Transtar Transfer Case Front Input Pinion Planetary Set, Duramax - 261XHD, 263XHD, 261HD, 263HD, NP246 | 1998-2007

This is a brand-new replacement six gear planetary set for GM transfer case models: NP246, NP261HD, NP263HD, NP261XHD and NP263XHD.

The planetary set is connected to the input shaft through the splines on the shaft. If there is an internal failure of the transfer case the planetary set should be closely inspected for damage to any of the teeth and to verify that the gears rotate smoothly without any binding. If ANY damage is noticed, be sure to replace the complete planetary set. Wear in the gearset can cause excessive noise in the transfer case when the vehicle is operated.

Click here to view the RTV Silicone needed to seal the case halves when reassembling.

Click here to view the Merchant Automotive Transfer Case Pump Upgrade kits.

To view/download Pump Upgrade installation instructions click here.

To view the Merchant Automotive Pump Upgrade installation video click here.

To view the Truck U segment on the Merchant Automotive Transfer Case Pump Rub kit click here.

What is a Transfer Case “Pump Rub” Failure?

GM transfer cases used from 1998 through early 2007 use a gear pump inside the case that is driven off the mainshaft. The pump forces oil to the planetary as well as the drive sprocket sleeve. Because the pump is driven by the shaft, the housing of the pump must "float" in the rear housing. There are tabs around the pump housing that fit into spots in the rear housing to locate the pump housing and prevent it from spinning inside the case with the mainshaft. Over time, the pump tabs can start to wear on the rear housing. GM installed a spring steel clip in the housing intended to prevent wear, but the clip can break and be rendered useless.

Since the pump housing is aluminum and is a harder material then the magnesium rear housing, it can wear a hole in the rear housing and cause a very small leak. This leak is frequently high enough on the case that it typically will not leak when vehicle is not moving and therefore not leaving any drops on the ground; it will however leak while the vehicle is in motion. Unfortunately, since the transfer case does not have a low fluid indicator the pump rub failure is often not found until there is transfer case damage from running the case out of fluid.

Avoid costly repairs to your transfer case by preventing “Pump Rub” by installing a Merchant Automotive Transfer Case Pump Upgrade kit in your transfer case today, before it happens to your vehicle.

With installation of this kit, you will have a LIMITED LIFETIME WARRANTY against pump rub. If your case ever wears a hole in the new rear housing with the upgrade installed. We will buy you a new transfer case. However, if you already have a hole in your case, we recommend installing a new rear housing for a complete repair. The MA Lifetime Warranty will only apply to installations with a new rear housing.

FAQ:

I hear a grinding noise at low speed after reassembling the transfer case. What could that be?

A low speed grinding noise is most commonly caused by the rear output bearing snap ring not being fully seated causing the bearing to move out of proper alignment. Verify that the snap ring is fully engaged and properly seated in the rear housing and the locating groove in the bearing.

What would cause a speed sensor correlation code after reassembling the transfer case?

A speed sensor correlation code is often accompanied by a low speed grinding noise and is frequently caused by the rear output bearing snap ring not being fully seated causing the bearing to move out of proper alignment. Verify that the snap ring it fully engaged and properly seated in the rear housing and the locating groove in the bearing.

What fluid should I use in the transfer case and how much is needed?

We recommend our Performance Transfer Case Fluid for use in ALL transfer cases and have seen improved performance over the factory recommended ATF or other alternate oil recommendations. Two-quarts are required to fill the NP261HD, NP263HD, NP261XHD and NP263XHD transfer cases.

How tight do I tighten the transfer case mounting nuts for the NP261XHD and NP263XHD at the transmission output adapter?

The factory recommended torque specification is 37 ft-lbs for the transfer case adapter nuts for both the NP261XHD and NP263XHD.

How tight do I tighten the transfer case assembly bolts for the NP261XHD and NP263XHD securing the case halves together?

The factory recommended torque specification is 27 ft-lbs for the transfer case assembly bolts for both the NP261XHD and NP263XHD.

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