Blow out fork seals with compressed air?

[Jonzilla]

As I was reading through the writeup on changing forks seals, and got to the part about disassembling the damper rod from the lower leg I was wondering why this is necessary... Or is it necessary? I (and many others) have done this on KLR650's in the past. The forks are built the same way.

All I did was remove the forks from the bike, drain the old fluid. Remove the spring and spacer. Then remove the dust seals and retainer clip. put the fork cap back on and pump them up until the fork seals pop out. No drama. No loud noise. And most importantly NO DISASSEMBLING THE LOWER LEG. I did hold a rag over the seal as it popped out to avoid any oil splatter, but this may not be necessary.

Is there any reason this cannot be done on a GS with air forks? Am I missing something? It makes the job easier and I plan to do my seals in the next week or two. Help me out please...

 

[Jonzilla]

It seems I've found my answer:

http://www.thegsresources.com/_forum/showthread.php?t=107324&highlight=BLOW+FORK+SEALS

 

[mike_of_bbg]

Mine blew at ~140psi. My wussy little air compressor couldn't go that high, but a $10 Wal-Mart special 12V tire pump was up to the task

 

[Jonzilla]

The first time I did this I must admit felt a little strange after waiting 10 minutes with my (also wussy) mini compressor up to around 150psi.

The only reason I can think of NOT to do this is if the seals are so bad that you can't build up enough pressure to blow them. Or if you really want to do some special cleaning to the lower end.

 

[sschering]

Even if I was going to tear down the lowers for cleaning I'd try this.
This way you don't have to go after the old seals with screws, hooks or picks.. No risk of damage to the lowers.

 

[hampshirehog]

You don't have to pull out the seals on these with a lever / screwdriver so there's no risk of damage (you use the lower bush on the stanchion as a slide hammer).

By the time you've found your pump it's nearly as quick and easy to strip the things plus you need to check those bushes and possibly replace. If the seal is leaking the chances are you've got a load of muck in there as well that will need cleaning out properly.

Blowing out with air is a shop trick - it saves a little bit of time, they charge for a full strip and replace but it isn't a proper job.

 

[bwringer]

The main thing you're missing by skipping complete disassembly is cleaning out all the years of muck and bug parts in there.

 

[lucabond]

put the seals under pressure then apply heat from a heat gun and they should pop right out, worked for me. Good luck

 

[salty_monk]

If you soak & flush with ATF fluid then all the gunk comes out in that in my experience. If done with care & purely for a leaking seal (i.e no nasty noises, movement etc) I don't see any issue with it personally....

 

[Jonzilla]

In my experience I have always purchased twice as much fork oil that I actually need. That way I can drain the old oil, pour in some clean, pump the fork a few times, then drain again (watch all the shiny metal powder flow out in that "clean oil"). Then go ahead and fill for the last time. I've seen more metal particles in the 2nd drain than in the first.

 

[mike_of_bbg]

It seemed to me that, in reading the manuals, the greatest risk of damage to the bushes was from the slide-hammer removal process. I disassembled my forks and cleaned them out, but I still blew out the seals with air. Yes, you still have to slide-hammer to get the upper bushes out, but the force and repetitions should be much less than if the seals were still in. If you have air valves and want to get your seals out, is there really any reason NOT to just blow them out if you're going to completely disassemble and clean anyway?

 

[hampshirehog]

It seemed to me that, in reading the manuals, the greatest risk of damage to the bushes was from the slide-hammer removal process. I disassembled my forks and cleaned them out, but I still blew out the seals with air. Yes, you still have to slide-hammer to get the upper bushes out, but the force and repetitions should be much less than if the seals were still in. If you have air valves and want to get your seals out, is there really any reason NOT to just blow them out if you're going to completely disassemble and clean anyway?

No reason whatsoever. Having said that I've slide hammered out some really stubborn seals and upper bushes in my time and never damaged those lower bushes. The lower bushes are cheap and really easy to replace though.

 

[Jonzilla]

I finally got around to doing my fork seals yesterday. I just wanted to add, for anyone who may read this thread and try blowing out their seals with air:

I could not get mine to pop out with just air alone. It has worked for me on other bikes but maybe since these seals are almost 30 years old they were really stuck.

Anyway I ended up pumping them up to an obscene level of pressure. Then taking the hair drying to them and after a couple mins. they popped right out!

I just want to add this in case someone was trying it with just air and wanting to pull their hair out because it just wasn't working... Thanks to Lucabond on post #8, I didn't have to pull my hair out.