What's the mechanism behind pump rub in our transfer cases?

Well, what rubs and what causes it to rub?

Is it at all times? Only in 4wd? Auto?

Speed dependent or vibration dependent?

the pump rides the mainshaft of the transfer case, it has to float in the rear housing. Over time, the five knife-like edges of the stock pump housing rub into the magnesium cover and create leaks.

Iirc there is a kit that corrects this issue if its caught before it rubs a hole in the case. I had looked into it with a previous vehicle but I ended up replacing the t case due to a hole.

I've only ever known it to be an issue with 4x4 models not awd. Maybe someone with more knowledge on awd models can chime in

By the looks of it i would think that it is speed and vibration depending on age and wear on parts.

Chris2144 said:

Iirc there is a kit that corrects this issue if its caught before it rubs a hole in the case. I had looked into it with a previous vehicle but I ended up replacing the t case due to a hole.

I've only ever known it to be an issue with 4x4 models not awd. Maybe someone with more knowledge on awd models can chime in

By the looks of it i would think that it is speed and vibration depending on age and wear on parts.

Click to expand...

There are kits that prevent the issue yes.

TheAutumnWind said:

the pump rides the mainshaft of the transfer case, it has to float in the rear housing. Over time, the five knife-like edges of the stock pump housing rub into the magnesium cover and create leaks.

Click to expand...

Vibration related then?

No, I would say it was GM being cheap, trying to save material. The part that rubs I believe is the pump cover pads, where it seats with the rear tail housing. They tried using some sort of clip to serve as a pad for it, but overtime the movement of the pump from side to side, caused by the splined shaft engaging the pump wears a hole through it. This happens after the clip just snaps out of position due to fatigue. Eventually after the clip falls off it will start moving side to side in the bare case due to the play tolerances within the design.
As you can see the OEM cover at the bottom, and the updated aftermarket version at the top, there is also a large thrust washer one available, but I prefer the one posted above, as it distributes the load evenly across all the pads, and slots in the tail housing.

Stole this pic from "
Dan2002"