Differential Carrier Breaks

Differential carriers are designed to accommodate a range of Ring & Pinion gear ratios for the various tire sizes and vehicle applications associated with them.  As the numerical ratio of a gear set increases, the diameter of the pinion gear gets smaller. The reduced size of the pinion gear requires an increasingly thicker ring gear to keep the gear surfaces meshed properly.

It becomes more economical at some point to change the carrier deck height, so that the ring gear is thinner, and requires less material. The illustration above indicates the different carrier deck heights for a Dana 44 differential.

The point at which a different carrier is needed is referred to as a “Carrier Break”. The Gear Ratio at which Carrier Breaks occur varies, depending on the type of differential. For example, if you have a Dana 44 axle with a gear ratio of 3.73 and want to install a 3.92 or numerically higher gear set, you will need a different carrier.  The Carrier Break for the Dana 44 is therefore referred to as 3.73 / 3.92.

The chart below lists the Carrier Breaks and Deck Heights for various differential models, as well as the range of gear ratios that work with each of the carriers available for each model.

	Differential Carrier Deck Heights
Model 35C	3.31 & Down 1.452″	3.55 & Up 1.637″
Dana 30	3.54 & Down 1.800″	3.73 & Up 2.410″
Dana 44	3.73 & Down 2.090″	3.92 & Up 2.410″
Dana 60	4.10 & Down 2.225″	4.56 & Up 2.420″
Dana 70	4.10 & Down 2.215″	4.56 & Up 2.410″
Dana 80	3.73 & Down 2.135″	4.10 & Up 2.312″
GM 12 Bolt Passenger	2.76 & Down 1.410″	3.07–3.73 1.825″	3.90 & Up 2.188″
GM 12 Bolt Truck	2.73 & Down 1.420″	2.76–3.42 1.700″	3.73 & Up 1.943″
GM 10.5″ 14 Bolt Truck	4.10 & Down 4.165″	4.56 & Up 4.520″
GM ’55 Passenger	3.70 & Down 2.260″	4.10 & Up 2.425″
GM 7.5″	3.08 & Down 1.660″	3.23 & Up 1.950″
GM 8.2″	2.73 & Down 1.615″	3.08 & Up 2.00″
GM 8.5″	2.56 & Down 1.530″	2.73 & Up 1.720″