Packard Forum Index » V-8 (1955-56)

At times people have asked what the difference is between the 1955 Ultramatic bands (470178) and the 1956 (6489039). I recently rediscovered the difference when reading through some original Ultramatic design documents. Measuring with a caliper, the 1956 bands have thicker metal, at 10 gauge vs. 12 gauge.

This is about a 30% increase in strength. This checks out considering the engine had about 15% more torque in 56, but also the converter had both a higher stall speed and higher torque multiplication.

It should be noted that there have been NO reports of 1955 bands breaking in 1956 cars. This change was preventative and not in response to any failures. Actually, it seems that the band tabs (unchanged between the years) were the weak point, as tab failures have been very occasionally observed.

Just a fun fact for everyone.

P.S. If you were already aware of this difference, I'd be interested to know, as neither I nor anyone I spoke to had known; I only realized it after reading a list of changes. In hindsight it's visible by comparison which band is which.