Creaking fork, rebuild on the horizon

[Mickeymoe]

I've posted about my creaking front fork before and thanks to the forum, I at least am now running the correct tire pressures! While the front seems a bit more stable (much less wobble at very slow speeds), and I put the ATK fork brace back on, the fork still makes that awful creaking noise. On my ride today I noticed that it also does it when the forks get fully compressed and released, in other words, pressing straight down makes the same creak as flexing the upper tripple tree area.

It looks like I'm going to have to rebuild and replace everything in the forks because the more I ride the bike I can now feel every little bump and pebble in the handgrips. Maybe I'm looking for stuff which isn't there, but either way there is a problem that has to be corrected.

The PO told me he had the dealer "upgrade" the front end with progressive uh....stuff. I don't know what that means but I think he either did it himself, or had a friend do it for "cheap".

Now to the point of this post- does anyone have a link to a .pdf, Youtube video or other info that specifically addresses what to do and expect when rebuilding the fork on a 1980GS1000G? I've seen generic vids but since I'll have to order parts I like to put my time into relevant research.

This will probably be a winter project since the bike seems to be safe enough, just a bit annoying with that creak. I haven't even put together my restored '79 Kawaski KL250 from its hibernation yet so I want to ride the bikes a bit before I start working on them again.


Any info would be appreciated.

Mark (mickeymoe)

 

[Mosquito13]

Did you change out the fork oil? Maybe add some more preload with long cut spacers? If you are running the length of the fork stroke under normal riding, something is really wrong. You got a manual on the bike right?
https://www.barnesandnoble.com/p/su...d=Google_&sourceId=PLGoP3485&k_clickid=3x3485
http://motodataproject.com/product_info.php?products_id=62

 

[Mickeymoe]

No, the bike never runs the length of the stroke unless I have to make a fast stop with the front brake only and feet down at low speeds. I don't know what "long cut spacers" are, that's why I was lookin for a link or tutuorial on these specific forks. I don't have a manual as yet but I"ve been told they are available online- don't know if that's true.

Mark

 

[2BRacing]

..... I don't have a manual as yet but I"ve been told they are available online- don't know if that's true.

Mark

Yes, it is true! And all the manuals are right here at GSR on BassCliff's collection of all the information you will ever need. You will find this treasure trove here:
http://members.dslextreme.com/users/bikecliff/

On that homepage, look at the topics down the left hand side, about half way down is one called "Fork oil seal replacement". Although that is for a 850G, your bike's forks are the same. More detailed information will be in the OEM workshop manual for your bike at the top of that page.

Use the "Search" feature on the forum to find many other threads on rebuilding these forks. I would suggest you spend some time reading those threads, and you will find information on preload and the use of spacers to adjust it, and lots more.

 

[Mosquito13]

Sonic springs has a good how to's. Can try cutting different length spacers for your springs you have with pvc . Fresh oil will slow things down. I went this route and it did not fix the ride on my 35 year old bike. Ended up getting 1Kg sonic springs for the fix on my ride along with a flush of the forks . These are quick and ez fixes, and if your getting noises from the front end you want to address them before riding. http://sonicsprings.com/catalog/index.php?cPath=31_222 Just did a thread in this section of the forum on it. Also check out the search tool on the upper right top of screen for researching previous posts on anything on this site.

 

[Dogma]

The stock 1000G fork is pretty simple. As other have said,download the factory service manual for instructions on rebuilding. But all you can really do is clean, inspect, and replace seals.

A harsh ride could have a couple causes:

There is a slide ring near the top of the aluminum slider, covered with something like Teflon. Mine had been destroyed by pitted forks, which led to pretty bad stiction and a really harsh feel. I never found a way to replace them. I replaced the lowers entirely. In fact, I replaced the whole fork with an eBay find. Anyhow, if those slide rings are worn, you get a lot of stiction that makes the ride harsh, even with lighter or old oil in the fork. If the fork sometimes stops high or low when you bounce the front end, this is what I'd suspect.

If stiction isn't the problem, and the front end is just too harsh, try a lighter fork oil. But that may make the front end more bouncy than you like. You have to find a happy spot in the middle, unless you add cartridge emulators. Emulators allow you to run a heavier fork oil to keep the front end well controlled under normal conditions, but they have a pressure-relief action that allow the fork to respond quickly to soak up harsh bumps. After adding them, I now ride over railroad crossings without having to stand up. If you can disassemble the fork to change seals, you can probably manage an emulator install. It does require a permanent alteration, though.

Progressive brand springs aren't anything special. As others here have recommended, Sonic straight rate springs with appropriate preload will support the front end better without adversely affecting how bumps are dealt with. But they won't fix a harsh ride.

A fork brace won't fix a harsh ride, but it can make the ride worse by making the fork legs bind against each other. That can be caused by incorrect spacing, or slightly bent forks. In fact, a brace is only meant to help the fork to be more stable in response to side loading. That's a performance cornering situation, so it's unlikely that a fork brace will help you.

 

[Mickeymoe]

Thinking a little bit more about the situaiton, things are starting to come back to mind that the PO said when I was looking at the bike. He had replaced the rear shocks with some fancy brand that cost ~ 300.00 to 500.00 depending on where you look. I remember him saying that they raised the bike about an inch which I don't like the sound of. (I have the boxes but can't remember the name) Also, when I was fitting my Vetter stuff to the bike, I had the benefit of pictures of my ex 1980 GS850G to go by. I noticed that the front forks hold the bike up higher by about an inch in the front too. I want to go back to all stock, expecially in the front forks but don't know what the guy had changed out and what I'll need to make it stock. (and lower it to stock hight = lower center of gravity)

BTW, are OEM fork parts still availabe for that fork? If they are I can't imagine they'd be the expensive. I'm thinking maybe he did all of this because of the sidecar he had on the machine for a while.

Mark

 

[Dogma]

Thinking a little bit more about the situaiton, things are starting to come back to mind that the PO said when I was looking at the bike. He had replaced the rear shocks with some fancy brand that cost ~ 300.00 to 500.00 depending on where you look. I remember him saying that they raised the bike about an inch which I don't like the sound of. (I have the boxes but can't remember the name) Also, when I was fitting my Vetter stuff to the bike, I had the benefit of pictures of my ex 1980 GS850G to go by. I noticed that the front forks hold the bike up higher by about an inch in the front too. I want to go back to all stock, expecially in the front forks but don't know what the guy had changed out and what I'll need to make it stock. (and lower it to stock hight = lower center of gravity)

BTW, are OEM fork parts still availabe for that fork? If they are I can't imagine they'd be the expensive. I'm thinking maybe he did all of this because of the sidecar he had on the machine for a while.

Mark

Some of the OEM parts are still available, but nothing much interesting. Have a look here.

It's starting to sound like what you need to do is take an inventory of what's been done to the suspension. Measure the shocks at full extension and see how long they are, center-to-center of the mounting studs. Compare that to stock. If the rear wheel is still on the ground when you put the bike on the center stand, they're definitely longer than stock. They may also be sprung too stiff to carry the weight of the sidecar. You can check that by measuring static sag to make sure it's in the right range. I don't remember what that should be off the top of my head. If the springs are too stiff, that might be what raised the bike an inch, just from removing the weight of the sidecar. If the shocks are a good brand (and the right length), they should be rebuildable, so you could have them re-sprung and revalved to suit how you plan to ride.

You could have a similar situation in the front. It may be oversprung to help carry the sidecar. Being oversprung for a few hundred pounds of sidecar would contribute to a harsh feel, and could definitely make handling and stability problems. riding an inch higher is a pretty big change.

But this creaking is weird. Is the chrome on the forks clean and bright, or is it kinda dull with a lot of scratches in the direction of motion?

It sounds like you have some homework to do, figuring out what you have. We can't really advise on what change to make, until it's known what you're dealing with.

 

[Mickeymoe]

Thanks Dogma, that's good info. The rear shocks that are on the bike are Koni adjustable 235-18/25/33 with a small "308" in the lower corner near the number. The virtually brand new original all-chrome shocks are in the box (came with the bike) and I may end up putting them back on. I really appreciate the back-and-forth, your phrasing "oversprung for the sidecar" makes a lot of sense now, thus the extra height. I'll have to read up on these shocks to find out what "adjustable" means, maybe they can be adjusted to lower the bike a bit. As far as the forks go, they look pristine also. NO scrapes, pits, rust....anything. That's the reason I bought the bike- he took great care of it since new and it still looks amazing 37 years later. I think I was so overwhelmed by the condition I discounted the info he was providing me about the mods. Will have to come up to speed on what a stock fork is comprised of and compare it to what I have. At least it's rideable for the rest of the season while I get educated and collect the parts to fix it.

The creaking is another issue. It "creaks" when the forks compress all the way, and it creaks when the fork is stressed against the tripple tree. Don't really understand what's happening, but if I visualize what might be happening it seems like whatever supports the fork tubes as they travel is either worn out or is the wrong size. (too large of a diameter) I guess it could be steering head bearings too, who knows. What I am quite sure of is the guy knew all of this when he sold the bike.

 

[Mosquito13]

you check your bearings ? https://www.youtube.com/watch?v=Fi_fmONC9Jg

 

[Mickeymoe]

Last night I put my bike on the centerstand and then jacked it up under the motor to check the fork head bearings as per the video you posted. I'm happy to report I could not find ANY play backward, forward or sideways so the creaking problem has to be in the fork tubes somewhere.

Marm

 

[Mosquito13]

Actually , too bad. The bearings are a inexpensive and a ez fix.

 

[jsandidge]

I'm having the same creaking issue you describe on my 83. I suspect the fork bushings, which are a wear item.