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rear shock

Decided that I was going to work on the rear shock a little.

As with most things, a tool is required. You can beg, borrow, buy or make a spring compressor. As usual I made my own out of some aluminum plate, four half inch bolts, nuts, and washers.

cutting plate

 

plates finished

 

compressor

 

You just crank down on the nuts until the spring is compressed enough to give you access to the jam nut helping to hold the mount in place. I had to heat this fairly hot with a torch to be able to unscrew the mount, this also forced the nut down onto the end of the threads really tight. Lots of locking compound to over come.

 

jam nut

 

Once you get the nut loose and the mount spun off the end of the damper rod, you can slowly back the compressor back out to have the spring removed.

 

spring off

 

I had to grind some flats on the end of the damper rod so that I could put a wrench on it, and remove the jam nut.

 

flats

 

After that you can let the air pressure out of the air bladder by pressing in the schrader valve, mine had somewhere around 75 - 100 psi of pressure in it. Then you can remove the hose and drain all the oil out of the can and the shock. You will need to pump the shock to get most of the oil out, same goes for filling it back up. the stuff that came out smelled like kerosene and was very thin. There is nothing clean about getting this job done, that's why it is in a plastic tub, oil goes everywhere.

 

shock oil

 

I tried several different weights, 10wt. and 5wt. seemed far too thick, I ended up putting 2.5wt. shock oil back in and I'll run it for a while to see how it handles. If it seems more under-damped than it was, I'll have to mix up something like a 50/50 of 2.5 and 5 weight oils. Or I'll need to take the extra steps to put the entire damper rod out and start figuring out what to do to the shims and valve holes to get what I'm looking for. Filling is as "simple" as putting all the oil you can fit back into all the pieces, and try not to leave any air inside. As mentioned, you'll need to cycle the shock many times to get the air out. I put about 100psi of regular air (the 78% nitrogen kind) back into the air bladder once everything was done, and used some blue Loctite on the threads for the mount and jam nut.. It appears that all this air pressure is doing is trying to prevent foam in the oil. I don't think the pressure is going to have much effect on how the shock really works, but I'll play with the pressures and see if it makes a difference like the air space in the front forks gives it extra spring rate.

 

My original intention was to pull it completely apart and get a good look at the valves, but this needs a pin wrench for the end of the tube. Eventually I'll pull it completely apart and see what I might be able to change to get better performance out of the stock shock. You can buy a performance Elka shock from SVRacing, it was fairly inexpensive compared to other performance shocks. Might be an option farther down this journey.