SYNCRO-MESH

 

GENERAL INFORMATION

The 1957 Syncro-Mesh transmission is similar in design except for the addition of heavy ribs on the case and larger gears to strengthen the transmission. End play of the second speed gear is prevented by the addition of a rear thrust washer. A thrust washer also has been added to the rear of the counter gear. The rear bearing retainer supports the companion flange rather than the main shaft.

Gear ratios have been changed to take full advantage of the increased engine power.

 

ADJUSTMENT OF SHIFT RODS

The Syncro-Mesh transmission requires two shift linkage adjustments to properly position the hand control lever with respect to the steering wheel.

 

Shift Lever Adjustment (Fig. 11-1)

  1. Set the transmission outer shift lever “A” in the second gear position (lever “A” forward, lever “C” rearward).
  2. Disconnect the shift rod from the steering column lower shift lever at clevis “B”.
  3. Hold the steering column lower shift lever upward against its stop in the mast jacket.
  4. Adjust clevis “B” so that the clevis pin freely enters the clevis and lever, then remove the clevis pin and shorten the rod by three full turns of the clevis.
  5. Install the clevis pin and cotter pin, then tighten the clevis lock nut.

    1957 Oldsmobile Shift Lever Adjustment

 

Cross Shift Linkage Adjustment

  1. Disconnect the cross shift rod from the steering column cross shift lever “E”.
  2. With the transmission selector lever “C” rearward against its stop, adjust clevis “D” so that the clevis pin will easily enter the hole in lever 11 E 11 while holding the cross shift lever rearward to take up the lash. Then remove the clevis pin and lengthen the rod by three full turns of the clevis. This should bring the hand shift knob to within 3-7 /16″ + 1/4 ” of the front face of the steering wheel. (See Fig. 11-2)
  3. Install the clevis pin and cotter pin, then tighten the clevis lock nut.

    1957 Oldsmobile Position of Shift Lever

 

THROTTLE CONTROL ADJUSTMENT (Fig. 11-3)

The throttle control adjustment must be made with the choke off.

  1. Shift transmission into neutral.
  2. Adjust rod “A” to obtain 11/32″ to 13/ 32″ clearance between accelerator bellcrank “B” and dash. Rod end must face away from engine after adjustment.
  3. Adjust rod “D” to obtain a height of 3-3/4″ from the pedal tip to the surface of the metal floor mat retainer.
  4. Set carburetor slow idle speed at 450 R.P.M.

Adjusting the idle speed does not affect the throttle control setting.

1957 Oldsmobile Throttle Control Adjustments

 

TRANSMISSION REMOVAL AND REPLACEMENT

  1. Drain transmission and disconnect control rods and the speedometer cable at the transmission.
  2. ark the location of the center bearing sup­ port on the frame. Disconnect the front and rear companion flanges and the center bearing support to frame attaching bolts. Slide the propellor shaft assembly out of the frame.
  3. Remove the 4 transmission to clutch housing attaching bolts and slide the transmission rearward until the main drive shaft clears the clutch housing. Lower the trans mission.

To replace the transmission, apply Lubriplate to the pilot and the first 1″ of the splines on the main drive shaft. Reverse the sequence of the removal operations, align the propellor shaft, and adjust the transmission shift linkage.

 

TRANSMISSION DISASSEMBLY

  1. Clean the exterior of the transmission thoroughly before opening the case.
  2. Remove the return spring, spring extension, spring clip and the cover and cover gasket. (See Fig. 11-4)

    1957 Oldsmobile Return Spring Assembly

  3. Remove the companion flange as follows: (See Fig. 11-5)
    a. Remove the companion flange retaining bolt.
    b. Thread Removing Screw (Tool6504) into the end of the main shaft until it bottoms.
    c. Install the Holding Tool (6544) on the companion flange.
    d. Install the Companion Flange Puller (6295-01) through the holding tool and place retaining nuts on the puller studs. (The long bolt in the puller seats in the depression in the head of the removing screw.)
    e. While holding the companion flange with the holding tool, tighten the long puller bolt until flange moves out to the head of there­ moving screw. Remove the puller, holding tool and removing screw.

    1957 Oldsmobile Removing Companion Flange (3)

  4. Remove speedometer driven gear.
  5. Remove rear bearing retainer and gasket.
  6. Remove the set screws from the two shifter yokes (See Fig. 11-6) and move the main shaft rearward until the rear bearing clears the case.

    1957 Oldsmobile Shift Mechanism

  7. Remove the synchronizing clutch from the main shaft. (See Fig. 11-7)

    1957 Oldsmobile Removing Syncronizing Drum

NOTE: If necessary to service only the main drive shaft, main drive gear, or main drive shaft bearing, the assembly can be re­ moved at this point in the disassembly. (Refer to step 22)

  1. Remove the snap ring holding the second speed gear on the main shaft. (See Fig. 11-8)

    1957 Oldsmobile Removing Second Speed Gear Snap Ring

  2. Rotate the wire ring in the snap ring groove until the ring gap lines up with the key on the second speed gear thrust washer.
  3. Remove the keyed thrust washer, the second speed gear, and the rear thrust washer from the main shaft. (See Fig. 11-9)

    1957 Oldsmobile Removing Second Speed Gear

  4. Remove the low a n d reverse gear retaining snap ring and slide the gear off the main shaft. (See Fig. 11 -10)

    1957 Oldsmobile Low and Reverse Gear Retainer

  5. Pull the main shaft from the rear of the case.
  6. Loosen the outer shift lever bolt. Position the lever so that the inner shift levers are vertical and remove the outer shift lever.
  7. Remove the se t screws from the inner shift levers. (See Fig. 11-11)

    1957 Oldsmobile Removing Shift Lever Set Screw

  8. Pull shifter shaft away from the second and third speed yoke shaft and remove the interlock retainer. (See Fig. 11-12)

    1957 Oldsmobile Removing Interlock Retainer

  9. Drive the shifter shaft out through the right side of the case. The welch plug will be driven out by the shaft. Do not allow levers or interlock to drop into the case. (See Fig. 11-13)

    1957 Oldsmobile Driving Shifter Shaft from Case

  10. Push or tap the low and reverse yoke shaft out through the rear of the case, taking care to prevent the poppet ball and spring from flying out. Remove the shift yoke, ball and spring. (See Fig. 11-14)

    1957 Oldsmobile Removing Yoke Shaft from Case

  11. Push or tap the second and third speed yoke shaft out through the front of the transmission case, taking care to prevent the poppet ball and spring from flying out. Remove the shifter yoke, ball, and spring.
  12. Remove the low and reverse interlock pin from the case near the shifter shaft seal. (See Fig. 11-15)

    1957 Oldsmobile Removing First and Reverse Interlock Pins

  13. Drive the counter gear shaft lock pin into the shaft. (See Fig. 11-16)

    1957 Oldsmobile Driving Lock Pin Into Case

  14. Drive the counter gear shaft out through the rear end of the case using Bearing Loader Tool J -1001 and a soft hammer. Make sure that the bearing loader tool follows the shaft closely so that the counter gear bearings and thrust washers will be held in place. (See Fig. 11-17)

    1957 Oldsmobile Removing Counter Gear Shaft

  15. Remove the snap ring from the main drive gear bearing outer race and tap the drive gear and bearing assembly toward the rear of the case to remove.
  16. Remove the counter gear assembly from the case.
  17. Remove the transmission outer selector lever nut, lock washer and lever, then remove the inner selector shaft and lever assembly.
  18. Drive the reverse idler gear shaft lock pin into the shaft. (See Fig. 11-18)

    1957 Oldsmobile Driving Lock Pin Into Idler Shaft

  19. Drive the reverse idler gear shaft out the rear of the case. (See Fig. 11-19)

    1957 Oldsmobile Removing Reverse Idler Gear Shaft

NOTE: A 1/2″ x 8″ brass drift should be used to remove the shaft by driving on idler gear shaft through counter gear shaft boss in front of case.

27 Remove the reverse idler gear shaft, gear, and thrust washer from the case.

 

COUNTER GEAR ASSEMBLY SERVICING MAIN DRIVE GEAR

If the counter gear bearings or gear requires replacement, the bearings, retaining washers, thrust washers, and bearing spacer must be re­ moved from the counter gear. (See Fig. 11-20) Assemble the parts as follows:

  1. Install the bearing spacer and the bearing inner retainer washers on Bearing Loader Tool J-1001, then insert the tool into the counter gear.
  2. Install 26 needle bearings in each end of the gear around the bearing loader tool. Position the first bearing under the loader tool so that the tool is centered in the bore of the gear.
  3. Install the front bearing outer retainer washer on the loader tool at the large end of the counter gear, then place the large perforated thrust washer against the large gear. Use petrolatum to retain the washer in place if necessary.
  4. Install a steel thrust washer on the loader tool at the small end of the counter gear, then in­ stall the bronze thrust washer and the remaining steel thrust washer on the tool.
  5. Leave the Bearing Loa de r Tool j-1001 in place until the counter gear is installed in the case.

    1957 Oldsmobile Counter Gear Assembly

 

SERVICING INDIVIDUAL UNITS

If necessary, the main drive gear ball bearing or the roller bearings may be replaced. (See Fig. 11-21)

  1. Remove the snap ring and washer holding the main drive gear bearing to the main drive gear.
  2. Remove the bearing by jarring the shaft on a block of wood.
  3. Pry the wire lock ring from the bore of the main drive gear, then re move retaining washer and 14 needle bearings.
  4. To assemble, hold the shaft in the vertical position and install the needle bearings in the bore of the gear, using petrolatum if necessary to retain the bearings. Install the retaining washer and lock ring.
  5. Install the main drive gear bearing on the shaft with the shielded side toward the gear, using a tool that contacts the inner race only.

NOTE: The Rear Bearing and Speedometer Gear Installing Tool J-6133-A, used on the jetaway Transmission, can be used to install this bearing.

  1. Install the washer, dished side TOWARD the bearing, then install the snap ring on the shaft against the washer.

    1957 Oldsmobile Main Drive Gear Assembly

 

SERVICING MAIN SHIAFT

The speedometer drive gear and rear bearing can be removed from the main shaft if necessary. The recommended procedure is as follows:

  1. Bend the speedometer gear spacer and remove from the shaft. The spacer will usually be ruined by bending, and a new spacer should be used when installing the gear.
  2. Using Snap Ring Pliers, remove the snap ring from the groove and slide it along the shaft toward the speedometer drive gear. (See Fig. 11-22)

    1957 Oldsmobile Removing Snap Ring (2)

  3. Place the first and reverse gear on the main shaft first and reverse splines with the flat side of the gear toward the bearing. Remove the speedometer drive gear and bearing from the shaft by jarring the shaft on a block of wood. (See Fig. 11-23) After the speedometer gear and bearing are jarred from their seats on the main shaft, remove the gear, the snap ring and the bearing.

    1957 Oldsmobile Removing Rear Bearing and Speedometer Drive Gear

  4. To assemble the parts, install the bearing on the main shaft with the shield toward the shoulder of the first and reverse splines on the main shaft. Using Rear Bearing and Speedometer Gear Installing Tool J-6133, seat the bearing against the first and reverse gear splines on the main shaft. (See Fig. 11-24)

    1957 Oldsmobile Installing Rear Bearing (2)

  5. Install the snap ring against the inner race of the bearing and install the speedometer gear spacer.
  6. Using Tool J-6133, install the speedometer drive gear on the main shaft against the spacer.

NOTE: Tool J -4390 and Tool J -358-1 can be used to remove and replace the speedometer gear, or to replace the bearing.

 

SERVICING REAR BEARING RETAINER

The rear bearing retainer bushing is not avail ­ able as a replacement part for the 1957 transmission. The bushing reaming tools used with past model transmissions are not usable on the new transmission because the diameter of the new bushing is larger. The only item serviced separately is the seal, which carries the same part number as the seal used on the Jetaway transmission. If the seal requires replacement, drive it out with a chisel and install a new one as follows:

  1. Apply a coating of seal lubricant (Part No. 567196 to the sealing lip of the seal.
  2. Apply a light coat of Gasoila or Permatex #3 to the outer diameter of the seal.
  3. Install the seal into the rear bearing retainer using Seal Installing Tool J -5154. (See Fig. 11-25)

    1957 Oldsmobile Installing Rear Bearing Retainer Seal

 

SYNCRONIZING CLUTCH

The synchronizing clutch detent springs are serviced separately and replacement, if necessary, can be accomplished by prying each spring loose from the gear and pushing it out of the groove. (See Fig. 11-26) New springs can be installed by pushing them into position in the grooves.

1957 Oldsmobile Removing Synchronizing Clutch Springs

 

SHIFTER SHAFT SEAL

The shifter shaft seal can be removed and replaced if necessary. Pry out the old seal from the case. Coat the sealing lip of the seal with Lubriplate, coat the outer diameter of the seal with a non-hardening sealer (Permatex #2), and install the seal in the case using a tool such as a socket to drive the seal until it bottoms in the case.

 

REVERSE IDLER GEAR BUSHINGS

The reverse idler gear bushings can be removed and replaced if necessary. However, the new bushings must be line rea med after they are in­ stalled. Drive out the old bushings, then install the new ones until they are positioned just beyond the chamfer in the gear. New reverse idler gears contain bushings which have already been machined to size.

 

ASSEMBLY OF TRANSMISSION

  1. Install the reverse idler gear as follows:
    a. Position the reverse idler gear and bronze thrust washers into the case with the chamfered teeth to the rea r of the case. (See Fig. 11-27)

    1957 Oldsmobile Counter Gear and Reverse Idler Gear

    b. Install the idler gear shaft (slotted end out) until the front of the shaft picks up the front thrust washer and just starts into the inner support in the case.
    c. Coat the protruding end (slotted) of the shaft with a non-hardening sealer (Permatex #2).
    d. Make sure the lock pin hole in the shaft is in line with the lock pin hole in the case. The slot in the end of idler gear shaft is for this purpose. Finish driving the shaft into the case using a brass drift and a hammer.
    e. Coat a new lock pin with a non-hardening sealer. Drive the lock pin 1″ below the sur­ face of the boss on the case.

  2. Install the counter gear as follows:
    a. Position the counter gear assembly in the transmission case. Note that a large bronze thrust washer is used at the front of the counter gear while a combination of a steel washer, a bronze washer, and a steel washer is used at the rear of the counter gear.
    NOTE: Locate the bearing loader tool so that it supports the rear thrust washers (steel, bronze, and steel). Although the large thrust washer at the front of the counter gear will not be supported by the tool, petrolatum can be used to hold it in place.
    b. Install the counter gear shaft, small end first, from the rear of the case until the front end of the shaft just enters the bore in the front wall of the case. Make sure that the shaft closely follows the bearing loader J-1001 so that the bearings and thrust washers are held in place.
    c. Make sure that the lock pin hole in the shaft is lined up with the lock pin hole in the case, then coat the protruding end of the shaft with Permatex #2 or any equivalent non hardening sealer. Finish driving the shaft into the case using a brass drift and a hammer.
    d. Install a new lock pin coated with Permatex #2. Drive the lock pin flush with the surface of the case.
  3. Install the spring washer, flat washer, and the oil seal on the inner selector shaft in that order, with the crowned side of the spring washer against the flat washer. (See Fig. 11-28)

    1957 Oldsmobile Inner Selector Shaft

  4. Apply Lubriplate to the inner selector shaft, insert the shaft in the transmission case, then install the outer selector lever, washer, and nut so that the bend of the lever is down.
  5. Install the shifter shaft interlock pin in the case. (See Fig. 11-29)

    1957 Oldsmobile Transmission Interlock

  6. Install the spring and poppet ball for the first and reverse yoke shaft in the case, then install the yoke shaft from the rear of the case with the grooved end rearward and place the first and reverse shifter yoke on the shaft with the set screw hole facing up. Use a punch to de ­ press the poppet ball and spring when installing the shaft. Do not install the set screw a t this time.
  7. Install the spring and poppet ball for the second and third speed shifter yoke shaft in the case. Install the yoke shaft from the front of the case with the 3 notched detents rearward and place the second and third shifter yoke on the shaft with the set screw hole facing up. Do not install the set screw at this time.
  8. Position both yoke shafts so that the notch in each shaft is directly above the selector shaft bore in the transmission case.

NOTE: This is the neutral position.

  1. Install a new welch plug coated with Permatex #2 or its equivalent, in the side of the case opposite the shifter shaft seal. The welch plug will be seated when it bottoms in the bore in the case.
  2. Install the shifter shaft and shifter levers as follows:
    a. Coat the sealing lip of the seal with Lubriplate. Raise the first and reverse interlock into the groove in the first and reverse yoke shaft, then insert the shifter shaft through the seal until it just protrudes inside the ca-se. Rotate the shaft so the set screw holes do not index with the interlock pin.
    b. Engage the first and reverse shifter lever with the inner selector lever in the case, then depress the inner selector lever while sliding the shifter shaft through the first and reverse shifter lever.
    NOTE: The flat ground surface of the shifter lever faces the first and reverse shifter yoke shaft.
    c. Install the second and third shifter lever on the shifter shaft, placing the flat ground surface of the lever toward the second and third yoke shaft. Place the second and third speed interlock on the shifter shaft. Install a new interlock retainer on the shaft. Slide the shaft to the right until the interlock is directly beneath the second and third yoke shaft.
    NOTE: The retainer can be easily in­ stalled and clinched with a pair of needle nose pliers.
    d. Install the set screws in the shifter levers and tighten with a screw driver socket and torque 15 to 20 ft. lbs.
    e. Install the outer shift lever, lock washer and bolt on the shifter shaft.
  3. Install the main drive gear in the bore in the front of the case and retain it with the large snap ring.
  4. Insert the main shaft through the bore in the rear of the transmission case, then slide the first and reverse gear on the shaft with the flat side of the gear rearward. Install the first and reverse gear retaining snap ring.
  5. Line up the small wire spacer ring in the snap ring groove in the main shaft with the machined thrust washer keyway groove on the second speed gear bearing surface. (See Fig. 11-30)

    1957 Oldsmobile Lining Up Snap Ring Spacer

NOTE: There are two grooves machined the full length of the second speed gear bearing surface of the main shaft. The shallow angle groove is for lubrication purposes only and should not be obstructed. The deep groove, similar to a spline, is designed to receive the tangs of the two second speed gear thrust washers.

  1. Install the second speed gear inner thrust washer, indexing the tang with the proper groove on the main shaft.
  2. Place the second speed gear on the main shaft with the cone clutch surface facing forward, install outer thrust washer and retain with a snap ring.
  3. Install the synchronizing drum on the main shaft with the counter-bored end of the gear toward the second speed gear. Engage the synchronizing drum with the second and third speed shifter yoke and index the first and reverse sliding gear with the first and reverse shifter yoke, then tap the main shaft forward until it pilots in the main drive gear and the rear bearing pilots in the case.
  4. Install the rear bearing snap ring.
  5. Install the set screws in the shifter yokes and tighten 15 to 20 ft. lbs.
  6. Coat the rear bearing retainer bushing with SAE 80 Multi-Purpose Gear Lubricant, then position a new rear bearing retainer gasket and the rear bearing retainer on the transmission case.
  7. Using Permatex # 2 on the rear bearing retainer screws, install the screws and tighten 28 to 33 ft. lbs.
  8. Coat the sealing lip of the rear bearing retainer oil seal with Special Lubricant (Part No. 567196). Coat the outer diameter of the seal with Gasoila or Permatex #3.
  9. Install the seal into the rear bearing retainer using Seal Installing Tool J -5154.
  10. Inspect the companion flange for scars, nicks or excessive wear on the bearing or sealing surfaces. Any of these conditions requires replacement of the flange.
  11. Using companion flange installing tool 6505, and companion flange holding tool 6544, install the companion flange. Place the holding tool over the companion flange, and the bolt of the in­ stalling tool through the holding tool and the flange. (See Fig. 11-31) Screw the bolt of the installing tool into the main shaft until it bottoms. With the splines of the companion flange lined up with those on the main shaft, tighten the nut on the installing tool until the flange is seated on the main shaft. Remove the companion flange installing tools.

    1957 Oldsmobile Installing Companion Flange (2)

  12. Install the companion flange bolt and tighten 27 to 36 ft. lbs. Remove holding tool.
  13. Position a new top cover gasket on the trans­ mission case and install the top cover, spring clip, attaching screws and lock washers. Torque 10-12 ft. lbs.
  14. Install the toggle spring and spring extension between the spring clip and the outer shift lever.
  15. Install the speedometer driven gear into the rear bearing retainer and tighten 6 to 8ft. lbs.
  16. Check main drive shaft to bearing retainer clearance.
    a. Install the bearing retainer sleeve on the main drive shaft.
    b. Attach a dial indicator to the transmission case as shown in Fig. 11-32.

    1957 Oldsmobile Checking Sleeve Clearance

    c. Move the sleeve upward on the shaft as far as it will go in each of six positions ap­ proximately 30° apart throughout 180 of travel.
    d. Total indicator reading at any of the six positions checked in step ”c” should not exceed .012″.
    e. If excessive clearance is found, install a new bearing retainer sleeve and seal the area between the sleeve and the clutch housing with Permatex #3. (See Fig. 11-33) If the clearance is too great between the retainer and the main drive shaft, trans­ mission grease will leak through to the clutch assembly.

    1957 Oldsmobile Sleeve Installation

  17. Fill the transmission to the level of the filler plug hole with SAE 80 Multi-Purpose Gear Lubricant (approximately 2-1/2 pints).

NOTE: Before placing the transmission in the car, tilt the transmission to allow the lubricant to flow into the rear bearing retainer. The lubricant will automatically correct itseIf when the transmission is installed. This will eliminate any chance of the rear bearing retainer bushing overheating or running dry until enough oil passes through the main shaft bearing and the oil drain back hole to fill the rear bearing retainer to the Proper running level.

 

LEAKAGE AT FRONT OF TRANSMISSION

If grease leaks between the front face of the transmission and the clutch housing, install two gaskets between the transmission and clutch housing.

 

DIAGNOSIS

If any of the following conditions arise, a misaligned flywheel housing is indicated:

  1. Excessive gear noise.
  2. Transmission jumps out of third gear.
  3. Early bearing failure.

 

CHECK AND ALIGN REAR FLYWHEEL HOUSING

NOTE: It is not necessary to have lower housing in place during this check.

  1. Install pilot mounting strip J -2548 on flywheel. (See Fig. 11-34)

    1957 Oldsmobile Checking Housing Alignment

  2. Install rear housing and tighten bolts.
  3. Install pilot shaft and mount a dial indicator (with a large contact button) on the.3haft.
  4. Tap crankshaft to the rear of the engine.
  5. Bring the indicator into contact with the face of the housing with approximately.015″ compression. The point of contact should be 2-3/8″ from the center of the crankshaft.
  6. Rotate the flywheel through 360° (Tool J -972- A may be used) and note the indicator reading. If the total indicator reading exceeds.003″ shim as necessary between the housing and the engine block.

 

RADIAL RUNOUT

  1. Assemble dial indicator and indicator lever so that the lever rides in the bore of the housing. (See Fig. 11-34)
  2. Place marks at the top, bottom, and both sides of the bore (90° apart).
  3. Position the indicator at either horizontal (Y) mark and set the dial at zero. Rotate the flywheel 1800 and note the indicator reading. Reading must not exceed.004″.
  4. Position the indicator lever at the top of the bore (X) with the dial set at zero. Rotate the flywheel until the indicator is at the bottom mark. Reading must not exceed.008″.
  5. If readings indicate misalignment, cap screws must be loosened slightly, dowel pins removed and housing shifted with a lead hammer to bring within limits.

NOTE: It will be necessary to remove the rear housing and saw off the dowel pins close to the block before driving pins through; other­ wise, the pins will strike the flywheel before clearing the dowel pin holes.

  1. After aligning housing, again tighten housing attaching bolts and recheck radial runout.
  2. Using reamer J -4832-3 (roughing reamer) and ratchet wrench J-808-6, ream the two engine block to rear housing dowel pin holes. Then finish ream using reamer J -4832-4 and install oversize dowel pins, Part No. 557754 (large chamfer end out).

NOTE: The above reamers must be shortened to 4″ over-all length in order to perform this operation with engine in car.

  1. Clean all cuttings from housing.
  2. Remove dial indicator setup and rear flywheel housing.

1957 Oldsmobile Syncro-Mesh Transmission Specifications

 

1957 Oldsmobile S88 2 Door Sedan (DK)