I've Lost My Bearings
Part 1 of 2
by Fritz Guenther #22T
Is it time to replace the engine bearings in that trusty old steed? If so I hope you were the one that scheduled the repairs and not your engine. When your engine does the maintenance scheduling, it’s usually bad news and much more expensive! The goal of this short article is to give you an idea what’s been going on in the bearing world for the last few years, most of its good or even great news but some not so good. Hopefully the information contained here will assist you in choosing the best bearings when it comes time to rebuild your engine.
Technology in every part of our lives has been moving at breakneck speeds, which can be good or bad depending on whom you ask. The good news is it’s been doing the same in the rolling element bearing world as well. The big buzz word in bearings these days seems to be ceramics, pure ceramic bearings, hybrid bearings and bearings that require no lubrication. For most of us in the vintage motocross scene these are nothing more than conversation starters around the garage or over a beer. What, my vintage bike won’t go faster with ceramic bearings? For example, let’s take a standard 6303 wheel bearing; these will run you about $10 for a quality, name brand sealed for life conventional bearing. Go to your friendly neighborhood bearing supply store and ask them for the equivalent bearing in a hybrid (ceramic balls and steel races) and they’ll ask you for $65 and that’s for each bearing! I would hope that most of you are going to do the smart thing and install the $20 bearings after all $110 buys a bunch of practice fuel, even at today’s prices. In the remote possibility you’re considering hybrid main bearings and the fact that you’ll move up at least 2 places on the track due to the advantages of hybrid bearings you’d better take out a line of credit………which really means you’ll be working to pay off the loan when you should be at the track racing or practicing. Please don’t get me wrong, I’m not against ceramic bearings, we use them in very select applications where I work and where needed they are nothing short of a miracle bearing.
Since the “golden age” of rolling element bearing design in the early 1900’s arguably one of the greatest technological advances in bearings over the last 100 years has been in the steel used to make bearings, specifically VAR or Vacuum Arc Re-melt steels. I’m not a metallurgist (or even remotely close) so you’ll have to trust me when I tell you its good stuff to make bearings from. Technological advances in elastomers (for bearing seals), self lubricating plastics (for cages or retainers) and advances in lubrication have come together to make a much more reliable bearing available today then when our bikes were manufactured 20-30 years ago.
The next and not so good part about bearings is the current rash of sub-standard bearings being “dumped” on the internet from 3rd world countries. Even more of a concern to the consumer is the growing number of counterfeit bearings showing up on the market. Some of the counterfeits are getting so sophisticated they sometimes look better than the real thing.
The best way to avoid getting a substandard or counterfeit bearing is to purchase from a reputable bearing supply house such as US Bearings and always insist on name brand, quality bearings. If you want to buy $2 wheel bearings off the internet and change them a couple times a season go for it. The consequences of a wheel bearing failure on a dirt bike are not usually life threatening. For a few more dollars and the piece of mind I’ll use the $10 name brand bearings thank you.
Take the wonderful 490 Maico engine for example, parts are expensive and can be relatively hard to get. I can save about $20 on the output shaft bearing if I install a “UIB 6505 2RS” or “Unknown Internet Bearing with a 25mm bore and 2 seals.” 1 month into the race season the tranny locks up solid. This bearing failed prematurely because the internal clearance wasn’t correct. The result? Some, if not all of those beautiful German gears have committed sympathetic suicide. That $20 savings is long gone my vintage Bro!
OK, so what are some of the name brand quality bearings I should be looking for? The list includes, but not limited to SKF, Timken, Fafnir, FAG, and MRC to name a few. If you plan to purchase new bearings from a bike shop that specializes in your favorite scooter then it is up to you to ask where the bearings are from and how long they’ve been on the shelf. The longer bearings are stored the more chance they have for corrosion, brinelling and damage due to improper handling. Never purchase a bearing that has had the sealed inner packaging opened and preferably the outer box should be sealed as well.
Please don’t think I’m picking on any of the 3rd world countries that are trying to break into the bearing market. After all, one of the signs a country has made a big leap towards modernization is their ability to produce good quality rolling element bearings. As always, buyers beware. As a side note the Swedish bearing manufacturing giant SKF has recently opened a new plant in China, I don’t know how many of these bearings are going to eventually end up on the market as it seems that most of the bearings being produced in this plant are being used inside China.
In part 2 we’ll cover some bearing basics such as how to decode all those bearing numbers, why different bearings are used where and some basic bearing mounting and dismounting practices used by the pros.
AHRMA & VDR 22T