First time servicing a rear hub for me.

I disassembled and cleaned my Shimano FH-M510 rear hub, removing the nut, washers and cone only from the left side of the axle. When I went to insert new bearings and grease I noticed a silver ring, and I don't understand where I have to put it (you can see it near the old freehub body).

Deconstructed rear axle

Did I put that ring with axle's parts by mistake? I just remember to have cleaned it from grease.

Maybe it's the left side dust cover:

Left side dust cover

Can someone help me?

  • I suspect the ring fits over the spacer (#12), and is used to hold the rubber boot in place.
    – mattnz
    May 23, 2016 at 0:29
  • If the first photo wasn't cropped so much at the top, I think we would see a second one on the freehub body for the right hand side
    – Swifty
    Jan 9, 2022 at 9:13

3 Answers 3


Nice picture. But you installed the dust cover (the silver ring) upside down. They way it works is that the bearings sit underneath it (but do not make contact) and are protected from all sorts of insults and wear. It keeps the grease in, and the bearings in place while servicing it.

The way it is now it will not allow for the race to be adjusted against the bearings. It's got to come out.

In the future, buy a small magnetic pick tool from a parts store. It makes digging out the bearings much easier and you won't be tempted to take it out. It's kind of a pain to get in there just right.

Good luck!

  • This is incorrect, I have added an answer to explain why it has been assembled correctly by the OP
    – Swifty
    Jan 9, 2022 at 16:39

For completeness, the part shown in the OP's photos, the silver recessed ring (dust cover) would appear to be the left hand counter-part of part #5, which doesn't appear to be shown in the exploded diagram:

Exploded diagram of FH-M510

As Swifty states in their answer, it may be that it is part of part #11 and sits within the recess of part #11. However, it is strange that it isn't shown on the diagram.

  • 1
    No, OP did not remove part 5 from the assembly, re "removing the nut, washers and cone only from the left side of the axle" emphasis mine. useful diagram though
    – Swifty
    Jan 9, 2022 at 9:09
  • Good point, I'd missed that. If you look carefully at part 13, there is something weird on the edging of the part in the diagram. I'm not sure if it is either: a double edge shown (which would imply a dust cap), but then the rest of the drawing of the part doesn't match a dust cap (i.e. the depth of the inner recess is missing), or; an error in the part's drawing. There certainly seems to be a mistake (omission) on the drawing (and the part list) for the left side's dust cap. Odd. Jan 9, 2022 at 11:34
  • Actually, scrub that, the left hand cone actually has the dust cap integrated into it (part # 11). I don't quite understand what or where the OP's ring came from. Either there is an extraneous dust cover in the OP's left hand side, or; it was reassembled incorrectly previously, prior to this cleaning, and it is in fact the right hand dust cover. Jan 9, 2022 at 14:10
  • 1
    "As Swifty states in their answer," not quite, I said it tessellates with part #11; it would more likely be considered part of the hub, which is not numbered
    – Swifty
    Jan 9, 2022 at 16:37
  • Hmm, ok. I think I see. I actually bought a pair of these wheels yesterday for 200 baht, hence why I landed on this question. As they seem to have been fished out of a river, I'm slowly in the process of taking them apart. I'll take some photos on the left hand side as I go, so we can see (or double check). I've just had to saw through one of the quick release shafts in order to get them off and the other QR just sheared off whilst trying to unbolt it with mole grips - the plastic covered bolts were welded on by the rust. Normally this wouldn't bode well for the rest, but the hubs do spin. Jan 9, 2022 at 17:10

Yes, it's the left side dust cover, you have installed it correctly in your photograph, into the left side of the hub. It should remain as pictured so it can tessellate with the dark grey ring on the cone, creating a 'labyrinth' seal to keep dust out. If it was reversed, then it would obstruct the assembly.

I don't see it on the exploded parts diagram, I believe this is because Shimano don't advise removing it for servicing, because it is delicate and gets distorted on removal, risking drag from a deformed part. Obviously it is hard to clean in there without taking it off!

You appear to have kept it in good shape and put it back in correctly, so no harm done, good job.

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