Driveshafts are used to transmit power from the transmission to the rear axle assembly. The Brougham, DeVille, and Seville use a one piece shaft, while the Limousine and Commercial Chassis use a two piece shaft.
A Single Cardan universal Joint is used at the front of the shaft on the Seville, Limousine, and Commercial Chassis, while a Double Cardan constant velocity universal joint is used on the other models. All models use the Double Cardan constant velocity universal joint at the rear, and also at the center of the two piece shaft.
A Double Cardan joint consists of two single joints connected by a special link yoke. A ball and socket centering device is located between the crosses to maintain their relative positions, causing each cross to divide one half of the total angle cross the joint equally. Virtually all problems with driveshafts, caused by universal joint angles, are eliminated by use of the Double Cardan joint.
Each Driveshaft is installed in a similar manner. A universal joint and splined slip yoke are located at the front of the shaft, where they are held in alignment by a bushing in the rear of the transmission. The slip yoke permits fore and aft movement of the driveshaft as the rear axle assembly moves up and down. The spline is lubricated internally by transmission lubrication or grease. An oil seal at the transmission prevents leakage and protects the slip yoke from dust, dirt, and other harmful material. In addition, the two piece shaft has (on the front end of the rear section) an external splined slip yoke that fits into a splined coupling in the rear end of the front section. This slip spline has the same function as the slip yoke in allowing up and down movement of the rear axle. The two piece shaft is supported in the center by a center bearing support and bracket attached to the frame cross member. The rear of each driveshaft is attached to the rear axle assembly by means of a double flange connection with four bolts or by means of retaining straps.
REMOVAL & INSTALLATION
- Raise the vehicle in the air and support it with jackstands.
- Mark the relationship of the driveshaft to the differential flange so that they can be reassembled in the same position.
- Disconnect the rear U-joint by removing the flange bolts, U-bolts or retaining straps.
- To prevent the loss of the needle bearings, tape the bearing caps in place. If you are replacing the U-joint, this is not necessary.
- Remove the driveshaft from the transmission by sliding it rearward. There will be some oil leakage from the rear of the transmission. It can be contained by placing a small plastic bag over the rear of the transmission and holding it in place with a rubber band.
- Insert the front yoke into the transmission so that the driveshaft splines mesh with the transmission splines.
- Using the reference marks made earlier, align the driveshaft with the differential flange and secure it with the U-bolts or retaining straps.
See Figures 1, 2, 3, 4, 5, 6, 7 and 8
- Remove the driveshaft as explained above and remove the snaprings from the ends of the bearing cup.
- After removing the snaprings, place the driveshaft on the floor and place a large diameter socket under one of the bearing cups. Using a hammer and a drift, tap on the bearing opposite this one. This will push the trunnion through the yoke enough to force the bearing cup out of the yoke and into the socket. Repeat this procedure for the other bearing cups. If a hammer doesn't loosen the cups, they will have to be pressed out.
A Saginaw design driveshaft secures its U-joints in a different manner than the conventional snaprings of the Dana and Cleveland designs. Nylon material is injected through a small hole in the yoke and flows along a circular groove between the U-joint and the yoke thus creating a synthetic snapring. Disassembly of this Saginaw-type U-joint requires that the joint be pressed from the yoke. If a press is not available, it may be carefully hammered out using the same procedure (Step 2) as the Dana design although it may require more force to break the nylon ring. Either method, press or hammer, will damage the bearing cups and destroy the nylon rings. Replacement kits include new bearing cups and conventional metal snaprings to replace the original nylon type rings.
- Using solvent, thoroughly clean the entire U-joint assembly. Inspect for excessive wear in the yoke bores and on the four ends of the trunnion. The needle bearings should not be scored, broken, or loose in their cups. Bearing cups may suffer slight distortion during removal and should be replaced.
- Pack the bearings with chassis lube (lithium base) and completely fill each trunnion end with the same lubricant.
- Place new dust seals on trunnions with cavity of seal toward end of trunnion. Care must be taken to avoid distortion of the seal. A suitable size socket and a vise can be used to press on the seal.
- Insert one bearing cup about 1 / 4 of the way into the yoke, then place the trunnion into yoke and bearing cup. Install another bearing cup and press both cups in, then install the snaprings. Snaprings on the Dana and Cleveland shafts must go on the outside of the yoke while the Saginaw shaft requires that rings go on the inside of the yoke. The gap in the Saginaw ring must face in toward the yoke. Once installed, the trunnion must move freely in yoke.
The Saginaw shaft uses two different size bearing cups (the ones with the groove) fit into the driveshaft yoke.