BMW X5 ATC-500 Transfer Case

The BMW X5 is on its third transfer case model. The first one was the New Venter 125, the second is the ATC500 and the latest one is the ATC700.

The NV125 is relatively a simple case to work on. It has three major bearings, three seals, a drive and driven sprocket, chain and other smaller parts.

The ATC500 on the other hand is a bit more complex. Unlike its predecessor it replaced the planetary gear with a clutch pack and contains a pump and a shift motor. This unit was introduced in late 2003; around October of '03.

If you are not sure which case you have you can simply go to the case and check for the transfer case shift motor. There are other exterior difference but this is the most obvious.

Internally you already know about the planet and clutch pack as well as the pump. You can also look at the chain. The chain has one blue link for the NV125 and two blue links for the ATC500.

The ATC-500 also has four instead of three major bearings and two plastic dust covers (the other having only one metal dust cover).

More information will be coming for the ATC700 as it comes in. Stay tuned!