Model A & B and AA & BB Ford

Ford Garage

Sealed Transmission Bearings

Double sealed transmission ball bearings are available for use in both three speed car and four speed truck transmissions. There have been a lot of discussions about sealed bearings for this application and many people are apprehensive or skeptical, but I believe sealed ball bearings are the best choice.

Consider several facts:

How many good used ball bearings have you ever found when rebuilding a Model A transmission?

Modern elastomer rubber sealed ball bearings are lubricated for life and are used in many demanding long life applications like prop shaft bearings and alternator bearings where they never receive additional lubrication.

Model A's have straight cut gears and generate a considerable amount of metal debris in the oil from shifting and gear grinding. This debris is circulated and is very abusive on bearings and shafts. Just look at any transmission and examine the countershaft, the wear and looseness of the ball bearings, and what comes out the drain plug. Model B's have a somewhat better condition, having helical cut gears except for first and reverse.

Worn and loose ball bearings typically found in Model A transmissions are the cause of uneven tooth wear and are a contributor to the cause of the shift lever trying to jump out of gear in 2nd and 3rd. This is due to the cam angle forces on the engaged teeth due to wear and misalignment of the shaft and bearings. This condition is especially noticeable with straight cut gears compared to helical ones.

Model A transmissions are also poorly sealed by the slinger and leak oil primarily out the back and into the universal joint housing. Oil can then find an even easier leak path, as well as lowering the oil level in the transmission.

By using double sealed ball bearings, the universal joint grease is kept in its housing where it belongs, the transmission oil is kept in the case where it belongs, and the bearings are run in clean grease without metal debris.

In the worst case scenario, the sealed bearing would develop a leak and would allow transmission oil or universal joint grease into the bearing.

Sealed Bearings:

The part numbers I've used for the Model A and B bearings are Torrington-Fafnir 208PP and Torrington-Fafnir 306PP. These are both double sealed ball bearings of the correct size. The 200 series is the front and the 300 series is the rear.

The part numbers I've used for the Model AA and BB truck bearings are Torrington-Fafnir 209PP and Torrington-Fafnir 307PP. These are both double sealed ball bearings of the correct size. The 200 series is the front and the 300 series is the rear.

The PP suffix on the bearing is important. It indicates a double elastomer/rubber sealed bearing. Bearings are also available with metal shields instead of seals, or with neither seals nor shields as original.

Additionally, bearings are also available with only one side sealed or shielded. The bearing series number is a standard, but each manufacturer uses somewhat different suffixes to identify seal configurations, so ask your bearing supplier.

Pictured above are the typical double elastomer/rubber sealed bearings used in Model A and B transmissions. Truck four speed transmission bearings are similar, but are larger sizes.

Some people have expressed concern that the sealed bearings may have inadequate quantity of grease when new, based on their experiences with different brands. If that is a concern it is possible to pop the seal out on one side using a small jewelers type screwdriver and then add more new clean grease. Then snap the seal back in and assemble to the shaft.

If you are still a skeptic, consider using a rear bearing with only one side sealed. I would put the seal side on the transmission side so that the universal joint grease will reach the bearing. I believe this is better because the universal joint grease is relatively clean compared to the transmission oil which is full of metal particles from worn gears.


January 2003