29 August 2011

FZ1 Mod: Rear Suspension Upgrade

The Poor Man's Shock Upgrade:  An R6 Shock and new dogbones.

When Devilsyam posted on the FZ1 forums about his version of a Penske or Olins shock, I decided that I should do my rear suspension too.  The R1 Fork Conversion is coming along better than I expected which means it should happen a lot sooner than I originally thought.  I decided to let a real mechanic tackle the front end conversion but for this upgrade, I'd do it myself (with a little help from Cruzman).

Okay, a lot of help from Cruzman!  I checked with him to be certain that he understood what needed to be done so he could explain it to me in a way that I understood before I committed any money to the project.  Once I learned he planned to do it too and that he was making his dogbones rather than getting a kit, I commenced getting a parts list so I could get my parts too.

Wrong shock! 
What's needed?  A 2007 or newer R6 shock, 2 x 2mm spacers, a 31/64ths inch drill bit, a dremel or something like it, and 130 mm center to center dogbones.  Cruzman was going to make his and when I asked about him making mine he said I needed to make my own.  He may have been joking but I took him seriously and started thinking about a way I could contribute to my mod.  I discovered I could buy parts to make adjustable dogbones for the price of what was available.

I got a nearly new 2008 R6 shock that had less than 3k miles on it from one of the R6 forums for a lot cheaper than many of the eBay sellers were listing at the time.  The shock should look like this:
My 2008 R6 Shock
After a few days of searching the internet, I figured out the parts I needed to "make" my own dogbones so that Cruzman wouldn't have to.  It took a little longer than I would have liked but I finally got all the parts in and put my dogbones together.

Due to the thickness of these versus stock, I'd also need longer bolts to accommodate them.  

Unfortunately for me, no local stores had them so I had to get them from an online store and it seemed to take forever for my new bolts to arrive.  I also ordered longer bolts for Cruzman.
Longer M12 bolts needed due to width of my dogbones vs stock.
For spacers, I used some washers Cruzman gave me.  With all the parts finally in my hands, it was time to get started!  Cruzman rode over to the house to pick up something I was holding for him and then I followed him to his house to do the shock upgrade.

First thing is to "convert" the R6 shock to an FZR6 Shock.  To do this, you use the 31/64ths inch drill bit to make the top mount hole wider.

And take a little off the top to prevent clearance issues.

Now you have a shock ready to install on the FZ1.  Cruzman told me to make sure I support the rear tire so that it doesn't drop when the old shock is removed.

Then I took the muffler off so I could have easy access to the bolts.  I needed a little help to break them free due to corrosion.  Apparently that can happen to those bolts.

I don't think there was any cursing when this was removed but boy there should have been!  It was tough to break free but we got it done.

Installation is basically a reversal of removing the stock shock with the exception of adding the spacers to the top mount.  As you can see below, the R6 shock is slightly narrower than the stock FZ1 shock so spacers are needed for a snug fit.

It's easier to install the r6 shock with the spacers glued into place but I couldn't find my glue so I had to do it the hard way.  That added a few sweaty minutes but it got done.  

FZ1 vs R6 Shock Absorber: 
Original pic is from post on katriders.com; I modified numbers to reflect use on the Gen1 FZ1.
According to the Owner's Manual, My OEM FZ1 shock "is equipped with a spring preload adjustment ring, a rebound damping force adjustment knob and a compression damping screw adjustment"  whereas the R6 shock "is equipped with a spring preload adjustment ring, a rebound damping force adjusting screw, a compression damping force adjusting bolt (for fast compression damping) and a compression damping force adjusting bolt (for slow compression damping)."  The spring rate for the OEM FZ1 shock is 425 lb while the spring rate for the OEM R6 shock is 550 lb.  (Actually it's 550 lb/in to 605 lb/in depending on the year.)

Spring rate is the stiffness of the spring or the amount the shock will compress when loaded.  Preload is the initial compression when the spring is installed.  Rebound damping controls the extension of the shock after it compresses from a bump.  Compression Damping is controlling the initial bump as the wheel is forced upward.

Anyway, I haven't adjusted mine yet.  I've got some more research to do so that I understand what's happening.  However I did the test ride with whatever it was set for when I got it because I forgot to make the "base" adjustments before I installed it.  That's what happens when a Lupie mods alone!  So for the short test ride I've done as I type this I could already tell the thing was much smoother than the FZ1 shock.  I'll make sure the shock is set the way it's listed in the thread as a starting point:

  • Preload: 4
  • Rebound: 15 clicks
  • F Compression: 3 turns (Hi speed in pic)
  • S Compression: 16 clicks (Lo speed in pic)
It doesn't seem like these are that much different than it comes from factory however based on Cruzman's feedback I'd have to say it's just a start.  Unless it feels terrible when I do it, I'll likely wait until the front end conversion is completed to tailor the adjustments to fit me.

As I was putting together some information for this post, I discovered the OEM R6 shock is a popular "upgrade" alternative to the aftermarket brands.  I was able to get info from an FZR site, a Katana site, a GSX-R site, and a VFR site!  Somebody's gonna notice that and the price for slightly used R6 shocks might go up a lot.

Thanks for reading,
patrice, theWolfTamer

My assistant.  He got in the way more than he helped!


  1. Hi Wolf Tamer.
    You are the....woman! :)
    Great pics and description. I have done the 4 degree Ignition Advancer and now I am getting parts for the R6 shock mod.
    I have found you on the FZ1OA site.
    Ciao for now.

  2. Yep I want to do this one too. Thanks for the info so when I get ready I know here to look. Too bad I moved from ATL else I would solicit you and David to help me. HA!
    //Donnie Aka Sammax

  3. My shock is in the works from Dean D. Looking forward to it!//Sammax

    1. Fantastic! I love mine. I should probably swap out the bolts on my adjustable bones but they are holding well. Here are my current adjustment numbers:
      Preload: 1 (3 when fully loaded)
      Rebound: 14 clicks
      F Compression: 4 turns
      S Compression: 16 clicks

  4. What did you use to make the dog bones? I would like to make a set like that.

  5. Thanks much for stiffness info :)

  6. Hi
    Maybe you can tell me how much i need to grind the top to modify the clearence, if you have more pictures you grinding it can be very helpful.

  7. Hi
    Maybe you can tell me how much i need to grind the top to modify the clearence, if you have more pictures you grinding it can be very helpful.


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