1982 GS850GLZ springs suggestion

[JTGS850GL]

I know that this has been asked but never go a clear answer on the "L" model. I'm looking at replacing the springs in my 1982 GS850GLZ but can't find progressive springs specifically for this model. I know I can use the GS850G springs and shim them but not sure how much and what part number to start with. What options do I have.

[Dogma]

The spring kit comes with a length of PVC tubing you cut into spacers, then adjust to get the correct static sag with you on the bike. So, there isn't a predetermined spacer size to adapt the G springs to a GL. If I'm not mistaken, all the 850s used 37mm forks, so the same spring kit is probably recommended for all of them. I know I used the G kit specified for my year ('80).

BTW, if you ride in a sporty fashion, you might prefer straight rate springs. Sonic, I believe is the preferred brand there.

[JTGS850GL]

So basically get the kit for a GS850G and cut the spacers a little longer to accomedate the "L" configuration. Reading from the Sonic web site they say to have a 3/4" preload and described how to acheive that simply. Progressive seems to be about the same at 3/4" to 1" preload.

Now I just need to decide on progressive or straight rate springs.

Right now I'm having issues with the front forks diving so I'm thinking weak springs and maybe low on fluid. Since I have to remove the top caps or even remove the forks to do the oil change I'm thinking of doing the springs at the same time.

Edit: I did find the progressives part #11-1107 for the GS850G and a dealer that has them for less then I've found at other locations.

http://www.powersportsuperstore.com/Progressive-Suspension-Fork-Springs-11-1107-p/4102331.htm

With shipping is still comes in at $67.84 for the pair or am I missing something?

The Sonics I'm looking at are the 1.0kg/mm version with part number: 03S-100. The only supplier I found was Sonic it self at: $79.95 +shipping.

[Dogma]

Check the air pressure in the forks too, if there's too much dive under braking. Even with everything sorted, there will be a lot of dive if you really clamp down on it.

Consider the spring manufacturer's ride hight recommendation just a starting point. Setting it high or low will affect whether the bike likes to go straight, or feels like it's falling into turns (in conjunction with tire pressure, of course).

[JTGS850GL]

What I'm working toward is to not need air in the forks at all. Just seems like one more area to create imbalance. Right now I'm leaning toward the progressives because I like a softer ride around town and on the highways, but I still want everything to tighten up if I hammer on it a little.

[Steve]

One major factor that affects dive is whether there is any oil in the forks.

Yeah, the springs will hold up the front of the bike and control how far it dives under braking, but fork oil will control how fast it dives.

If the seals have been leaking, you will be low on oil. If you got the bike recently and have not noticed the seals leaking, it might be because it's already out of fork oil.

While the switch to better springs is commendable and recommended, you might also want to plan on doing the fork seals at the same time. You can test to see if they are leaking by bleeding off any air in the forks, then opening the drain plug to see how much (if any) oil comes out. (If you forget to bleed the air, there will be some interesting patterns on the far wall of the garage. ) If there is not much oil in there, I would suggest adding the proper amount of oil and riding for a while to see if there is any leakage at the seals. It's a good idea to change the seals anyway, but this will prove to you that it was really necessary. It will cost a few bucks for the fork oil, but you should be able to get two sessions of filling both forks out of the same quart of oil.

.

[JTGS850GL]

Will do. So, first on the list is to replace the oil in both legs and see what I find.

What would be the easiest and fastest way to replace the oil only? If I jack the bike up on the center stand to remove the front wheel and then let it down onto the forks depressing them completely, would that make the tubes vertical enough to get an accurate oil fill? From what I understand it's more about keeping them equal and not over filling them then it is about getting the exact amount of oil as specified in each of the fork tubes. Does this make sense?

I'll look for any pitting in the slide area of the tubes that could cause the fork seals to fail early as well. If so, looks like new forks would be in order unless someone can explain the "JB Weld" method. I'm guessing that you just use the JB Weld to fill in the pits and lightly "sand" the tubes using steel wool. Just a guess though, since I've not seen a write-up on doing this.

[Steve]

What would be the easiest and fastest way to replace the oil only?

The "quick and dirty" method is to bleed off any air, open the drains. When the flow slows to nearly a stop, pump the forks a bit to get the last bit of fluid out. Put the drain plugs back in, open the tops of the fork tubes. If you have a syringe, you can remove just the brass air fittings, not the entire top that holds the spring in place. Measure out the oil, squirt it into the forks. Even though the level is important, you can get by for a few days with it slightly mismatched. This will be good enough to let you determine if the seals are leaking.

To do the job properly (including changing the fork seals), you need to remove the fork tubes from the bike.
HINT/SUGGESTION: Before removing the tubes, loosen the clamps, slide the tubes up half an inch or so, re-clamp them into place, then use a wrench to loosen the top of the tube (spring retainer).
HINT/SUGGESTION #2: When you have the tubes back in the bike, before installing the springs, thread the top back in about one turn. Slowly turn it back out, but pull UP on it, as if you are trying to pull it off, instead of threading it off. Note where the last thread finally lets go, mark the edge of the cap in relation to the gap in the triple clamp. When you install the springs and any preload spacer, you wil now KNOW exactly where to line up the cap so that the first 1/4 turn will start to engage threads.

If I jack the bike up on the center stand to remove the front wheel and then let it down onto the forks depressing them completely, would that make the tubes vertical enough to get an accurate oil fill?

No, that will not get the forks anywhere near vertical. To leave the forks on the bike and get them vertical, you will need to raise the rear of the bike with a hoist.

From what I understand it's more about keeping them equal and not over filling them then it is about getting the exact amount of oil as specified in each of the fork tubes. Does this make sense?

Yes, it makes sense. The reason for the equal volume is that air is trapped inside. When it is compressed, it adds quite a bit to the spring rate. If the oil level is unequal, the air in the two tubes will be compressed unevenly, giving you different spring rates in the two tubes. Could make things "interesting".

I'll look for any pitting in the slide area of the tubes that could cause the fork seals to fail early as well.

Actually, pitting won't really make the seals fail. What does make them fail would be raised sharp edges (might be around the pits) or other stuff that is stuck on the fork tube that will cut into the seal.

If so, looks like new forks would be in order unless someone can explain the "JB Weld" method. I'm guessing that you just use the JB Weld to fill in the pits and lightly "sand" the tubes using steel wool. Just a guess though, since I've not seen a write-up on doing this.

You have most of it right there. Before filling in the pits, I would lightly run a fine file over the pits to remove any sharp, raised edges. Next, you need to CLEAN the tubes to remove any oil or dirt. Then you can use JB to fill in the pits. When it is set up, file or sand the tubes smooth. You should see mostly shiny metal, with nothing extra around the pits.

.

[JTGS850GL]

Thanks for the assistance on this issue. I inspected the forks and it seems like there are no pits in the normal range of the forks so I'm assuming that there should be no issues with the forks damaging the seals. I'll drain and replace the oil with 15W oil (I like it a little stiff ) and then verify that I have no obvious leaks. If so, I'll replace the fork seals and look into replacing the springs at the same time. Still looking at replacing them with progressive rate springs unless someone can give me a reason otherwise.

[JTGS850GL]

Just a quick question... If the forks hold air is that a pretty good sign that the seals are in working order? I've never see any oil on the fork tubes either. Just thinking that I may simply change the fork oil out until the winter shut down. I live in Georgia so that doesn't last very long.

[Dogma]

Just a quick question... If the forks hold air is that a pretty good sign that the seals are in working order? I've never see any oil on the fork tubes either. Just thinking that I may simply change the fork oil out until the winter shut down. I live in Georgia so that doesn't last very long.

If there's oil in the forks and not on the tubes, the seals are OK. My 850 never held air for more than a couple days, even with good seals. If yours hold air longer than that, I guess you have good seals in the air fitting too!

Depending on the condition of oil you get out of the forks, you may elect to rebuild the forks anyway, just to clean sludge out. If you have the tools on hand it's only a weekend job. A couple hours if you've done it before. Several hours longer if you lose your mind and decide to strip the yellowing clear coat off the aluminum and polish it while it's apart. Not that there's anything wrong with that.

[JTGS850GL]

What I'm planning on doing is to flush the forks out with mineral spirits before filling them with 15W oil. I'll do a complete rebuild some time this winter with new springs and seals. Right now I just want to make sure the oil that is in there now is good and level. Figure running the bike with the new oil in it will make the rebuild a little easier since much of the more stubborn crud will get diluted with the new oil.