Introduction
This is the second part of overhauling a Brompton 6 speed hub. The first part is in my previous post “Disassembling the Brompton BRW hub“.
Please do take extra care to fit all the parts back together. The position where a clip ring should fits, the orientation of the gear ring pawls, etc. Do take a test for the movement of parts in every step, ensuring all movements are smooth.
Take note on step 10 in how to adjust the cones. Fail to do so might affect the function of the hub or even breaking the actuator plate and jam the hub.
Special tools
A 16mm cone wrench to handle the cone.
It would be nice to have a Sturmey Archer Ball Ring Spanner. Though some people just use a puncher to knock the Ball Ring loose.
An axle vice or a small table bench vice could be handy for holding the hub.
Lubrications
There are a lot of suggestions for what kind of lubricant you could use on a Sturmey Archer hub. Older hubs are recommended to use oil like Phil Wood Tenacious Oil. Some use different grades of engine oil and synthetic oil.
The denser the lubricant will give better protection against wear and corrosion. And will last longer before the next maintenance. The lighter the lubricant will give faster rolling speed. But you need to maintain it more frequently.
Grease is denser than oil. The higher the NLGI number of a grease, the denser it is. The lower the SAE number of engine oil, the thinner it is.
Sturmey Archer recommend NLGI 0 grease for their newer hub like our BRW. Which is not that great for rolling speed but can allow the hub almost a lifetime maintenance free status.
I would like to follow Sturmey Archer’s recommendation to use NLGI 0 grease for the gears and pawls but some NLGI 2 grease for the bearings.
For NLGI 0 grease, you can use the Sturmey Archer Internal Grease or the ALCO Super Lube 00 Grease.
For NLGI 2 grease, I use Park Tool PPL-1 Polylube. That should give a better protection for Singapore’s humid and wet weather.
In this post when I mention “bearing grease”, I meant the NLGI 2 grease while just “grease” meant the NLGI 0 grease.
Changing the bearing balls
Unless the bearing balls are visually imperfect (which is rare) you don’t have to change the bearing balls. If you want to change anyway, use a better grade balls. The steel bearing balls are cheap.
Changing to ceramic bearing balls is totally another ball game. The ceramic balls are expensive, the Ceramicspeed 1/4″ ball is 7 USD per ball. And once you use the ceramic balls for better rolling speed, It only make sense that you use a much thinner lubricant or specific lubricant for ceramic balls. So you get the best out of the rolling speed. As we can see from the previous topic, a thinner lubricant has less protection and need more frequent maintenance.
Well, most of the super road bikes use the ceramic bearings and they do overhaul frequently. It will be up to you to decide what kind of trade off you are comfortable with.
Procedure
Step 1 the driver assembly
Put the ball cage assembly and outer dust cap into the driver assembly.
The out dust cap must be about 1 mm below the rim of the driver. Or the cone cannot be properly adjusted later. Using a coin or thick washer with smaller diameter could be used as a temporary shim.
Fit the circlip and the pawls on the driver.
The ends of the circlip must be fitted to the stop as shown. Ensure the pawls are moving smoothly.
Fit the actuator plate on.
Use the sliding clutch to test if the movement is smooth and the plate can catch the pawls easily when the clutch is turned as shown.
Apply a drop of grease on the pawls then move the actuator plate to open and close the pawls. Use finger or a brush to put on a film of grease over the both the plate and the lower part of the driver.
Put a thin film of grease on the internal spines of the driver.
Step 2 the gear ring assembly
Fit the pawls, pawl springs and the pins into the assembly.
The pawls and pawl springs must be fitted in the orientation as shown. The tip of the pawl on the other side is flat.
Apply a drop of grease on each of the pawls, make sure they move smoothly.
Apply grease on to the lower internal gear.
Put a thin film of grease on the upper side of the internal spines.
Step 3 the Axle/Planet Cage/Pinion Assembly
Apply a tad of grease on the axle / sun gear and on the top part of the planet cage (where the sun gear will sit). Enough to lubricate the gears but not to flood the whole cavity.
Too much of grease would slow down the rolling speed unnecessarily, but too little could not protect the gears adequately.
Put the axle / sun gear in to the planet cage, with the longer side (where it has a slot for the axle key to slide on) pointing to the top plate side (not the pawls side).
Put a drop of grease on the top part of the sun gear, apply a thin film of grease on the center of the lower side of the top plate.
Try not to spill grease to the screw thread on the planet cage.
Secure the top plate on to the planet cage with the four screws. Put a dab of threadlocker like Loctite 222 near the head of each screw. This should be good enough to secure the screws in place and not giving a nightmare for the next one who need to open it.
Put the pawls and circlip on the planet cage. Put a dab of grease on to each pawls and make sure they can be moved freely.
The pawls should fit onto the profile of the slots. The circlip end that pointed upward must be fit into the groove on the underside of the planet cage.
Slot the planet gears into place and put the pin in. Put a dab of grease on each of the planet gears. Turn the whole assembly to let the grease run and cover all essential surfaces.
Step 4 the axle key and the sliding clutch
Put a dab of grease onto the axle key and fit that into the slot on the axle, with the threaded bore facing upward.
If you carelessly put the axle key in side way, you may find it frustrating that you can’t put the Indicator Mark in any more. You have to open up everything again to check this out.
Apply a thin film of grease on all sides of the sliding clutch and fit it on the axle. This is a good time to put in the Indicator Mark to test everything move smoothly.
Step 5 the gear ring
Fit the gear ring on to the planet gear assembly.
Make sure the gear ring fit properly on to the planet gears and can move freely.
Step 6 the ball ring
Apply grease on the inside ratchet of the ball ring.
Fit the ball ring on to the gear ring.
You need to push the gear ring pawls in to let the ball ring sit in properly.
Test the movement of the ball ring forward and backward.
Step 7 the ball cage assembly
Apply bearing grease on the ball cage assembly.
Again, this would act as a shield for any water to get into the hub, so be lenient with the grease.
Step 8 the driver and the cone
Fit the driver assembly on to the ball cage assembly.
You may need to turn the driver anticlockwise (from top) to let the actuator plate close the driver pawls to slide it in the internal splines of the gear ring.
Test the movement of the driver is smooth.
Put in the cone until it is just hand tight.
Step 9 the hub shell
Pack the ball cage assembly with bearing grease. This would act as a shield for any water to get into the hub, so be lenient with the grease.
Tap the outer dust cap gently into the place. It should be flushed with the rim.
Apply grease on the ratchet inside the hub shell.
Fit the whole hub core back in the hub shell.
Turn the core both way to ensure the planet cage’s pawls fit in the hub shell’s ratchet.
Put in the left side cone until it is just hand tight.
Step 10 ***adjustment of the cones***
This is a very important part to reassemble the hub.
Loosen both cones until you feel free play on both sides.
Fix the right side’s cone first, hand tighten it and turn back 1/8 to 3/8 of a turn. In practice, I turn it back just enough to fit the lock washer.
Make sure the left side cone is still loose when you hand tighten the right side cone.
Put in the 3.2mm lock nut to hold the lock washer in place (do not tighten yet).
If you fix the left side first, you might pull the core too far to the left, to the extent that the sliding clutch splines might barely catches the driver. Your high gear may not work. Or even worse, you break your actuator plate and jam the whole hub.
Now you can hand tighten the left side and turn back slightly, just feel the wheel can be running freely.
Put in the 1/8″ spacing washer and 6.4mm locknut slightly.
Push the axle both sides, it may has a little free play and that is fine.
Try to shake the driver, it should have a bit of free play. If it doesn’t, the adjustment is too tight. Loosen the nuts and cones and redo the adjustment again
Use the 16mm cone wench to hold the cone and tighten the lock nut by a 17mm wench. There should be no relative movement between the cone and the axle when you are locking the nuts. Do this on both sides.
Step 11 the sprockets
Put the sprocket dust cap, 16 teeth sprocket, the sprocket spacer, the 13 teeth sprocket (some models use 12 teeth) and secure them with the sprocket circlip by using a small flat head screwdriver.
Step 12
Fix your wheel back to your brompton.
And you are done! Go for a test drive.
Test drive
If you have followed the procedure carefully and have not make any mistakes, you should have a very smooth and pleasant test drive.
However, just for safety, please be gentle for the beginning of your test drive. In particular on the 5th and 6th gears, feel if your hub is catching your pedaling properly. Then try reverse paddling VERY SLOWLY. If you feel any slight glitches (it should not!) stop your bike immediately and check your work all over again.
It is not likely you could break the hub down to the extend that you need a new one to replace it. Most parts are not easy to break, even when they do, there are parts you can order from UK.
Don’t feel too frustrated if you have made some mistakes. All the good technicians and mechanics gain their skill and experience not just by learning from their masters but by making their own mistakes.
Reference
The “Part List: BWR Three Speed Gear Hub” is a must have
The “Sturmey Archer Tips” is a good read for all.
Do read on the Sheldon Brown’s “Cone Adjustment“
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