Monoshock Rebuild

Now slide the spring off:

Step 9) Remove the rest of the oil. At this point your shock will determine how to do this. Most shocks have the reservoir attached, so you hold the reservoir over your drain pan an pump out the oil by working the shock absorber back and forth. Since my shock has a remote reservoir, I removed the banjo bolts from the hydraulic line, and then pumped out the oil.

My oil was black, watery, and had very small debris suspended. It looked very much in need of replacement. This would be my second problem with lack of dampening.

Step 10) Remove the lower dust cap from the shock body. You can carefully wedge a chisel in between the small gap. Also, you could use a small punch and drive out the cap by use of the two small holes in opposite sides of the cap. Either way, be careful and work your way around using lots of small hits. It's a light press fit and it will come out with a careful hand.

The cap is out:

Step 11) Once again, there is an aluminum seal body that is retained by a circlip. You need to push the seal body down to expose the clip, and then carefully remove the clip with a small screwdriver.

Step 12) Remove the shaft assembly from the bottom of the shock body. First check that there are no burrs on the circlip groove, and then try to pull the shaft carefully out the bottom. There is an o-ring on the outside of the seal body which will hang up in the circlip groove. Just be careful and work the assembly back and forth to get it out.

Step 13) Clean everything, and inspect your seals. Replace any damaged o-rings and there is a teflon seal around the chrome shaft inside the aluminum seal head. You can generally order any needed parts from Race Tech. Obviously, you don't want to use solvents on any rubber seals, just wipe them down with a clean cloth.

At this point there is a fork in the road. If you are merely rebuilding the shock, then you can skip over the next portion where I install the Gold Valve kit from Race Tech. Go to the part where I start to re-assemble the shock and re-fill with oil.

The inside of the shock body:

Before I start to install the Gold Valve, I have a few thoughts to share about the kit. First of all, Race Tech did an excellent job of customer service. I called to order the parts, and actually spoke to a human being. She confirmed that everything I needed was in stock and took my order. I received the parts three days later in good condition. Not bad for suspension parts for a 15 yr old GSXR.

Second, Race Tech's installation instructions, and documentation are very helpful. They actually included a DVD that details the entire shock rebuild process with some very good tips that I will try and pass along. Nice to see an experienced person perform the task before you try it the first time. Plus it was filmed in 1995 with one video camera, and it looks like it. Nice and cheesy, but very good info. Think about those safety videos you have to watch at work. AWESOME!

During the install process, you will build a custom shim stack that is suited to your bike, your weight, your bike's weight, and your riding style. I won't get into the details since everyone's is different, and the instructions tell you what to do. The kit includes a one time use code to log into their website and download your shim stack info. In your printout, you will receive the shim stack info as well as preload, compression dampening, and rebound dampening baseline settings. It also recommends what weight oil and what nitrogen pressure.

My only complaint, is that it doesn't seem like their machine shop made any effort to de-burr the valve itself. In their defense, they tell you to check for burrs and remove them if necessary. However, I am a machinist, and I guess that I am picky when it comes to burrs. I am not impressed with a machined part that is shipped with burrs. It's brass and it would probably take 15 min in a tumbler with the correct media to remove these tiny burrs and give your customer a proper part. So I spent about 30 min deburring my new valve. Insert cuss word here.

Gold Valve versus Showa valve:

As you can see in the previous picture, the ports in the gold valve are substantially larger than the stock valve. This allows more potential flow, and shifts the flow control to the shim stack rather than the ports and the shims in the stock valve. Basically, this just gives a much larger range of adjustment in dampening which I needed since my shock is going on a bike that is 100 lbs heaver, and I'm 80lbs heavier than the 150 lb average rider that the GSXR would be set up for.

What Race Tech's calculations told me to do was switch from the normal 5wt oil to 10 wt, and I completely eliminated the low speed compression and rebound shim stacks. This combined with a spring rate change should help to control all the extra weight.

Now lets get on with the installation.
Step 14) This is the most tricky part of the valve installation. Removal of the nut on top of the valve stack. That nut is peened on from the factory. In the case of the Showa shock, it's actually peened inside and out, and we must ONLY remove the outside peening to remove the nut. If you remove the inside peening, then the rebound adjuster will fall out. Not good. The instructions tell you what to do, but I'll give you a picture anyway. What you do is grind away at the top of the nut on an angle until the peening is gone and the nut unscrews freely. If it fights, then you haven't gotten it all out yet, keep grinding. You want to leave enough hex so that you can get a wrench on the nut, and you'll probably wind up removing the top two threads from the shaft.

Step 15) Install the valve with the custom shim stacks per the Race Tech instructions. Cap it off with a new nut from the kit, with some Red Loctite (included.)

Don't forget the loctite, if that nut unscrews inside the shock your shock is trashed. Just like dropping a valve.