Fork Seals on '96 R1100RT

Hi all,

I am going to need to replace the fork seals on my bike.

Since we're pulling the front end apart sufficiently to do that job, can anyone recommend other maintenance jobs that I might want to do while in there? (may as well max out the time spent!)

Thanks,

Mike

IIRC you won’t be that deep into disassembly since you only need to strip off wheel, brakes, fender, etc. to get to the point where the sliders can be slid down off the fork tubes. So a check of wheel bearings and seals, brake pads and rotors, fresh fork fluid, and a bleed and flush of the front brake system when it’s all back together. If you have a service manual all the torque values you need should be listed there.

Best,
DeVern

The exposed rubber pieces covering the fork seal (not sure why but it's called a cup, we used to call them scrapers...), and the 'O' rings on the fork drain plugs. You might also consider changing the original brake lines and upgrade them to stainless. It's all pretty simple, straight forward work.

Good luck.

GTRider said:

IIRC you won’t be that deep into disassembly since you only need to strip off wheel, brakes, fender, etc. to get to the point where the sliders can be slid down off the fork tubes. So a check of wheel bearings and seals, brake pads and rotors, fresh fork fluid, and a bleed and flush of the front brake system when it’s all back together. If you have a service manual all the torque values you need should be listed there.

Best,
DeVern

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Thanks! I hadn't considered the wheel bearings, good idea! And thanks for the speedy reply, too!

Safe riding,

Mike

Many thanks!

I will order up the cups and o rings, good thoughts on both.

The brake lines are in really good shape, but will certainly give them a closer look when I get to the task.

Cheers,

Michael

6322 said:

The exposed rubber pieces covering the fork seal (not sure why but it's called a cup, we used to call them scrapers...), and the 'O' rings on the fork drain plugs. You might also consider changing the original brake lines and upgrade them to stainless. It's all pretty simple, straight forward work.

Good luck.

Click to expand...

phrip said:

The brake lines are in really good shape, but will certainly give them a closer look when I get to the task.

Click to expand...

The brake lines might look like they're in good shape but if they're rubber then they're just waiting to give you a huge headache, as in having your brakes seize on or failing completely and leaving you with no brakes whatsoever. Buy a set of Speigler lines, front and rear, and replace them all...NOW.

Mike, yes replace the dust covers along with the seals. There are two great videos on the fork seals replacement, one from Chris Harris and the other from Kirk of the Illinois BMW club. Harris shows it from above and Kirk does it from below. Kirk does it on a K12LT but it’s the same fork and procedure. When you pull the lower fork legs you have to disconnect the brake lines where they are attached on each leg. The right side should come off easy, the left has a little 3 mm hex screw which is easy to strip. Use some penetrating oil and then some heat on it before you try to remove it.

OMG, you still have the original rubber brake hoses? Get them off the bike NOW.

The OE rubber lines HAVE to go.
Spiegler Brand is my go to.

BC1100S said:

The brake lines might look like they're in good shape but if they're rubber then they're just waiting to give you a huge headache, as in having your brakes seize on or failing completely and leaving you with no brakes whatsoever. Buy a set of Speigler lines, front and rear, and replace them all...NOW.

Click to expand...

I have sectioned the OEM brake lines from my 2003 K1200RS and found they have a very impressive semi-rigid nylon-type liner that actually contains the brake fluid. It also looks like it would be very difficult for that liner to ever "stretch out" or get soft due to its composition without splitting (which I'm not aware of as a problem)or conversely collapse, so while the outer rubber covering can deteriorate over time, I think the internal construction of the OEM lines I've seen would be good for a very long time. This bike has the power "whizzy" brakes so it makes sense to me that the brake lines would need to be compatible with extremely high pressures.

One other consideration is that BMW specifically recommends against using steel braided brake lines on the "wheel circuits" of any whizzy brake bikes. Those are the lines from the power brake pump to the calipers. They state that the slight elasticity of the OEM lines is figured into the design of the power brakes and ABS system, and that the more rigid steel braided lines can potentially create a pressure spike that could trigger the pressure relief valves in the power brake system. Using steel braided lines for the "control circuit" (i.e. from the levers to the power pump) is permitted.

I've done as much research on this as I can and haven't found a single documented or ever presumed case where such a thing happened, and I know many people have replaced their OEM brake lines with steel braided ones. Still, BMW did issue such a service bulletin. YMMV

Fork Seals

phrip said:

Hi all,

I am going to need to replace the fork seals on my bike.

Since we're pulling the front end apart sufficiently to do that job, can anyone recommend other maintenance jobs that I might want to do while in there? (may as well max out the time spent!)

Thanks,

Mike

Click to expand...

Did the seals on my '04RT over the weekend. I chose the Illinois BMW Riders method of working from the bottom. Pretty straightforward. You should find about 14oz. of fluid in each leg that you'll want to replace. I re-filled with Ravenol 5w fork fluid, but I'm told just about any type of lube can be used.

When removing the fork bridge from the forks, remember that they might be loctited and you'll want to heat them up first.

RPGR90s

GREGFEELER said:

I have sectioned the OEM brake lines from my 2003 K1200RS and found they have a very impressive semi-rigid nylon-type liner that actually contains the brake fluid. It also looks like it would be very difficult for that liner to ever "stretch out" or get soft due to its composition without splitting (which I'm not aware of as a problem)or conversely collapse, so while the outer rubber covering can deteriorate over time, I think the internal construction of the OEM lines I've seen would be good for a very long time. This bike has the power "whizzy" brakes so it makes sense to me that the brake lines would need to be compatible with extremely high pressures.

One other consideration is that BMW specifically recommends against using steel braided brake lines on the "wheel circuits" of any whizzy brake bikes. Those are the lines from the power brake pump to the calipers.

Click to expand...

I've seen pictures of a "bulged out" (technical term) brake line failure on this forum so I have to respectfully disagree with how strong the inner brake line is. As well, I believe K bikes from 2005 onward, including ones with "whizzy" brakes, came from the factory with steel braided lines.

I think BMW issuing a statement on how sponginess is built into the system might be similar to one they might have issued stating that the final drives on some oilheads were designed to disintegrate at a variably determined point in time or that the HES wiring issue was a safety feature to control (very effectively) the speed of the motorcycle.

GREGFEELER said:

I have sectioned the OEM brake lines from my 2003 K1200RS and found they have a very impressive semi-rigid nylon-type liner that actually contains the brake fluid. It also looks like it would be very difficult for that liner to ever "stretch out" or get soft due to its composition without splitting (which I'm not aware of as a problem)or conversely collapse, so while the outer rubber covering can deteriorate over time, I think the internal construction of the OEM lines I've seen would be good for a very long time. This bike has the power "whizzy" brakes so it makes sense to me that the brake lines would need to be compatible with extremely high pressures.

One other consideration is that BMW specifically recommends against using steel braided brake lines on the "wheel circuits" of any whizzy brake bikes. Those are the lines from the power brake pump to the calipers. They state that the slight elasticity of the OEM lines is figured into the design of the power brakes and ABS system, and that the more rigid steel braided lines can potentially create a pressure spike that could trigger the pressure relief valves in the power brake system. Using steel braided lines for the "control circuit" (i.e. from the levers to the power pump) is permitted.

I've done as much research on this as I can and haven't found a single documented or ever presumed case where such a thing happened, and I know many people have replaced their OEM brake lines with steel braided ones. Still, BMW did issue such a service bulletin. YMMV

Click to expand...

Greg,
On my '00 R1100RS, 115,000 miles, I had my front brake line split. This was the line coming off of the front master cylinder. Also, changing the brake lines changed the feel 100%, to a much more solid, firm grip and pedal. When the line ruptured, it wasn't in a panic braking type of situation. It just let go. For my money and piece of mind, I have stainless. For a twenty four year old bike, it might be a good choice.
Best to you in Boise.

BC1100S said:

I've seen pictures of a "bulged out" (technical term) brake line failure on this forum so I have to respectfully disagree with how strong the inner brake line is. As well, I believe K bikes from 2005 onward, including ones with "whizzy" brakes, came from the factory with steel braided lines.

I think BMW issuing a statement on how sponginess is built into the system might be similar to one they might have issued stating that the final drives on some oilheads were designed to disintegrate at a variably determined point in time or that the HES wiring issue was a safety feature to control (very effectively) the speed of the motorcycle.

Click to expand...

With all respect, anything can fail - that is how the tails of any curve are created - so an anecdotal occurrence doesn't represent sufficient proof to me support a general statement. To say that the tech bulletin BMW *did* issue about brake lines is somehow unimportant because of some hypothetical statement they didn't make doesn't seem relevant to me. The fact is they went to the trouble for some reason to issue a very specific warning. And, yes, BMW did convert to steel braided lines but only after the power whizzy brakes were discontinued. Both good moves, in my opinion.

I'm not at all opposed to steel braided brake lines, and I believe in proactive immanence and upgrades. But, I also wonder how many people who quickly claim that 10 or 20 year old "rubber" bike brake lines are dangerous have ever changed out the rubber brake lines on their cars? You should do what makes you feel comfortable. My point was in sharing some more information for consideration.

6322 said:

Greg,
On my '00 R1100RS, 115,000 miles, I had my front brake line split. This was the line coming off of the front master cylinder. Also, changing the brake lines changed the feel 100%, to a much more solid, firm grip and pedal. When the line ruptured, it wasn't in a panic braking type of situation. It just let go. For my money and piece of mind, I have stainless. For a twenty four year old bike, it might be a good choice.
Best to you in Boise.

Click to expand...

Not good! To be clear, I'm a believer in good maintenance, and especially for critical systems like brakes. I had to change the wheel circuit lines on my 2003 K1200RS because of an impending failure of the front brake line where it goes into the right caliper. That line is routed such that it "drapes" when you are riding the bike in a way that bends it at a 90-degree angle as it comes out of the caliper. This eventually damages that nylon-like liner inside the line that I described earlier and it splits at which point brake fluid passes right through the rubber sheathing. (Here I go with my own anecdotal examples), and I know of three personal friends who have had this happen with that vintage of R and K bikes (the lines were routed the same on both). When I examined my bike I could see the sharp bend, so I replaced it. When I cut the old line apart I found that inner liner was severely compromised so it was only a matter of time before it would have failed. My assessment of how those lines are constructed is that they should be very strong but do not like to be bent which could cause the liner to crack or split. Was there any chance there was a lot of flex to the area of your brake line where the split occurred?

It was during this process on my K12 that the lead mechanic at my old BMW shop gave me a copy of the BMW tech bulletin about not using steel braided lines on the wheel circuits of whizzy brake bikes. In my experience because the hand and foot lines only engage the power pump (which is like a hydraulic relay) there is little "feel" improvement to be gained by going with steel lines because you just don't have to pull/push that hard to generate strong braking. So, at that time given the low mileage on that bike and some other constraints I went with the stock lines on the wheel circuit and left everything else in place. Having said all this, I do have a set of new Spiegler lines on hand for this bike which I intend to swap out myself fairly soon when time allows. Steel lines can fail in different ways over time, but all together seem to be just a superior solution.

Best back to you in Riggins! I can't wait to go up your way on 95 once the restrictions lift!

Greg, with all respect, the original post is about a 96 R1100RT which is not a whizzy braking system and doesn’t have the brake hoses that you have on K bike.

Thanks!

Thanks, I'm definitely doing seals/covers. Checking for lines with supplier, too!

m_stock10506 said:

Mike, yes replace the dust covers along with the seals. There are two great videos on the fork seals replacement, one from Chris Harris and the other from Kirk of the Illinois BMW club. Harris shows it from above and Kirk does it from below. Kirk does it on a K12LT but it’s the same fork and procedure. When you pull the lower fork legs you have to disconnect the brake lines where they are attached on each leg. The right side should come off easy, the left has a little 3 mm hex screw which is easy to strip. Use some penetrating oil and then some heat on it before you try to remove it.

OMG, you still have the original rubber brake hoses? Get them off the bike NOW.

Click to expand...

GREGFEELER said:

I'm not at all opposed to steel braided brake lines, and I believe in proactive immanence and upgrades. But, I also wonder how many people who quickly claim that 10 or 20 year old "rubber" bike brake lines are dangerous have ever changed out the rubber brake lines on their cars? You should do what makes you feel comfortable.

Click to expand...

As a matter of fact, that's the first thing I change on every car I get.

BC1100S said:

As a matter of fact, that's the first thing I change on every car I get.

Click to expand...

One fine spring day our good friend, Jim Shaw was finishing his several day visit from chilly Ohio, here in the Texas Big Bend. He had left snowy Hinckley headed the long way to Daytona for Bike Week, by way of Texas. He towed his GS here with his Buick. We spent several days riding the local area. Then it became time to head to Daytona.

He backed his Buick and trailer up to the garage and we loaded the GS. From there it was a slight downhill to a 90 degree turn in the driveway. As he approached the turn he applied the brakes, the pedal went to the floor, and he made a rather startling hard left turn to stay in the driveway. The Buick had burst one of its METAL pre-formed brake lines which had rusted through. The failure was no doubt caused by the extensive use of road salt in his local Ohio locality.

NAPA ordered a replacement brake line but the wrong part arrived. We tried another store. Finally a Buick dealership overnighted the correct part but poor Jim was several days late to Daytona.

PGlaves said:

One fine spring day our good friend, Jim Shaw was finishing his several day visit from chilly Ohio, here in the Texas Big Bend. He had left snowy Hinckley headed the long way to Daytona for Bike Week, by way of Texas. He towed his GS here with his Buick. We spent several days riding the local area. Then it became time to head to Daytona.

He backed his Buick and trailer up to the garage and we loaded the GS. From there it was a slight downhill to a 90 degree turn in the driveway. As he approached the turn he applied the brakes, the pedal went to the floor, and he made a rather startling hard left turn to stay in the driveway. The Buick had burst one of its METAL pre-formed brake lines which had rusted through. The failure was no doubt caused by the extensive use of road salt in his local Ohio locality.

NAPA ordered a replacement brake line but the wrong part arrived. We tried another store. Finally a Buick dealership overnighted the correct part but poor Jim was several days late to Daytona.

Click to expand...

At least the thing let go at the right time - not when he REALLY needed the the brakes!

BC1100S said:

At least the thing let go at the right time - not when he REALLY needed the the brakes!

Click to expand...

Had he left the property headed to Daytona his first 53 miles would have been on TX 118 north to Alpine. About 40 of those 53 miles are hilly and curvy. I would not have wanted to have been on that road when the brakes failed. He and I agreed he was lucky.