Leaking Fork Seals

I recently bought an Australian 1990 Yamaha TT350. When I bought it the
fork seals were leaking so I bought new ones from my local Yamaha shop
and installed them. The new seals never seemed to really seal correctly
(they left a smear of oil on the tubes) and now, after only maybe 20
hours use, they are leaking so bad that the fork oil is running down the
fork legs again.

I had expected one to leak as I made a mess of the installation and
tried to use a piece of PVC pipe that was not quite the right size to
press it in - I slipped and (probably) damaged the seal. But, for the
second one I remembered that I had read (maybe here) that you could use
the old seal to press the new seal into place. I am confident that at
least one seal was installed correctly, but they are both leaking just
the same.

I Know that these forks originally came with gaiters. Mine did not have
them when I bought it and I have never installed any. Could a couple of
muddy rides really ruin the seals this quickly? These forks have a dust
seal above the oil seal and it works. When I removed the dust seal to
try the "get the grit out with a piece of plastic film" trick it was
nice and clean between the dust seal and the oil seal and I didn't find
any grit with the plastic film.

Could I have just bought a poor quality (they were not genuine Yamaha,
but I suspect they were OEM as I did get them from a Yamaha dealer) set
of seals? Could they have been ruined this quickly by using the forks
without gaiters? Is there something else that could be causing them to
be leaking so soon? I can't see or feel any imperfections in the chrome.

Thanks,

Brian

 

One muddy ride is all it takes sometimes. But just because the seals
leak doesn't mean they are "ruined."

Not unusual that you didn't find anything with the film trick. But does
the seal still leak?

What condition are the fork tubes in? Any pits or dings or scratches you
can feel with a fingernail and there is no hope of the seals sealing.

Is likely you can disassemble the forks, clean everything, reassemble,
and all will be fine once again until you hit a big mud puddle.

 

Speaking of which, my current bike ('81 CB650C) does not have gaiters on the
fork tubes, but my first bike ('71 CB500-4) did. As I am more concerned with
function over form, is there any way to add gaiters to a bike's fork tubes
without disassembling the whole front end?...

 

30 sec. on Google turned up:
http://faq.f650.com/FAQs/ForkProtectorsFAQ.htm

http://faq.f650.com/GSFAQs/ForkProtectorsFAQGS.htm#Shield Type Fork%2
0Protectors:

http://advrider.com/forums/showthread.php?t=69200

There's plenty more out there.

So, is it consensus around here that the disappearance of fork gaiters
was a triumph of fashion over function? I don't really know anything
about the subject one way or another.

--
Later,
John



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

 

Are you sure you've got the right amount of oil in the forks ?
If they're overfilled, leaking would follow. Also, check the
fork legs to be sure they're not pitted or rusted.

 

I am sure about the stanchions not being rusted or pitted - they are
very nice.

Oil volume is an interesting question - I have 533cc as per the Clymer
manual. It does seem a lot...

Thanks,

Brian

 

No, not really, because modern seals and dust seals (and the
smart little plastic whatsitsname that protect the stanchion
just above the seal from stones) are quite adequate for
most bikes in most situations.
OTOH, if you subject your bike to a lot of dirt, sand and
stones there is no substitute for gaiters. So called "adventure"
bikes without gaiters is one of the jokes in that particular
market segment.

 

I know more folks who swear at Clymer than I do folks who swear
by them. I usually work with the Haynes and Clymer manuals
both open and compare them carefully. I suppose it could also
be some kind of plumbing problem too. If it were me, I think I'd
double check the volume, then start asking owners groups for
ideas.