roccobike

I picked up a Trek 800 at a sale recently. I took it for a quick spin before cleaning and lubricating the main bearing surfaces. In quick succession, there was substantial, (almost painful), slippage when applying power to the crank. The slippage turned out to be the freehub. After removing the cassette, the Shimano freehub turned freely by hand when turning clockwise, only occaisionally engaging. I noticed that there was a substantial amount of grease on the outside of the freehub body. Much more than I've seen on other bikes. Unfortunatley, my Downs Repair manual has almost no information on how to remove a freehub, but it did have a section on cleaning grit from a freehub. I tried the recommended method of spraying WD-40 on the inside of the freehub body, to penetrate/clean the inside of the freehub. It appears to have worked, the freehub engaged 100% of the time almost immediately. Finally, I lubricated the freehub bearings with some non-detergent oil by placing oil droplets between the inner side of the freehub body and the hub. So my question is, am I done? Was it simply grease preventing the pawls from engaging? Is this corrective action all that's needed?
I'm asking this because a slipping freehub really hurts the shin and ankle, I don't want to risk injury to my legs for a fun project bike. If removal and dissassembly of the freehub is required, does anyone know of a website that can help, I couldn't find any help in Downs.

bigbossman 

More than likely, you're done. In my experience, dried or thickened grease/sludge binds the little pawls and keeps them for engaging properly. Usually (as in your case) a good hosing with a penetrant such as WD-40 or Kroil flushes the crap out. Followed up by a lightweight oil (WD-40 has a tendency to gum up itself, after a while) the problem is solved. I like to remove mine and flush from the rear as well.

If this indeed a freewheel and not a cassette, it is very easy to remove with the proper (inexpensive) tool. For example, Park Tool FR-2 or FR 3 (for Suntour 2 and 4 slot freewheels, respectively) can typically be had for $5-6 ea. Then all you need is either a big cresent wrench or a bench vise, and freewheel removal becomes a snap.

Check Bike Tools Etc for the tools and prices.

EDIT: just re-read your post. You're talking about a freehub - not a freewheel. Sorry! I still think you're done, though.....

roccobike

Thanks BigBossMan. I finished cleaning the hub with WD-40, then followed with engine oil.
Apparently, the previous owner or his mechanic decided to grease the rear hub by placing a wad of grease on the outside of the hub (incredible) between the frame and the hub. That resulted in grease on the cassette, chain and of course, the hub. What a mess. The grease travelled inside the hub and affected the pawls from engaging. I've completed cleaning all the parts and have begun reassembly. The only good thing about this incident, grease sure kept rust in check!