It's easy for water and dirt to get into your freehub, and once it's there it'll make your bike clunk and grind like an old lift.
Fixing this problem requires special tools and a little extra know-how. If you follow the guide below, you should be fine. But if in doubt, especially on step three, have it done by a pro.
Nine-step guide to fixing your freehub
These are the tools you'll need:
- 10mm and 12mm Allen keys
- Allen key multi-tool
- Extension tube/bar
- Chain whip
- Lockring remover
- Cone spanners
- 17mm spanner
- If you have a Campagnolo hub, you'll also need a Campag pawl holder (www.campagnolo.com, www.chickencycles.co.uk)
1 Remove your cassette
Remove the rear wheel and immobilise the cassette using a chain whip. Wrap the chain whip in a clockwise direction on the third cog or the one allowing maximum chain wrap. Insert the cassette lockring tool and align a longish spanner to the left of the chain whip handle, close enough to enable a two-handed grip. Now squeeze ﬁrmly, unscrewing lockring and cogs. The tolerance between the cassette lockring and axle locknut can prevent certain splined tool brands from ﬁtting correctly, but a Shimano or Park tool will always work.
2 Remove axle and ball bearings
Check the freehub (the cassette body containing the freewheel mechanism) for wear to see if it needs replacing or just cleaning and relubing; do this by grabbing the splined body and give it a shake. If it moves more than a couple of millimetres side to side, replace it. Otherwise, a good clean and oil will do ﬁne. Slip a 14 or 15mm cone spanner onto the left (non-drive side) cone, and break loose the (usually) 17mm left locknut with a spanner. Unscrew the locknut, then the cone, and withdraw the axle assembly, catching the loose balls on a clean rag.
3 Remove freehub body
To get to the back of the freehub body and remove the seal for cleaning – or to simply replace it – it needs to come off. Insert a 10mm Allen key into the hollow tube-like bolt holding it in place from the right (drive side), and turn counter-clockwise using a fair amount of muscle power to dislodge the bolt. It might help to use a small extension bar to make the Allen key handle longer. Shimano lookalike freehubs, made by companies such as Joy Tech, can be a bit trickier to remove. The retaining bolt will usually be removed from the left side, inside the hub shell, requiring a longer, more stout Allen key.
4 Flush twice
Wearing goggles, grab a can of GT85 or WD-40 and spray the freehub's internals until grittiness is reduced. Follow this with a generous application of oil. Let it drain, wipe off the excess and make a final application. Then re-insert the seal. Grease the interface and install the body. Re-torque the bolt ﬁrmly. Wipe away any excess oil before reassembling the axle and bearings by reversing the previous steps, ensuring the bearings are clean and greasy. Some clone freehubs will use 7/32in balls and a slightly different shaped cone on the freehub side, and standard cone and 1/4in balls on the left; don’t mix them up. Dab grease over the splines and reinstall the cassette cogs. (Note the thin spacer required for 10-speed Shimano cassettes on nine-speed bodies.)
5 Campag hubs
For new Campagnolo Centaur, Chorus and Record hubs, immobilise the axle from the left side using a 5mm Allen key. Now, with a 17mm spanner, turn the right side locknut clockwise and remove it. The freehub assembly should come away with a tug, leaving the axle assembly in the hub. The pawls and spring will remain in place. Mirage and Veloce hubs, along with the older style Chorus and Record hubs, might require that you loosen a small Allen grub screw ﬁrst (about 2mm), located in the right locknut; on more recent versions it’s no longer present, so remove the locknut on the right using a 17mm wrench, while immobilising the axle from the left with a 5mm Allen key or a second 17mm wrench.
6 Campag old style versus new style
On current Mirage/Veloce, the left locknut might release ﬁrst, but this should pose no problems, since the axle and freehub will slide right off with a ﬁrm tug. Do this over a rag to catch any parts, as the springs and pawls can go ﬂying off. There are two types of springs in use at the moment: multiple small coil springs and single-circle clip springs. The former are found in older Hope and current and older Campagnolo, the latter in newer Hope, Campag, Shimano and a host of other lightweight hubs. Note the disassembly order, paying attention to orientation and shape, in particular the edge that engages the drive ring, and the pawl seat.
7 Lube it up
Squirt a few dabs of light grease onto the drive ring and make sure there’s a small dab of grease between the pawl base and seat. This is the spot subjected to the greatest level of load and friction; considering the entire brunt of each pedal stroke is channelled through these four or six contact points, they deserve and require attention. Dab a bit of grease into the spring seats to help hold them in place. Squeeze a few drops of oil onto the drive ring. Ensure ﬂat seals are on correctly, using your ﬁngernail to ease the thin rubber edge into its groove; with O-ring seals, ensure they’re correctly seated into grooves, and avoid pinching and displacing them when reinserting the freehub.
8 Tricky bits
After spring and pawl installation, wrap the compression tool around the pawls with the hook facing outwards. Carefully slide the freehub body back onto the axle, partially inserting the pawls into the ring drive but allowing enough space to remove the tool; unhook it and pull it down and away, while gently pulling it apart. The freehub should drop into place; turning it counterclockwise while inserting will help nudge the pawls into place. If you don’t have a compression tool, a length of strong sewing thread will do. Wrap it a couple of times over the compressed pawls, then over itself. Once the body is partially inserted, you should be able to gently pull the thread free with a tug. Install the locknut.
9 Tighten lockring
Ensure the lockring is correctly threaded – they’re easy to cross-thread, especially alloy ones. Remove and start again until you get it right. Torque is best set at about 40Nm (about 30ft/lbs). Use a spanner about 12in long, applying a little less force than for axle nuts. For singlespeed chains, nip up the wheel nuts enough to hold the wheel and check for tension ‘high spots’ (manufacturing tolerances are such that circular components are often slightly off-centre); rotate the crank slowly backwards to where the chain shows the least sag, and tighten nuts ﬁrmly. Setting the chain tight at the loose point will amplify any crunching noises.