Last summer I re-sprung the forks and shock on my bike for my weight. It did the trick to prevent my bike from bottoming out on jumps and G-outs, but my bike went from plush to rather harsh on the forks. I was able to adjust my rear PDS shock with rebound and compression to my liking and my forks were fair, but far from plush. I ended up with the compression adjustment (valve bypass) alot further open than I wanted which pretty much takes the compression valve out of the circuit. So on sharp edges, roots and rocks the front end would deflect.
On my last ride I had a fork seal go out and thought this would be a good opportunity to adjust my shim stack, allowing me to close off the bypass (compression adjustment) and put my valve back in the picture. Typically, if I can catch a leaking seal early, I can use a goggle tear-off to slide between my fork seal and the fork tube to clear any sand causing the leak. I'll probably get some Seal Savers next time I order from Rocky Mountain.
Disclaimer: I’m not a suspension expert, photographer or story teller, but I’m more than willing to learn new stuff, even the hard way occasionally. I don't own alot of specialty tools, so I improvise at times.
I figured since these are open chamber, cartridge forks used on most of the KTM EXC’s and XCW’s, that I’d post my low-budget suspension tuning and fork seal change to share with the group and I’m open for tips and suggestions….
I won’t go thru pulling the front wheel and caliper, and I’ll start with loosening the fork cap.
I pull the handle bar clamps to allow the fork-cap tool to fit under the bars. The reason is that I use the bottom triple tree clamps to hold the forks while I break the caps loose with the fork cap tool.
Be sure to loosen the top triple tree bolts first, before trying to break the cap loose. Use only the bottom triple tree bolts to hold the fork while loosening the cap.
Finish stripping the forks by removing the lower fork guard, bushing and cap for the compression adjustment screw. Then clean, clean, clean… (I use cheap brake cleaner)
Open the rebound and compression settings all the way. (counter-clockwise) If you’re just replacing the fork seals, make note of your rebound and compression settings.
Finish unscrewing the fork cap.
Always measure and mark distances and orientations so that it goes back like it was.
Next break the fork cap loose from the cartridge shaft. Be careful not to booger-up the threads, this can be done by taping the jaws on the chanel-locks. (This stuff is’nt atomic-tight and does’nt need to be going back together)
Pull the spring and drain the oil.
I secure the fork leg in a vice, using a rag to protect the finish.
Next remove the compression valve from the cartridge. I use an impact because you can’t hold a backup on the cartridge, (stop cringing) I adjust my impact’s choke down so low I can almost stop it with my hand. This allows the speed of the impact to remove the valve without the cartridge spinning.
Then remove the rebound adjustment rod from the cartridge shaft.
To disassemble the valve the threads have to be straightened out from being peened over.
Note: the valve doesn’t need to be disassembled to replace the seals.
The shim stack contained 5 main shims, along with numerous step down shims. Utilizing the SWAG method, I determined removing 2 of the main shims should be close to where I wanted to be. We'll see, my first ride feels pretty good over tree roots with my compression at 18 clicks.
I re-assembled the valve and peened the edge to prevent the nut from backing off. Make sure the nut goes thru the check valve plate and doesn’t pinch it. Go easy this is soft aluminum. Also inspect the O-rings on the valve and replace if damaged.
Be sure the check valve moves freely.
Now for the seal replacement. Remove the dust cover and the spring clip that holds everything together.
Using the inner and outer fork tubes like a slide hammer, just tap them apart.
Inspect the bushings and replace if they show wear. I have very few hours since mine were replaced and they still looked good to me.
They make a seal-bullet to protect the new seals during installation, but remember earlier when I said this was low budget… I use Glad-Wrap instead, plus a little grease on the new seal to protect it during installation.
Then washer, outer bushing and inner bushing.
Put the inner fork tube into the outer fork tube.
Use the seal driver to drive the new seal into place, install the spring retainer, and the dust cover.
Install the cartridge. Important: use your fingers and feel inside to make sure it bottoms out in the lower fork tube.
Next comes the compression valve. Use the impact, choked back, then torque at 35 nm.
Don’t forget to put the rebound adjustment rod into the cartridge. Push down on it and it should move freely with a little spring resistance.
With the top fork tube bottomed out, add the oil. Don’t let any oil get into the rebound adjustment rod hole. Then raise the top fork tube 10” to 12” while holding the bottom fork tube with your feet, cover and seal the tube with your hand, then push down to pressurize the oil into the cartridge. Add oil and repeat the process until bubbling stops appearing around the cartridge.
Raise the cartridge up and down to check for resistance both directions. This will verify all the air is out.
With the top fork tube bottomed out, set the oil level. I’m running 120mm.
Raise the cartridge and thread the spring over the cartridge until it’s all the way down into the fork.
While still holding the cartridge up, compress the spring to expose the threads to screw the fork cap on to.
Carefully snug it up.
Screw the cap into the top fork tube.
Before putting the forks back on, return the compression and rebound settings to where they were, put the fork guard bushings and fork guards back on. Slide the forks back into the triple clamps and snug the bottom clamps only.
With the fork cap tool snug up the fork cap.
Now set the forks where you want them in the triples and torque them up. Set the spring preload, I’m at 2 turns. Install the handle bars and torque the clamps, and mount the front wheel and torque.
Then the final most critical step of the whole process. Clean the caliper bolts, apply Lock-tite and torque 25nm.
Pump up the front brakes, check your work, go ride.
On my last ride I had a fork seal go out and thought this would be a good opportunity to adjust my shim stack, allowing me to close off the bypass (compression adjustment) and put my valve back in the picture. Typically, if I can catch a leaking seal early, I can use a goggle tear-off to slide between my fork seal and the fork tube to clear any sand causing the leak. I'll probably get some Seal Savers next time I order from Rocky Mountain.
Disclaimer: I’m not a suspension expert, photographer or story teller, but I’m more than willing to learn new stuff, even the hard way occasionally. I don't own alot of specialty tools, so I improvise at times.
I figured since these are open chamber, cartridge forks used on most of the KTM EXC’s and XCW’s, that I’d post my low-budget suspension tuning and fork seal change to share with the group and I’m open for tips and suggestions….
I won’t go thru pulling the front wheel and caliper, and I’ll start with loosening the fork cap.
I pull the handle bar clamps to allow the fork-cap tool to fit under the bars. The reason is that I use the bottom triple tree clamps to hold the forks while I break the caps loose with the fork cap tool.
Be sure to loosen the top triple tree bolts first, before trying to break the cap loose. Use only the bottom triple tree bolts to hold the fork while loosening the cap.
Finish stripping the forks by removing the lower fork guard, bushing and cap for the compression adjustment screw. Then clean, clean, clean… (I use cheap brake cleaner)
Open the rebound and compression settings all the way. (counter-clockwise) If you’re just replacing the fork seals, make note of your rebound and compression settings.
Finish unscrewing the fork cap.
Always measure and mark distances and orientations so that it goes back like it was.
Next break the fork cap loose from the cartridge shaft. Be careful not to booger-up the threads, this can be done by taping the jaws on the chanel-locks. (This stuff is’nt atomic-tight and does’nt need to be going back together)
Pull the spring and drain the oil.
I secure the fork leg in a vice, using a rag to protect the finish.
Next remove the compression valve from the cartridge. I use an impact because you can’t hold a backup on the cartridge, (stop cringing) I adjust my impact’s choke down so low I can almost stop it with my hand. This allows the speed of the impact to remove the valve without the cartridge spinning.
Then remove the rebound adjustment rod from the cartridge shaft.
To disassemble the valve the threads have to be straightened out from being peened over.
Note: the valve doesn’t need to be disassembled to replace the seals.
The shim stack contained 5 main shims, along with numerous step down shims. Utilizing the SWAG method, I determined removing 2 of the main shims should be close to where I wanted to be. We'll see, my first ride feels pretty good over tree roots with my compression at 18 clicks.
I re-assembled the valve and peened the edge to prevent the nut from backing off. Make sure the nut goes thru the check valve plate and doesn’t pinch it. Go easy this is soft aluminum. Also inspect the O-rings on the valve and replace if damaged.
Be sure the check valve moves freely.
Now for the seal replacement. Remove the dust cover and the spring clip that holds everything together.
Using the inner and outer fork tubes like a slide hammer, just tap them apart.
Inspect the bushings and replace if they show wear. I have very few hours since mine were replaced and they still looked good to me.
They make a seal-bullet to protect the new seals during installation, but remember earlier when I said this was low budget… I use Glad-Wrap instead, plus a little grease on the new seal to protect it during installation.
Then washer, outer bushing and inner bushing.
Put the inner fork tube into the outer fork tube.
Use the seal driver to drive the new seal into place, install the spring retainer, and the dust cover.
Install the cartridge. Important: use your fingers and feel inside to make sure it bottoms out in the lower fork tube.
Next comes the compression valve. Use the impact, choked back, then torque at 35 nm.
Don’t forget to put the rebound adjustment rod into the cartridge. Push down on it and it should move freely with a little spring resistance.
With the top fork tube bottomed out, add the oil. Don’t let any oil get into the rebound adjustment rod hole. Then raise the top fork tube 10” to 12” while holding the bottom fork tube with your feet, cover and seal the tube with your hand, then push down to pressurize the oil into the cartridge. Add oil and repeat the process until bubbling stops appearing around the cartridge.
Raise the cartridge up and down to check for resistance both directions. This will verify all the air is out.
With the top fork tube bottomed out, set the oil level. I’m running 120mm.
Raise the cartridge and thread the spring over the cartridge until it’s all the way down into the fork.
While still holding the cartridge up, compress the spring to expose the threads to screw the fork cap on to.
Carefully snug it up.
Screw the cap into the top fork tube.
Before putting the forks back on, return the compression and rebound settings to where they were, put the fork guard bushings and fork guards back on. Slide the forks back into the triple clamps and snug the bottom clamps only.
With the fork cap tool snug up the fork cap.
Now set the forks where you want them in the triples and torque them up. Set the spring preload, I’m at 2 turns. Install the handle bars and torque the clamps, and mount the front wheel and torque.
Then the final most critical step of the whole process. Clean the caliper bolts, apply Lock-tite and torque 25nm.
Pump up the front brakes, check your work, go ride.