during my trip i noticed oil on left fork slider, obvious that the seal is blown and my question is this, i believe it happened when we were cutoff on highway and got on brakes hard on bumpy road, after reading posts on andidive is this telling me that there may be a problem with the plunger, i cleaned and serviced it over the winter and think it is fine but recall posts saying that the anti dive, although working properly can be the cause of a blown left fork seal, i put progressive springs and new oil in over winter also, am about to order new seal and thought maybe i should be prepaired to maybe need somethig else as well,, rode 1000 miles home with seal leaking?? thanks
blown left fork seal
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You might remove the anti dive for a short time and see if it stops leaking,also your forks should be stiff if it is stuck. I replaced my seal only to have them leak again a very short time later. Try using just your foot pedal only this will not allow anti dive valve to work.
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The anti-dive valve will be actuated when using the rear brake as well through the linked system. If the seal blew when applying the brakes hard on a bumpy road, the problem may be the valve at the bottom of the slider and not the actual anti-dive plunger. :shock:Mike Moran said:
My left fork seal went out at 48,000 miles. I have always ridden my wing fast on horribly bumpy one lane roads. My thinking is that the original equipment survived a pretty long time, so I would expect similar survivability out of my rebuild. I know the upper half of my anti-dive valve was stuck because when I removed it, the plunger was stuck in the protruded position. There is a simple test to see if the lower half of the anti-dive valve is stuck. Remove the upper have of the anti-dive valve by removing the two allen head cap screws. Use a small pointed object to push on the lower valve to actuate the lower valve. The lower valve actuates with very little pressure and easily returns to the original position when you remove the force you applied. I will try to find one of Fred H. pictures. I share your concern. I am sure that big bumps will be hit with the brakes on hard. I also wonder if that additional load on the fork seal can be mitigated or reduced without deactivating the anti-dive.
Here is one of Freds pictures.
http://www.pbase.com/fredharmon/image/21042039
Here is one of Freds pictures.
http://www.pbase.com/fredharmon/image/21042039
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2,349 Posts
Hi Crow,
99.9% of fork seal leaks happen over time, not in a moment. So it is almost completely impossible that your seal blew because you drove on a bumpy road.
What most people don't realize is that long before you see any oil on the tube, the main seal will have been leaking under the dust seal, and the dust seal will wipe the tube clean (for the most part) up until the point the whole space underneath it is full of oil, and then it will begin to ooze over the dust seal. This can take thousands of miles sometimes.
Fork seals are pieces of rubber sliding against metal. They simply wear out. Some go 50,000 miles, some go 5,000 miles.
You will never get the same service interval out of a rebuild, because the fork tubes will not be in the same condition as when they were new. The will have pitting and scratches in them from normal use.
The entire left fork and brake assembly are an engineering joke. When you apply your brakes, the left fork is hydraulically locked by the anti-dive. This causes the entire wheel and axle assembly to **** against the fork tubes. The rotating left caliper induces an unnecessary load into the leg as well.
Disabling the anti-dive is the single cheapest and one of the biggest improvements to ride quality you can do to a GL1800. The bike will not "dive" if you do this... it has no where to dive to... it is almost completely bottomed out when stock. Roughly 60% of the travel is lost in "sag" before you even get on the bike.
If possible have someone polish your fork tubes on a lathe using a fine (400 grit) emory cloth to remove pits and scratches.
Then fill the sliding lip of the seal with a proper seal grease. If you don't grease the seals, they will wear out much faster, and you will have more drag. (you may notice some white slimy stuff in your seals when you take the forks apart... this is the factory grease from Showa...).
99.9% of fork seal leaks happen over time, not in a moment. So it is almost completely impossible that your seal blew because you drove on a bumpy road.
What most people don't realize is that long before you see any oil on the tube, the main seal will have been leaking under the dust seal, and the dust seal will wipe the tube clean (for the most part) up until the point the whole space underneath it is full of oil, and then it will begin to ooze over the dust seal. This can take thousands of miles sometimes.
Fork seals are pieces of rubber sliding against metal. They simply wear out. Some go 50,000 miles, some go 5,000 miles.
You will never get the same service interval out of a rebuild, because the fork tubes will not be in the same condition as when they were new. The will have pitting and scratches in them from normal use.
The entire left fork and brake assembly are an engineering joke. When you apply your brakes, the left fork is hydraulically locked by the anti-dive. This causes the entire wheel and axle assembly to **** against the fork tubes. The rotating left caliper induces an unnecessary load into the leg as well.
Disabling the anti-dive is the single cheapest and one of the biggest improvements to ride quality you can do to a GL1800. The bike will not "dive" if you do this... it has no where to dive to... it is almost completely bottomed out when stock. Roughly 60% of the travel is lost in "sag" before you even get on the bike.
If possible have someone polish your fork tubes on a lathe using a fine (400 grit) emory cloth to remove pits and scratches.
Then fill the sliding lip of the seal with a proper seal grease. If you don't grease the seals, they will wear out much faster, and you will have more drag. (you may notice some white slimy stuff in your seals when you take the forks apart... this is the factory grease from Showa...).
good post Max...
shame about the
Max please try ...
take spring and spacer out of left fork while on the bench (verticle) leave the end cap off and opperate the antidive valve ... now slide the fork up and down it will move as there is no hydraulic lock,
Your devils advocate Nigel Fenton
shame about the
There is no Hydraulic lock and the calipers put load into both fork legs as all twin disk systems do.
Max please try ...
take spring and spacer out of left fork while on the bench (verticle) leave the end cap off and opperate the antidive valve ... now slide the fork up and down it will move as there is no hydraulic lock,
Your devils advocate Nigel Fenton
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I have. Yours must be broken.Nigelf said:
We can hang on the fork with the valve actuated. It absolutely, without a doubt, hydraulically locks.
I am not sure if you are kidding are not about dis- assembling your left fork, but I am interested in your results if you really do this. When I manually activated my anti-dive valve and visually looked at the piston in the oil transfer port, I could not see any oriface area remaining. If there was, it was very very small. At just a glance, it looked like it darn near shut the oil transfer port totally shut.
Yak... thats the point it does block the oil Xfer port its either on or off. This causes the effect of two different spring rates, one just the spring and the second spring and the air in the fork tube with the spring.
Its probably semantics im getting confused with here as to me hydraulic lock means no further travel possible due to fluid not being compressable. There wil always be an amount of air within the spring section of the fork that can be compressable therefore hydraulic lock should NOT be (edit) possible.
The left fork is there only for two reasons, one to hold the wheel, second to house and utilise the function of the ADV. The ADV has one job that is to switch between two different spring rates. These rates are for normal use ie road bumps the other is to account for the increase of weight under brakeing that the forks come under. Because of the air within the spring section i doubt there is any damping performed by this fork side.
Nigel Fenton
Its probably semantics im getting confused with here as to me hydraulic lock means no further travel possible due to fluid not being compressable. There wil always be an amount of air within the spring section of the fork that can be compressable therefore hydraulic lock should NOT be (edit) possible.
The left fork is there only for two reasons, one to hold the wheel, second to house and utilise the function of the ADV. The ADV has one job that is to switch between two different spring rates. These rates are for normal use ie road bumps the other is to account for the increase of weight under brakeing that the forks come under. Because of the air within the spring section i doubt there is any damping performed by this fork side.
Nigel Fenton
BLOWN FORK SEAL
A few weeks ago I started hearing a churp from the front end. My first thought was that the fork seal was going out, but no leaks yet. Then one day at work my amature engineering started to work. If all of the bug buts and dirt and tar end up on the fork , the dry fork, then I just needed to clean it with some penetrating oil. It took a complete trip home and back to work, but it worked, no more churping. So, is this the reason so many seals go out that the forks are just dry and dirty? And does any others clean and lube the forks?
A few weeks ago I started hearing a churp from the front end. My first thought was that the fork seal was going out, but no leaks yet. Then one day at work my amature engineering started to work. If all of the bug buts and dirt and tar end up on the fork , the dry fork, then I just needed to clean it with some penetrating oil. It took a complete trip home and back to work, but it worked, no more churping. So, is this the reason so many seals go out that the forks are just dry and dirty? And does any others clean and lube the forks?
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There is absolutely almost nothing correct in this entire post. It is so completely wrong that to analyze it is pointless.Nigelf said:
The left fork works VERY simply, although BADLY.
The fork spring and the air spring are interelated. They have ABSOLUTELY nothing to do with the anti-dive system.
The anti-dive system is HYDRAULIC. It has NOTHING to do with the fork spring and airspring.
The anti-dive system is designed to stop the bike from compressing when the brakes are applied.
The springs you see on the valve oppose one another. The fork will and does hydraulically lock at low wheel velocity. It can BARELY "blow off" if you ram the bike into something big and sharp. So it is technically not always hydraulically locked, just most of the time while the brakes are applied.
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2,349 Posts
Re: BLOWN FORK SEAL
Honda Polish works great on loosening up dead bugs.
Debris is a very common cause of seal failure. The most common debris being a dead bug. They will splat on your tubes while you are riding on the freeway. Then you warm hot bike bakes the bugs to the tubes. Then you get off the freeway and hit some big bumps, and the seals will drag over the bugs and get messed up.ib-OHto said:
Honda Polish works great on loosening up dead bugs.
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We have worked on hundreds of GL1800 forks. I can assure you that I have personally hung on an extended GL1800 left fork with no cap on it and no spring in it.Blind Yak said:
All it takes is a second person with a pick to push on the valve while you hang on the fork.
We do this all the time to show people how jacked up the design is.
We are going to (finally) film a video about all of this during a class at Wingstock here at the end of this month.
Well here is my quick video!
http://www.youtube.com/watch?v=JJOzb5zC29Q
top cap off, spring and spacer left in place to enable a better view. The dust cap was also placed so that movement can be more easily seen.
Two full strokes with no ADV enabled then two further strokes with ADV enabled. I am presuming the slow movement is due to fork oil passing between the outer fork leg and the lower guide. I made a quick measurement with a set of bath scales and with the ADV enabled the downward force was approximately 35 Lbs a mere fraction of the weight the fork would receive in normal opperation.
I want to do a further video with a balloon on the end to show the pressure buildup but I have no balloons!
Comments please
Nigel Fenton
http://www.youtube.com/watch?v=JJOzb5zC29Q
top cap off, spring and spacer left in place to enable a better view. The dust cap was also placed so that movement can be more easily seen.
Two full strokes with no ADV enabled then two further strokes with ADV enabled. I am presuming the slow movement is due to fork oil passing between the outer fork leg and the lower guide. I made a quick measurement with a set of bath scales and with the ADV enabled the downward force was approximately 35 Lbs a mere fraction of the weight the fork would receive in normal opperation.
I want to do a further video with a balloon on the end to show the pressure buildup but I have no balloons!
Comments please
Nigel Fenton
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304 Posts
My left fork seal Did blow when I hit a pot hole. I was in El Paso on I-10, saw several pot holes Hit my brakes to slow down & tried to miss them. Missed the first hole, but caught the second one. I emediatly started pumping out oil with stroke of the fork.
Just drove it home to Houston. I thought , screw it, it's just the way Honda whats/designed it!
Got home pulled the dust cover & the lip seal had a portion of the lip had turned inside out & when pushed by had, oil pumps out.
It did not wear out, it was over pressured. I used a plastic scraper pushed the seal lip back in place & it sealed off again. How ever, there is a spring inside that keeps tension to the bore contact that may have come off. I did not take a chance of a loose spring damage to something, so I took it apart & rebuilt both forks. The O-rings on the anti-dive piston had swollen & would not move.
This is the third time for me & Honda says Nay! Argued w/ Honda tech Mgr & 1-800-P.O.S. person that doesn't know squat about machinery.
Repaired every thing & disabled the anti-dive. fine for two years now.
DangerousDAn
Just drove it home to Houston. I thought , screw it, it's just the way Honda whats/designed it!
Got home pulled the dust cover & the lip seal had a portion of the lip had turned inside out & when pushed by had, oil pumps out.
It did not wear out, it was over pressured. I used a plastic scraper pushed the seal lip back in place & it sealed off again. How ever, there is a spring inside that keeps tension to the bore contact that may have come off. I did not take a chance of a loose spring damage to something, so I took it apart & rebuilt both forks. The O-rings on the anti-dive piston had swollen & would not move.
This is the third time for me & Honda says Nay! Argued w/ Honda tech Mgr & 1-800-P.O.S. person that doesn't know squat about machinery.
Repaired every thing & disabled the anti-dive. fine for two years now.
DangerousDAn
Wow Nigelf you must take this stuff seriously. I hope you did not take apart your bike to make a point. Thanks for sharing your video though.
My anti-dive is back up a running and behaving well after the new seals and new ADV o-rings.
I ran the bike for about two weeks with the ADV disabled to better understand what the ADV was doing for me and my riding style. Very different, but not bad. Some aspects were better and some were worse. Now that I have my anti-dive enabled again, I am much more observant of the bahavior of the ADV. With the ADV active, I swear my front end is still going to the bottoming stops, it just goes there more slowly and controlably relative to the slam it got when the ADV was deactivated. My next test will be to place a nylon tie wrap around the fork tube as a witness marker to record the maximum fork compression and do a panic stop on a very smooth road. After the panic stop, I will inspect the location of the tie wrap (as a witness limit sensor) to see if the front suspension still bottoms out with the ADV activated and the progressive springs. Again Nigel, thanks for sharing your video. Your video appears to be consistent with controlling the rate of the dive instead of eliminating it and totally locking up the front fork.
BTW, my fork seal did not wear out either, it folded the lip identical to what DangerousDan described. It is probably a minor difference on fork seal load whether the ADV totally lockes the front fork or almost locks the front fork with extremely high damping.
My anti-dive is back up a running and behaving well after the new seals and new ADV o-rings.
I ran the bike for about two weeks with the ADV disabled to better understand what the ADV was doing for me and my riding style. Very different, but not bad. Some aspects were better and some were worse. Now that I have my anti-dive enabled again, I am much more observant of the bahavior of the ADV. With the ADV active, I swear my front end is still going to the bottoming stops, it just goes there more slowly and controlably relative to the slam it got when the ADV was deactivated. My next test will be to place a nylon tie wrap around the fork tube as a witness marker to record the maximum fork compression and do a panic stop on a very smooth road. After the panic stop, I will inspect the location of the tie wrap (as a witness limit sensor) to see if the front suspension still bottoms out with the ADV activated and the progressive springs. Again Nigel, thanks for sharing your video. Your video appears to be consistent with controlling the rate of the dive instead of eliminating it and totally locking up the front fork.
BTW, my fork seal did not wear out either, it folded the lip identical to what DangerousDan described. It is probably a minor difference on fork seal load whether the ADV totally lockes the front fork or almost locks the front fork with extremely high damping.
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Nigel;
I sure appreciate all the effort from you to demonstrate that. I look forward to Max's response and video. Both of you are good teachers!
By your demonstration, the forks are still "effectively" locked so far as hitting a sizeable bump at highway speeds. The inertia of that slow bleed-by mode is still going to put all of the stress on the left seal. That the antidive system is a big part of the reason these seals are failing is pretty much ef evident. How many right seals have failed? Normal seal failure as Max was describing with wear and bug shellack will eventually occur, but it will be just as likely on the right as will be on the left. Good show!
prs
I sure appreciate all the effort from you to demonstrate that. I look forward to Max's response and video. Both of you are good teachers!
By your demonstration, the forks are still "effectively" locked so far as hitting a sizeable bump at highway speeds. The inertia of that slow bleed-by mode is still going to put all of the stress on the left seal. That the antidive system is a big part of the reason these seals are failing is pretty much ef evident. How many right seals have failed? Normal seal failure as Max was describing with wear and bug shellack will eventually occur, but it will be just as likely on the right as will be on the left. Good show!
prs
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