The steering head pipe, which is the key component of the steering wheel, incorporates bearings that allow the steering wheel to move smoothly. Older cars often had a number of steel balls arranged in a regular pattern, commonly known as a cone-race type.
At the end of the 1970s, a type that incorporated the outer race of a tapered roller bearing into the head pipe on the frame side appeared. There is also a type in which the steel poles are integrated into a cage instead of coming apart, which is the same type used in the old cars.
Depending on the design philosophy of the era, several types of bearings have been selected and incorporated into the head pipe. If this bearing is damaged, steering operation becomes difficult. For example, if the front wheel goes over a rut while driving straight ahead, the driver may suddenly feel the steering wheel being taken away from the vehicle. If there is any discomfort in the steering operation, be sure to check the operability of the stem bearing.
- It rarely breaks down, so it’s the worst of the worst.
- It can be pulled out by hitting it with a hammer and trowel.
- Grease is the lifeblood of stem bearings
It rarely breaks down, so it’s the worst of the worst.
When practicing maintenance on a model that had been ridden for decades and was in a state of disrepair, I felt a sense of discomfort when I pushed the bike I had entrusted to him to walk around.
The steering feeling was strange, so we disassembled the steering head pipe and found that the bearings were in bad shape. This is what happens when you continue to ride a bike with no maintenance! This is a typical example of what happens when you continue to drive with no maintenance. The steel balls were no longer moistened with grease and looked as if they were covered with moss. In the case of this bike, we replaced all the steel balls, upper and lower outer and inner ball races, with new parts without any hesitation. The feeling of catching during steering operation can be understood from the steel ball dents on the outer race. These dents create a snagging sensation.
It can be pulled out by hitting it with a hammer and trowel.
Both the outer race on the frame side and the inner race pressed into the stem pipe can be punched out by using a steel pipe or a chisel. However, there is a common point of caution when removing each part. That is, do not strike only one part and do not tilt the part. Be careful to pull out the parts in an average and parallel manner as you proceed with the work. Failure to do so may result in the worst possible outcome, such as damage to the bearing holder. Although it is instructed to use the manufacturer’s genuine special tool for removal, we proceeded with the work as described above at our own risk.
Grease is the lifeblood of stem bearings
Modern models incorporate dust covers and dust seals to prevent dust from entering, but many older cars did not have such parts, and if they did, they only had a rubber washer-like cover installed on the underside of the stem shaft. When installing the new outer race, use a bearing screwdriver or tapping tool with the same dimensions and make sure that the outer race is press-fitted deep into the holder side on average. When lining up the steel balls, put grease on the outer race on the frame side on the upper side and on the inner race on the stem shaft side on the lower side, and line up the required number of steel balls so that they are bonded to the grease.