rear shock maintenance?

[qdog]

can i do this work myself or is it better left to a professional? and what is involved? i have had the bike 2 seasons and have'nt touched the rear suspension.

 

[adam728]

You can tear into the linkage and swingarm pivot to great things up, or replace as neccisary. As for the shock, if you are looking to rebuild it that will be a job for the pros, unless you have the specialty tools and a tank of nitrogen.

 

[qdog]

what is involved in tearing into the linkage and swingarm pivot for greasing?

 

[dddford]

Not too bad

I just replaced the bearings in my son's '96 KDX200 this weekend. Remove the bolts from the bottom of the shock, linkage-to-frame, and linkage-to-swingarm (easy). Then remove the old seals/bushings/bearings from the linkage and swingarm (3 bushings & 6 bearings total). How easy this is depends on the condition of the old bearings, mine came out with a dowel and hammer. Purchase a rear suspension bearing kit (about $70.00 @ bikebandit.com) and install new seals/bearings/bushings. I used a plastic mallet and wood dowel. This is a good time to replace the swingarm bearings too ($45.00) using the same procedure. My son's linkage ended up being shot due to a bad lower shock bearing (sold separately) and I had to buy a used linkage. All in all it was a 2-hour job once I had the parts. It would be even easier to just bring the linkage and swingarm to a machine shop and have the old bearings pressed out and new ones pressed in.

 

[McRider]

1) Set the bike up on a sturdy stand with the rear wheel off the ground, and remove the rear wheel.

2) Unbolt the dogbones that connect the bottom of the shock to the swingarm and the shock pivot link. Also unbolt the bottom of the shock.

3) Remove the rubber plugs at both ends of the swingarm bolt. Remove the nut on the right hand side and drive the swingarm bolt out. Remove the swingarm.

4) Remove the pivot link from the frame. Take out all oil seals and inspect the needle bearings for rust and to make sure they move freely. Inspect the bushings that the bearings ride on for rust and pitting. The bearing at the bottom of the shock is especially prone to rusting. Press out any bad bearings and replace. Replace any bad bushings.

5) Apply a liberal coating of chassis grease to all bearings and reassemble. Whether or not you replace the grease seals is up to you. It probably is called for, but they are darned expensive. I just did this work on my bike after a two year interval and had to replace one bearing, two bushings, and four seals and it cost me about $100.

 

[cweingartz]

It is not that difficult to rebuild a shock if you have a manual. I did mine with no specialty tools. When you are finished you will need to get it charged. I charged my own but shops usually will do it for 5 to 15 dollars.

 

[qdog]

thanks for the help!

 

[DirtRoller]

Shock Maintenance

Here are some tips for servicing your shock. Basic tools will get you through removal and install.

Parts to remove; fender, air box, left side sub-frame bar, right side dog bone (linkage), and of course the shock.

Grab a pencil and paper and write down your rebound and compression settings. Once you have the shock off, turn the clickers all the way out. Count the turns out from where you have them set and write it down.

You need to measure your spring pre-load or installed height, and write that down, too. Next loosen the spring all the way.

Pull down the lower spring seat so you can remove the split shaped collar or ring. A soft jawed vise will come in handy. If you don’t have one, put a rag over the jaws so you don’t damage the shock. (The shock should be clamped into the vice with the Schrader valve facing up.) Now push in on the schraeder valve to let the pressure out. Use a deep socket that will fit over the valve. Tap down on the reservoir top enough to expose the circlip. Remove circlip from the reservoir, be careful not to scratch the inner body with tool(s), small flat-headed screwdrivers.

Now you can remove the bladder from the reservoir. Twist, wiggle, and tap up lightly. Clean and set aside.

To remove the shaft assembly there is a cap that is pressed into the shock body. This cap can be removed several

ways, for example; chisel, pliers, a bearing puller is what I use. Softer and slower is better, tap up on the cap. The seal head is below this cap and there is a circlip holding it in place.

The circlips are not the same size so make sure you remember which goes where.

Racetec makes a tool for tapping the seal head down, but I’m sure you could make something else work. Just be careful not to damage or scratch anything.


With the seal head tapped down remove the circlip, and pull the shaft assembly out of the body. Yes, you should have

a catch pan or rag for the oil.

Having fun yet?

Clean all the parts with a cleaner that will not damage the rubber on the shaft assembly or bladder. Blow dry with compressed air.

There are different oils to choose from, brands and weights.

I used a 3 wt. but a 5 wt. works fine for me also. Do your research and get what shock oil will work best for you (3,5,7,10wt).

Now that everything is dry and clean enough to eat out of. It’s time to add your oil to the reservoir side of the shock.

Pour oil past the half way point in the reservoir. The oil will self-level in the shock body. With your catch pan in place,

push the bladder into the reservoir. The oil should overflow out of the top of the reservoir. Push the top of the bladder past the circlip grove slightly. Put the circlip in and make sure it is seated all the way around.

Add 35 lbs. of compressed air to the bladder. This is to bleed out the air in the reservoir.

Next add oil to the shock body until it’s about ¾ of an inch from the top. Now put the shaft into the shock body. Push down slowly and steadily. Watch for air bubbles in the oil as you push down. Cycle the shaft up and down several times. Be sure you don’t pull the shaft up too high, as it will allow air to suck in. Now pull the shaft high up into the shock body without sucking any air and fill with oil to the top of the shock body. Take a rubber hammer and tap hard (a quick strike) on the clevis end of the shock. This is to knock the air out from between the shims. Push the seal head in, holding pressure on it until it stops going into the body. While pushing down, release the air pressure from the Schrader valve on the reservoir. This will allow the seal head to go in further, just slightly past the circlip groove. Install the circlip. Again, make sure the circlip is fully seated.

Now fill the reservoir with 90 to 100 psi of compressed air. Test your shock on a block of wood by pushing it in and allowing it to come back up completely by itself. The shock should move smoothly in both directions. (check for leaks)
Bleed all compressed air out after testing.

Clean any excess oil off of the shock, and set spring preload and settings back to the positions you marked before removal.

Compressed Nitrogen
You will need to research how much pressure you want to use for your type of riding. There is some debate about whether there is any effect on performance within a certain range of pressure (130 to 170 psi.). I'm at 170lbs. nitrogen.

The job time was just under 2hrs.
I have some pictures that can guide you thru each step.
Have fun!

 

[mitchw]

qdog: Great step-by-step instructions from DirtRoller and if you are mechanically inclined go for it. I noted that you have a '96 KDX, which is the same bike I have. I just picked it used and got a sweet deal on it; however, as I expected the previous owner never serviced the shock. I took it to my local professional (Fineline Suspension - shameless plug because they do nice work and treat me right) and had it serviced. In short, every bushing and seal had to be replaced and the inside was a gooey mess. Additionally, both upper and lower shock bearing had to be replaced. It cost a little $ but it is spot on perfect now. If yours has never been apart, be prepared for a similar situation. Good luck

 

[cweingartz]

Great step by step instructions. Only forgot one step. After assembly, before charging with nitrogen, you should remove the air bleeder screw with the shock upright. Oil should flow out. Put the screw back in when it stops. If it does flow out, add oil until it does. Other than that, awesome instructions.

 

[qdog]

mitchw- how much did the work cost?