harrier6

Hi,

I've been riding a Shimano Tourney 7 speed freewheel, 14-28, MF-TZ500 on my commuter for awhile, and while I appreciate the hyperglide teeth, one problem I've had is with a knocking sound while pedaling that comes from play in the freewheel body. With the chain off, you can grab the sprockets and twist them a small amount. It's done this since it was new. Searching the forums, it looks like this is common among freewheels these days, and has something to do with poor manufacturing tolerances because they are meant to be cheap parts.

Yeah, sure, upgrading to a freehub wouldn't cost that much, but I thought I'd ask if there was a way to take these freewheels apart and fix them. Sounds like it could be just a matter of adjusting bearing preload somehow?

grumpus

If you think a whole new wheel, or a wheel build with your existing rim, is cheap then go for it - it's generally a superior system
I don't have experience of your freewheel but generally freewheels have shims to set bearing play - if you're lucky removing one or more of the shims will reduce the play without making it too tight. There are usually a couple of dents on the front plate that can be turned with a pin wrench or tapped with a punch to unscrew the plate, that's where you'll find the shims (possibly multiple, possible different thicknesses, if any). You'll also find lots of balls and springs and pawls that will try to escape, so work over a towel to catch them - hopefully you can remove the shims without making a big mess. Remove a shim, replace the front plate, check the spin, repeat as necessary.

NB I don't recall if the front plate is right or left hand thread. If nobody turns up to put me right, and you can't see the end of the thread, then try both directions.

BTinNYC

An exact replacement freewheel is about $20.

Iride01 

A knocking sound? Are you sure it's not that your pedaling isn't as smooth as it should be and the speed of the wheel is occasionally out pacing your feet?

That will have the pawls about to disengage and then when your feet catch up the pawls slam back into their proper position. Along with all the other drivetrain components suddenly going from slack to tension. And that is about the only thing that ever sounds like a knock to me that concerns the rear wheel and freewheel or free hub.

cyccommute 

Freewheel wobble isn’t a “these days” thing. Freewheels have always wobbled just about the same amount independent of the freewheel. Here’s what Jobst Brandt said about it back in 1996:

In other words, there’s no fixing the problem. Live with it or get a freehub. Freehubs don’t have that problems because they aren’t concentric mechanisms mounted on a concentric thread.

mpetry912 

these are actually very good FWs especially considering the price but yeah, if it's clunking, why not just replace it?

do the chain too, get a Sachs PC-850 and enjoy a smooth riding summer !

/markp

harrier6

I'll give that a shot. It seems unintuitive that removing a shim would reduce play, but I'm no professional mechanic. If 15 minutes of DIY can fix it for free, then I'll give it a go first. From what I've heard in places, this knocking problem is common in new freewheels from Shimano and others, so replacing it might not fix the issue. But of course, maybe that was just someone who likes to say "they don't make them like they used to?"

Re: Iride01 – I'm reasonably sure that that is not the case, as the knocking sound only happens when the drivetrain is engaged and is there even when I am pedaling very smoothly.

Re: cyccommute – I don't think Brandt is talking about the same sort of wobble there. The play/wobble I'm talking about can be felt if you take the freewheel off the bike, hold the freewheel body with one hand, and try jiggling the cogs with the other. Not saying that there isn't also some eccentricity in the hub-freewheel threading, but that is a separate issue from the one I'm trying to solve here

dedhed

Build-a-long freewheel!!!! Photo heavy

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andrewclaus

Ditto this. In my commuting days, I kept a stock of freewheels and chains. (I still do, except they're cassettes now, and I keep things cleaner.) They're wear items, along with tires, tubes and brake pads.

grumpus

The cone tightens against the shim, removing the shim allows the cone to be tightened further.
I was, this isn't something I'd do for a paying customer but did for myself, although the freewheels I used were very high quality and worth the effort. But with yours as you say, it's worth having a go. You might find it works better than it did from the factory - that's certainly been my experience with cheap pedals.

KerryIrons

Not really. In the 1980s Regina made a line of freewheels that were essentially wobble free.

harrier6

So I went ahead and did it today. It was pretty straightforward, and no more difficult than doing hub bearings or anything like that. I removed the thinner shim, which reduced play some but did not eliminate it. I'm going to ride it for a little bit to see if that's good enough. If not, I'll go back and play with the shims some more. I'd bet that just keeping the thin shim would work well. FWIW, the current small amount of play now resembles a similar 6 speed Tourney freewheel that I found in the parts bin that hasn't given me any troubles. Notes from the job for posterity's sake:

• Model: Shimano MF-TZ510-7, 7 speed 14-28
• Loosen the cone while the freewheel is on the hub. It is left-hand threaded.
• Outer (drive side) bearings: 30 x 1/8"
• Inner (non-drive side) bearings: 35 x 1/8"
• Shims: 1 x 0.014" (0.36mm), 1 x 0.005" (0.13mm). Thinner one was stacked on top (drive side).
• I used White Lightning Crystal grease for the bearings and paraffin-based sewing machine mineral oil for the pawls. I don't know much about lubricants, so don't take my word as gospel. Mixing grease and oil probably isn't a best practice.

7 speed, 14-28

left hand threaded cone

Watery inside, from just washing it

came with 2 shims

grease + oil