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SMOOTH IS IN - ROUGH IS OUT
March 13, 2017

A serious misconception, still held by many, is that a rough steel surface is necessary for a "good clutch apply". Actually it IS NOT. A thin film of oil between the paper and the steel creates a powerful holding bond. The bonding created by this oil film makes it possible for a clutch pack to apply and release thousands of times without wear. The friction paper never wears because it never makes physical contact with the steel plate. That is why an old transmission with 100,000 miles can have clutches inside with the print still on the friction plate. Smooth is better when installing steel plates.

Sanding creates numerous grooves and high sharp peaks that breaks the oil bond. Not only does this decrease the bonding, but it creates a cutting surface that seriously accelerates the wearing and abrading of the friction paper. Remember this; new transmissions at the factory are not assembled with sanded steels.

There is another benefit to using smooth steels. That is, a consistent quality shift from day one through the life of the transmission. Smooth steels stay smooth and customers stay happy. Sanded steels have a tendency to become smooth with time and change the shift feel. A customer would think his transmission was "going bad" because the shift feel was changing. A word of advice, throw away the sand paper. The surface of a smooth steel, one with a very consistent surface, has the right finish for a quality shift in todays's electronic controlled units. For happy loyal customers, (or transmissions that last) smooth steels are a must.

posted by: Nick Truncone   comments: 0