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Fork Seals

mrhedges

mrhedges

Forum Mentor
Past Site Supporter
My motorcycle sat for 8 months before I got it running last week. When I bought it I noticed that the fork seals were leaking and by now I think they must be mostly drained out. The bike really easily bottoms out. So before I do anymore serious riding I want to fix this next. Is this an easy project? I looked at basecliff's tutorial and watched some youtube videos but I'm still a bit confused. What parts should I order? what tools do I need? is this an easy project? I'm not a total novice like I can do a brake job but rebuilding carbs is a bit over my head. While we are talking about shocks, the rear shocks have some surface rust should I replace them?
 
Replacing for seals is a fairly easy job, especially with the walk thru tutorials found on Cliffs site. The most complicated tool you'll need is the tool to put down the fork in order to hold the hex bolt while you loose it at the end of the fork. Easily made though with a thread rod and a few nuts. You'll also need a piece of PVC piping the correct size to drift the seal into place, easy to find. Something to think about before you do this is do you want to replace the fork springs? If your rear shocks are stock then yes you should replace them, they're 35 years old....but with that in mind there's plenty of members on here to scrape their foot pegs and still have the 1979 stock shocks on their bikes. It's all about what you want.
 
Now that I think about it I'm not sure if they are the original rear shocks. How can you tell? Either way they have some surface rust. Yea I took it for a ride around a couple miles and scraped the pegs making a pretty normal 30mph turn
 
Post a picture of them, we'll be able to tell. Sounds like the rear shocks may be gone but also the front springs. Like I said you may want to put in some new springs while you're in there. Hey, why not put these bad boys on?

20170413_143119 by Rob Ert, on Flickr

20170413_143311 by Rob Ert, on Flickr

They all ready come with new progressive springs, new fork seals and new lower rings (or what ever they're called).
 
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It's raining right now but I'll take a quick snap tomorrow. I just ordered the fork seals. I guess I gotta get'em off and gett'em apart to see how bad the fork springs are.
 
Yup, stock shocks. Rust isn't a problem, you can even clean that up if you want but if there's oil coming from the shock that's a done deal but I bet those shock springs are gone by your description of peg scraping.
 
mrhedges said:
I guess I gotta get'em off and gett'em apart to see how bad the fork springs are.
Click to expand...
I can tell you how bad the fork springs are, and I haven't even seen your bike. :-k

Replace them.

The stock springs were rather marginal when they were new. They required additional air to help hold the front of the bike up, and that additional air was always looking for a way to escape. That happened often enough when the forks were new, you can imagine how well they hold air now. :-\\\

Progressive Suspension makes springs that do a decent job, but there are better options. Because a certain amount of air is trapped in the fork leg when you put the cap on, you still have some air acting as a spring. Air is a spring that has a progressive rate. Cut the volume in half, pressure doubles. Compress farther to one quarter the volume, the pressure quadruples, etc. The Progressive springs are also ... progressive rate. Add the two progressions together and you get some interesting spring rate changes.

Sonic Springs are straight-rate springs, and are available in a few different rates. Yes, you still have some air and its progression, but now it's only the air that is progressive-rate. I have 5 running bikes in the stable at the moment. 4 of them have Progressive springs in the forks, one has Sonic. I prefer the Sonic suspension. The spring rate will depend on your personal gravitational attraction and riding style. I started with basically the same bike as yours, but have a full touring setup (see picture in my sig) and my gravitational attraction is about 16 1/2 stone, so I went with the heaviest springs offered, 1.1, and am using 10w fork oil. The ride is great, handling is everything that I need. Bonus time: the owner of Sonic Suspension is a member here and regularly offers suspension advice. Look up Rich Desmond for some of his posts.

.
 
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Geeze,

I'm rebuilding my forks but have not considered new fork springs. I like progressive....Hmmmm. decisions-decisions.


Ed
 
The idea of progressively-wound springs is rather appealing, but as I mentioned earlier, the air that is trapped inside will do a fine job of adding progression.

Stick with the Sonic straight-rate springs, you will be happier. I think Z1 carries both.

.
 
Steve said:
I can tell you how bad the fork springs are, and I haven't even seen your bike. :-k

Replace them.
Click to expand...

Steve said:
Stick with the Sonic straight-rate springs, you will be happier.
Click to expand...

+1 to both. Not mentioned is that the Progressive springs will be too long (at least the set I had were), resulting in limitations on preload adjustment and they will still be too soft a rate. Get the Sonics in the correct rate, set oil weight and level as per Rich Desmond's recommendation and enjoy much better suspension performance than OEM ever offered.


Mark
 
GSXR7ED said:
Geeze,

I'm rebuilding my forks but have not considered new fork springs. I like progressive....Hmmmm. decisions-decisions.


Ed
Click to expand...

Sonic Ed sonic. Progressive springs (talking fork springs) on the street aren't all that, you get the best benefit with progressives on the track. Add the cartridge emulator and you gots a nice set up then. No air is required either....remember the air spew?
 
mrbill5491 said:
Add the cartridge emulator and you gots a nice set up then.
Click to expand...

like he said ;)

I first did one of my forks with new OEM springs, oil, oil seals.
That improved things a little bit.

Next i tried progressive springs, and preload adjusters - works better but still ...
not to be compared to a modern fork.
Then i added Racetech cartridge emulators to this setup.
Removed the preload adjusters because of the emulators height.
Wow ... it's just not the same bike.
21st century tech and i love it !

Not affiliated with Racetech ... just impressed with the results !

For my next front fork rebuild i ordered MikeXS cartridge emulators because of
price considerations. Will have to make adapters to make them fit my fork
internals.

Interesting read : http://www.motorcyclecruiser.com/installing-race-tech-cartridge-emulators-motorcycle-fork

Because of the argument Paul Thede makes : "progressively wound springs address the problem in a backwards way. The spring becomes its stiffest when he believes you need the most flexibility -- absorbing large bumps." i will use the cartridge emulators in combination with the new OEM springs i have left over.
 
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mrbill5491 said:
Sonic Ed sonic. Progressive springs (talking fork springs) on the street aren't all that, you get the best benefit with progressives on the track. Add the cartridge emulator and you gots a nice set up then. No air is required either....remember the air spew?
Click to expand...

Gotcha! Yeah, that AIR made a mess in your shop!

There's nothing wrong with the ones I have....BUT...since I'm gonna rebuild them...

Steve said Z1 has them...I'll ask for the cartridge emulator too.


Ed
 
mrbill5491 said:
Progressive springs (talking fork springs) on the street aren't all that, you get the best benefit with progressives on the track.
Click to expand...

That is backwards. Progressive springs allow a softer ride on the street while stiffening up to accommodate increased loads due to luggage, passenger, etc. No track bikes or race bikes use progressive springs or linkages if they can help it, the non-linear wheel rates complicate tuning significantly.


Mark
 
mmattockx said:
That is backwards. Progressive springs allow a softer ride on the street while stiffening up to accommodate increased loads due to luggage, passenger, etc. No track bikes or race bikes use progressive springs or linkages if they can help it, the non-linear wheel rates complicate tuning significantly.


Mark
Click to expand...


Uh, no it isn't. http://sonicsprings.com/catalog/straight_vs_prog_tech_article.php
Another article stated they are better for the tracks because the way progressive springs can react to track loading conditions.
 
I just sent request to Z1 for Sonic fork springs as well as cartridge emulator.


Ed
 
mrbill5491 said:
Uh, no it isn't. http://sonicsprings.com/catalog/straight_vs_prog_tech_article.php
Another article stated they are better for the tracks because the way progressive springs can react to track loading conditions.
Click to expand...

Sonic states : "I think it’s safe to say that there’s not a single reputable suspension tuner who advocates progressive springs."

i've found one in 10 seconds, Hyperpro is a reputable manufacturer.
Google is happy to provide an article for every point of view :-)

Every single suspension manufacturer makes progressive springs...
that must mean something.
Progressive springs have been hot for decades now.

We're talking road use, not track use or motorcross.
Ever try race tyres on the road ? They work like crap.

It is a known fact progressive springs are an improvement over 35+
year old straight springs for my GS.
But in combination with cartridge emulators and/or air preload, straight springs
may be better.

There are so many factors and different applications it think is not ok to try to apply
one remark from one manufacturer to all situations.

I happily accept this is complicated stuff and i am happy with an improvement
over stock suspension - and i believe the progressive springs are just that.
 
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Rijko said:
Sonic states : "I think it?s safe to say that there?s not a single reputable suspension tuner who advocates progressive springs."

i've found one in 10 seconds, Hyperpro is a reputable manufacturer.
Google is happy to provide an article for every point of view :-)

Every single suspension manufacturer makes progressive springs...
that must mean something.
Progressive springs have been hot for decades now.

We're talking road use, not track use or motorcross.
Ever try race tyres on the road ? They work like crap.

It is a known fact progressive springs are an improvement over 35+
year old straight springs for my GS.
But in combination with cartridge emulators and/or air preload, straight springs
may be better.

There are so many factors and different applications it think is not ok to try to apply
one remark from one manufacturer to all situations.

I happily accept this is complicated stuff and i am happy with an improvement
over stock suspension - and i believe the progressive springs are just that.
Click to expand...

My bike come stock with progressive front springs, I went to the straight rate springs and they work much better. Odd that it seems like so many of us here have gone to the Sonic straight rate springs on our GS bikes and like them. You do whatever you want.
 
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