Fork Seals

[GaryZ]

My '92 only sat for a couple of months this winter. I noticed the forks air was down from 16 to 6 and pumped it back up. Note: I have a problem dragging the center stand when carrying my best friend, so I run 16lbs of air in the forks and 71lbs in the rear most of the time. I have been doing this for around 5k miles.

 

When I fired her up and rode to the car wash, the forks went limp. The fork seals are blowing oil all over and air leaked out!

 

The only thing different this year is I had removed the 'gator dust covers a couple of rides before parking her for the cold weather.

There are no dust covers at all protecting the seals right now . . .

 

 

 

OK experts (and all others):

Did grit get into the seals, or should I bleed air out of the forks when she sits for awhile?

[cowpuc]

Back in the old days I used to use 35mm film to clean the fork seals on my dirtbikes and it worked really well. I am almost positive that there is an actual tool made for this nowadays. Probably walk into any bike shop that sells MX Bikes and get one.. All you do slide the film (or tool) between the seal and the tube and drag the dirt out..

IMHO - 16 pounds of air is to much.. If your springs are sacked to the point that you need that much air there is a good chance your bike is ready for Progressives.

Also, it is not uncommon to lose a little air pressure in forks, tires and the like over a winter storage. Sounds fairly normal IMHO.. While your filling those forks dont forget to double check tire pressures cause they usually lose a little too over the winter..

[GaryZ]

Back in the old days I used to use 35mm film to clean the fork seals on my dirtbikes and it worked really well. I am almost positive that there is an actual tool made for this nowadays. Probably walk into any bike shop that sells MX Bikes and get one.. All you do slide the film (or tool) between the seal and the tube and drag the dirt out..

IMHO - 16 pounds of air is to much.. If your springs are sacked to the point that you need that much air there is a good chance your bike is ready for Progressives.

Also, it is not uncommon to lose a little air pressure in forks, tires and the like over a winter storage. Sounds fairly normal IMHO.. While your filling those forks dont forget to double check tire pressures cause they usually lose a little too over the winter..

 

Thanks for the ideas . . .

 

I will probably try cleaning the seals. In my experience, it is uncommon for both fork seals to start leaking at the same time if rough roads and wheelies have been avoided. I usually use a strip on a feeler gauge to clean the seals . . .

 

There is a total of 32,000 original miles on my '92. It is unlikely the springs are wore out. I run the maximum air because if I don't, it has very little ground clearance. The issue of this bike dragging the center-stand has been cussed and discussed since I bought the beast. No suggestions seem to help the ground clearance compared to my '85 VR. The '85 has Progressive fork springs and I will run 6lbs of air when carving corners with a passenger. I have posted a picture of the rear tire on my '85 after some aggressive twisty roads and the edge of the tread is feathered. Most of the time there isn't air in the '85s forks.

 

Yes, it normally will lose about 4lbs of air from the forks when parked for awhile. This was 10lbs . . .

[Flyinfool]

The front springs do not die from mileage they die of old age. Your 92 is old and I would bet they are weak at best. Those springs are holding up the weight of the bike whether it is sitting in the garage or flying down the road, either way they are still working.

[MiCarl]

The springs weren't great shakes the day the bike rolled off the line.

 

The air didn't leak out because of springs though. Aside from miles those fork seals are likely 25 years old. Rubber doesn't last forever.....

[BlueSky]

Yep, it's time to install new progressive springs and new seals.

[GaryZ]

Thanks everyone for the ideas and thoughts.

I am not believing that the springs are simply "old" as I have been around lots of old bikes and cars.

It is very real, after owning two VR's, that the stock fork springs are not very good.

The best comment for me seems to be that the seals are old and dried out.

Especially since the bike has been sitting in a car port for the past 18 months.

I ordered and recieved seals and now need to make room in the shop to replace them . . . and I ordered the springs just now.

Maybe the thing will quit dragging the center-stand!

Edited March 18, 2016 by GaryZ

[Max]

Did grit get into the seals, or should I bleed air out of the forks when she sits for awhile?

 

Back in the old days I used to use 35mm film to clean the fork seals on my dirtbikes and it worked really well. I am almost positive that there is an actual tool made for this nowadays. Probably walk into any bike shop that sells MX Bikes and get one.. All you do slide the film (or tool) between the seal and the tube and drag the dirt out..

 

I keep one of these tucked away in the owners manual on the bike. Used Sealmate once on the road a couple of years ago. It worked for a few days as a temporary fix until

I replaced the seals, bushings and fork oil. Picked it up for about 6$ at Royal Distributing.

[blaine1]

has anyone tried this seal mate blaine

[Patmac6075]

Like Puc said.....use 35mm film, it's basically the same stuff (the store bought stuff DOES have that nifty little hook, so I guess it's got that going for it)

[dna9656]

35mm film? like photographic film or mylar?

 

Does anyone have a recommended parts list for re-building the forks?

I have a set of '86 forks I plan on installing on my 83 along with the R6 brakes, I hope to install the progressive springs as well.

My thoughts on proper fluid in the forks; I solicit feedback on my thoughts here as I haven't done this.

When draining the existing oil measure how much is in there as you pour it out. Just FYI record that number. Check out how much came out against the book amount FYI.

Service the fork with the book's recommended amount of oil and (using some tape) mark the level on the outside of the fork tube and install new spring; (hopefully it won't overflow) note how far up the tube the oil moved with the increased displacement of the larger spring. If it looks like it will overflow the fork tube you could remove the spring, reclaim the oil, reinstall the spring and refill the tube until the original oil lever is reached. Note how much you used and record. If it doesn't overflow you can use a straw (or any other tool that can draw oil from the fork tube) remove the (now) excessive amount of oil to the original level you put in there to start with. Note how much you remove, subtract that number form the book amount and record that in your notes for the next time you change the oil or for a subsequent owner.

Edited April 4, 2016 by dna9656
clarity

[GaryZ]

OK, here's an update:

Replaced the fork seals and installed Progressive springs. For re-assembly I eliminated the stock spacer (metal tube) and reused the washer on top of the spring, and I reused the stock aluminum spacer instead of the PVC spacer in the Progressive kit. I also poured in 10wt fork oil until it was 5.25" from the top with the forks fully compressed. This combination required approximately 3/4"- 1" compression of the springs to install fork caps. I found that a speed handle and socket worked wonders for installing the fork caps!

We rode nearly 300 miles for a test of the set-up. No leaks! The ride is firmer than before and I might remove more fork oil to reduce damping. Ground clearance is slightly better, but, with 70lbs of air in the rear shock it still wants to drag on certain driveways (slightly leaned over, riding double).

I am still puzzled that the '92 seems to have much less ground clearance vs the '85 . . .

[Patmac6075]

Sorry I can't help with dragging the center stand....but would like your feedback on using 10wt fork oil. I just did a total rebuild (sliders, springs, both seals, even changed o-rings on the anti-dive), I went with 360ml (as per another member suggestion) of 10wt and I'm experiencing a wicked "pogoing" effect at low speed (10-25 mph). Have been too lazy to make the change to 12.5 or 15wt, goint to wait until the off season. FYI, at speeds above 30 mph, it's solid with no pogo.

[GaryZ]

I always want a soft, responsive and controlled suspension. My sport bikes have adjustable rebound damping (newer sport bikes have adjustable rebound and compression). My habit is to set the springs soft and adjust damping to my liking. My recent changes have resulted in a bit too much damping. In a perfect world I would have used something lighter than 10wt fork oil. Unfortunately my local shop only had 10wt. That is why I reduced the level from 5.5" (suggested by Progressive) to 5.25" of oil. Removing more oil will be less damping.

 

A total lack of damping would pogo, think of a car with bad shocks. However, it seems to me that since your bike is smooth at speed, the pogo could be a brake binding or front wheel out of round, sticking bearings. I would start troubleshooting by raising the front wheel off the ground and spinning it. It is normal for brake pads to drag slightly.

[Patmac6075]

Not the case at all. Bearings are brand new, the entire braking system has just been completely rebuilt (hydraulics, pads, calipers, masters, SS hoses...the whole shootin' match), and front wheel spins easily and true, brand new E3 tires, balanced, new progressive springs, and even a super-brace. No wobbles at speeds up to 100mph (as fast as I'm willing to go), as I said solid as a rock above 30mph.

Numerous other members have reported a pogo effect with 10wt which was cured by changing to 12.5 or 15wt (although I have read some members claim 15wt is too viscous). I find it interesting that you're not having this issue....what brand of fork oil did you use?

[Flyinfool]

Hmmmm, Interesting.

I just went from 10W to 12.5 W and felt the "pogoing" at low speed got worse, I am thinking of trying 15W next.

[BlueSky]

Seems to me that if you install the Progressive fork springs that are much stiffer, the dampening has to be stiffer in its action to match the stiffer springs. Just seems to me. I would think thicker oil would be needed to achieve this.

[GaryZ]

I used Maxima Racing Oil (see pic below). My '85 is running 7.5wt oil and Progressives and I ran my E3 rear tire all the way to the tread edge with a passenger in NW Arkansas. The stock rear shock was running 55psi and the front was Progressive springs, 7.5wt fork oil, added 6psi of air for more ground clearance. The '85 went on a diet as soon as I got it (removed floor boards, CASS system, CB radio, front fender bumper, trailer hitch/rear bumper, and bobbed the rear fender. I really, really like the way the '85 handles. The '92 is probably carrying 60+ pounds more weight. Neither bike exhibits low speed pogo.

 

Could you be porpoising (rocking like a hobby horse)?

How much air are you running in the rear shock?

Riding double?

Lots of stuff in saddle bags and trunk?

Bike loaded with bling?

 

Could you have too much oil? Have you measured the oil level with the forks collapsed?

Progressive suggests no more than 5.5" below the top.

[BlueSky]

The first time I replaced the fork seals in my 85 Kawasaki ZN700 I used Kawasaki OE seals and Belray 10W fork oil. The dealer sold me the 10W, probably because that is what they had. The seals didn't last very long. The second time I replaced the fork seals I used All Balls Racing seals and SAE 5W30 motor oil, the Walmart brand. Seems to work just fine. The manual specified SAE 20W. The second set of seals are holding up much better. I just ordered All Ball Racing seals for my Venture. I may use the SAE 5W30 or maybe 5W20 when I replace the seals in my Venture. I suspect fork oil is just overpriced motor oil. Then again, I'm just learning.

[Patmac6075]

Same brand of oil that I used?! Not sure I can define the difference between pogoing and porpoising? I am defining pogoing as very pronounced up and down motion of my handle bars on a known smooth road...I'm sure if you were driving towards me at night, you'd think I was driving on a washboard or over a rumble strip. I normally ride one up with rear shock set at MED (what is that? 43psi?). Not an overly bling'd out bike...I do have a rear bumper, but my bags are empty.....BTW, 0 psi, LOW setting MED, or HIGH it'll still pogo down the road at low speed. Also...did not measure, I used a known quantity of oil (360ml, exactly), this is the amount another member (I can't remember who, he had claimed to do hundereds of experiments with oil quantity and different weights with progressive springs).

I must also say, at speed or on the twisties...this bike night and day difference to what it was before I rebuilt the front end and braking system....it handles waaaaaay better than before...I'm not a "peg dragger", but I'm confident I could be, the way this bike handles now!

Edited June 1, 2016 by Patmac6075

[GaryZ]

Not sure I can define the difference between pogoing and porpoising?

 

I would define pogo as the front end bouncing like a pogo stick and the rear suspension working normal.

I would define porpoise as rocking like a child's rocking horse where the front goes up and the rear goes down, then the front goes down and the rear goes up.

 

The question is to try and see if the rear suspension could be the problem . . .

[GaryZ]

...did not measure, I used a known quantity of oil (360ml, exactly), this is the amount another member (I can't remember who, he had claimed to do hundereds of experiments with oil quantity and different weights with progressive springs).

 

I am not saying the other member is wrong. However, I slightly under filled my '92 forks and used more than 360mL (12oz) per fork. If the other member is a heavy rider, and you are a lightweight, you might be needing more oil to accomplish the correct damping. BTW: I am a heavyweight

[camos]

I'm going to be doing some maintenance on the forks with OEM springs so looking around to find any tips that might be helpful before getting started.

In a perfect world I would have used something lighter than 10wt fork oil. Unfortunately my local shop only had 10wt. That is why I reduced the level from 5.5" (suggested by Progressive) to 5.25" of oil. Removing more oil will be less damping.

When you say level are you referring to inches down from the top? So 5.5" would have less oil than 5.25". About how much oil would that be? I guess a liter of oil will be more than enough to do both.

[GaryZ]

I'm going to be doing some maintenance on the forks with OEM springs so looking around to find any tips that might be helpful before getting started.

When you say level are you referring to inches down from the top? So 5.5" would have less oil than 5.25". About how much oil would that be? I guess a liter of oil will be more than enough to do both.

 

The more oil poured into the fork, the higher up that oil goes. So, you are correct. I put more oil in rather than less. This could be why the forks seem too stiff . . . I might be oil binding the forks. Thanks for getting me straight!

 

I purchased a 1 liter bottle of fork oil and used about 66% of the bottle for both forks.

[BlueSky]

I'm no expert. But, I think as long as oil covers the cylinders that restrict oil flow when the fork tubes move it doesn't matter how much higher the oil is from that standpoint. However, the higher the oil level is, the less air above the oil that compresses. When the forks compress, this smaller amount of air is compressed to a higher pressure quicker making the fork action stiffer. The danger as I see it is putting in too much oil to the point that it locks up the forks when they are compressed. That is why if you measure from the top, you have to compress the forks to get the reading. If you have stock springs, Yamaha tells you exactly how much oil to put in. If you have progressive springs, they occupy much more space and less oil is needed.