I've went through my parts bin recently and came upon these two throwout bearings. I have no history on them, no known mileage, pressure plates that were used, etc. I cleaned them up and discovered that they were an OEM NSK bearing and a Nachi aftermarket bearing, P/N 48SCRN32K.
I disassembled and cleaned both, but put back together only the OEM. Here's why. The Nachi is comprised of the bearing, the inner plastic sleeve, a plastic thrust washer, and the metal backing plate. The bearing in itself still rotated, but it felt gritty. However, the concern is the backing plate itself. The TOB sees immense amount of pressure, especially with a heavier pressure plate like the ACT2600. All the pressure required to compress the pressure plate is focused on two points where the clutch fork rides on backplate. Combined that with vibration forces from the engine and you have a recipe for substantial wear.
The service manual states to lubricate the contact points on the forks, pivot ball, and sleeve. The backing plates on both show wear with the Nachi having more. Whether is this due to a heavy pressure plate, engine vibration, lack of lubrication or a combination is unknown. The OEM backing plate also has a support ring that surrounds the plastic sleeve and thus creates a sort of U-channel where the clutch forks ride. This makes the plate stronger since there is less of a focal point for where cracks to begin. The Nachi plate also has notches where the plastic sleeve aligns, making it another weak point.
In my opinion, the Nachi could be used as a stock replacement TOB or with light pressure plates but certainly not anything that requires a lot of exertion on the clutch pedal. The notches and lack of a U-channel design can cause cracking in the plate. However, any TOB can fail without proper lubrication on key areas. If and when in doubt, replace it with an OEM.
Picture 1: OEM NSK on the left, disassembled Nachi on the right
Picture 2: Nachi backing plate.
Picture 3: The more severe side of the backing plate. Notice where the crack originates.
Picture 4: The opposite face of the more severe side. Cracking has penetrated completely and is starting to make its way up to the tab.
Picture 5: The less severe side. No crack evident but there is heavy wear.
Picture 6: Cracking is shown on the opposite face. Cracking on one side but not the other shows that the plate was in the process of folding. The plate was put on a flat table and it was warped inward. Again, notice where the crack starts to form.
Picture 7: a used but serviceable OEM NSK.
I disassembled and cleaned both, but put back together only the OEM. Here's why. The Nachi is comprised of the bearing, the inner plastic sleeve, a plastic thrust washer, and the metal backing plate. The bearing in itself still rotated, but it felt gritty. However, the concern is the backing plate itself. The TOB sees immense amount of pressure, especially with a heavier pressure plate like the ACT2600. All the pressure required to compress the pressure plate is focused on two points where the clutch fork rides on backplate. Combined that with vibration forces from the engine and you have a recipe for substantial wear.
The service manual states to lubricate the contact points on the forks, pivot ball, and sleeve. The backing plates on both show wear with the Nachi having more. Whether is this due to a heavy pressure plate, engine vibration, lack of lubrication or a combination is unknown. The OEM backing plate also has a support ring that surrounds the plastic sleeve and thus creates a sort of U-channel where the clutch forks ride. This makes the plate stronger since there is less of a focal point for where cracks to begin. The Nachi plate also has notches where the plastic sleeve aligns, making it another weak point.
In my opinion, the Nachi could be used as a stock replacement TOB or with light pressure plates but certainly not anything that requires a lot of exertion on the clutch pedal. The notches and lack of a U-channel design can cause cracking in the plate. However, any TOB can fail without proper lubrication on key areas. If and when in doubt, replace it with an OEM.
Picture 1: OEM NSK on the left, disassembled Nachi on the right
Picture 2: Nachi backing plate.
Picture 3: The more severe side of the backing plate. Notice where the crack originates.
Picture 4: The opposite face of the more severe side. Cracking has penetrated completely and is starting to make its way up to the tab.
Picture 5: The less severe side. No crack evident but there is heavy wear.
Picture 6: Cracking is shown on the opposite face. Cracking on one side but not the other shows that the plate was in the process of folding. The plate was put on a flat table and it was warped inward. Again, notice where the crack starts to form.
Picture 7: a used but serviceable OEM NSK.
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