How To service your forks

[Gas Man]

Ok, lets just say you don't want to just change your fork oil as Narrow did a great job describing in his thread http://www.bigdogbiker.com/forums/how/640-how-change-your-fork-oil.html

Let's say you're like me and want to clean out all that old crude and also change your fork seals.

you will need some fork oil. BDM recomends 30W but everybody else says use 20W or maybe even less.

Then unless you have a true seal push installer you will need to make one.

You will need the following from your local hardware type place. All PVC/DVM stuff
1 1/4" coupler

2" to 1.5" adapter coupler

5' stick of 2" pipe

Then take a rat tail file and file off the small ridge on the inside of the 1 1/4" coupler to allow it to slide all the way down.

Cut the 5' leg down to about 3' for easier use.

 

[Gas Man]

Now time to get to work on the forks themselves. Goal is to change the fork oil, fork seals, and re-grease the neck bearings.

Remove the top cap, remove the large allen under the lower tripple by pulling the set screw on the back and spin off the large allen nut. This seperates the upper and lower trees.

Then pull the unit as a whole (forks, lower, wheel, ect)

Then pull the upper tripple and you get this

Place the top fork cap back in the fork while you move it all around... that way you don't spill any of the disgusting old fork oil.

Now to break down the unit. loosen the pinch bolts on each side of the forks for the front axle and remove the axle

then loosen the pinch bolts on the tripples and get some plastic wedges to jam in the lower tripple. This will help you not scratch the shit out of your fork tubes. Then slide the lower off the forks.

Then you get this

Now remove the fork brace and pull the front axle so you can get the wheel off as well

Your bare forks

You can also take this time to inspect your front wheel bearings if you so please.

Take your neck bearings, wipe them down, clean them off a bit, clean out the neck races.

Now re-grease the neck bearings and the races... put them back together.

Re-assemble the tripples (don't mind my accutronix, your chore will be the same). All ready for forks.

 

[Gas Man]

Now Remove the lower cap

Then remove the plug, which also disconnects the inner rod dampner inside the fork tube. This is also the bolt that holds the fork leg to the fork tube. You may also see that there is some silicone on this to help with sealing it.

Pull the top cap, and inner topper off, slide the upper spacer and sping out.

Then drain the old crap out.

Now time to seperate the legs from the tubes.

Spin off the dust cover on the top of the lower leg, lube the o-ring with some vasoline and set aside

Now you will see the o-ring and the retaining clip

Take a flat head screw driver and pop that clip out.

 

[Gas Man]

This next step will take 2 people. Further, from this point forward the job gets nerve racking.

Now with one person holding the leg horizontally, grab the tube.. slide it in and pull out fast and hard. Basically doing a slide hammer motion. This will take 6-12 blows depending on how hard you're pulling.

Then POP, the seal comes off along with the tube out of the lower leg. Now you have the pieces... there is a small cup (can't remember the name and no manual with me) that will fall out of the bottom of the tube.

You can see the said cup

Wipe off and inspect the bushings. If this is the first time and you have around 5,000 miles I doubt the bushings will be worn. But they wear by getting thinner not nessicarily by the scratches you can see on mine. However, being these have worn off all the copper plating they should be replaced.

Now remove the spacer, washer, and old seal from the tube.

Now clean out the lower fork legs and upper fork tubes with some brake clean. You will be amazed at the sludge you'll see at the bottom of your fork legs.

Turn them upside and let them drain. The brake clean will rinse out and/or evaperate. Do the other fork while the first one is drying.

Now time to re-assemble the first fork while the second one is drying.

Slide the spacer, flat washer and new seal back onto the fork tube. Put the small cup back in the bottom of tube with the bottom of the cup facing outward. Slide the lower leg over the tube and re-install the lower plug. This threads into the dampner rod that you may have heard clank around. Put a bit of silicone back on the bolt before installing it. To ensure no leaking. Leave the spiked cap off the bottom.

Now your forks are back together or at least connected. Slide the spacer, washer and seal down into the top of the fork leg. Put the inner plug and top cap back on to keep debris out of the forks. You can leave the spring and spacer out.

Get your seal pounder out and slide it over the forks and seat that 1 1/4" coupler on top of the new seal.

 

[Gas Man]

Now grab a big hammer and whack the shit out of the tube to push the seal in. This will take some time, alot of effort, and patience. Basically it sucks and will kill your arms. YES they are EXTREMELY hard to put in.

Keep inspecting their progress and once they are installed all the way, you will be able to see the groove for the retaining clip. Once you do, you are done pounding the seal in, replace the retaining clip and the fork is now assembled.

Remove the top cap and inner plug from the top of the tube. Replace your spring and top spacer and reinstall the inner plugs on the top. Leaving teh top cap off.

Measure out the fluid that your manual calls for. In my case 10 oz.

Grab a funnel and pour in. Sometimes, this goes slow as the fluid has to work its way down into the fork.

Put the top cap back on and you're done. Repeat the last section of steps on the other fork and re-install the everything back onto the bike.

 

[Gas Man]

Whew... it was a nasty and tough job. Takes alot more time then you would think.

If you get lost here's a few manual pages if you get them all out of order.

Sorry for the grease firnger prints... but that's what happens when you have a service manual and USE IT!

 

[narow37]

Great Job as always man.

 

[hoat]

great job with the how to.

I have put the top bushing and the new seal back in the forks using an old seal on top of the new seal then beating it with a dead blow hammer. you can then use a pick to get the old seal back out. I may try your way next.

 

[Mickeetwo]

great job Gas

 

[Rick]

Great post Gas it's printing and will go in my manual for future reference.:2thumbs:

 

[Gas Man]

great job with the how to.

I have put the top bushing and the new seal back in the forks using an old seal on top of the new seal then beating it with a dead blow hammer. you can then use a pick to get the old seal back out. I may try your way next.

I never thought of that. But I had asked a few people what to use. Vickie said the guys at the shop used white plastic pvc of some kind. It took about 25 mins in the isle at the store to figure out what would work.

Thanks as well boys! I try to do my part.

 

[Ronbo]

Hello gasman, Great article...it helped me tremendously...one question please.. can you tell me how the dampner attaches to the spring? I have bent my tubes and have to replace them but my spring and dampner are stuck in the tube.{hell of a bend huh!!!! long story} I got tubes, springs and dampners ordered but i dont know if im missing something. Can you give me some detail on that part of the assembly? thanks in advance.... Ronnie

 

[Gas Man]

Maybe the dampner rod is bent as well...

There is a layout in the service manual... maybe order that too.

 

[Ronbo]

thanks man, but the spring is suppose to be seperate or not connected to the dampner.. right?

 

[Gas Man]

No they aren't suppose to be connected... and I went the extra mile... I posted the manual sheets above

http://www.bigdogbiker.com/forums/how/2498-how-service-your-forks.html#post38965

 

[scbdm]

Been out for a while. Great thread! Wish I would take the time to take photos like that. Them are some cool triple trees. :flag:

 

[Ronbo]

thank you very much gasman, helped me a lot. i had to cut the tube in half in order to get the rest of the parts i needed..thanks again

 

[mouse]

I just want to send thanks out to gas man for the info on fork seal replacement did mine over the weekend, the pictures helped out a lot. This site is fabulous for info thanks again.

 

[Gas Man]

You're welcome.

Did everything seem to flow like the how to??

What did you use to pound in the seals?

 

[mouse]

Gas Man
If you follow the steps you set up and pay attention to what you are doing you can't go wrong. It took me a while as I was nursing a bad hang over. I did do one thing differant, I seperated the tubes on the bike as it made it eaiser for one person to pull apart, then I took the uppers off the trees, other than that the directions are on the money. As for setting the new seals I just used the old seal with a piece of pvc pipe. No leaks put 400 miles on the bike in the past 2 days. Thanks again