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OBJECTIVES

OBJECTIVES. After studying Chapter 17, the reader should be able to: Properly perform the standard overhaul procedures. Describe the methods used to clean an automatic transmission and its components. Inspect, remove, and replace bushings and thrust washers.

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OBJECTIVES

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  1. OBJECTIVES After studying Chapter 17, the reader should be able to: • Properly perform the standard overhaul procedures. • Describe the methods used to clean an automatic transmission and its components. • Inspect, remove, and replace bushings and thrust washers. • Disassemble, inspect, and assemble a clutch assembly. • Remove and replace the various seals used in an automatic transmission. • Complete the ASE tasks related to inspection and replacement of bushings, thrust washers, friction material, and seals.

  2. INTRODUCTION • A transmission overhaul is a complete reconditioning that will bring the transmission back to like-new vehicle operation. • This requires that worn parts be replaced so the original clearances are restored. An overhaul should include the following: • complete disassembly and cleaning • careful inspection of each part and component • replacement of any worn or damaged hard parts • replacement of any worn or damaged bushings or thrust washers • replacement of all clutch friction plates • replacement of any worn or damaged clutch steel plates • replacement of the intermediate band and any other worn or damaged bands • replacement of all internal and external seals and gaskets • disassembling, cleaning, and reassembling the valve body • rebuilding or replacing the torque converter • adjusting all clearances to the manufacturer’s specifications

  3. FIGURE 17-1 Expensive transmission failures can be caused by debris in the cooler. (Courtesy of Sonnax) COMPONENT CLEANING • The internal parts, case, and extension housing are cleaned after disassembly. • Some technicians set major components aside to be thoroughly cleaned as they are disassembled and serviced. • Cleaning methods that are commonly used are hot spray wash, water solution wash, cold dip, and solvent wash.

  4. FIGURE 17-2 A spray wash cabinet contains a pump that sprays heated cleaning solution as the parts basket is rotated. (Courtesy of ATEC Trans-Tool and Cleaning Systems) COMPONENT CLEANING

  5. FIGURE 17-3 This parts washer contains a pump that delivers the heated cleaning solution to a cleaning brush and flexible outlet. (Courtesy of ATEC Trans-Tool and Cleaning Systems) COMPONENT CLEANING

  6. FIGURE 17-4 Parts 8657, 730, 677, 5443, 670, 2279, 6749, and 655 are thrust washers. The nine replaceable bushings for this transmission are not shown. (Courtesy of Slauson Transmission Parts,www.slauson.com) BUSHING, BEARING, AND THRUST WASHER SERVICE • Bushings and bearings are used to support rotating shafts. • Thrust washers are used to separate rotating parts from each other or from stationary parts

  7. FIGURE 17-5 The inner and outer bearing journal of this carrier show severe wear (a). The nylon thrust washer shows that it is deformed and nearly melted (b). Both failed because of poor lubrication and overheating. BUSHING, BEARING, AND THRUST WASHER SERVICE

  8. FIGURE 17-6 A thrust bearing can have a specially shaped race at each side or use the transmission component for the race. The race can be part of the bearing or separate. Correct installation is essential. BUSHING, BEARING, AND THRUST WASHER SERVICE

  9. FIGURE 17-7 These bushings have failed from embedded debris (a), abrasion (b), wiping and overheating (c), and spin out (d). (Courtesy of Sonnax) BUSHING, BEARING, AND THRUST WASHER SERVICE

  10. FIGURE 17-8 A quick and simple check for bushing clearance is to place a strip of paper between the converter hub and bushing. The paper is about 0.003 in. thick, so you should be able to remove it with a slight drag. TECH TIP • Most manufacturers do not publish clearance or size specifications for bushings; a few publish thrust washer thickness specifications. • If you want to measure bushing clearance to gain experience, use the rule of thumb that anything over 0.006 in. (0.152 mm) is excessive.

  11. FIGURE 17-9 Special tool SP-3629 is being used to drive the bushing out of the clutch housing (top). Note that special tool SP-5511 for the bushing installation has a lip that prevents installing the bushing too deep (bottom). (Courtesy of Chrysler Corporation) BUSHING, BEARING, AND THRUST WASHER SERVICE • Bushing Removal • Several methods can be used to remove a bushing. • Always check and note the position of any grooves or oil passages.

  12. FIGURE 17-10 A slide hammer (a) with a remover adapter (b) can be used to pull a bushing from its bore. (Courtesy of ATEC Trans-Tool and Cleaning Systems) BUSHING, BEARING, AND THRUST WASHER SERVICE

  13. FIGURE 17-11 A chisel is being used to cut a groove through the bushing so it can be collapsed. Be careful to not damage the bushing bore. BUSHING, BEARING, AND THRUST WASHER SERVICE

  14. FIGURE 17-12 The special toolset threads into the bushing; turning the nut at the top will pull the bushing out. (Courtesy of Chrysler Corporation) TECH TIP • Very small bushings are usually removed by cutting threads in them so a slide hammer can be threaded into the bushing.

  15. FIGURE 17-13 This band-adjusting screw from a C6 has a cutting groove in the threads, and the nut has been welded into place. With the use of an air wrench, it can cut threads into the bushing at the front of a TH 350 mainshaft; it will bottom in the bore and force the bushing out. TECH TIP • Technicians are very resourceful; they design special tools that may be better than those designed by the vehicle manufacturer.

  16. FIGURE 17-14 Bushing drivers are used to drive bushings into the proper position. (Courtesy of Chrysler Corporation) BUSHING, BEARING, AND THRUST WASHER SERVICE • Bushing Installation • A bushing installer should be used to push the new bushing into its bore to prevent damaging it or the bore. • This is often the same tool that was used to remove the bushing.

  17. FIGURE 17-15 Some bushings are locked into position by staking them using a blunt punch. Any raised metal is then scraped off. (Courtesy of Chrysler Corporation) BUSHING, BEARING, AND THRUST WASHER SERVICE

  18. FIGURE 17-16 The cup, rollers, and cone of a tapered roller bearing are machined at an angle as shown. This allows them to resist a thrust in the direction indicated by the P arrows. The bearing is preloaded in this direction; any clearance at the sides of the bearing (C arrows) is called freeplay. BUSHING, BEARING, AND THRUST WASHER SERVICE • Tapered Roller Bearing Service • Some transaxles use tapered roller bearings.

  19. FIGURE 17-17 Special tools are often required to remove tapered roller bearings (a) and the cups (b). (Courtesy of Chrysler Corporation) BUSHING, BEARING, AND THRUST WASHER SERVICE

  20. FIGURE 17-19 This bearing set is adjusted with a selective shim placed under the bearing cup; a thicker shim will reduce the clearance or increase the preload on the bearing. (Courtesy of Chrysler Corporation) FIGURE 17-18 When roller bearings are to be reused, they should be marked or tagged so they can be put back in the same position with the same races/cups. BUSHING, BEARING, AND THRUST WASHER SERVICE

  21. FIGURE 17-20 If this bearing set is adjusted correctly, it will take 2.2 inch-pounds (in-lb) (0.2 N-m) of torque to rotate the differential. BUSHING, BEARING, AND THRUST WASHER SERVICE

  22. FRICTION MATERIAL SERVICE • There are three opinions concerning replacement of automatic transmission friction material (lined plates, unlined plates, and bands) during an overhaul: • Replace all friction material as a standard practice. • Replace all lined plates and the unlined plates and bands as needed. • Replace only the worn or damaged items.

  23. FIGURE 17-21 The lining is lifted off of this friction plate. It shows rust and corrosion that are evidence of water damage. (Courtesy of Raybestos) TECH TIP • If the lining appears to be delaminating or coming loose from the core, peel the lining off and look for rust on the steel core.

  24. FRICTION MATERIAL SERVICE • Lined Plate Service • If lined plates are to be reused, they should be carefully inspected. • The requirements for reuse of a lined plate are as follows: • The lining wear is minimal. • There must be no breaking up or pock marks in the lining. • There must be no metal particles embedded in the lining. • The lining must not come apart when scraped with a coin, fingernail, or knife blade. • The lining must not have a glazed, shiny appearance. • The lining material must not be severely discolored. • The plate must be flat. • The splined area must be flat and even.

  25. FIGURE 17-22 The lining can be easily scraped from the plate; this disc should not be reused. FRICTION MATERIAL SERVICE

  26. FRICTION MATERIAL SERVICE • Steel Plate Service • Unlined steel plates are often reused. • They must be carefully inspected before reuse: • The plate must be flat (except for wave or Belleville plates). • There must be no sign of surface irregularities. • The splined area must be flat and even. • Slightly burned plates must be replaced or reconditioned.

  27. FRICTION MATERIAL SERVICE • Band Service • If a band is to be reused, it should be checked to ensure that: • the lining material is sound with no breaking up or pock marks • the lining material does not come apart when scraped with a thumbnail or knife blade • the lining thickness is almost the same as that of a new band • the lining material is not badly discolored or does not appear burned • there are no metal particles embedded in the friction material • the end lugs appear tight and unworn

  28. FIGURE 17-23 A profilimeter shows the profile of a steel plate (a); one micro-inch (1μ in) equals 0.000001 in. The actual shape of the surface roughness can vary (b), but both of these plates have the same surface roughness. (Courtesy of Raybestos) FRICTION MATERIAL SERVICE

  29. FIGURE 17-24 This tool can rotate a basket of steel plates and special media to cause a tumbling action that cleans and retextures the surface. (Courtesy of ATEC Trans-Tool and Cleaning Systems) TECH TIP

  30. FIGURE 17-25 Two badly worn drums (a and b); both are scored and polished, and (b) shows burn marks. Four faulty bands: (c and d) two broken bands; (e) burned and flaking lining; and f is worn out. FRICTION MATERIAL SERVICE

  31. FIGURE 17-25 (CONTINUED) Two badly worn drums (a and b); both are scored and polished, and (b) shows burn marks. Four faulty bands: (c and d) two broken bands; (e) burned and flaking lining; and f is worn out. FRICTION MATERIAL SERVICE

  32. FRICTION MATERIAL SERVICE • New Friction Material Preparation • New friction material must never be used in a dry, unlubricated condition. • Dry lining acts like an insulator. • It easily overheats and burns from the heat of friction created during the first shift. • The lined material should be soaked in ATF for at least 20 minutes before installation; some shops soak the plates overnight.

  33. FIGURE 17-26 Stamped steel drums should be checked for dishing. There should be no clearance between the drum and the straightedge. TECH TIP • Some transmissions use a drum made from a steel stamping rather than from a forging or a casting. • These units should be checked for dishing by laying a straightedge along the drum surface

  34. FIGURE 17-27 If a drum surface is polished, it can be sanded to roughen the surface. If a paper band is used, sand around the drum using 120-or 180-grit emery cloth or sandpaper. If a fabric band is used, sand in a front-to-back direction using 40- to 60-grit sandpaper. TECH TIP • If the drum surface is smooth but polished, it can be sanded to produce a better finish. • If a paper-lined band is used, use 150- to 160-grit sandpaper, and sand in a direction that goes around the drum

  35. FIGURE 17-28 Four styles of Teflon rings; the uncut, continuous ring requires special tools for installation. The other styles are placed into the groove with overlapping ends positioned properly. INTERNAL SEAL SERVICE • An important part of a transmission overhaul is the correct replacement of the internal seals.

  36. FIGURE 17-29 Each of these accumulator pistons has an O-ring seal that should have a snug fit in the bore. (Courtesy of Toyota Motor Sales USA, Inc.) INTERNAL SEAL SERVICE • Fitting Rubber Seals • Always check a seal in the bore where it will operate. • In most cases, this takes very little time. An O-ring seal (round or square-cut) is first checked by placing it in the bore by itself.

  37. FIGURE 17-30 The inner piston seal is installed, and the piston is slid into the bore to check its fit (step 1).The piston is removed, and the fit of the outer seal is checked (step 2).Then both seals are installed and lubricated, and the piston is installed for the final time (step 3). TECH TIP • The seals can be checked for size by placing them one at a time in their operating position. • Start with the seal that is easiest to remove and replace. • Place one seal on the piston, lubricate it with ATF, and work it into the bore. • Now stroke the piston, and feel for drag

  38. FIGURE 17-30 (CONTINUED) The inner piston seal is installed, and the piston is slid into the bore to check its fit (step 1).The piston is removed, and the fit of the outer seal is checked (step 2).Then both seals are installed and lubricated, and the piston is installed for the final time (step 3). TECH TIP

  39. FIGURE 17-31 A piston should be checked for any signs of damage, porosity, nicks at the seal groove, and a missing or stuck check ball. INTERNAL SEAL SERVICE • Installing Pistons with Lip Seals • The clutch piston should be inspected before seal installation

  40. FIGURE 17-32 Piston and seal installation can be made easier if a film of wax lubricant is smeared around the seals and seal area. TECH TIP • Wax lubricant, often called door ease, is commonly used for vehicle door or hood striker plates. • Smearing a film of wax lubricant around the seal and at the edge of the bore is often just enough lubricant to allow the seal to slip into the bore.

  41. FIGURE 17-33 When the piston is installed, the seal tends to catch on the upper end of the piston bore (a,arrow). A thin feeler gauge or shop-made seal installing tool can coax the seal past this edge (b). TECH TIP • Seal installation tools are commercially available or you can make one by rounding the edges of a feeler gauge that is 0.005 to 0.010 in. (0.15 to 0.25 mm) or squeezing a bent, thin piece of piano wire into the end of a small tubing.

  42. FIGURE 17-34 Two seal guides can be placed into the clutch drum. With the new seals lubricated, the piston can be installed without seal lip damage. TECH TIP • Seal guides are available for some clutch units. • These are smooth steel bands with a slight funnel or cone shape.

  43. FIGURE 17-35 An extension housing O-ring seal has been placed over the piston lip seal of this front clutch. It reshapes the sealing lip to make installation easier. TECH TIP

  44. FIGURE 17-36 After the clutch is completely assembled, the condition of the seals can be verified by an air check. The dial indicator will give an accurate measurement of the clutch pack clearance. (Courtesy of Toyota Motor Sales USA, Inc.) TECH TIP

  45. FIGURE 17-37 A sealing ring is forced outward, away from the fluid pressure. It tends to wear into the sides of the seal grooves. INTERNAL SEAL SERVICE • Fitting Sealing Rings • A sealing ring has to make a seal on one of its sides and at the outer diameter. • Fluid pressure plus the elasticity of the ring pushes the ring outward, where it engages the bore.

  46. FIGURE 17-38 A metal sealing ring has been hooked and placed into its bore. It should enter with a slight pressure and make full contact with the bore. There should be a slight gap at the ends of the ring as shown. INTERNAL SEAL SERVICE

  47. FIGURE 17-39 Side clearance of a metal sealing ring is checked by placing the ring into the groove and measuring the clearance using a feeler gauge (a). While making this check, look for damage to the seal groove (b). INTERNAL SEAL SERVICE

  48. FIGURE 17-40 Compressing a seal ring helps it fit tight in its groove (a). During installation, make sure the ends interlock properly (b). (Courtesy of Chrysler Corporation) INTERNAL SEAL SERVICE • Installing Teflon Sealing Rings • Scarf-cut, Teflon sealing rings are easy to install. • Merely place them in the groove with the ends lapped in the correct direction.

  49. FIGURE 17-41 This Teflon seal installation set allows you to stretch a seal ring, position it in the groove, and resize the seal so it has the proper fit. (Courtesy of ATEC Trans-Tool and Cleaning Systems) INTERNAL SEAL SERVICE

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