fork seal question and fork seal parts number question

Joined
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soCal
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'97 ST1100
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687
Question:
What is the interval for changing the fork oil?
I don't have the Honda common service manual, which is what the ST1100 service manual references, but typically you should change it every 20k miles. The 1300 should be similar. I typically change mine with every front tire, because its an easy enough job and then I always know I haven't forgotten about it for too long.
 
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Well I'm not a fan of anything AllBalls, especially their bearings. Anyhoo, I shop PartZilla.com. IMO their OEM stuff it a decent price. Yes the OEM will cost more. Also, since the forks have to come apart, it would be wise to change out the bushings. Usually the inner (slider) is worn out, so anyones call if you want to buy the set. I haven't tried Amazon to see what they have yet.
 

dduelin

Tune my heart to sing Thy grace
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I read that suspension bottoming out will cause a fork seal to leak , why / how does that cause a leak ?
It supposedly works the same way as a toilet plunger. Compress the incompressible fluid and something has to give.

I don't agree with the bottoming the forks thing though. Seals wear out or get a nick or cut and start leaking.
 
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It supposedly works the same way as a toilet plunger. Compress the incompressible fluid and something has to give.

I don't agree with the bottoming the forks thing though. Seals wear out or get a nick or cut and start leaking.
Only have 22K miles on bike , fork surface looks perfect , I did have accident 2 years ago but still don't have memory during then ( concussion time ) that tells me fork bottomed out during that as no other fork damage is visible and is still working well , bike was laid over on right side / plastic damaged.
 
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It supposedly works the same way as a toilet plunger. Compress the incompressible fluid and something has to give.

I don't agree with the bottoming the forks thing though. Seals wear out or get a nick or cut and start leaking.
I agree with that 100%. Seals start to leak because they get damaged by a rock ding in the fork tube, or when a piece of debris lodges under the seal and allows fluid to pass.

Unless you completely fill a fork with oil, the air gap over the top can always get compressed and stop and hydraulic lock occurring.
 

dduelin

Tune my heart to sing Thy grace
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If bottoming out once, twice, or twenty times causes a continuous leak I'd be interested in the mechanics of how that happens.

Possible a bit of foreign object is lodged in the offending seal? Sometimes a strip of thin stiff plastic can be slipped between the seal and fork leg to remove a bit of something caught between the upper and lower lips of the seal.
 

ST Gui

240Robert
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I've known two instances where someone has hit a bump/pothole at speed and immediately blown a seal.

Not having inspected the fork tubes I don't know if there was some knick in the tubes or other pre-existing condition but in both cases the forks weren't leaking previously. I think the rapid compression of a full stroke of the forks may cause a leak or worse where a partial compression might not.

I don't know any of the science and may be way off base but it seems logical anyway that bottoming out would generate more stress through either greater pressure or greater duration than riding over a smooth road.

With one exception the seals on my bikes developed slight leaks from what I think was just environmental wear. The tubes themselves looked great but would accumulate a thin film. Then it was time to R&R.
 

dduelin

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I've known two instances where someone has hit a bump/pothole at speed and immediately blown a seal.

Not having inspected the fork tubes I don't know if there was some knick in the tubes or other pre-existing condition but in both cases the forks weren't leaking previously. I think the rapid compression of a full stroke of the forks may cause a leak or worse where a partial compression might not.

I don't know any of the science and may be way off base but it seems logical anyway that bottoming out would generate more stress through either greater pressure or greater duration than riding over a smooth road.

With one exception the seals on my bikes developed slight leaks from what I think was just environmental wear. The tubes themselves looked great but would accumulate a thin film. Then it was time to R&R.
I have seen quite a few bikes with rust pitting in the chrome surfaces above the normal wiped area. Bottom these forks once and the rust pits easily damage the seals which then can't seal against the smooth usual portion of the leg against which they normally move. The bump caused the leak but not from the compression of a full stroke. Undamaged forks or shocks that cannot withstand a full stroke or twenty like it without leaking are poorly designed.

To avoid environmental wear on the fork tubes you can rotate them 90 degrees each 15-20,000 mile fork service. That's what I do.
 

Paawpabear

Ken Morse
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I had the seals and bushings replaced 3000 miles ago and they both leaking pretty heavily. Don't know if it was a poor install job or I hit some railroad tracks too hard. Either way they have to be redone. Reading the comments here makes it sound like it's not that big of a deal to do. Is there a video or PowerPoint out somewhere that will walk me through the process? So far I'm getting quotes in the neighborhood of $200 plus to have both sides done. Any suggestions?
 
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I don't believe that hitting bumps causes fork seals to leak. Things that do cause leaks are 1). bike parked up with no use for months at a time or 2). a rock dent in the fork tube that causes a tear in the seal or 3). debris caught under the seal.

It is worthwhile assuming the last one first, if you get a very fine feeler gauge of something similarly thin (there are commercial fork seal cleaners available too) you can work that down under and around the seal and may have success knocking any debris out. If that doesn't work then you will need to replace the seals, and when you do take a very close look/feel of the fork tube where it slides through the seal and look for any nicks that might tear the new seal. Dress those down with a fine file so they don't cause more damage.

Here's a link to a generic seal replacement.

[video=youtube;0TCYIEcDcts]https://www.youtube.com/watch?v=0TCYIEcDcts[/video]

For the ST just make sure you have some means of driving the new seal into place; IIRC the ST13 uses an unusually large 45mm diameter fork tube so you will need something that slips over this. On my 41 and 43mm forks I have a piece of 50mm PVC conduit pipe that I use as a driver.
 

rogo

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Question:
What is the interval for changing the fork oil?
I use the OEM service manual. I do not see anywhere to change fork oil other than while
replacing seals or other fork disassembly.
My 05 has less than 30k so I maybe lacking some foresight on issues which may be caused
by older fork oil. Condensation and contamination may be more rampant than I expect.
 
Joined
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soCal
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'97 ST1100
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687
I use the OEM service manual. I do not see anywhere to change fork oil other than while
replacing seals or other fork disassembly.
My 05 has less than 30k so I maybe lacking some foresight on issues which may be caused
by older fork oil. Condensation and contamination may be more rampant than I expect.
About 25 years ago I started changing it at the same time I changed the front tire, which worked out to about 10k miles, and I'd never have to write down when I changed it last. Before that I did it every 20-25k. Seemed like my fork seals lasted longer after reducing the change interval, but maybe the seals got better or it was just random bad luck on my previous bikes. It does accumulate dirt over time, so the longer you wait the more abrasive it becomes on the fork internals.
 

rogo

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000155
Question:
What is the interval for changing the fork oil?
Read a few threads and come across bad trans' , diff' oil enough to know that is not what I want controlling my suspension. Cleaned seals twice. I'll replace seals and oil before the BRG.
 

rogo

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Read a few threads and come across bad trans' , diff' oil enough to know that is not what I want controlling my suspension. Cleaned seals twice. I'll replace seals and oil before the BRG.
I will let you know what 30k factory fork oil looks and smells like in a well pampered pig.
 

rogo

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I will let you know what 30k factory fork oil looks and smells like in a well pampered pig.
Disassembled my r/h fork last night. Oil looks like old transmission fluid. No pungent stinky odor noticed. seal had a coating of white slime, probably from the teflon worn off the bushing. New seals, bushings and oil needed. Hopefully be riding this weekend.
 
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