New fork seal not sealing

First off i want to apologize for not scouriung the forums for my answer. I hope this isn't a FAQ.

I just replaced the fork seals on my "1 year old" 86 VFR 700. The original ones weren't terrible, but I was starting to nitice oil on the pistons, especially on the one where the metal structure in the seal was all rusted. After putting in new seals, I have the same problem on the side with the bad seal. I will say, I thought I did a pretty good job. I was gentle, I used a PVC driver, and was generally pretty clean.

Which is more likely?

A. The fork is scored and no matter how new the seal is it doesn't matter.
B. I F'd up the seal putting it in, regardless of how god a job I thought I did.

And a follow up question;

Is there anything I can do to clean the seal w/o tearing everything apart again?

Here's a little more info...


I'm not talking a lot of oil, thats after 50-100 miles


spared myself 1000 words...

 

Kinda bummed nobody got back to me...

So, for anybody's information, I should have replaced the bushings that keep the two tubes concentric to each other. At least I have a Saturday project... I'll let you all know if that does the trick.

 

How do the fork tubes feel? Are they very smooth? I would think you would be able to notice a scratch big enough to cause a leak. My first guess would be the seal is kinked. My paranoia over this very thing is what caused me to take mine to the shop for the seal job. Good luck.

 

if there are rust pits or scratches on the fork that damage the seal you can see or feel them.

on REALLY high-mile bikes the seals will leak if the upper bushing has not been replaced.

did you use OEM or aftermarket bits??

you don't pressurize the fork with air, right??

 

Did you figure out what was wrong with it???

bob

 

use stop oil leak and it will fill the scratches....

 

Did you replace the seal underneath the dust-cap that's showing in that pic, or just the part showing in the pic?

Also, the seal that's under that dust-cap can be installed upside down, are you sure it's correct side up?

I don't know if those forks can be filled with air, but if so, and if you did fill them, did you use an air compressor hose to fill it? (them) This can damage seals too....

(not trying to insult you by any means, just asking. I've seen people throw multiple answers at a problem assuming some basics are in place only to find out the OP wasn't aware of those basics)

 

doug's points are good, and i totally forgot to mention that the oil seal can easily be installed upside -down...and he may have identified your prob right there !

 

Answers to questions

Okay...

Forks weren't originally pressurized when the seals were installed. After I noticed the leaking, I did put in around 20 psi (w/a bike pump) and reduced it to about 10 on each fork.

I replaced the dust seals as well as the fork seals, installed right-side-up (wrong side down?)

There isn't any scouring on the fork tubes, they are smooth and pretty

Bike has ~50,000 miles

I am picking up new seals, bushings and the little rings that go above the bushings today (OEM). I will install them on saturday, and you will all know how it turns out.

Only one side leaks, am I crazy to install two new seals? I figure with all the work I do tearing the bike apart, I might as well pay $50 extra bucks to do both, kinda like insurance...

Just for my information (as a mechanical engineer), what happens when you run out of oil in the forks? I would imagine the oil is there to lubricate, as well as dampen the oscillations. Am I correct? Any other reasons those buggers are full of oil? Could I have an accident?

Thank you all, I am convinced forums are one of the best ways to learn how to do stuff. I heart internet.

 

I had the same problem on my 87 when I replaced the seals and it turns out I had indeed instaled them upside down, I just popped them off, cleaned them up, flipped them around and havent had a problem in the 7k or so Ive ridden on them since. Without going and looking at them on the bike I cant remember which side is up, I believe the compression spring that is inside the seal should be facing down, but I could be wrong. take it to a cycle shop and see if you can ask a tech which way it should go in, thats what I did. Hope this helps

 

the manufacturers imprint, size designation and any other graphics face up.....

be sure not to over-fill.....use 10 wt. FORK OIL, not the ATF, and fill to 6" below top of tube with spring out and fork fully compressed.......just like it says in the Bible !

 

The oil is in the forks, because liquid doesnt compress. The forks have small passageways that the oil flows through in a controlled manner to dampen the road imperfections. If you had no oil in the forks, you'd have no damping effect. I would think that if you had a leak as small as yours, that it would be next to impossible to run out of oil in the forks. That's not to say that you shouldn't fix the issue.

I am unfamiliar with how the older style of fork works (the ones with the schrader valve at the top for adding air), but I was under the impression that this was for adjusting the ride height under load.

BTW - I've also installed fork seals upside down, too - they leak when you do that... :tongue:

 

i feel like a dick

The fork seal was.... UPSIDE DOWN! That's one of those times when i'd rather learn from somebody else's mistake than mine. It won't happen again though.

 

Air Pressure

I was advised by a Honda tech. to not use air in the forks. He said it was a good way to blow oil seals and recommended using heavier oil. I've been using 15w in the forks and zero psi and it has served me well for ten years. Also, my Clymer manual recommends 6 psi max. (not sure if that is what Honda recommends). I've always been curious about the performance with air in the forks but just haven't taken the time to experiment. Anyone ever played around with forks in this manner? Good luck with the seals---M

 

The oil is a component of the hydraulic damping circuit of the fork. The damping is to control the action of the spring.

 

At a very basic level, due to the thermal expansion properties of "air", it is not ideal for pressurizing suspension components.