What is a CAD unit and do I have a CAD unit?

What is a CAD unit and do I have a CAD unit?

What is a CAD unit and do I have a CAD unit?

The C in CAD doesn't stand for a computer, but Center Axle Disconnect (CAD). If I were the engineer who came up with the name, it would've been SETB. That's short for Something Else To Break. CAD is a way for your rig to engage in four-wheel drive without the use of locking hubs. I'm going to go over how to tell if you have a CAD and what your options are if you have one. The great thing about CAD axles is they're simpler than working on a computer.

A CAD unit is on the front axle of some 4x4 rigs. Instead of a solid axle shaft the shaft is split in two. A sliding collar connects the two-axle ends to engage four-wheel drive. The two ways they work are a vacuum unit or an electric actuator assembly. The best answer I have found in why engineers went to a CAD axle was to save on fuel.

Torque King has the parts to fix or delete your CAD unit. We have premium, high-quality, American-made, original equipment replacement kits for most Dana axles with vacuum-controlled CAD. Beware of cheap imported substitutes! We tested some motors from China and none of them would hold vacuum-like ours in our quality control testing! Also, we sell everything from electric actuator assemblies, seals, gaskets, axles, and tools for your 4x4 rig. Below is a partial list with links to the CAD parts Torque King sells.


CAD System

CAD Delete Kits



CAD shift fork with pads

CAD electric actuator assembly 2013-2018 Ram


XV1020 CAD front axle exploded view

XV1021 CAD front axle exploded view

Does your 4x4 have CAD or not? For most domestic vehicles with solid beam type front axles, start by looking at the back or top of the front axle on the long side. If you see a rectangular plate with either an electric actuator assembly or a vacuum style housing, you have a CAD axle!

Here are three options for your rig's CAD unit. 

1. The first option is to leave the CAD system intact. The downside is, if any part of the CAD system fails, then the front axle will not engage.

2. Install a spacer to permanently lock the CAD axle. This is more reliable than leaving CAD functional. However, under extreme conditions, CAD fork or CAD axle shaft splines have been known to fail.

3. Install QU11309 or TK4836 a CAD delete kit. This is the most reliable option. One axle replaces two axle shafts and all CAD-related parts. This will leave less to break and will make your 4x4 rig the strongest.

Many mid-size models and 1988-up GM full-size 4x4s with independent front suspension may also have a CAD system. We will take a look at those vehicles in a future blog! We may also take a look at the weird, diff housing mounted vacuum controlled CAD unit used on some 1982-1984 Jeep J-series full size models.

Feb 25, 2022 Torque King

Latest News

Video Updates
Joel Nov 02, 2022

Video Updates

     I am excited to announce that we have a new format for our service videos. Thes...