Changing fork seals the easy way !

Using the ‘SMITHY’ patent hydraulic fork seal press.

Health and Safety

• The procedures depicted here have been performed by a professional Engineer.

• Please do not attempt any of these operations unless you have been deemed to be a competent person.

• Wear the correct PPE, adhere to appropriate Health and Safety guidelines and dispose of any wastes created in accordance with local regulations.

Remove the fork oil drain screw using the correct tool for the fastener type.

Drain the stinking,

contaminated and probably carcinogenic

oil into a convenient receptacle.

• The owner of the 1984 YZ125 forks forgot to loosen the top nut before removing them from the bike.

• I had to make a 43mm hole in a piece of softwood using a hole saw.

• A slit was cut from the edge to the hole to allow the wood to grip the slippery chrome plated fork inner.

With the fork inserted into the

wooden fixture and clamped in the

vice, the top nut can be removed.

A hexagonal socket was used rather than a bi-hex as

they are kinder to the alloy nut.

With the nut removed, fill the fork to the brim with kerosene, paraffin, diesel or thin oil.

Fuming Nitric acid and other dangerous liquids should be avoided !Replace the fork nut.

Place the victim into the Patent ‘SMITHY’

press.

Remove the wire circlip.

Wrap some cloth around the seal

area to contain any eruptions caused

by trapped air escaping when the

seal breaks free from it’s seat.

The fun bit !Pump away until the seal blows !

This fork required about 25mm of hydraulic jack movement before the seal broke free

This image shows the old seals freshly

blown from the forks.

Very little kerosene escaped as I made sure that there was

no trapped air left in the fork.

Remove the fork drain screw and

carefully pump out the kerosene into a

container. If the fluid comes out clean, you can use it for the other

fork later.As you can see in

this image, the kerosene is a bit grim and will be

disposed of.Refit the drain

screw.

Clean the area where the new seals will fit.

Apply a thin coat of grease to your new seals……….

I said a thin coat !

That’s much better !

Carefully fit the oil seal to the

chrome fork leg.

Tap the seal into place with the

seal fitting mandrel.

Fit the dust seal.

Using the other end of the mandrel, carefully tap the dust seal into position

Fit a new wire circlip.

Undo the fork nut and fill your fork with the correct amount of fork oil.

Replace the fork nut and fit to your bike !Repeat the procedure on the remaining fork.

Using this method, the seals can be changed in both forks in about 11 minutes !

That means more time for riding !

CREDITS !

• Thanks to Smithy for the idea !• To my Daughter for getting this PowerPoint

presentation to work.• Members of the Aussie IT forum.

http://www.yamahait.com.au/ for their support.

• My work place for putting up with me !