Mack differentials

[Joe Goralski]

I am a transmission and differential rebuild technician I'm getting ready to work on a big project to rebuild a bunch of Mack differentials and I know that they have three main gears as opposed to just a pinion and ring gear. And I can't remember the proper way to calculate the ratio for this type of  differential. Any help would be much appreciated.

[Vladislav]

Hmm... Pretty easy.

To get a final ratio you should multiply a ratio of one stage to a ratio of the other one.

Or having teeth counts you just divide the larger number of teeth by the smaller number of one set of gears, than divide the larger number by the smaller of the other set, than multiply the results.

Vlad

[theakerstwo]

Mack had a chart for what gears to use for which ratios.I dont have one but some one on here had one.

[Vladislav]

Mack differentials sure have 2 gears, not 3.

Or 4 gears of 2 gear sets if you count gears as toothed wheels. Ring gear of the first stage (an upper gear set) is unified with a small gear (a kind of pinion) of the lower set (which is used to be called a bull gear)