Winter Projects: Suspension Bearings

With the weather getting to that point where it makes it very hard, if not impossible, to convince yourself to get out and ride, it might be time to take care of some of the maintenance tasks that you have been putting off. One of the most common things we run into around the shop is bad bearings, particularly suspension bearings. Most modern bikes and many ATV's don't have good old fashion grease fittings that can be used to keep the bearings greased. On top of that, bearings in the swing arm, suspension linkages and lower shock are constantly being exposed to water, dirt, mud, sand, etc. Which means they are the most likely to need service regularly. 

You might be thinking, "if it ain't broke, don't fix it". The reality is it may be broke, you just haven't noticed. Catching failed bearings early can and is, the difference between a huge repair cost and one that is only mildly painful. I say mildly painful because replacement bearings are not cheap (if you are buying half-way decent parts) and there is a fair amount of labor involved, assuming you are taking it to a shop for the work.  However if you let it go too long, swing arms, linkages and shocks are really expensive. 

Assuming that your bearings are not completely rusted and can be saved here are some tips for taking care of them. First thing you need to do is determine what parts need attention. On most motorcycles and ATV's there are bearings where the swing arm meets the frame. While you are looking at your swing arm, be sure to inspect the chain slider, if the plastic is worn it should be replaced. If it is worn completely through you need to make sure the chain hasn't worn through the swing-arm and into the bearing. Motorcycles typically use needle type bearings, where many ATV's use either a bushing or a cone bearing. The next place to tackle is where the shock connects to the swing arm. How this area is designed can vary quite bit from one manufacturer to the next. Most Japanese bikes use some sort of linkage between the shock and the swing arm. On many bikes, but not all there is a needle bearing in the shock as well. While you have bearings on the brain, don't forget both wheels have bearings that are prone to go bad, and even though most of the time they are a "sealed" bearing you can pop the plastic seal off and re-pack the bearings. The problem with doing this is there is really no good way to clean the bearing while it is in the wheel; if you pull the bearing out of the wheel it should be replaced since the process of pulling it out usually damages the bearing.

Once you have identified all the bearings that need to be serviced it's time to take them apart. Do yourself a favor and only do one set of bearings at a time. They look very similar and can be easy to mix up. However once a bearing has been used it should only be put back into the same location, otherwise it will fail earlier than it should.

In most cases needle bearings are used, be very careful that you don't lose any of the bearing rollers. They are very small and missing just one means it's time to buy a new bearing. You will not be removing the race (the part that is pressed in). Once you have the bolt(s), seals and the rollers out inspect everything very carefully. If the seal is damaged, looks ragged or egg-shaped, replace it. If there is surface rust on the rollers or race spray it down with some sort of oil like PB Blaster or WD-40 and clean with a wire brush. Inspect the surfaces carefully for pitting. If there is pitting, the bearing should be replaced. Assuming that everything looks good make sure clean everything thoroughly with clean solvent. I recommend non-chlorinated brake cleaner. Once everything is squeaky clean it's time grease and re-assemble.

Choosing the correct grease is very important. You should use a product that is resistant to water fouling. A marine grease is cheap and easy to find, there are many other products that work well also, but that is a topic for another post. Keep in mind, these are precision manufactured machines (sort of), which means you don't need grease coming out of everywhere. Make sure wipe off any excess, not only does it look better but it reduces the amount of dirt and assorted debris from collecting on or around the bearings. Be sure when re-installing that you put any spacers back in that came out, ignoring the spacers can cause some pretty serious damage when you torque things back down. Follow the manufactures torque specifications for bolts and nuts. Once you have things tightened back up check to be sure everything moves freely, a slight resistance is good; but if anything doesn't move freely you probably missed something and need to go back and find it. Don't fool yourself, if anything is binding it won't get better with time. Ignore you inner redneck. If it involves duct tape, bailing wire or hoping it will better if you just force it a little more, you are going to be sorry later.

Finally, keep a couple things in mind through the process; take your time, be very very clean and avoid drinking beer until you are finished. However, you can always bring it to us and then you can drink all the beer you want and we'll call you when it finished!