The following procedure must be used to center the engine in the frame and adjust the 1951 Buick engine mountings and transmission mountings.

  1. Disconnect torque tube from torque ball.
  2. Tighten 1951 Buick engine mounting brackets to the crankcase and frame front X bar. Loosen the engine front mounting pad top stud nuts.
  3. Tighten transmission support to frame X member attaching bolts.
  4. Tighten transmission mounting pad to transmission support and to transmission rear bearing retainer.
  5. Tighten thrust pad to thrust plate stud nuts (rear) and loosen thrust pad to transmission support stud nuts (front). Remove shims between thrust pad and transmission support.
  6. Measure the distance between the front edge of crankshaft balancer, at horizontal centerline, and the center of the nearest shock absorber bolt head on each side. If distances on both sides are not equal, shift front of engine sidewise as required to center engine in frame, then tighten engine mounting pad stud nuts securely. The mounting pad stud holes in 1951 Buick engine mounting brackets are oversize to permit sidewise adjustment of engine.
  7. With engine and transmission resting freely and normally on 1951 Buick mounting pads, install sufficient shims between the thrust pad and transmission support to snugly fill the existing space. Insert shims from above, with tabs on right side in Synchromesh cars or left side in Dynaflow Drive cars. See figure 2-40.
    1951 Buick Transmission Mounting Pad, Thrust Pad and Shims

    1951 Buick Transmission Mounting Pad, Thrust Pad and Shims

  8. Tighten thrust pad front stud nuts and tighten front engine mounting pad stud nuts.
  9. Connect torque tube to torque ball.



Removal of Flywheel (synchromesh only)

Flywheel and ring assemblies are balanced separately from the crankshaft during manufacture; however, all completely assembled engines are given a running balance test in a special machine during production. In this test the flywheel is drilled, if necessary, to finally balance the entire engine to very close limits. For this reason, the flywheel and the crankshaft flange should be marked before flywheel is removed so that flywheel may be reinstalled in its original position on the crankshaft. It is also advisable to run the engine after the clutch is removed to note the degree of vibration with the original flywheel.

Flywheels are attached to the crankshaft with bolts, lockwashers and nuts. It is necessary to remove the crankshaft rear bearing cap and remove bolts from crankshaft in order to remove the flywheel. CAUTION: When turning crankshaft with rear bearing cap removed, hold the bearing inner oil seal to prevent it from moving out of the groove in crankcase.

Replacement of Flywheel Ring (synchromesh only)

To remove a flywheel ring from the flywheel, drill a 5/16″ hole in the ring between two teeth and split the ring at this point with a cold chisel.

The flywheel ring is a shrink fit on the flywheel and must be heated to approximately 600° F. in order to expand it sufficiently to go over the flywheel. Heating the ring in excess of 800° F. will destroy the effect of the heat treatment given during manufacture.

Excessive heating may be avoided by first polishing several spots on the ring with emery cloth, then heating the ring only until these spots begin to turn blue. Heat the ring to approximately 600° F. on a hot plate if available; otherwise, place ring on a sheet of metal or asbestos and heat it with a torch that is kept moving to secure even heating. When ring is at proper temperature, quickly place it over flywheel and allow the ring to cool slowly until it is tight in place.

Installation of Flywheel (synchromesh only)

If old flywheel is being reinstalled be sure to place it in original position on crankshaft flange in accordance with marks made before removal.

If a new flywheel or a new crankshaft is being installed, the flywheel bolt holes must be reamed to provide a very close fit for the bolts. Two bolt holes are reamed to size in replacement flywheels and crankshafts. Use these reamed holes to bolt the parts together, then ream the other holes and install bolts.

After installation of a new flywheel or a new flywheel ring, be sure to run the engine and check for vibration before installing the clutch. If engine has vibration that did not exist before installation of new parts, make correction as described under Correction of Engine Vibration (par. 2-34).



The flywheel housing is attached to the cylinder crankcase with six 7/16″ bolts. Two 1/2″ straight dowel pins are installed in reamed holes in both parts to maintain alignment.

Misalignment between the pilot in rear face of housing and the pilot bearing in rear end of crankshaft may cause the transmission to be noisy or to slip out of high gear. To insure correct alignment in production, the pilot hole which receives the transmission main drive gear bearing is bored in the housing after it is assembled to the cylinder crankcase. The flywheel housing furnished for service is completely machined, but it must be checked for alignment after installation.

If an existing housing is suspected of being out of alignment it may be checked after removal of the transmission and clutch assemblies. If a new housing or cylinder crankcase is being installed, alignment should be checked before the flywheel, clutch and transmission are installed. When checking alignment the engine must be in an upright position, dowel pins must be installed, and all housing bolts must be tight.

Checking Alignment of Flywheel Housing (synchromesh only)

  1. Remove transmission (par. 4-13) and clutch (par. 4-5), leaving flywheel in place.
  2. Attach Indicator Support J 4710-1 to flywheel with two flywheel bolts. Mount Dial Indicator KMO 30-B and Hole Attachment KMO 30-F on pilot with Sleeve KMO 30-K. Adjust ball end of hole attachment to bear against side of pilot hole in flywheel housing. See figure 2-41.