8N Steering Gearbox Lubrication & Oil Filler Plug Locations
It is recommended that the steering gearboxes are filled with S.A.E. 90 gear lubricant. The early 1947-1949 steering gearboxes (before S/N 216989, September 2, 1949) had a 1/4 square pipe plug on the right side of the steering gearbox under the column that supports the dash and steering wheel. This unit could also be filled by removing the steering wheel nut and pouring gear oil down through the steering shaft.
In September 2, 1949, the 8N-3503 steering gearbox assembly was replaced with a new beefier steering gearbox 8N-3503-B starting with serial number 216989.
The first oil filler plug on the new steering gearbox was an 1/8 pipe plug located behind the instrument panel support bracket on the upper left-hand side of the steering gearbox. As seen in the picture below, it was nearly impossible to get to.
On April 20, 1951, the first oil filler plug was discontinued. The hole is filled with metal, completely sealing it. At this time the cap screw on the right hand side, which secures the instrument panel support to the steering housing, was used as the filler plug.
The housing should always be filled to the level of the cap screw hole to insure that the top bearing (8N-3571), receives lubrication. Fill when the level falls below the cap screw.
In 1952, starting with serial number 452913, the filler plug location was changed to the front side of cover and steering tube assembly (8N-3509-B). Here is a photo of this location:
The plug used was a 1/4"-28 x 5/6" fillister head screw. This was a handy to get to location and when filling added oil to the upper steering thrust bearing.
Hope this helps,