Changing ST1100 Fork Seals Without Separating Forks

Joined
Nov 12, 2016
Messages
5
Location
D'Aguilar, Qld, Australia
Bike
ST1100PY
If it is not necessary to separate the forks it is possible to remove the seals using hydraulic pressure.

Make up a box similar to this. (I made the section which houses the lower fork leg of a size to permit the projection which comes out at 90 degrees on both fork legs to sit inside the box and it is this projection which takes the load when the fork is compressed):

Fork Seals 1.jpg

Put some plastic in the section designed to hold the lower leg of the fork:

Fork Seals 2.jpg


Fill the (extended) fork leg to the top with oil (I used less than 500ml of light weight cheap engine oil + the existing fork oil). Filling the RH fork leg with the damper is a bit of a pain. Replace the fork leg cap, remove the dust seal and oil seal retaining clip, and place the fork in the box:

Fork Seals 3.jpg

Place a bottle jack (or similar) in the box in line with the fork:

Fork Seals 4.jpg

Then start jacking. The hydraulic pressure will force the seal out. Make sure you keep control of the fork when you start jacking to prevent the leg rising out of the box. I was forced to do it this way today because I was not able to separate the RH leg and was not worried about inspecting the bushes as the bike only has 55,000km on the odometer. Very little oil flowed out past the seal when it came out so I did not end up with a great pool in the plastic inserted in the lower section of the box.

Would not recommend this method if it was necessary to do a thorough clean out of the lower fork legs or if it was necessary to inspect the bushes.

I have done this before with a low km GPZ1100 and it was much easier because it did not have the one piece damper through fork cap system of the ST1100. On that occasion I just used an upturned wooden pallet as my 'box' with a semicircular cut in the centre 4x2 of the pallet to house the fork tube.

Anyway - all care no responsibility with this advice - use it at your own risk :)

Apologies to any granny I am teaching to suck eggs.
 
Last edited:
Joined
Feb 2, 2009
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2,304
Location
Dahlonega, GA
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2018 NC750X
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7666
While I would agree this is a viable method for removing seals, but it is a lot of trouble to go through just to avoid taking a cir-clip and a bolt at the bottom of the fork. If you were unable to remove the bolt, try doing that first with the fork still intact. Use an extended allen socket and an impact driver. Locktite was applied during assemble, so it sometimes takes a sudden movement from the impact wrench to brake it free. Not dis-assembling the top cap keeps some pressure on the internal components and allows some resistance to rotation while removing the bolt. I admire your ingenuity!
 
OP
OP
Joined
Nov 12, 2016
Messages
5
Location
D'Aguilar, Qld, Australia
Bike
ST1100PY
Vinny, I adapted an allen key to my impact driver and could not move the bolt (with fork leg cap on) so opted for the 'hydraulic' method. I will have to purchase an (air driven) impact wrench at some time and will try that next time I have to service the forks as I expect by that time I will need to inspect the lower fork legs. My method was an act of desperation rather than choice on this occasion.
 
Joined
Mar 20, 2016
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1,201
Location
Auckland, New Zealand
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2005 ST1300
STOC #
8901
That's a good post Newby.

This method would also be useful to folks whose fork seal is seized in place and can't be slide-hammered out, but I suspect you'd need a more robust frame around the fork/jack.
 

Ron

Joined
Feb 5, 2005
Messages
1,665
Location
Orlando
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ST1100s
STOC #
2432
I will have to purchase an (air driven) impact wrench at some time and will try that next time I have to service the forks as I expect by that time I will need to inspect the lower fork legs. My method was an act of desperation rather than choice on this occasion.
You can buy a manual impact driver for about $20. You put the allen bit socket on the impact and hit it with a hammer. The larger the hammer the sharper the impact. Of course the fork must be held fairly secure. Be sure the driver is set to remove the screw.
 
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