Jump to content
Sign in to follow this  

Shock Sagging

Recommended Posts

This is strange. I've had my '06 bike up on a stand (both wheels unloaded) for about a month. Had forks re-built and re-shimmed valves. Between waiting on parts and shop to rebuild forks so the rear wheel must've been unloaded and off the ground for over 4 weeks. Finally get it all back together tonight (starts w electric start on 1st try....YES!) but something is odd. The rear shock has a huge amount of sag! (6"+) Like the "gas" has leaked out or something. Has anyone ever heard of this? Do I just need to ride it to get it "warmed" and/or "pumped" back up?? Any ideas would be much appreciated.

Share this post


Link to post
Share on other sites

If its got 6" of sag (static) with only the weight of the bike on it something is really wrong because the spring should hold it up alot further than that.

Is it static sag your talking about? or with the weight of a rider on it?

Share this post


Link to post
Share on other sites

It's static sag. Meaning, after I had bike all back together I fired it up, let it warm up a few minutes, then took it off stand and rode it up and down street a few times. When I pulled back into garage, shut bike off and got off of it I noticed it was low. I can pull back end up and it sits high but as soon as you weight it with a rider it goes down and stays down.

On a side note, what is the air valve for on the bottom of the shock canister? Is that ever meant to be refilled or recharged in some way?

Thanks for any help.

Share this post


Link to post
Share on other sites

That's not static sag.   Static sag is the bike sitting there with it's own weight.  Your putting a rider on.  That's sag.

 

As far as the air valve, there is a rubber bladder in the shock.   It's charged with 300 psi of nitrogen.

 

Double check the spring.  Make sure it's not broken and setting in the bottom collar correctly.  The spring should be pushing back up and letting it level out again.

 

Can you pull the back end up manually, and if it sits there, does it stay there?

 

 In any case, if nothing is wrong with the spring, then you should rebuild the shock.  There's not much else there<g>.

 

 I would though disconnect the shock and make sure your swing arm and pivot linkage is moving freely without binding.

 

Jim.

Share this post


Link to post
Share on other sites

Thank you for the reply, Jim. I can pull it up manually and it stays. When I sit on it and bounce a couple times it goes down. It goes down just a little more than normal sag - about 5"-6" - but when I climb off it does not come back up on its own. I have to manually pull it back up.

I think you're probably right that it's just 8 years old. I will take apart the lower linkage and grease it all real good. May turn the ring down on the spring as well. It's fully out at 10-1/2" and I weigh 185. Besides that I may be into a rebuild or new shock.

On that valve, you mentioned that it's got 300psi nitrogen in it. Does that degrade over time? Can it be re-pumped up? I just figure if they put the valve there it was meant to be used in some maintenance fashion.

Share this post


Link to post
Share on other sites

After eight years the shock needs a professional servicing. Now! And I'll bet you need all new suspension linkage/swingarm bearings.  Sounds like no one maintained the bike properly.

Share this post


Link to post
Share on other sites

Thank you for the reply, Jim. I can pull it up manually and it stays. When I sit on it and bounce a couple times it goes down. It goes down just a little more than normal sag - about 5"-6" - but when I climb off it does not come back up on its own. I have to manually pull it back up.

I think you're probably right that it's just 8 years old. I will take apart the lower linkage and grease it all real good. May turn the ring down on the spring as well. It's fully out at 10-1/2" and I weigh 185. Besides that I may be into a rebuild or new shock.

On that valve, you mentioned that it's got 300psi nitrogen in it. Does that degrade over time? Can it be re-pumped up? I just figure if they put the valve there it was meant to be used in some maintenance fashion.

 

Does sound like its due or past due for service.

Part of the shock service maintenance is getting the fluid changed and nitrogen refilled to the spec which is between 140-150 psi. The diaphram can easily be changed at that time also.

Share this post


Link to post
Share on other sites

Correct me if I am wrong but the shock slows the action of the spring, up and down.  The shock does not push the bike back up when you get off.  That is done entirely by spring preload.  If your bike is sagging, something is different with the spring.

Share this post


Link to post
Share on other sites

The spring does most of the work but isnt entirely holding the bike up by itself, if you remove the spring from the shock completely and push down on the shock it returns to the fully extended position relatively quickly depending on where the rebound clicker is set. It does this because of the nitrogen charge in it, so if the nitrogen has leaked out it wont return like its designed to.

Edited by TDW

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×