Cleaning fork seals instead of replacing them

This may be amazingly hard for you to comprehend, but the word "splash"
comes to mind. Also, forks compress and... oh, never mind.

Did I mention England? No.

<Holds head in hands>

Nobody, but nobody can be this stupid, can they?

It's good advice. You ought to read one yourself, but to judge from your
inability to read a schematic ("The battery's behind the fairing panel"
or "I have no idea what this bolt is") it would be a waste of effort.

 

Exactly. I mentioned air-assisted front forks, but he dodged the issue,
as is his wont when someone points out the blindingly obvious to him.

Agreed. A solution for a problem that didn't exist.

If we accept his logic to be true, then *every* vehicle that goes up and
down hills will suffer from leaking suspension since (and this will
obviously come as a surprise to the ignoramus) just about every vehicle
uses hydraulic dampers.

Returning to those air assisted front forks, there were a right PITA. I
had them on a Guzzi, and also on a Kawasaki GT750 shafty, and the forks
held a gnat's fart of air, and in checking the pressure you lost about
half of what was in there, so in the end I never bothered and ran them
on atmospheric.

As the world does these days, of course.

 

You don't think the world has moved on, in terms of construction and
seal technology, since then?[/QUOTE]

Well, 25 years ago, Honda put a schrader valve and a crossover tube on my
CB900's forks, and declared that the system was to be pressurized to (I
think, without checking the specs) around 10 PSI for normal operation. So I
do, and the fork seals hold that pressure nicely for months and months of
riding.

Considering this, I doubt that fork-burping was ever anything more than an
old wive's tale about a non-existent problem. Mind, I don't know anything
about Booger's DT-1, but if his claims about the fork vent are true, I'd
probably chalk that up to Yamaha's engineers falling for the same OWT.

-Scott

 

Ah, good, I'll wait until I go home before buying a bike with USD forx.

--
Ivan Reid, School of Engineering & Design, _____________ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
GSX600F, RG250WD "You Porsche. Me pass!" DoD #484 JKLO#003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".

 

To be perfectly fair to the guy, I never did actually write out the word
"splash" in my post (to which I'm going to assume he was responding,
since I don't see originals of his).

Didn't we just cover this in the "how much power does the CL350 have"
thread? The answer is "yes."

I wonder if he realizes that he's contradicted himself?

His GSX-R had a bunch of oil running out of his oil seals because the
pressure _inside_ the fork leg was higher than the pressure _outside_ of
the legs.

And in the above quote, he's claiming that not much air is going to pass
the seals if there's higher pressure _inside_ the fork leg. Surely, it's
not air but oil that's going to pass the seal, right?

<VBG>

--
Later,
John



'indiana' is a 'nolnn' and 'hoosier' is a 'solkk'. Indiana doesn't solkk.

 

Never suggested you did.

I'm waiting eagerly to see how he copes with the suggestion that as
almost all vehicles have hydraulic suspension, by his logic, they should
all leak like sieves.

Let's see.... OK, the highest I travelled last year was about 14,000
feet, albeit on four wheels. Can't say I noticed any leaking suspension
then.

 

How does oil splash, or forks compress, when a motorcycle is stored,
motionless, for two years?

You're doing a pretty good job.

The schematic for the Ducati was extremely vague.

And nobody except Honda ever had caliper adjusting bolts, as far as I
know,

But how much time should I spend, looking up information for people
asking questions, when they could look up the information for
themselves, if they only knew enough about mechanics to interpret the
published technical information?

 

Air-assisted forks were an experiment of the late 1970's/early 1980's
that didn't work out well. Suspension engineers wanted to install
lower rate springs to increase initial suspension compliance over
small bumps and still avoid bottoming the forks over larger bumps.

Air seemed like an ideal infinitely variable spring medium.
Unfortunately, air pressure inside the forks
caused the seals to grip the fork tubes tightly, and the increased
seal friction worked against the desired goal of better compliance
over small bumps.

Air assisted forks were abandoned and fork development changed to
using stacks of thin washers that would provide variable compression
damping during high speed stroking.

The fork could use that light spring, while depending upon the
viscosity of oil to slow down fork dive.

You weren't *there*, why throw out a wild-assed guess, with nothing to
back it up?

Pay close attention, Scott. There were NO "old wives" racing in the
desert and racing motocross to spread these "Old Wives' Tales" you
speak of.

And, there weren't a lot of yuppies without any engineering experience
hanging around Starbuck's back in those days, gathering their
information from *other* yuppies before they submitted their copy to
the editor for publication.

Motojournalists back in the 1970's were often mechanical engineers or
they at least had an associate's degree in science (even when their
day job was at a movie studio) and they had close connections to the
product testing departments of the motorcycle distributors.

What a dirtbike fan read about dirtbikes back in those days generally
came from the correct end of the horse.

 

But, you cannot say that you actually inspected the suspension units
for oil leakage, either, because you weren't planning to have this
debate with me at that time.

 

Oh, do **** off. Do stop trying to extrciate yourself from complete
idiocy, imbecility, ignorance and ridicule.

 

Did you read the posting? Did you? The seals leaked because they dried
and hardened slightly. It happens.

Not when I looked at it.

I can think of a car manufacturer that did.

You are a fraud. I don't know where you get off, on your "FOAK"[1]
persona, but it doesn't work.

[1] Google it.

 

Utter crap. Another attempt of yours to turn the subject away from your
own imbecility and side-track it.

Not all of them. Some very good ones didn't. What they had, and what *I*
have is experience. Experience from decades of riding many, many bike,s
on road and track. Experience from having owned literally hundreds of
motorcycles.

And you? You give a load of misleading advice rgearding (for example) a
CB350's disc brake, and then say: "I never owned a Honda with disk
brakes."

Well, that means you haven't owned a Honda for 38 years. Your "advice"
is therefore useless.

 

Coo, yoiu're better than I am at spotting this sort of thing. And again,
you're quite right.

I find him amusing because of his belief that he's imparting worthwhile
knowledge, in the face of all evidence to the contrary.

 

I never said that my GSXR had air-assist in the forks, but you'll have
to take responsibility for your own confusion about who said what to
whom if you kill-filed me.

 

No, it doesn't mean that I haven't owned a pile of Honda for 38 years.
I owned *other* piles of Honda that didn't have disk brakes.

Pot or kettle?

When was the last time a newbie thanked *you* for
helping him straighten out his carburetors?

 

OK, I stand corrected. So you haven't owned a disc braked Honda for 38
years. Still renders your advice useless, doesn't it?

Oh, you know about carbs. You just don't know jack shit about anything
else. That includes diesel engines, Honda brakes, mountains,
earthquakes, fork seals and Christ knows what else.......

 

Erm, this assumes that the fork caps on an old DT were airtight, which
I strongly doubt. Most fork caps I've seen have had a little rubber O-
ring to hold back what little oil ever manages to splash its way right
to the top of the fork, but that's not going to be airtight And I've
seen plenty of fork caps which have no O-rings at all.

Ths whole business about suspension leaking because of altitude is a
complete Green Pea fiction. As I've pointed out, if it were true, then
just about every road vehicle ever made would piss oil from its
suspension the moment it went up any decent-sized hill.

Returning to old Jap air suspension for a moment, and my old Kawasaki
GT750 - not a model that was sold in the US, I think. You got the
Spectre, didn't you? Air-cooled Z750 engine and shaft drive? Well, the
GT was a budget tourer using the same engine and final drive.

Here: http://www.chateau.murray.dsl.pipex.com/images/gt750.jpg

Five-gallon tank, fat seat, and air suspension at both ends.
Crucially, the rear shocks were springless. They ran at quite high
pressure - from about 30-70psi, IIRC. On the bike in the picture, I
remember trying to up the pressure when I had my wife and a lot of
luggage on the back. You weren't supposed to use an airline, but I
knew that if you blipped the trigger, it was OK.

The garage airline was bust, and it let out all the air. Damn thing
squatted down at the back like a shot elephant, with the suspension on
its bumpstops :-(

 

On Sun, 25 Mar 2007 17:56:37 +0100, in rec.motorcycles.tech,

Yup, that's about right. What I do is run 'em up to about 20 pounds (use
the compressor's regulator to limit pressure), then keep hitting it with the
gauge until it coasts down to what it ought to be.

Unfortunately mine are too soft without air, and don't have enough travel if
I shim them. I'd need higher rate springs to do it properly. In truth I'll
probably never bother, it's just not that hard to maintain them as-is.

-Scott

 

Actually, I've got every motorcycle on the showroom floor today to back me
up. You're trying to give us the engineering perspective of those times,
which in this case have been proven incorrect. It's not my fault that
modern motorcycle engineering proves that the 1970s worry about fork air
pressure was completely unfounded.

Don't nitpick. There's nothing worse than a bunch of men together when it
comes to fabricating bullshit and calling it gospel.

-Scott

 

Ouch.