Bicycle Mechanics - Freewheel Question

Please forgive my newbiness.

The freewheel on my ooooold trek 1000 sounds horrible. I'd like to take it apart, lube it, see how it works, overhaul it, and put it back together. How do I get into the actual freewheel? Baring that, how do I lubricate it?

The freewheel is a Shimano MF-Z012, circa 1988

Thanks for your help.

First, new freewheels are cheap enough that disassembly for repair is only for the most dedicated tinkerer.

Removal requires a specific removal tool (Park Tool's FR-1 is commonly available and inexpensive), and a BIG wrench.

To lubricate it in place, remove the rear wheel and lay in on it's side, freewheel up. Dribble light oil such as Tri-Flow, into the small space between the fixed core and the outer shell while rotating the cogs by hand. That should get the oil down into the bearings and quiet everything down.

Sheldon Brown's web site has a very comprehensive article on freewheels and their care and feeding. Look here: http://www.sheldonbrown.com/freewheels.html

Either a BIG wrench or a BIG vise mounted to a really heavy bench. The second option being my own personal favourite....

If the oil down the crack doesn't smoothen it up then the insides are rusty. At that point just adding oil or even tearing it apart is not going to do the trick since all you'll do is open it up to confirm that it's rusty. In that case you're back to Hill's option of just buying a whole new freewheel assembly.

Please forgive my newbiness.

The freewheel on my ooooold trek 1000 sounds horrible. I'd like to take it apart, lube it, see how it works, overhaul it, and put it back together. How do I get into the actual freewheel? Baring that, how do I lubricate it?

The freewheel is a Shimano MF-Z012, circa 1988

Thanks for your help.

Inside the smallest cog there's a threaded ring that requires either a two-pin wrench or some other special tool. You also (I think) need a way to hold everything still, and there used to be a freewheel vise available for that purpose. I really don't agree with taking them apart, because it's a hassle (I never figured out the easy way, if any) to get the spring-loaded pawls back in place durig reassembly. +1 to getting a replacement.

You can flush the freewheel once it's off the hub by soaking it in a solvent, letting it drain, then seeing if the drainage runs clean. Try a second time. Then if you have access to an air line, you can blow it out. You can re-oil using an oil injector or just running in oil from the front or back groove, or through an oil port if you find one. New Winners have an oil port on the threads, nad the front and back grooves are sealed.

Seeing how it works might be a luxury.

A makeshift freewheel vice (English spelling - sorry!), is really easy to make if you decide you want to take it apart. Remove the freewheel from the wheel. Lay it on a stout piece of flat wood with the largest sprocket against the top of the wood. Screw in two or three dome-head wood screws (slotted dome heads are easiest) so the shank of the screws fit in between the teeth where the chain rollers would normally go. Put the wood in a bench vice and follow Road Fan's instructions. When you've finished and decided whether tp remount or discard the freewheel, simply remove the screws to release the freewheel. Hope this is helpful. Personally. Id just replace the unit with a new one, my success rate with freewheel pawls is less than 30%, but it only costs time to try!

Inside the smallest cog there's a threaded ring that requires either a two-pin wrench or some other special tool.
Sun Tour freewheels have the threaded ring with the pin-spanner holes and it is, IIRC, left-hand threaded. I haven't seen a Shimano freewheel in a while but I believe the "ring" is just a plastic insert and has to be pried out. Morningstar made replacement rings to allow their freewheel lubricator (grease injector) to work with these.

BTW, along with the springs, pawls and dozens of tiny bearings, most freewheels also had one or more shims inside to set the clearance and play between the core and outer shell. If you take one apart, be sure to note their number and location.

Shimano freewheels can have the cap removed with pin-tools as well:

http://www.born2bike.freeuk.com/images/gear02.jpg

Not sure about this particular freewheel, but some of Shimano's freewheels have seals and you won't be able to drip lube into them without disassembly. If you leave the freewheel on the bike, you won't need a freewheel vise.

Just lay the wheel flat, take off the end-cap being careful not to tip the wheel and have the freewheel and its 1,000,000000 tiny ball-bearings fall out. Drip some heavy-old down there, and spin the outside to work the lube all the way to the inner bearings. Re-install cap and you're done! :)