soshjosa

Hello, I recently bought my first road bike (used), and as I was taking it apart to clean and lube everything, I noticed the plactic cover for my freewheel is pretty shredded: imgur.com/a/woOv7AD

Is this something I should be worried about? I haven't been able to find some way to replace it other than buying a new freewheel. Also, I made this thread in case someone miraculously has an unusable MF-6208 freewheel, so that they can send me the plastic cover thing, in case I actually need it. Obviously I'd pay for any shipping.

Bigbus

I just replaced my freewheel and it didn't come with any plastic dust cover or any plastic pieces whatsoever. If you're referring to the dork plate behind the freewheel, that's to keep the chain from going into the spokes if your low stop screw isn't adjusted properly. Most people remove those and keep their bikes tuned properly. If you're concerned about it, you can buy them individually in many different colors for a few bucks. HTH

soshjosa

The part that I'm talking about is the plastic cover used to cover the housing of the freewheel where the bearings are. The picture of it is in the imgur link in the first post.

Bigbus

Sorry, I didn't look at your link till now. I rebuilt my old one a year ago and I would have sworn that piece was brass, but my memory could be failing me. But you're right, if you can find someone that has one with worn out teeth, that part should still be fine. Good luck,

JohnDThompson 

I suspect you'll either have to salvage one from a donor freewheel, or find someone with a 3-d printer and a good piece to use as a template.

madpogue 

Photo link assist: https://imgur.com/a/woOv7AD

You might try snapping it back in, and sealing the cracks/gaps with clear RTV silicone, just for a "form follows function" repair.

soshjosa

I had thought of something like that, but wasn't sure what to use to fill it in. Thanks!

oneclick 

You can fix it off the freewheel. Get a bit of aluminium foil and fold a narrow strip, use that to form a dam around the outside curve where the freewheel will be, hold it in place with some sticky tape. Tilt the arrangement so the surface of the bad spot is level(-ish), mix up a bit of epoxy, fill the bad spots with a toothpick and come back tomorrow.

dddd

I believe that the 6208 freewheels are simply a Z-series freewheel with the plastic shield added on!

Upon removing the shield, doesn't the lockring/cone have Z-something "MF-Z" perhaps stamped into it?

The shield threading isn't really needed, and as madpogue mentioned just snap it back in and it should stay put.
I simply pounded one of these shields into a Dura-Ace 7s freewheel after removing the smallest cog, to close the resulting huge gap caused by the missing small cog (with it's external threads). Made a Shimano 13-26t "ultra"-6 freewheel that way.

madpogue 

Interesting idea. A while ago, I was comparing a 6208 with an MF-Zsomething, and couldn't find any real differences. So I weighed them, figuring the "higher end" freewheel would be lighter. It was actually heavier by a bit. This might explain it. I never took the shield off the 6208 to see what's underneath it, and I'm not that curious.

dedhed

I'd probably measure ID & OD and fabricate one out of a nylon thrust washer

verktyg 

These were Shimano Uniglide "Twist Tooth" freewheels. They were rated as some of the best on the market

Never had a cause to remove the plastic outside "seal".

This calls for an expert: Paging Pastor Bob! pastorbobnlnh

verktyg

pastorbobnlnh 

It is just that, a seal to keep contaminants away from the freewheel's internals. The edge is fitted with a hard plastic spring which assists further. The spoke side of the inner body utilizes a similar plastic ring to seal the other side. The outer race/retaining ring has a large gap between its outer edge and the inside wall of the outer body.

I also guess that the plastic cover somehow works as a "lock ring" for the outer race/retaining ring. In my experience, this model Shimano (and its Dura Ace 6 speed equivalent) can be over tightened when servicing and reinstalling the race/retainer. Whereas using a punch, hammer, and vise to apply the final torque on a Regina, (most) Suntours, Atoms, etc., Shimano 600 and DA freewheels should only be hand tightened with a pin spanner.

madpogue suggestion is a valid one, but the RTV Silicon might impede future service. Hot paraffin might act as a better temporary seal.

My final 2 cents of advice--- is to be extremely careful with the shim spacers between the outer race/retaining ring. Shimano utilized many of these (I've seen as many as 6-10 on this model) and some are thinner than household aluminum foil. They are extremely easy to damage yet are crucial to final assembly when tightening.

Iowhat

I've got one (13-30t) with the (broken) shield removed - it has "LE", which is most likely a shimano date code for 1987, May.

Yesterday I picked up 2 other 6-speed MF-6208 freewheels at our regional co-op ($5/ea!) soley for scavenging a dust shield/seal. One is a corn-cob (like 12-21t - the one to be scavenged) the other with a bit more teeth (which I'll keep for my 1986 Fuso)

For the record - the dust shield/seal is made out of plastic - I was originally thinking it was brass, but nope. The freewheel is completely fucntional without the shield/seal, but looks better with it on.