Curse of the Spinning Damper Rod – Tips for Disassembly & Reassembly

Anyone who has ever completely disassembled and reassembled their fork legs knows that one of the bigger frustrations that one can encounter is the curse of the spinning damper rod or damper assembly.  If you review the picture below, you will see a nut at the very base of the fork slider.  In this case, it is #12 – the Damper Valve Stud Lock Nut.

head bearing nut

It sits right above the axle and attaches to the bottom of the damper assembly inside the bottom portion of the fork leg.  The issue here is that as you turn this nut, there is a tendency for the entire damper assembly to spin as opposed to the nut coming loose.

If you Google “spinning damper rod,” you will find a myriad of results as people all over the country and world struggle with this very issues and post it in various forums.  With that in mind, I put together this very post.

In particular, I have put together a list of tips/tricks for both loosening the nut at the base of the damper rod and then re-tightening it.  Hopefully, this helps anyone who is currently struggling with the spinning damper rod issue issue.

Tips for Loosening and Re-Tightening Your Damper Assembly Lock Nut

Loosening:

1) This should be one of the first things you do as part of the fork leg disassembly.  DO NOT (I repeat, DO NOT) remove the slider tube plug (#10) and the fork spring.  The reason is that the spring exerts a lot of force down on the top of the damper assembly.  This creates a lot of friction, which hopefully keeps the damper rod from spinning while trying to remove the nut.  Remember this trick for later.

2) Perform the loosening while the fork leg is still in the frame (holding the fork leg tight) or if the leg is out of the frame, figure out a way to fasten it securely to your workbench.  This was tricky for me, but I ended up using some tie downs and cinching it to a heavy duty shelf in my garage.

3) Get ready with either an impact wrench or the largest breaker bar you can find.  I did it with a 2-foot long breaker bar.  The key here is QUICK FORCE.  With one quick strike, you want to break the nut free from its current position and get it spinning relative to the damper rod.  Typically, more force is required to get the nut to start turning.  Once turning, the force required to continue and ultimately remove it entirely from the damper rod is less.  Again, the key is that first exertion of force to get it started.  So be careful, set things up just right, and then give it a hard and quick pull.

4) If you are really worried the nut is not going to break free, feel free to spray it with some penetrating oil and let it soak in first.  Also, people sometimes mistake of installing this particularly nut with thread-lock.  If you think that is the case (or remember doing it yourself), apply some gentle heat to the nut first – i.e. heat gun, not blow torch.

Re-Tightening:

1) Re-tightening and preventing a spinning damper assembly is a little trickier than loosening it, but careful planning will make this part a whole lot easier.

2) Inspect the top of your damper assembly and make sure there isn’t an Allen or hex key indentation.  Sometimes, friendly manufacturers include one for this very reason.  In this case, you can hold the damper assembly in place on one end with an Allen socket and can tighten the nut on the other end with a hex socket.  Easy-peasy.

3) However, more often than not, there is nothing there.  The other thing to keep in mind is that the damper sits in the base of the fork leg, so you are going to need a 2-foot socket wrench extender bar or a DIY way to hold the Allen head socket in place if you are one of the lucky ones.

4) Assuming there isn’t an Allen or Hex Socket, we are going to figure out another way.  But before that…..

5) Critical step here.  Clean the heck out of the threads at the bottom of the damper rod using a wire brush.  Buy yourself new Grade 8 nuts from your local hardware store.  With the damper assembly outside the fork leg, thread the nut on and off.  Do this over and over – first with a socket wrench, if required.  Ultimately, however, you want to be able to thread the nut entirely on and entirely off the bottom of the damper rod by hand.  “By Hand” – I actually mean with your fingers.  The key here is to make sure that the amount of force required to thread the nut back on and into place is minimal.

6) Next, jumping back to “Loosening Step 1” above, reassembly the fork leg.  This means get the damper back into the bottom of the fork leg without the nut and also put the spring back in.  You can either push down on the spring yourself or if you don’t have six hands available, you can put the slider tube plug back in place.  Again we are going to use the frictional force of the spring down against the top of the damper assembly.  The reason we took Step 5 above is because we want the frictional force against the top of the damper assembly from the spring to be GREATER THAN the force required to put the nut back on.  Some people use wooden dowel rods shoved down the slider tub leg to exert this frictional force, but you already have the fork spring available (so why not use it).

7) Finally, do not use thread-lock when reinstalling this nut.  I think after all this drama you will realize why that is a bad idea.  However, to reassure you further, the addition of thread-lock is unnecessary.  Even if the nut were to fall off, the leg probably won’t leak and damper assembly is unlikely to move much.  You definitely still want to attach the nut to keep things from shaking around and you should look to make sure it is still there during regular inspections.  The point here is that you don’t want to make your life more difficult the next time you are doing fork leg maintenance.

Okay, I had no idea I was going to write 1,000 words on the issue of a spinning damper assembly, but I guess I had a lot to say.  By the way, I had a fun surprise while doing this very repair on my Shovelhead.  The threads on the bottom of my two damper rods were different – one was fine thread and one coarse!  Keep your eyes out my friends – you never know what you are going to find when you really start taking things apart.

Good luck if you have a spinning damper assembly.  Please let me know if you need additional assistance.

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