Driveshaft and U-joints

[hotwheels]

The driveshaft is the means by which the power from the engine and transmission (which are in the front of the car) can be transferred to the differential, rear axles and finally to the rear wheels. The driveshaft assembly incorporates two universal joints, one at each end, and a slip yoke (at the front end of the assembly), which fits into the back of the transmission.

All driveshafts are balanced when installed in a car. It is, therefore, imperative that before applying undercoat to the chassis, the driveshaft and universal joint assembly be completely covered or removed to prevent the accidental application of undercoating to the surfaces and the subsequent loss of balance. For this same reason, it is also a good idea to matchmark the driveshaft to the rear axle drive pinion flange before removal.

DRIVESHAFT REMOVAL

1) Block the wheels which are to remain on the ground, then raise and support the vehicle safely.

If the front end is raised, be sure to block the drive wheels and firmly set the parking brake before lifting the vehicle. If the rear is raised, then the front wheels MUST be blocked, but the parking brake will be of no use. Also, keep in mind that lifting the vehicle at the rear may help prevent transmission fluid from leaking out of the transmission extension housing.

2) Matchmark the relationship of the rear driveshaft yoke and the drive pinion flange of the axle. If the original yellow marks are visible, there is no need for new marks. The marks facilitate installation of the assembly in its exact original position, thereby assuring you will maintain the proper balance.

3) Remove the four bolts or U-clamps which hold the rear universal joint to the pinion flange. Wrap tape around the loose bearing caps in order to prevent them from falling off the spider.

4) Pull the driveshaft toward the rear of the vehicle until the slip yoke clears the transmission housing and the seal. Plug or cover the hole at the rear of the transmission housing (a plastic bag and a few rubber bands are helpful for this) or place a container under the opening to catch any fluid which might leak.

UNIVERSAL JOINT OVERHAUL

5) Position the driveshaft assembly in a sturdy soft-jawed vise, BUT DO NOT place a significant clamp load on the shaft or you will risk deforming and ruining it.

6) Remove the snaprings which retain the bearings in the slip yoke (front only) and in the driveshaft (front and rear).

A U-joint removal and installation tool (which looks like a large C-clamp) is available to significantly ease the task, but it is very possible to replace the U-joints using an arbor press or a large vise and a variety of sockets.

7) Using a large vise or an arbor press along with a socket smaller than the bearing cap (on one side) and a socket larger than the bearing cap (on the other side), drive one of the bearings in toward the center of the universal joint, which will force the opposite bearing out.

The smaller socket is used as a driver here, as it can pass through the opening of the U-joint or slip yoke flange. The larger socket is used to support the other side of the flange so that the bearing cap has room to exit the flange (into the socket).

8) As each bearing is forced far enough out of the universal joint to be accessible, grip it with a pair of pliers and pull it from the driveshaft yoke. Drive the spider in the opposite direction in order to make the opposite bearing accessible and pull it free with a pair of pliers. Use this procedure to remove all the bearings from both universal joints.

9) After removing the bearings, lift the spider from the yoke.

10) Thoroughly clean all dirt and foreign matter from the yokes on both ends of the driveshaft.


"When installing new bearings in the yokes, it is advisable to use an arbor press or the special C-clamp tool. If this tool is not available, the bearings should be driven into position with extreme care, as a heavy jolt on the needle bearings can easily damage or misalign them. This will greatly shorten their life and hamper their efficiency."


11) Start a new bearing into the yoke at the rear of the driveshaft.

12) Position a new spider in the rear yoke and press the new bearing 1/4 in. (6mm) below the outer surface of the yoke.

13) With the bearing in position, install a new snapring.

14) Start a new bearing into the opposite side of the yoke. Press the bearing until the opposite bearing, which you have just installed, contacts the inner surface of the snapring.

15) Install a new snapring on the second bearing. It may be necessary to grind the surface of the second snapring.

16) Reposition the driveshaft in the vise, so that the front universal joint is accessible.

17) Install the new bearings, new spider and new snaprings in the same manner as you did for the remaining joint.

18) Position the slip yoke on the spider. Install new bearings, nylon thrust bearings and snaprings.

19) Check both reassembled joints for freedom of movement, If misalignment of any part is causing a bind, a sharp rap on the side of the yoke with a brass hammer should seat the bearing needle and provide the desired freedom of movement. Care should be exercised to firmly support the shaft end during this operation, as well as to prevent blows to the bearings themselves. Under no circumstance should the driveshaft be installed in a car if there is any binding in the universal joints.

DRIVESHAFT INSTALLATION

20) Carefully inspect the rubber seal on the output shaft and the seal in the end of the transmission extension housing. Replace them if they are damaged.

21) Examine the lugs on the axle pinion flange and replace the flange if the lugs are shaved or distorted.

22) Coat the yoke spline with special-purpose lubricant. The Ford part number for this product is B8A-19589-A.

23) If installed to prevent fluid leakage, remove the plug or cover from the rear of the transmission housing.

24) Insert the yoke into the transmission housing and onto the transmission output shaft. Make sure that the yoke assembly does not bottom on the output shaft with excessive force.

25) Locate the alignment marks made (or the original marks noted) during removal. Install the driveshaft assembly with the marks properly aligned.

26) Install the U-bolts and nuts or bolts which attach the universal joint to the pinion flange. Tighten the U-bolt nuts to 8-15 ft. lbs. (11-20 Nm). Flange bolts are tightened to 70-95 ft. lbs. (95-130 Nm).

27) Remove the jackstands and carefully lower the vehicle.