Scotty's Dirt Bike Spares

Gas Gas 45mm Mazzochi shiver fork service.

If you are looking here for tips on servicing another type of fork other than the shiver the following might be useful for open cartridge style forks. 
Remove fork from bike. It is a good idea to loosen the top fork cap after loosening the top clamp pinch bolts but with the lower triple clamp pinch bolts still tight. Retighten all fork pinch bolts to 15ftp

Remove top cap

You will need 2 19mm spanners to remove the top cap from the dampener rod. When refitting, remember that the fork cap only tightens to home then 20-30degree, no more.

Once top cap and seating washer are removed pull out rebound adjuster rod and fork spring.

Tip fork to empty the oil gently moving the fork through its stroke.

The spring preload spacer if fitted might fall out so be ready.

Carefully remove the dust seal and oil seal holding clip.

Remove the cartridge nut with a rattle gun. Slide out the cartridge from the fork leg. Pump the dampner rod a number of times to get out all the fork oil. Now spray contact cleaner in the cartridge and pump some more to completely clean all the components.

The cartridge retaining bolt is also the compression adjuster valve. On a number of occasions we have seen the shim stack bolt (or nut de-pending on what year fork) loosen off resulting in poor dampening control and performance. When removing the main retaining bolt with a rattle gun this can also loosen or spin off the shim stack bolt. If you happen to spin off the shim stack bolt use a pickup magnet to gather the shims in the original order. If for whatever reason the shim stack order is lost and you can not work it out from the other fork take the lot to a suspension tuner. 

Spray clean the cartridge bolt with contact cleaner. Remove shim stack retaining bolt and refit with low strength loctite taking care not to loose the shims order.     

You now have a empty fork leg. To separate the lower leg from the upper I like to use a heat gun on the area around were the seal and bush sit, it seems to make the separation job less violent. To remove the lower leg from the fork assembly gently pull away from the upper in a slide hammer motion. The inner fork bush on the lower leg will force the outer bush and oil seal from the upper fork body.

Remove and inspect the fork bushes then the oil seal. Thoroughly clean both half’s of the fork.

Now reassemble fork. Slide on dust seal, retaining clip then fork seal. Use a plastic bag when sliding on the new (lubricated with rubber grease) fork seal. This helps prevent a snag cut on the seal lip. Refit spacer then bushes.

To get the new seal to seat properly in the fork you should use a fork seal driver (the heat gun helps here to). You can buy them but the ones available are ordinary at best.  We machined ours from a hollow nylon block then cut it in half to clamp around the leg.

Gently tap the seal home with your driver. Fit the retaining clip making sure it is seated in the groove. Refit the new or cleaned oil dust seals.

Refit and tighten the cartridge assembly. Pour 500ml of fork oil into the leg and pump the dampner rod up and down several times so it sucks some oil in.

Pour in approx 150 ml more oil and adjust the oil hight. We have the tool for this job see tools section. Standard is 5wt oil, 110mm from the top. Approx 650ml of oil per side. You can vary the oil hight/air gap from a 100mm to 130mm from top.