Introduction: Rebuild a Bicycle Rear Hub
Yes, the "bitmap-bandit" is back......This project is focused on the typical Shimano Hyperglide hub circa 1997-ish, but covers most mid-level freehubs on the market today. Designs may vary between manufacturers, but the basic principal remains amongst many others. Some information provided here applies to ALL bicycle hub-bearings in general, so this is worth a once-over by those interested in DIY bicycle maintenance.
Since I lack the specialty-tools, and you might not have $25 to spend on each tool required as well, I will demonstrate my method for you to try at your own risk.
Please review the entire project before attempting to start this for the first time, and be meticulously clean with your workspace. Hair, lint, and dust can undermine the whole of this project, so treat this as a surgical procedure. Effort taken now toward perfection saves effort later walking home and getting new parts later on.
The picture will show you a cross-section of the typical Hyperglide freehub used in this project. I will make reference to the color-coding in following steps and reference this image again...
This project is for those serious about longevity of their machine....The careless need not apply...
USE OF "IMPROPER" TOOLS IS NOT AN APPROVED METHOD IN A COMMERCIAL ENVIRONMENT. NO RESPONSIBILITY FOR DAMAGE OR MISUNDERSTANDING OF THESE STEPS SHALL BE HELD UPON ME, THE AUTHOR. USE THESE METHODS AT YOUR OWN RISK. Many of these parts are made of case-hardened-steel / triple-tempered Chromium-Molybdenum, which is very to extremely brittle. Use eye protection and great care when exerting stress on these parts with the dictated method. Use the minimum force possible and do not put the face or the eyes within view of brittle parts or serious injury will result. Shattering of any such part can result in a spark and a projectile traveling at greater than 2000 feet-per-second, so don't think you have an ice-cube's chance in a fusion-reactor-core's chance at dodging it.
I thought I had these in focus, but it seems the focus-finder does not have good aim on my camera. My apologies for the blurry pix, but you should get the idea.
As I like to say, "Use care or lose hair" (applied to loose hair around mechanical equipment....same philosophy applies)
If this is your first attempt, I recommend much paranoia of part-explosion and attempting this on a non-valuable part as practice first. Attempt this only with a laced (already complete) wheel. NEVER clamp a freehub in a vice for ANY reason, or any part of it thereof.
If you have read this far, I take it you are serious about doing this as safely as possible without all of the specialty tools, and understand the risks. If so, proceed...Refer to the shown image or save it to your computer for reference as needed...
On to step 1
Step 1: Remove the Cassette Lockring
I lack a photo for now as my camera is being a retard, I hope to upload it soon...
Basically use a pair of needle-nose pliers on the bearing-cone-locknut as if trying to remove it, but wedge it's "noses" into the splined keyway of the external lockring....Hold the sprockets firm as you try to turn in the direction that they freewheel. For the right-handed wheel, this is the same "righty-tighty / lefty-loosey" method, so force the freehub lockring to turn counter-clockwise.
The external lockring is a "right-hand" thread....Anytime when working with bicycle drivetrains, always remember the direction of pedal pressure. this will always be the direction of tightening, so the CCW direction of the freewheel spinning is often the "loosey-way"...All rear hubs incorporate the RH-threading when the drivetrain is on the right-hand side.
Step 2: Remove Cassette Cluster and Axle
Once the lockring has been removed, simply slide the cassette off....Most are riveted, but if you went custom on your gearing, you will have a mess of spacers and cogs. Some freehubs have two different diameters for cogs, so do your best to keep the sprocket-cluster in the same order as removed. If you are a pro cyclist, now's the time to grind those rivets off if you intend to alter your gearing setup for any reason....If you are not going to alter your gearing with spare parts, leave the rivets alone.
If the cassette was never riveted, or you ground the rivets out, feel free to soak all of the cogs in acetone / MEK / kerosene to remove excess slime....There is a very good opportunity to take them to a wire brush at this point for deburring at the least. DO NOT soak the spacers in anything lest they be aluminum. Simply wipe clean and maintain order in your disassembly.
In this step, also remove the axle itself. Start with the end opposite the sprockets and remove the axle hardware there....pull the axle out only enough to let the loose bearings free....
GENTLY pry the external seal opposite the freehub working around it's circumference. Again, this requires somewhat of a skilled hand. Just be very careful to "nudge" it out, rather than using force. The idea is to attempt to pull it as straight out as possible...
By now you will notice two equidistant slots on the hub's bearing cone......
Step 3: Carefully Remove the Freehub / Hub Combination Bearing Cone
either using the correct tool, or using the shown method, unscrew the freehub combination cone in a CW manner. Shown is one method in which I gained leverage (be sure that this makeshift-tool can "at-least nearly" fill each slot on either side)
Pic is blurred, what I used was a scrap "multi-tool" needle-nose and a ratchet-handle for leverage. Fortunately this wasn't that tight when I did this. If in doubt of the direction to loosen, look carefully for the threading on the inside diameter.
If you get it to move but it only moves a little, try the other direction, repeating until you have worked it free. Try not to allow the tool(s) to slip at all, or you will have much deburring work if not more in your future before this project can continue.......
Carefully get it to loosen and proceed to the next step...
Step 4: Prepare for a Mess of Parts
Once you have loosened the combination cone, be sure to hold the freehub shell down against the wheel as you remove it. This is where things get rather complex, and your need for order is essential.
With the combination cone removed, you will be faced with a flood of loose ball bearings and shims determined to make life hard on you for disturbing them. If there is any grease left in the freehub at this point, life is good. If not, sacrifice some grease and spread on the ball bearings to keep them in place.....no one said this job wasn't gonna be messy soldier!...Flood the area with grease if need be. Contamination is not an issue at this point as this grease will not be in the hub after cleaning...You are using the grease as a binder for now...
Using a suitable fine tool, carefully remove the 3 or more shims on the freehub core and be sure not to distort them. If possible, keep them in the correct order as you clean each of them individually. They are usually steel, so just about any solvent will do, including automotive brake cleaner (Uber-Kleener :D )....just allow to dry before reassembly. Ideal is to return each part to it's previous position as the armed-forces would do. Use a small screwdriver to pry out the bearings and place them on a rag.
NEVER lose or omit any of these shims unless there is a significant problem with shifting. In nearly all cases, these should all be returned to their place. If you are experiencing shifting problems and have corrected everything else, experiment by removing the thinnest shim first and temporarily reassembling the hub, progressing by replacing the thinnest shim and removing the next larger size. If you have to leave only the thickest shim to attain acceptable preload, consider the fact that the hub may be too worn out to continue. ANY binding means that there has not been significant wear to readjust preload, and you definitely do not want this too tight.
A persistent *clunk* when going from coasting to power, or "brinneling" of the bearing race in the freehub core or shell, may indicate an excess preload, but not in all cases. Some freeplay is expected, but it's hard to tell when this becomes excessive. Test before assuming changes to be permanent, and nonetheless do not discard the spare shim. The aim is the lowest amount of freeplay without binding. Dry bearings should have a just barely detectable amount of freeplay when the cone is set to normal torque.
If you do not know for sure, or are unsure about the procedure, do not omit any shims at all. Adjustment here is ONLY for pro bike mechanics or engineers, and improper adjustment here can severely hinder proper operation. If in doubt, leave it alone!
There's no such thing as too much precision...
Step 5: Re-establish Order on Your Workspace
Make sure you keep each "set" of bearings to the race that it previously came from. It is ideal not to mix bearings from one side of the wheel to another, as the wear tends to work them into their clearances. Treat each race (outer), cone (inner) and ball-bearing group (middle) as a complete and matched set, for best results, or you may be adjusting preload for many hundreds of miles before ever getting it right.
The same goes for the now-released freehub bearings. The freehub bearings are much smaller, so be sure not to lose ANY of them. Try to avoid using a magnet as magnetized bearings will pull in and hold any ferrous particulate, which does an excellent job of grinding them away. In the case of this hub, preload on the freehub was far too loose for a stringent part-return policy, but I still followed it anyway. The hub bearings are FAR more important when it comes to part-matching....
As a general means of cleaning, roll the entire group of bearings in a rag (like you are trying to rub a glob of grease into it) to remove the excess grease, then add solvent to a new rag and repeat the process....If any ball-bearing looks "galled" (should be outstandingly obvious), or anything less than a mostly polished surface all around, replace it from a part's pile or get a new set from a bike shop or even an industrial source (It pays to keep *every* hub you can get your hands on (as spares or parts), as even the low quality hubs generally use the same bearings, just make sure the gauge matches for what you are replacing......compare to a known-good part before calling it matched.....you should not be able to tell it from the rest of the group)
Assuming all is good for now, you should be at least this organized by now...
Step 6: Remove the Freehub Lock-screw
Since I do not have the appropriate 12-point key for this bolt, I used a pair of allen-wrenches paired-up in the fashion shown. Find the combination that provides the tightest fit to minimize the risk of damage. This lock bolt has a right-hand thread, so turn it CCW to loosen it. You can slide a "cheater-pipe" over it, but be careful not to split the bolt in the process. If you cannot remove this bolt without risk of splitting it or other damage, leave it alone until you have the right tool. Do not use too much force or you are in the market for a new hub. Attempt this only if you are willing to take the risk.
Step 7: Clean All Parts Not Already Cleaned With a Suitable Solvent
Refer to the drawing on the first step if necessary....DO NOT attempt to remove either the bearing cup opposite the freehub or the insert that the freehub keys into. If these parts are in disrepair, replace the entire hub as these parts are not serviceable. Even if you manage to remove them, there is no way to put them back into place without warping the hub shell or damaging the parts. Leave good enough alone...
At this point, you should be down to this...No further disassembly is possible. Now would be a good time to blast the hub through with brake-cleaner to remove excess grease to avoid contamination with another grease's base-type. If you are using the same grease as was packed before (don't guess), then this step is not necessary. Set on the side to drip-dry.
At least clean out the old grease as much as possible while you are here with a rag pulled through it...
Step 8: Time to Get Dirty
It is suggested that you run the freehub lock bolt under a wire-wheel to clean and polish the threads, as you should do with all other threaded areas of all the parts. While not absolutely necessary, it helps to prevent seizing. Check all parts, especially the ratchet pawls for chipping or breakage. they can be removed by pulling them backwards and lifting the snap ring free. Use care as this ring will not tolerate being distorted very well. It is very springy though, so with reasonable care this should not be a concern. Replace any faulty parts if you have them. It may look like there is a pawl missing of three, it is not. Generally there is only two pawls, and be sure upon reassembly that you do not put a pawl in the "false landing", and that they are properly oriented or the freehub will not rotate. A close look at this picture will show proper orientation.
I also advise putting a little grease or anti-seize on the threads of the freehub lock-bolt prior to securing the freehub core. Using the same method as you used to remove it, secure the freehub core to the hub by tightening to at least 25 foot-pounds With the correct tool, secure to about 55 foot-pounds. This is not something you want to come loose during normal use.
Remember to tighten in a clockwise fashion.
Step 9: Start Packing Grease
With the freehub core secured to the hub, dip into your grease tub and fill the channel that the bearings sit in. Try to generate a bead of grease within the race, to help keep the bearings in place as you assemble the parts. The grease will act as a binder to keep the bearings in place. You cannot use too much grease at this point, so be liberal with it. You can clean up the excess later.
(in the shot is a can of the BEST nutcracking penetrant I have ever found. Worth finding if you ask me, as it depleted over 100 ft-lbs torque to get this project in motion...)
Don't shy away from globbing the ratchet-ring on the inside of the shell with grease as well....Again, there is no such thing as too much grease at this point...
Step 10: More Grease...
Once you have gotten one side of the shell ready, carefully place it onto the race for the freehub core, and hold it down as if it were spring-loaded. Place the preload shims for the freehub into place now, an be careful not to warp them. Liberally cram grease into the exposed0 side of the shell, and start pressing each bearing into place in the race.On occasion, be sure that the hub will freewheel properly. make sure that no bearing falls into a gap that can lock the hub from any rotation. Cram a liberal amount of grease to lube the ratchet mechanism and to act as a reserve as time goes by.
Once all bearings are in place, start screwing in the combination-cone. you may have to rotate the freehub shell CCW some to ensure that the bearings find their place. If after bottoming it on it's seat, the hub still freewheels properly, proceed to the next step. If anything otherwise, back up and start over again, locating what went wrong until you find the problem.
Once you are sure, tighten the combination cone to about 35 foot-pounds.
Again, the proper tool is recommended, but in this case i had little choice...Tighten firmly without allowing whatever tool you use to slip...
Step 11: Pack Your Wheel Bearings
Using the same grease and the same method, start packing your wheel bearings. Easiest is to start with the freehub side. Shown is halfway through packing the grease and bearings. Again, better to use too much than too little grease at this point.
Step 12: Now Prepare the Axle
You want to be able to adjust bearing preload easily, and if the cone buried in the freehub is loose against it's locknut, you will never get it right.....Here I suggest locking one side of the axle to make adjustment in the present and the future alot easier. Since this is the driveline side, and if you have a derailler hangar adapter instead of it being a dropout-mount, err on the excess slack to be on this side. If this is a bolt-on axle, just try to keep it as centered as is reasonably possible.
Here I used a pair of Vice-Grips to hold the cone as I tightened the locknut against it as firmly as possible. This way I can consider the freehub-side locknut to be as good as the head of a bolt in terms of adjustment. Between locknuts on either side, I want this to be the one to give way last, and act as a semi-permanent part of the axle itself. Once locked, I'll know that wrenching between both locknuts wil always result in the "freehub-opposite" side loosening first.
Step 13: Close It Up
Using the same method on the freehub side, you should be able to grease that side's bearings as well. Start closing the cones into the bearings to set an initial preload. This is a good time for a simple bearing check. With the locknut free from the cone, rotate the bearing in the direction that would tighten the cone (or clockwise from the now-locked freehub-end). The cone should only tighten to the point of giving minor resistance, and should not feel too gritty or rough. If this procedure results in the axle wanting to act as a bolt and clamp down with the loose cone as a nut, then replace the hub as a set. A little resistance is to be expected, but if it simply screws in and locks, the bearings as a set is shot and unrecoverable.
The axle should never be able to tighten the bearings down to the point of needing hand tools to maintain that direction when one bearing cone is loose and free to tighten on it's own.Under no circumstances should the bearing tighten itself regardless of a reasonable amount of torque, including that which would exceed acceptable preload. If for any reason this test fails, replace the entire hub.
Slide the cassette on (it only goes on one way) and tighten the locknut down to about 40 kg/cm. There still might be some freeplay in the cassette itself, and it may not seem tight enough, but don't worry about it. The locknut is designed to resist loosening and you don't want it too tight or you may not be able to remove it again.
Using the proper cone wrenches, lock the loose cone to allow a just-barely detectable amount of free-play in the hub. With the chain diverted so that the wheel spins free, double-check for freedom-of-rotation and the lack of freeplay laterally at the brake pads. Once you have the preload perfect, hold the cone steady as you lock the locknut down. Again, double check to see that you have everything square and that there is no wiggle or binding in the bearings. The closer to perfection in setting the bearings you get, the longer they will last.
The quick-release lever should require no less than hand pressure on the lever to safely hold the wheel in place (at least for the front wheel) and no more....I suggest you keep them as tight as you can without having to hammer on them, which you should never do...
With the chain mounted again, spin the wheel forward while backpedaling to squeeze out excess grease from the hub, and wipe up any that escapes. do this for a minute or two and all the excess should be purged and you are good to go.
While you are at it, now might be a good time to do the same for your front hub as well, and the procedure is much more simple as well. Enjoy!
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