Cannondale DL80 seal replacement

Over the summer I have been working on some headshok forks. I have overhauled a DD60 and two DL80's. Below is a few pictures of how I tackled the DL80

Both sets of forks below have the same DL80 oil and air damper inside them. The only difference between them is the one on the left doesn't have "V" brake mounts.

The tools I used are shown below
Pin spanner
Supercastle tool KT31
Red grease
Replacement seal kit HD166 (£3.99)
Fork oil 5WL
Bullet tool FT70
Shaft Clamps HDTL187


To remove the top cap I used a pin spanner to screw the cap off. (Please note leave the aluminium nut well alone. The aluminium nut is press fitted onto a spindle and if you rotate it with a spanner you could ruin it)

Once the top cap was removed below is the view inside. Then I let all the air out of the air piston and used the super castle tool to remove the cartridge.

Below is the supercastle tool in use. It takes a 3/8" socket wrench in the square hole in the top.

Once removed the oil damper is shown below

The air piston was still in the air damper I removed this by putting my hand over the top of the fork and putting a bit air into the damper and the piston shoots out. First time I did this it hit me in the face along with all the fork oil that had drained into the air cylinder - so be careful. There was also a return spring above the air piston.

Air piston and return spring removed shown below

On one set of forks the air cylinder came out and the other it stayed put. I don't think there is any benefit in removing it. Below is what it looks like.

Once removed I drained the oil out of the damper and used the pin spanner to take the oil damper apart. In both instances I replaced the top and bottom piston seals. The bottom seals are the ones that wear out first and are often all that needs to be replaced.
Below is what the bottom seal looks like removed.

To get the bottom seals back with out the risk of damaging them I used the bullet tool and red grease. Got the grease from Ebay great stuff which helps to lubricate the seals until the oils works its way back into them. Bullet tool on the end of the shaft below

I don't have any images of how I replaced the top seals. I had access to a brake press. Used the shaft clamps to hold the shaft and pressed the centre rod out of the shaft. I will go into more detail at a later date when I get a chance.

Once I had replaced all the seals I filled the damper up with oil and moved it up and down to work the oil into both sides of the damper. Then to bleed it close the top nylon cap turned it upside down and then opened up the bleed screw inside the damper shaft. It took a few goes and eventually there was less noise inside when you moved the piston up and down. Then gave it a final top up oil to replace the space the air had taken up.

When finished there a thin film of oil on the shaft each time it goes up and down this is apparently normal.

Bruce

Nice write-up. I will have to service my wife's Headshok fork so a detailed write-up will help. Thanks! already booked-marked it. What about servicing the roller bearings? Did you have a go at that? Some additional info on replacing the top seals would be great too! My take on all those forks is: it's not rocket science and if you do your homework and get some specialty tools (e.g. castle tool) one could service any fork or rear damper there is out there. Some companies might make it sound like it's an impossible job and those forks run on black magic of sorts but it's not the case. I've taken my fair share of forks apart and serviced them and put them back together but haven't gotten around to work on a Headshok. Where did you get the seal kit from?

Re:

In both sets of forks the needle bearings were in good condition and grit free. So there was no need to strip down. With the cartridge out it is easy to grease from both sides. It is not essential to have the cartridge out but it is more effective. You can do the same process by lifting the rubber boot.

All I did was covered the outside race with grease, stuffed the void where the cartridge had been with grease and worked the fork up and down. This pulled the grease into the needle bearings and you could feel the difference in movement afterwards. Just used a general purpose grease.

Cleaned the inside of the tube out prior to refitting the cartridge. It is quite a messy process but very effective.

Re:

This is a useful link with an exploded photographs of the DL80 cartridge

http://www.headshok.it/italiano/s0/fatty_super.html

Do you know where to source the seals from? I have a '95 fork with the Marzocchi cartridge (recart version without externally adjustable damping). Would the more modern seals still work on that cartridge? The regular castle tool will defo not work on my fork, will have to improvise something...

CannondaleSpares.com

Re:

Do you know where to source the seals from? I have a '95 fork with the Marzocchi cartridge

Click to expand...

Unfortunately the Marzocchi cartridges are no longer supported and have not come across spares for them. Not sure if the Headshok seal kit would fit. The o ring seals are fairly standard items but the wiper seals are much more specific in size.

I guess I'll just have to buy a set of the more modern seals and roll the dices hoping that either I won't need to replace those seals or the new ones happen to fit.

Re:

I have a bag of the old seals you can have if you want. Found them when I was clearing up the other day. They are worn out but they would let you see if they are the right size. PM me your address and I will send them to you for free there is no weight in them.