Thumping noise when shifting to drive

Hi,

My first suspect is the rear drive shaft center support. There is a bearing that can go bad and cause what you have described.

To check, put the parking brake on and have a helper (engine off) while holding the brake pedal securely, place the shifter in neutral. That will remove any tension on the driveshaft. Then, grab the drive shaft near the center support and see if there is play in it. If there is, the bearing needs replaced.

This is where I would suggest starting. Also, make sure there are no issues with the universal joints or axle joints between the differential and wheels.

Here is a link that describes a universal joint:

https://www.2carpros.com/articles/how-u-joints-work

If you find the prop shaft center support bearing is the problem, here are the directions for replacement. The attached pics correlate with the directions.

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2006 Cadillac CTS V6-3.6L VIN 7
Propeller Shaft Center Support Bearing Overhaul
Vehicle Transmission and Drivetrain Drive/Propeller Shafts, Bearings and Joints Drive/Propeller Shaft Service and Repair Procedures Propeller Shaft Center Support Bearing Overhaul
PROPELLER SHAFT CENTER SUPPORT BEARING OVERHAUL
Propeller Shaft Center Support Bearing Overhaul

Tools Required
J25863 Pinion Cone and Side Bearing Installer
J22912-01Split-Plate Bearing Puller

Removal Procedure

pic 1

1. Using a paint stick, mark the shaft on both sides. The splines are not keyed, therefore, alignment marks are necessary for assembly.

Notice: Never clamp propeller shaft tubing in a vise. Clamping propeller shaft tubing in a vise could dent or deform the tube causing an imbalance or unsafe condition.
Always clamp on one of the yokes and support the shaft horizontally.

Important: Proper alignment on assembly is critical in order to maintain correct balance.

pic 2

2. Remove the clamp holding the dust boot to the shaft. Discard the clamp.

Important: The clamp is not reusable.

pic 3

3. Pry the dust boot off the shaft tube.

pic 4

4. Hold the shaft on both sides of the bearing and pull or separate the 2 halves.

pic 5

5. Remove the O-ring from the end of the spline shaft.

pic 6

6. Remove the dust boot.

pic 7

7. Pry off the bearing slinger from the spline shaft. Discard the slinger.

Important: Do not reuse the slinger.

pic 8

8. Remove the snap ring from the groove.

Important: Grease may have to be removed to see the snap ring.

pic 9

9. Install the J22912-01 around the shaft behind the bearing. Place shaft in a press and remove the bearing.

Clean and Inspect

pic 10

1. Clean grease from the splines on both halves of the shaft.
2. Remove any corrosion or debris from the bearing area.

Installation Procedure

pic 11

1. Slide a NEW bearing over the spline shaft.
2. Using the J25863, drive on the bearing until it seats and the snap ring groove is visible.

pic 12

3. Install a NEW snap ring in the groove.

pic 13

4. Apply 5 - 6 grams (0.18 - 0.21 ounce) of grease from the kit in the snap ring area, ensuring that the surface of the bearing is covered.

pic 14

5. Install a NEW slinger from kit with the J25863 until it seats on the shaft against the bearing.

pic 15

6. Apply 1 gram (0.03 ounce) of grease to the inside of the dust boot.
7. Slide the dust boot over the splines with the clamp end out.

pic 16

8. Install the NEW O-ring on the end of the spline shaft.
9. Apply 1 - 2 grams (0.03 - 0.07 ounce) of grease to the splines for assembly.

pic 17

10. Install the NEW dust boot clamp over the splines.

pic 18

11. Align the paint marks on the shaft to ensure proper assembly balance. Push the splines together.
12. Push the dust boot and clamp over the shaft.

pic 19
13. Compress the dust boot retaining clamp.

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Let me know if this helps or if you have other questions.

Take care,
Joe