Optimal Fork Tube finish ???

Well, as I reported on another thread, I flushed & re-filled my front forks a few days back.

What I noticed since then is if I pump the cartridge fork, I can see more than just a film of fork oil on the tube. So I removed the dust seal and yup, there looks like the seal is leaking. I soaked up all the fork oil I can see and tilted the tube down and after about 10 minutes, fork oil is dripping onto the paper towel below. Not sure if I had a leak with the 10W fork oil I had before. Now I'm using the 5W that RaceTech recommends.

The tube has no imperfections or rust - shiny & smooth. I have a new OEM seal kit on order. And I have some RaceTech seal lube that I will be coating the new seal inner lip with.

Question : What is the best surface finish to have on the fork tubes to help prevent leaks ? As shiny & smooth as possible or slightly burnished with some 800 or 1000 wet & dry ?? Or some other finish ?

Jim,
My left seal started to leak a few months ago on my 1300. I rode all winter here, so I presume it had ingested a bit of sand or salt. I never tried to clean my seals before, but tried a thin piece of plastic in the shape of the tool on the web page below. I should of mic'd the piece of plastic I used, but I believe it is about 0.010" to 0.015" thick. Viola, the leak stopped.
Now with 75,000 miles on my bike, it's due for a fork seal change, but at least I bought some time using this fork seal cleaner.
Also, I never touched or cleaned the right seal. I used the approach, if it ain't broke, don't fix it.

Thinner oil may be your problem, you may want to go back to 10W.

As for finish on the fork tubes, I believe smoother is better, but remember a write up where a guy swore 400 grit emery in a figure 8 pattern was better.



http://sealmate.net/

There must be a reason why all the hydraulic cylinders on excavators, dozers, etc. are polished bright and chromed. If your fork tube is rough, it might seal initially, but it will act like sandpaper wearing away your fork seal.

The factory chrome smooth finish is what you want. If you can feel any dings in the metal with your fingernail, then you want to sand those smooth with some 600 grit wet-dry paper (or 800/1000 like you mentioned). If there are no dings that can be felt, leave the chrome surface alone.

Seals eventually leak, its not an indication of a problem unless you just changed the seals recently.

Jim Van said:

Well, as I reported on another thread, I flushed & re-filled my front forks a few days back.

What I noticed since then is if I pump the cartridge fork, I can see more than just a film of fork oil on the tube. So I removed the dust seal and yup, there looks like the seal is leaking. I soaked up all the fork oil I can see and tilted the tube down and after about 10 minutes, fork oil is dripping onto the paper towel below. Not sure if I had a leak with the 10W fork oil I had before. Now I'm using the 5W that RaceTech recommends.

The tube has no imperfections or rust - shiny & smooth. I have a new OEM seal kit on order. And I have some RaceTech seal lube that I will be coating the new seal inner lip with.

Question : What is the best surface finish to have on the fork tubes to help prevent leaks ? As shiny & smooth as possible or slightly burnished with some 800 or 1000 wet & dry ?? Or some other finish ?

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Before you go all crazy on that fork consider this. If you FULLY extended the fork tube, while upside down, as you pumped old fluid out, you will have exposed an orifice ABOVE the fork seal, which allows some fluid to collect in that cavity between the dust seal and fork seal. That is the oil you saw there when you pulled the dust seal.

If you just clean it up well, you get most of it, but it will persist as a slight film on the fork tube until the seal is free of any more fluid. This happened to me and it took a couple days of wiping the fork tube until it stopped leaving any trace of oil.

If your fork tube has no dings or marks, I wouldn't touch it with anything. I think you are asking for more trouble by trying to improve the surface. I doubt you even need a new fork seal.

Bush said:

Before you go all crazy on that fork consider this. If you FULLY extended the fork tube, while upside down, as you pumped old fluid out, you will have exposed an orifice ABOVE the fork seal, which allows some fluid to collect in that cavity between the dust seal and fork seal. That is the oil you saw there when you pulled the dust seal.

If you just clean it up well, you get most of it, but it will persist as a slight film on the fork tube until the seal is free of any more fluid. This happened to me and it took a couple days of wiping the fork tube until it stopped leaving any trace of oil.

If your fork tube has no dings or marks, I wouldn't touch it with anything. I think you are asking for more trouble by trying to improve the surface. I doubt you even need a new fork seal.

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Thanks for that info. But since I removed the old seal ( and it's toast, now ) , looks like I will be installing the new seal after it arrives. No problem with the other fork, so I will let it be. I really cleaned up the area under the dust seal, well. Just a slight film of fluid, all accumulation removed. And there was a lot of fluid under the dust seal after I removed it. After cleaning up the fluid that was present, it continues to leak out after I inverted the fork at about a 45 degree angle. After I replace the seal, I'll repeat that test and report back. I'm hoping it won't leak and I don't have fluid accumulating under the dust seal either, after installing the new seal.

Jim Van said:

What is the best surface finish to have on the fork tubes to help prevent leaks ?

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There is no DIY finish on fork tubes, and dare you to use any sand paper or other abrasive stuff on them!

Fork tubes (or any hydraulic piston rod) are hard-chromed to give them a smooth, tough, corrosion protected surface the seals can slide and caulk on with minimal friction or wear...

All you can do is keeping that surface clean and inspect for any damage, grooving or discolouration...
Things like bug-splash, dust and contaminated road-spray will penetrate through the dust-seal and cause seals to wear and fail over long periods...
Gravel hits can cause pitting in the chrome layer, which will cut the seals when the fork compresses...
And last but not least is there regular and irregular wear due the top fork-bushing, accelerated once their worn and/or contaminated with foreign substances...
You'll note this by fine, longitudinal scratches and or some discolouration in the chrome layer...

What you can do is:
- keep them clean as good as possible
- wipe with an old pantihose to detect any pitting (the fine fabric will catch on any metal chip or scratch...)
- keep an eye on any signs of wear, scratches and discolouration
- replace fork oil frequently
- replace the fork-bushings on any, even the slightest sign of wear
- accept the fact that fork tubes will wear out eventually, requiring replacement*
(* AFAIK are there shops who offer polishing and re-chroming of fork tubes; dunno how durable such a repair is, never used one...)

ST1100Y said:

- wipe with an old pantihose to detect any pitting (the fine fabric will catch on any metal chip or scratch...)

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Hmmmm . . . . do you prefer the fishnet or sheer style Martin??

ST1100Y said:

There is no DIY finish on fork tubes, and dare you to use any sand paper or other abrasive stuff on them! Snip .........

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I'm glad you didn't double-dare me, that would have been too hard to resist !!

I polished out a nick with superfine whetstone, carborundum cloth, and 600 grit wet paper about 130K ago. Work circumferentially.

The pantyhose idea is a good tip. The back of ones fingernail will detect any imperfection also.

John
via iPhone 4S

Bush said:

Hmmmm . . . . do you prefer the fishnet or sheer style Martin??

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Whatever goes with a chequered, flannel lumberjack-shirt...

Just polished two scratches out of my Honda CRF 250X left fork. I used 600 grit emery cloth & 30W oil. Wiped clean w/ a clean pair of my old Jockey briefs......nice & soft!

This was prior to installing new fork & dust seals. No issue w/ the hard chrome coating.

Installed the new seal today - no more leak.

Looks like I will be replacing fork seals about every year when I have the forks off to do a flush & re-fill. It only takes an extra 15 minutes to replace the seals on each fork tube and even the OEM seal kit is not that expensive ( seal and dust seal included in the kit ). A lot cheaper than payments on a new or newer bike, for sure.

I'll add this task to my PM List.

the dust seal is a waste of money, they never wear out unless something physically damages them. 3rd party oil seals also work well, haven't compared them in price to the OEM ones, but I suspect they're less. If you're changing them every year anyway, what difference does it make if they're Honda parts or not.

dwalby said:

the dust seal is a waste of money, they never wear out unless something physically damages them. 3rd party oil seals also work well, haven't compared them in price to the OEM ones, but I suspect they're less. If you're changing them every year anyway, what difference does it make if they're Honda parts or not.

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This is what Racetech has to say about forks seals :

" In general, OEM seals manufactured by NOK are the highest quality available. We stock OEM seals or NOK in most cases. Our purchasing volume allows us to beat most OEM prices on seals."

But I can get the OEM Honda seals for about the same price as RaceTech's prices. So I'll be purchasing the OEM items from my regular supplier, Partszilla. I bought the leaky seal from RaceTech when I installed the GV & E Kit. I think I'll stay with the OEM Honda seal from now on, even though I have to purchase the fork oil seal & dust seal packaged together. Sometimes you just have to bite the bullet.

ST1100Y said:

- wipe with an old pantihose to detect any pitting (the fine fabric will catch on any metal chip or scratch...)

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I was going to ask if you needed to remove said pantihose from the woman first, but, hey, I haven't seen this article of clothing on any women for years. So the pantihose have to be old!. You might have to break down and buy them new. (I used to use them to strain paint - hint: only ask very close friends for these.....).

Jim Van said:

This is what Racetech has to say about forks seals :

" In general, OEM seals manufactured by NOK are the highest quality available. We stock OEM seals or NOK in most cases. Our purchasing volume allows us to beat most OEM prices on seals."

But I can get the OEM Honda seals for about the same price as RaceTech's prices. So I'll be purchasing the OEM items from my regular supplier, Partszilla. I bought the leaky seal from RaceTech when I installed the GV & E Kit. I think I'll stay with the OEM Honda seal from now on, even though I have to purchase the fork oil seal & dust seal packaged together. Sometimes you just have to bite the bullet.

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I haven't bought an OEM fork seal in 35 years and haven't noticed any difference in replacement intervals between the ones that came new on the bike and the cheap OEM replacements I've installed over the years. But you're right about the cost differential, its not really enough to make much difference anyway. I got in the habit of avoiding OEM parts whenever possible back in the pre-Internet days when the local soCal dealers would mark up the already inflated factory prices even higher and make the cost difference substantial. Old habits die hard.

Jim Van said:

Installed the new seal today - no more leak.

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Looks like before I replace any fork seals in the future, I will try using this first :


FYI : Sealmate

I Just ordered two - one for me and an extra for a Christmas present for a friend.

Will fish net stockings work ??

I have no idea - Ask the guy with the Lumberjack shirt .....