Freehubs - at last, a picture!

[mikeymo]

I've got some newish wheels with Shimano M525A hubs. Reading here it seems like a good idea to adjust the hubs when new. I've read the discussions about how to lubricate the freehub. But a lot of it didn't make sense to me, as I couldn't imagine what a freehub looked like inside, photographs and Shimano exploded diagrams not really helping too much.

Then I found this:

from here:

https://www.instructables.com/Rebuild-a ... -rear-hub/

Now the instruction to use SFG on the drive side bearings, so that it will migrate into the freehub, makes sense.

The only things that I think may be missing from that diagram are:

1. Shims from the inner face of the freehub? Do these adjust for chainline, or something?

2. The seal on the inner face of the freehub?

Am I right?

Does that diagram seem correct?

Many thanks.

[TheBomber]

Nice diagram.

1) The shims - labelled 'freehub preload spacers' in the diagram are required because the purple bit (labelled 'freehub/hub bearing combination race') simulataneously acts as the race for the drive side hub bearing and the cone for the outer freehub bearing and it screws into place. It needs to screw down firmly against something (the shims) as it doesn't have a locknut, but it also needs to apply preload to the freehub bearings. As usual the preload needs to be just enough so there isn't slop in the freehub but not so much that the freehub bearings are squashed. This is achieved by adding or removing very thin shims.
2) The seal isn't shown - perhaps because 7 speed freehub bodies didn't have them. You can see where there is daylight shining into the inner freehub bearing in the diagram. The seal plugs that gap.

[elPedro666]

Lovely, thank you for sharing that!

I'm a trendy consumer. Just look at my VOG-L09 using hovercraft full of eels.

[mikeymo]

Nice diagram.

1) The shims - labelled 'freehub preload spacers' in the diagram are required because the purple bit (labelled 'freehub/hub bearing combination race') simulataneously acts as the race for the drive side hub bearing and the cone for the outer freehub bearing and it screws into place. It needs to screw down firmly against something (the shims) as it doesn't have a locknut, but it also needs to apply preload to the freehub bearings. As usual the preload needs to be just enough so there isn't slop in the freehub but not so much that the freehub bearings are squashed. This is achieved by adding or removing very thin shims.
2) The seal isn't shown - perhaps because 7 speed freehub bodies didn't have them. You can see where there is daylight shining into the inner freehub bearing in the diagram. The seal plugs that gap.

Thanks. I got the impression that there were also some shims/spacers/call them what you will, on the outside of the inside seal, to space the freehub relative to the hub. Maybe I've got that wrong.

[TheBomber]

I got the impression that there were also some shims/spacers/call them what you will, on the outside of the inside seal, to space the freehub relative to the hub.

There are no spacers there - but MTB hubs (like yours) always seem to have a single washer set into the hub body. Hubs from road groupsets don't seem to. Not sure why the difference. Any additional spacers there will increase the 'over locknut dimension' of the hub and consequently require a greater spacing between the frame dropouts.

Edit: I should also have said they will also reduce the amount of interface on the spline between the freehub body core and the hub - too many and the freehub body will spin uselessly, independent of the hub.

[gregoryoftours]

Thanks. I got the impression that there were also some shims/spacers/call them what you will, on the outside of the inside seal, to space the freehub relative to the hub. Maybe I've got that wrong.

Yes there's often a washer between the freehub core and the hub shell, either circular or shaped like this:

The freehub binds on the hub shell if the washer is removed from a hub that has one fitted.

[hoogerbooger]

So where do you get extra spacers and what thicknesses available/do you add them in? ( I did have a quick google but wasn't jumping out at me)

[gregoryoftours]

So where do you get extra spacers and what thicknesses available/do you add them in? ( I did have a quick google but wasn't jumping out at me)

Which ones do you mean? If the washer between the freehub and the hub shell there's only one and if it needs to be there it will generally have come with the hub. If you do need to buy one it's this sort of thing:
https://www.google.com/url?sa=t&source= ... 9561098242
If you mean the shims under the cup race inside the freehub, again, they are there to start with - if your freehub develops play you can try removing them one at a time to eliminate or minimise the slop.

[colin54]

I just took a freehub apart today to take out some excess end-float , I was getting a very occasional cracking sound ( after freewheeling and resuming pedalling ).Shimano FH-LX570 hub. I thought I'd take a few photo's of the internals to add to this thread - click to enlarge.
I first removed the dust shield with a blind bearing puller, it came out easily, I've ruined one before when driving out with a screw driver. I bought a cheap chinese freehub tool off of ebay and used it to undo what is called 'the freehub bearing combination race' pictured in Mikeymo's post up-thread. The hub bearings run on the outside of this and one half of the freehub bearings run on the inside, as well as holding the whole freehub assembly together.This is left-hand thread so untightens clockwise. The shims are directly under this once removed, bearing on it's end face and encircling the inner part of the freehub.
Picture 1 shows (with outer part of freehub removed); dust shield, combination race with notches for removal tool, spacer shims ,(one thin & 1 thick in this case, measurements with a cheap aldi calipers - 1 off 0.15mm & 1 off 1.20 mm resting on top of unit), one of the pawls and rubber seal at base attached to inner part of the freehub. The thinnest shim was on top.

There are two pawls fitted which act against a circlip like spring ( called a snap-ring in the diagram) which encircles the freehub core in a groove & also locates on a shaped part of the pawl (picture 2). The pawls themselves pivot on two semi-circular grooves machined or cast along the length of the core, there are only two of these grooves and they continue through the thread on the end of the core (picture 3).
Picture 2

Picture 3

On inspection the pawls looked to be in perfect undamaged condition, though the tips of four of the teeth on the inside of
the freehub body were showing slight damage , it shows as a thin silver line (picture 4) and indeed I found a sliver of material off the end of one of the teeth.
Picture 4

The bearings all looked in good condition , there are 25 balls per side, there was still plenty of grease (picture 1) it was a mix of the original and some semi-fluid spray grease which I added at some point I think.
I think I'll remove the thin shim and see what the end float is, I've got a couple of old hubs I can cannibalise for shims if needed.
Picture 5, Internals and hollow securing bolt (10mm allen key).

Edit ; anti-clockwise, replaced with clockwise of course, whoops !
Edit; Shim measurements corrected.

[mikeymo]

Thanks for posting these pictures and description.

This is left-hand thread so untightens anti-clockwise.

Is that right? Wouldn't a left-hand thread, a "reverse" thread, untighten clockwise? Or have I misunderstood?

[colin54]

Thanks for posting these pictures and description.

This is left-hand thread so untightens anti-clockwise.

Is that right? Wouldn't a left-hand thread, a "reverse" thread, untighten clockwise? Or have I misunderstood?

Thanks Mikey, well spotted, you are absolutely correct, a bit of brain-fade on my part, I'll edit my post.
Just to add a couple more pictures; picture 6 a better view of the pawl set-up & picture 7 showing the inner rubber seal in place, note the taper shape goes inwards be sure not to replace the other way around. You can flip this seal out without stripping the freehub to add lubricant if you have the hub apart anyway . I've not added it via the hub bearings as mentioned in the other thread you mentioned (only because I don't have a suitable semi-fluid grease and never thought of doing it that way ).
Picture 6,

Picture 7,

[mikeymo]

Thanks Mikey, well spotted, you are absolutely correct, a bit of brain-fade on my part, I'll edit my post.

Sorry, I wasn't being "picky". I just worry about future generations reading this and making the freehub really tight, when they thought they were undoing it!

In my head I'm working on some sort of replacement for the freehub buddy:

https://products.mtbr.com/product/acces ... buddy.html

Which I don't think is available anymore.

[JimAW]

J A Stein tool company is selling Freehub Buddy tools again on ebay. They're not cheap though.

[mikeymo]

J A Stein tool company is selling Freehub Buddy tools again on ebay. They're not cheap though.

Ah, yes. Thanks for finding that. The link is here folks:

https://www.ebay.co.uk/itm/124001100581 ... SwI11d6dhG

However, it doesn't seem to be the same as the "original" Morningstar freehub buddy:

http://www.bikepro.com/products/hubs/hubacces.html

For one thing the original, as far as I can tell, forced stuff (cleaner, lubricant) through the outer end of the freehub. The J A Stein one forces it through the inner end. Which means

1. You have to take the freehub off the bike to use the J A Stein version. Whereas I think (please correct me if I'm wrong) you could leave the hub on the bike to use the Morningstar one.

2. You have to remove the rear seal to use the J A Stein one. Not so with the Morningstar. I've got a seal pick and am fairly careful, but I still worry about damaging seals when removing and replacing them. I don't suppose Shimano sells new seals, though I might be wrong.

3. The stuff (cleaner/lubricant) is being forced into the freehub in different directions with the two versions of the freehub buddy. It may or may not matter, though I do remember Brucey saying he thought forcing it in past the seal at the back was a bad idea. EDIT - it seems to me that forcing lubricant in the front/outer end and out through the back/inner end of the freehub (taking old stuff and dirt with it) is preferable, as that's nearer where it has accumulated anyway, and doesn't risk contaminating the hub bearing area. Maybe. END EDIT.

And yes, the J A Stein is a little more than I'd want to spend. My incipient design idea is based around a spare cassette locking ring, lots of J B Weld, and one of those syringes that injects sealant into an inner tube. I'll let you know when I've got it patented and production ramped up to 10,000 units a week, as there's bound to be massive demand.

[JimAW]

It's been many years since I've used the Morningstar version (and I've not used the Stein version), but from my recollection:
- The 1/4" bearings had to be removed from the freehub to use the MS tool, so removing the freehub from the hub shell, which is almost the same/as difficult as removing the freehub. And the MS was easier to use with the freehub removed from the hub shell.
- To use the MS tool, one had to remove the metal cover/seal at the outboard side of the freehub. This is hard to do without deforming it, so for me was more of a pain than removing any rubber seal from the inboard side of the freehub (which ideally would be done as well). Naturally, Brucey describes a better technique for removing these metal seals.
- I used to flush enough Phil tenacious oil through, using compressed air, that it didn't make much difference to me which direction it was going. Keep flushing until clean. The 1/4 bearings should really be removed for either tool or direction, so contamination was not an issue.

I can understand different preferences for either tool. Personally, I've taken to opening up the freehub to clean and re-shim.