100 seals twice, replacing the bushings second time.

 

Why? Have you got play in the fork leg? If not, then you are wasting your time and money. 99.99% of the time it is just crud or the dust seal (and/or) the oil seal weeping /worn out.