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Mar 14 2009, 4:04 AM EDT (current) Mackerz
Mar 14 2009, 3:12 AM EDT Mackerz 47 words added, 8 words deleted

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At 51,000km the righ-hand fork of my Stone began weeping. I decided to have a go at replacing the seal myself. When I bought the new seals, the Guzzi mechanic said that 50,000km was pretty good going for a heavy bike. The job took me 3 hours, including full removal and replacement of the fork, seal, wheel, windscreen, mudguard, etc. I took my time but could now do it in half that time, I reckon.

Moto Guzzi Metal Stone Fork Seal Replacement - Moto Guzzi Maintenance The tell-tale signs of a worn fork seal. Rings of grime where dirt meets weeping fork oil. Closer examination show fork oil spatters on the fuel tank and crash guard.
Moto Guzzi Metal Stone Fork Seal Replacement - Moto Guzzi Maintenance Remove the fork and drain the oil.
Moto Guzzi Metal Stone Fork Seal Replacement - Moto Guzzi Maintenance The dust cover can be levered up with a knife blade.....
Moto Guzzi Metal Stone Fork Seal Replacement - Moto Guzzi Maintenance ....then a broad-bladed screwdriver.

Slide it off the fork stauchion.
Moto Guzzi Metal Stone Fork Seal Replacement - Moto Guzzi Maintenance A wire spring-clip sits in a groove above the seal to hold it in position.
Moto Guzzi Metal Stone Fork Seal Replacement - Moto Guzzi Maintenance It comes out - and goes back in - simply; you don't need circlip pliers, a screwdrive will do.
Moto Guzzi Metal Stone Fork Seal Replacement - Moto Guzzi Maintenance Up end the fork and remove the bolt. This was in very tight and I eventually had to place the fork leg in the vice and put a length of pipe on the Allen key for leverage.

When the bolt comes undone, a teflon plunger will slide out of the fork staunchion, so be prepared for it and catch it.

This now frees up the staunchion which can be slid out of the lower fork leg.
[I found out later that there is also a washer with the bolt. Mine must have stayed up there because there hasn't been any leaks.]

[I now stopped taking pictures because everything was really greasy with fork oil!]

Remove the old seal. This took some time. I used a broad-bladed screwdriver and slowly worked around the seal. I put an old leather glove on the edge of the fork leg to protect it as I worked around. Eventually, and with patience so that I didn't scratch the inside of the fork, the old seal moved up and then came free. (You can buy a tool for this job which is bent, for leverage, and has a rounded end so you can't scratch the fork. I've been told that a bike tyre-lever works well, too.)
Moto Guzzi Metal Stone Fork Seal Replacement - Moto Guzzi Maintenance Now replace the stanchion and the teflon plunger and replace the bolt in the bottom of the fork leg.

The new seal came with some special grease so I gave it a good coating and slid it over the staunchion and down to the lower fork leg. (Use fork oil if you don't have any grease).

You need to seat the seal evenly so I took the seal into my local hardware store and bought this piece of PVC pipe which fitted perfectly.

I found the best technique was to lift the lower leg with my left hand and hold the PVC with my right, and drop the leg on to a cloth-covered wooden stool, letting momentum do the work (like putting a sledge hammer head onto a new handle). Only a two or three gentle drops were needed.

Replace the spring-clip, then the dust cover using the momentum method.


Refill the fork, reassemble the bike, then go for a test ride. And check the front brake with a few pumps of the handle before you do. I didn't....but I certainly will next time!