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!
When was the last time you thought about the oil in your suspension? How about the gas charge in your shock? It's easy to forget about maintaining your suspension, but a little maintenance can save lots of money, not to mention improve handling.
Over time the oil in both your forks and shocks starts to break down, losing viscosity and gets fouled with debris as the piston slides wear. In addition, believe it or not, you can get rust forming inside from condensation. Your shock is filled with high pressure nitrogen that will slowly leak out over time. All of these things add up to a decrease in performance and can lead to expensive repairs if not addressed.
How often should you have your suspension serviced? It really depends on your riding habits and your budget. In a perfect world you would have your suspension serviced annually. But, like many things that is not a hard and fast rule. The real question is has it ever been done? If so, do you remember who was the president at the time? If not, or if it's been a while it's time to get your machine into the shop.
The next big question that comes to mind is the cost. Most of us don't have buckets of money stashed around the house. The simple, and very un-helpful answer is--it depends. Cost often depends on how much you can do yourself. Your least expensive route, if you plan to have a professional do the suspension work, is to pull the forks and/or shock yourself and bring them into the shop. But if you don't have the tools, place or skills then you will need to take the entire machine to your favorite mechanic to have the work completed. It also largely depends on what your machine actually needs, and the quality of the parts used. Having said all that, here is a very rough idea of what you can expect to pay. Assuming you can pull your forks and/or shock, labor on a set of forks is probably going to run you somewhere between $100-$150 depending on your forks and how much your mechanic charges. Most forks will require a little over a quart of oil (for both) so that means you get to buy 2 quarts, so you can figure around $30 for oil. Again, keep in mind the type oil you use can vary in price considerably. A set of seals will run you somewhere around $40. Now before you start thinking about buying a cheap set of seals for $20, remember you get what you pay for and if the cheap seals fail (and they do) it will not only cost you for another set of seals but the oil and labor as well. My personal preference when it comes to seals; OEM is your friend. But, that a discussion for another post! So for a service on a set of forks you are going to be somewhere around $200.00 assuming you don't need parts replaced besides seals. Your rear shock will probably be about half that since there is only one. This seems like allot at first blush, but like all things mechanical if you let it go too long it will cost much more later.
Another thing to consider when it comes to having any work done is timing. Many shops offer discounts in the off-season when business is slow. So the best time to get your work done is when you really want to go ride, but the weather is terrible. If you wait until the season starts you will most likely pay more and have to wait, sometimes quite a while, before the work is completed. You don't want to be the guy that is watching Youtube videos of riding when everyone else is actually out riding. Finally, resist the temptation to have the neighbor kid do it since he is always "tinkering". Suspensions are actually quite delicate when it comes foreign material (aka dirt) and parts left over. You should only have a qualified mechanic touch your suspension. It could mean the difference between a great day of riding or ending up in crumpled pile on the side of the trail.