New rear axle kart bearing
I have been working on race cars for over 40 years and certainly understand the compromises made in engineering for the sake of cost but the engineer in me is always wondering if there isn’t a better way. I will admit that I have never had, seen or heard of an axle failure cause by the locating set screws in a kart rear axle but I just don’t like them. I have to clean up the scratches and indentations they make every time I pull an axle and there just seemed to me that there had to be a better way.
Naturally I was intrigued by the SKF bearings which feature three areas of potential advantage.
- An axle location method that does not involve the use of a set screw. Their method allows for easy removal of the axle and no scratches!
- Removable seals. This allows easy cleaning and re-lubrication while retaining the shields which help prevent dirt, water, etc. from entering the bearing.
- They can be purchased with either steel or ceramic bearings.
The obvious issue with the SKF bearings is the price and was not an option for us because of that fact. But the winter is long and the Internet is the greatest research tool ever. I began a search for 50mm bearings that used some location method other that set screws. I discovered that a Japanese company named Nippon Pillow Block, Ltd manufactured bearings under the FYH Bearings name that used a concentric clamp ring. These were industrial bearings marketed as Nu-Loc. I also discovered that they marketing 40mm and 50mm rear axle bearings using the traditional set screw locating method. Nowhere in their literature did they mention a kart bearing using their Nu-Loc technology but I was intrigued by the concept. So I contacted the company and they had already developed the product and had some in stock.
I arranged with them through Laukaites Racing, an FYH distributor, to get three of the 50mm bearings. Upon receipt, the first thing I noticed was the exceptional quality. They were well made with quality dust shields and a precision feel. The lubricated appears to be fairly light oil. They spun freely and installed easily.
Per the pictures, the shoulder does extend out and the locking ring also takes up some room. I had to do some planning to make sure the seat struts, radiators mounts and anything that mounts to the bearing hangers cleared. It wasn’t difficult but needs to be considered. The only very small issue I has is that when you tighten the locking ring, the ring can cock very slightly. This may not cause an issue but I make sure that they stay straight when I tighten them.
After a couple of months and 8 races I can say that I doubt we ever run a different rear axle bearing. They have performed flawlessly and axle changes are a breeze with no scratches to clean. I have been impressed with the quality and like the engineering solution. Does it make us faster? No. Does it make changing axles easier? Yes.
Let me address a couple of other points in the comparison with the SKF bearings. I would like it if the shields were removable so the bearings could be cleaned and re-lubricated. My contact at FYH has indicated that they have that capability and would add that feature if there was some demand.
The FYH bearings are available only with steel balls while the SKF is available with either steel or ceramic. Ceramic bearings came in to existence to solve some very specific engineering problems, mainly high rotational speeds in high temperature applications. The rear axle in a kart is not a gas turbine engine and I really believe that ceramic balls don’t offer any appreciable advantage in this application. I would rather have a quality bearing that is kept clean and properly lubricated and spend the money I save on other things. And with a Retail cost of $70, you will have saved a bunch of money.Thanks to Michael at Laukaitis Racing and Scott at FYH!