Young Gun Tip#133

Nerd department:

GM six wafer and Chrysler five pin cylinders have the same theoretical different key combinations per pin stacks. In reality Chrysler has more combinations per pin stack due to GM cut protocol. That being said, a GM lock is much more resistant to a wrong key working in it due to its side bar design where Chrysler is a Yale pin tumbler design.

Yale pin tumbler locks are more susceptible to accepting incorrect keys if lock has excessive wear. Pin tumbler locks are generally easily picked, where GM’s sidebar wafer locks are very resistant to manipulation.

To calculate the different key cut combinations of a lock, one multiplies the number of depth cuts (five in both cases), and number of pin stacks or wafers. So in this example 5x5x5x5x5= 3125, and Chrysler used two different keyways one for ignition & doors, and one for trunk & glove box.

GM cannot have a more than a four depth difference between adjacent key cuts. In other words there are 5 different depths used labeled as; 1,2,3,4,5, 5 being deepest, and 6 wafers. 5x5x5x5x5x5=15625 theoretical combinations; however a 1 cut cannot be used adjacent to a 5 cut. This 1 & 5 convention considerably reduces the theoretical available pinning to around 15625 (3/5)= about 9000 combinations available with a GM side bar lock. GM overcame this deficiency by using different keyways using the same pining combinations. A different key way means that an “A” key blank won’t slide in to a “B” key way; GM used four different keyways for ignition, and four more for door locks for a total of eight over many years into the early nineties.

This is why someone else’s Chrysler key is more apt to work in your friend’s Mopar, than a GM key will cross work in some other GM car.