FW 4 Speed Rebuild

Moultons as usual

The Sturmey-Archer FW was used in the 1960s on the Moulton Deluxe initially, then later on the Standard, Speed, Mini Super 4 and Safari too. Over the years I've collected Moultons, sold some again and many of my purchases have had to be scrapped, therefore I've built up a collection of FW hubs. Some are in wheels and some cut out. Because I tend to build the hub up from memory I vary the order of the operations a little; you can make up different sub-assemblies at different times and it all works out in the end. In this rebuild I did jump the gun a little with putting on the annulus before the axle collar and it is arguably better to do it in the reverse order.

Wear and damage

The hub rebuild shown has a lightly worn gear train but evidence of rusting on the teeth which may have been caused by lack of oil and condensation in the hub. The planets of FWs are normally in pretty much perfect condition and there's very rarely any damage to the gear changing components. What does suffer, from lubrication neglect, are the wheel bearings, the ball ring (driver) bearing and the toggle chain. When the driver bearing is galled up the hub feels much less silky. You can substitute a ball ring from an AW hub to restore your FW to health. Several other parts are shared with the AW, the clutch, axle key collar, clutch spring and collar, high gear pawls and pawl springs. I suggest that if your FW is looking a little tired you should purchase an AW from ebay and compare the parts between them to see what might be replaced. The cones for the wheel bearings are exactly the same from hubs of a similar vintage. Even the shell is the same size so you can put an FW into an AW wheel without rebuilding the wheel.

As I was doing this mainly for the photo strip, I ignored the slight rusting and pressed ahead with the rebuild. With fresh oil of the right viscosity I hope the hub will have many multi-ratio years ahead of it.

Toggle chains

Toggle chains for the FW are in very short supply as they have not been made for over 50 years. DO NOT throw any parts away! Please! However, if you have the indicator rods and it is just the chain that is damaged or worn (the usual case), you can remove the chain from a new AW toggle and re-rivet it on to the FW indicator rod. I do perform this service for Moulton members and my contact details are in the back pages of the Moultoneer magazine.

If you have an FW hub with no toggle chain or indicator rods at all, there is still a way to get the hub to work. What you need to do is substitute the FW axle key for a threaded type as found in the AW. That way, you can screw in an ordinary toggle chain and these are readily available. That will give you three of the speeds, 2nd, 3rd and 4th. To get first gear, it is necessary to push the two suns across to disengage locking on the small sun and engage locking on the larger. This can be done by pushing on the small sun axle key with a rod down the axle from the left hand side. A similar arrangement was used in combination with a bell-crank on the first five speed hub, the S5. However you can do the same job in a simpler way as shown here. You will need a second trigger, and just use 2nd and 3rd positions.

Conversion to a 5 speed hub?

As has been mentioned in other parts of the site, the FW could have been a 5 speed hub if it had used the forbidden top ratio. Using the system described in the paragraph above, if you push the suns over to get 1st gear but then leave it there and change your normal right hand trigger into 3rd, you will be attempting to engage the 5th gear! FWrebuild site001 However, there is a problem (well, there would be!) The drive on the large sun is reversed and will be pushing on the back of the castellated projections on the sun gear. As you can see, these are ramped to enable easier changing into 1st. In 5th, the pressure would force the sun to slide out of the castellations on the axle. So it is only those ramps stopping any FW from becoming a 5 speed! What a shame. I have thought about squaring them off to about half height and making sure that my suns were pushed very solidly over to keep the gear engaged. I've not tested this yet but perhaps it will be successful. The main worry is that 1st gear will break the ground down castellations.

It's only gloves

One last thing: on many of the photographs you will see the poor state of the skin on my fingers and thumbs. Apologies for this. It is a result of many years of not wearing gloves when handling oily parts and using hand-cleaners that dry the skin. The photos were taken in 2010 when gloves were not worn as assiduously as they are now. If you are going to be coming in contact with oil, please wear latex gloves.

Sturmey Archer's own maintenance leaflet is found on this link. The last pages give good tips on fault finding if you experience any trouble selecting gears etc. Enjoy your rebuild!

Here is the large sun gear with ramped dogs. These engage on the castellated part of the axle in first gear.

Here is the cup for the small sun that locks the sun to the axle in 2nd, 3rd and 4th gears.

This is the small sun showing chipping at the ends of the teeth where it is locked by the cup. It's not too bad.

The sun has some wear and rusting. Neither would happen if lubrication had been applied.

Here are the castellations on the axle, or "dogs" that lock the large sun in 1st, (and 5th).

Very little wear on the clutch which sees most of the gear changing action. It is a robust machine.

The small side of the compound planets has slight wear and damage, mostly caused by rust.

Another planet. Although it is rusted it doesn't look too severe for re-use on this planet.

This planet is from a different hub. It was pretty chewed up on the large cog for some reason.

Here is another from a different hub, just to show what can happen when they get very worn down.

Lay out all the cleaned axle parts in order as shown.

The axle has a long slot for the three-speed side on the right and a short slot for the low ratio on the left.

First put on the sun spring. It can go either way up.

Next, the large sun with the ramped dogs facing towards the castellated axle dogs.

The S52 5-speed hub had the spring on the other side of the sun to push it on the axle castellations.

Put the small sun on next. I am placing the worn end towards the large sun.

Slide on the collar that the small axle key will fit into.

Push the collar halfway into the small sun.

Pull the suns and collar down against the spring and align the hole in the collar with the slot in the axle.

Put the axle key into the collar hole. Align the hole in the key with the hollow axle.

Let the suns slide back to secure the axle key in position.

Put the locking cup on next...

...followed by the thin locking washer. The little tab fits into the slot machined in the axle.

Screw on the locknut with the chamfered face away from the washer.

Tighten the locknut with a 15mm spanner.

Use a thin screwdriver to begin bending up the sides of the thin locking washer.

When you can get a thicker screwdriver in, bend up two edges opposite one another.

Press the edges up using the vice.

Test that the axle key hole is in alignment by pushing the indicator rod through it.

Put in the toggle chain side of the rod and screw the two parts together.

Lubricate the sub-assembly so that you can test it.

Pulling the toggle chain pulls the suns over to engage 1st gear. The castellations should mesh.

This is for information only. I have put the centre spring in and the clutch components and screwed the indicator rods together...

...to show you that when the clutch is pulled to the right, the indicator rod is flush with the end of the axle.

This is the position where the rod is flush. Note that the central spring not compressed, so we are in second gear.

Take out these parts again if you did put them in, and take the planet cage. Note that the pawls are not removable.

Slide the planet cage down over the suns.

Mesh a planet in with the two suns and put a planet pin in to hold it.

The next step is very important! You MUST time the planets.

Take another planet. Observe that every planet has a small tick mark on one of the teeth. Put the planets in so that...

...all the tick marks are in the same position relative to the sun. For example they should all be facing directly out radially.

Rotate the planet cage on the axle to check that it does so smoothly with no tight spots. Take the clutch collar...

Slide the clutch collar down aligning the holes with the slots on the axle.

Drop the clutch down on top of this. Note the steps on the arm ends must be uppermost.

Take the cetral gear spring ensuring that it's collar is at the bottom.

Drop the gear spring into the axle, collar first.

Take the axle key, holding it with the steps uppermost.

Lift up the clutch collar and push the axle key in through the hole in the clutch collar and out the other side.

It's a good idea to test the movement of the gears now. Take the toggle chain side...

...and push it into the axle, through the axle key at the clutch and the central spring.

Take the indicator rod and screw it in at the other end. You will have to compress the central spring.

The indicator rod will be flush with the end of the axle in 2nd gear.

Make sure that you can pull the toggle chain up into first gear and rotate the planet cage to check.

Hold a pawl spring on with the short wire on the inside and the engaging end of the pawl to the left.

Carefully push it into the annulus slot and push the pawl pin in tapered end first.

Make sure that it goes through the rounded part of the spring. Note that it has chamfered sides inside the annulus.

Here is the assembly after adding both of the high gear pawls. Test them for springiness.

You can lubricate with light machine oil as you go along. Also you can leave the toggle chain in place too.

Locate the annulus on the three planets by rotating it slightly.

You can lubricate the pawls while they are accessible.

Take the axle key collar. (I could have done this before putting the annulus on).

Slide it down over the axle to locate on the flats of the axle key.

Take the thin washer that protects the end of the clutch spring.

Place the thin washer on top of the axle key collar.

Drop the clutch spring down over the axle.

Take the small clutch spring collar.

Place it down on top of the clutch spring and engage with the spring end.

Grease the ball ring with lithium grease...

... take a set of 3/16" balls...

...and fill the ball ring. Then remove one ball at the end.

Position the retainer on the ball ring.

Tap the retaining ring on with a hammer working carefully around the circumference.

Take the driver...

...and a 1/4"wheel bearing ball race.

Put the race in to the driver. (I would normally grease the driver first).

Knock the retaining ring into place, flush with the end of the driver.

Add grease to the ball bearing and the U shape of the retainer, which is a dust trap.

Here is the assembly all nicely greased.

Place the ball ring over the top of the annulus and rotate into place.

If you rotate the ball ring you will hear the pawls ticking.

Take the driver and the right hand cone.

Put the cone into the driver.

Now screw the cone on to the axle keeping it in contact with the driver to avoid the clutch collar popping up through the balls.

Rotate driver to get it to mesh with the clutch. Screw the cone fully home and finger tight.

Back the cone off between 1/2 and 3/4 of a turn. It is critical to get this right.

Take the drive side tab locking washer.

Lock the cone in place with the tab washer.

Screw on the cone locknut and tighten it down. Not too aggressively!

Here is the completed gear assembly. All the hard work is done.

I use 4 stroke lawnmower oil to lubicate hubs. Commonly available in hardware shops.

Pour a teaspoon of oil into the annulus and rotate the mechanism to disperse it.

The next step is to put the wheel bearing into the left side of the shell.

Apply lithum grease to the hub shell bearing.

I don't have the ball race so I am using individual balls.

If you are using just 1/4" balls, fill the track with balls. Grease over the top to hold them in place.

Take the retaining ring...

...and tap it into place with a plastic mallet.

The ring should be flush with the end of the race.

Oil inside the shell. Don't go overboard; about a teaspoonful should be enough. Insert the mechanism.

Screw the ball ring into the shell. Rotate the mechanism if the low gear pawls are catching.

Fill the left hand U channel dust trap with grease. Take the cone...

... and screw on the left hand cone.

Screw the cone down finger tight initially.

This is easiest with the right hand of the axle gripped in the vice.

Take the wheel out of the vice and tap the ball ring up tight with a hammer and old screwdriver.

The hub didn't have an anti turn washer for the left hand side, just a plain washer.

Install the washer.

Take the left hand cone locknut.

Adjust the left side cone. Sturmey Archer suggest that there should be a trace of play at the rim of a 26" wheel.

Rotate the driver to test for adjustment. Put the dust ring on the driver.

Drop a sprocket spacer on...

...then your chosen sprocket, another spacer and locate the circlip in the ring in the driver.

Hub Gears

FW 4 Speed Rebuild