Repair Pontiac Mid-size 1974-1983 Repair Guide

Driveline

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Mid-size Pontiac driveshafts are of the conventional, open type. Located at either end of the driveshaft is a U-joint or universal joint, which allows the driveshaft to move up and down to match the motion of the rear axle. The front U-joint connects the driveshaft to a slip-jointed yoke. This yoke is internally splined, and allows the driveshaft to move in and out on the transmission splines. The rear U-joint is clamped or bolted to a companion flange fastened to the rear axle drive pinion. The rear U-joint is secured in the yoke in one of two ways. Dana and Cleveland design driveshafts use a conventional type snapring to hold each bearing cup in the yoke. The snapring fits into a groove located in each yoke end, just on top of the bearing cup. A Saginaw design driveshaft secures the U-joints differently. Nylon material is injected through a small hole in the yoke during manufacture, and flows along a circular groove between the U-joint and the yoke creating a non-metallic snapring.

There are two methods of attaching the rear U-joint to the rear axle. One method employs a pair of straps, while the other method is a set of bolted flanges. Bad U-joints, requiring replacement, will produce a clunking sound when the car is put into gear and when the transmission shifts from gear to gear. This is due to worn needle bearings or a scored trunnion end possibly caused by improper lubrication during assembly. U-joints require no periodic maintenance and therefore have no lubrication fittings.

Some driveshafts, generally those in heavy-duty applications, use a damper as part of the slip joint. This vibration damper cannot be serviced separately from the slip joint. If either component goes bad, the two must be replaced as a unit.

REMOVAL & INSTALLATION
Driveshaft


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Fig. Fig. 1 Exploded view of a driveshaft assembly



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Fig. Fig. 2 Driveshaft flange attachment



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Fig. Fig. 3 Strap-type retainer type of driveshaft mounting



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Fig. Fig. 4 To remove the driveshaft from the vehicle, unfasten the retaining bolts



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Fig. Fig. 5 Remove the strap-type driveshaft retainer ...



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Fig. Fig. 6 ... then slide the driveshaft rearward and out from the vehicle

  1. Raise the vehicle in the air and support it with jackstands.
  2.  
  3. Mark the relationship of the driveshaft to the differential flange so that they can be reassembled in the same position.
  4.  
  5. Disconnect the rear U-joint by removing the U-bolts or retaining straps.
  6.  
  7. 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.
  8.  
  9. 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.
  10.  

To install:

  1. To install the driveshaft, insert the front yoke into the transmission so that the driveshaft splines mesh with the transmission splines.
  2.  
  3. Using the reference marks made earlier, align the driveshaft with the differential flange and secure it with the U-bolts or retaining straps.
  4.  

U-JOINT OVERHAUL


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Fig. Fig. 7 Tap the yoke to seat the retaining ring



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Fig. Fig. 8 Install the retaining ring



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Fig. Fig. 9 Partially inserted bearing cap

NEVER clamp a driveshaft in a vise, as the tube is easily dented. Always clamp on one of the yokes, and support the shaft horizontally.

  1. Remove the driveshaft as explained above and remove the snaprings from the ends of the bearing cup.
  2.  
  3. 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 trunion 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.
  4.  

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.

  1. 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.
  2.  
  3. Pack the bearings with chassis lube (lithium base) and completely fill each trunnion end with the same lubricant.
  4.  
  5. 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.
  6.  
  7. Insert one bearing cup about 1 / 4 of the way into the yoke and place the trunnion into yoke and bearing cup. Install another bearing cup and press both cups in and 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.
  8.  

The Saginaw shaft uses two different size bearing cups (the ones with the groove) fit into the driveshaft yoke.

 
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