Cannondale Headshok DL80

Hi I have been working on a Cannondale headshok. Bought it as scrap as I wanted the headset but I couldn't resist trying to get it working again. I have managed to get all the seals replaced with assistance of a break press at an engineering workshop. The needle bearings all in great condition and ready to go.

One dilema I have is that from the extensive reading up I have done some people say there should be a return coil spring on the air spring. I have found the cross section drawing from Cannondale and it does not show one and when I took the cartridge apart there was not one inside. The damper had signs of being removed in the past so it could be the spring had been removed





As I don't have a spring and can't source one I will put it together and see how it performs as it has only cost me a set of seals and some hydraulic oil.

What are other peopled experience. Is the return spring only in the upgraded damper which is still available for the DL80. Any thoughts.

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Are the drawings you have these ones?
http://www.fastglass.net/bike/headshok/ ... ltrafat70/

From this list, http://www.fastglass.net/bike/headshok/manuals/

As you say, there's doesn't appear to be a spring on the shock in drawing.
It may be that on later Headshoks that they were added to aid small bump sensitivity as they were coloured to signify which stiffness for different rider weights.

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Yes that's the drawings i have been looking at. I have spent a fair bit of time looking for info and there is so much conflicting information on headshok. The articles on MTBR have the most contradictory information.

When we took the piston apart in the press the insides did not tie up exactly with that drawing either. The only point I would agree with on all the research is that you need a press to replace the top seals.

I agree that the return spring might have been a later improvement. The only thing that is making me doubt this is that the fork is described as "air sprung, coil negative spring" in the brochure below.

http://jumpsport.cz/media/files/4_HeadS ... 281%29.pdf

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I forgot I had that PDF with the info on Headshoks.
I have a brand new, therefore unmolested, FT80 cartridge and it has a spring, orange I think, with an thin elastomer inside it on shock shaft. The elastomer might be to stop spring rattling about. I assume the FT80 is later than the DL70.
I got the FT80 cartridge from Edin Co-op in one of their New Year sales. They usually have a few old stock Cannondale spares in their sale. Having been a Cannondale dealer they seem to find more old stuff every year for their sale. Might be something to look out for, if you're interested, in the new year.

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I have just remeasured the forks and they actually have 80mm of travel rather than 70mm as previously mis-measured. The cartridge looks more like the drawing of the DL80 in that it has a bleed screw. The parts diagram does not show the return spring but when you look at the PDF drawing below there is a return spring shown on that parts diagram.

http://jumpsport.cz/media/files/4_HeadS ... 281%29.pdf

I have sourced another set of forks that I think have the same cartridge in them which are working and I will open them up to confirm if they have a spring. Waiting on the correct castle tool to arrive before I dismantle the new set.

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Just to close this out myself. It did in fact have a return spring. It had gone missing during the dismantling of the damper. Careless I know... :roll:. Anyway put the damper back together a few months back and it is working great. Working on a lefty now....