SERVICE BULLETIN (Not applicable to Mack Trucks Australia) (Supersedes bulletin SB-323-006 dated 8/7/01) NUMBER: SB-323-006 DATE: 3/11/03 MODEL: T2060A, TM309, TM308, T306G T2060A, TM309, TM308 AND T306G TRANSMISSION SHIFTABILITY/ RELIABILITY IMPROVEMENTS In order to improve shiftability and reliability of the T2060A transmission, several enhancements to the shift cover, countershafts and mainshaft were implemented into production December 1, 2000, beginning with transmission serial No. 0Y0005. These enhancements can be made to any T2060A transmission manufactured prior to December 1, 2000 should instances of hard shifting, gear lever hang-up or gear disengagement be encountered, or if the transmission is disassembled for repair. REV One of the shiftability/reliability enhancements implemented into production on T2060A transmissions was a shorter first-speed spacer (part No. 31KD1162P7). The length of this spacer is 1.425 (36.20 mm), whereas the length of the previously used spacer (part No. 31KD1162P6) is 1.5 (38.1 mm). It has been determined, however, that the shorter spacer allows the shift lever to get caught on the reverse shifter stop inner plunger. To correct this condition, the first-speed spacer reverted back to the original part number spacer (31KD1162P6). This change, which was implemented into production approximately early December 2002, also affects TM309, TM308 and T306G model transmissions. Should gear lever hang-up in first gear be experienced on a T2060A, TM309, TM308 or T306G transmission, the existing first-speed spacer should be replaced with spacer part No. 31KD1162P6. 1 Figure 1 First-Speed Shift Rail Hang-Up on Reverse Shift Stop Inner Plunger SB-323-006 Page 1 of 9 SERVICE PUBLICATIONS, ALLENTOWN, PA 18105 MACK TRUCKS, INC. 2003
T2060A Shift Cover Improvements Whenever the shift cover is removed from the transmission for any type of service or repair, the following improvements should be made. 2 Figure 2 T2060A Shift Cover Arrangement Exploded View REV Key Part No. Description Replaces 1 31KD1162P6 1st speed spacer/stop 31KD1162P7 2 699KC344B 3rd/4th shifter 669KC344A 3 31KD1162P8 3rd speed spacer/stop 31KD1162P4 4 107KD259 5th/6th shifter detent spring 107KD254 5 699KC352 Reverse shifter 669KC345 6 107KD258 Inner spring, reverse shifter plunger 7 446KC26 Retainer, reverse shifter plunger spring 8 97AX106 Snap ring 97AX106 9 107KD254 Outer spring, reverse shifter plunger 107KD254 10 411KC33 Plunger, inner, reverse shifter stop 11 411KC221 Plunger, outer, reverse shifter stop 411KC220 12 301KC283 Shift rail interlock pin 48AX19 13 301KC242 Shift rail interlock pin 301KC248 SB-323-006 Page 2 of 9
3 Shift Lever Stops Shift lever stops provide the operator with a positive feel for gearclutch engagement, and they keep the shift lever in a consistent position. Stops were always used in the reverse, fifth and sixth speed positions, and were added to the shift cover arrangement in the first, second third and fourth speed positions on 6/2/99, beginning with transmission serial No. 9M0112. Beginning 12/01/00 (transmission serial No. 0Y0005), the stop spacers in the first and third speed positions were made narrower to ensure full engagement of the gears. If a shift cover is being overhauled, these spacers should be checked to be sure the proper spacers are installed, and if the cover does not have the spacers, they should be installed. Part numbers for the stop spacers are as follows: Figure 3 T2060A, TM308 and T306G Shift Cover Stop Spacers REV Key Part No. Description Replaces 1 31KD1162P8 3rd speed spacer, 0.300 (7.62 mm) 31KD1162P4 2 31KD1162P3 3rd/4th speed spacer, 0.220 (5.58 mm) 3 31KD1162P6 1st speed spacer, 1.5 (38.1 mm) 31KD1162P7 4 31KD1162P5 2nd speed spacer, 0.450 (11.43 mm) After installing the spacers, shift the rail into gear and make sure the spacer can be rotated when the shift rail has completed the shift. SB-323-006 Page 3 of 9
4 3rd/4th Speed Shifter To improve durability and maintain shift quality, the 3rd/4th speed shifter has been changed to an induction hardened component. Figure 4 3rd/4th Speed Shifter Key Part No. Description Replaces 1 699KC344B 3rd/4th speed shifter 699KC344A SB-323-006 Page 4 of 9
5 Reverse Gear Shifter Plunger Arrangement A new-style dual plunger for the reverse gear shifter has been designed to prevent inadvertent or unexpected first gear engagement from neutral. The plunger extends from the reverse gear shifter into the first-speed shifter fork slot. Spring load on the plunger provides resistance against shift lever movement, and requires approximately 12 pounds of force to move the lever. Figure 5 Reverse Speed Shifter Spring and Plunger Arrangement Key Part No. Description 1 97AX106 Snap ring 2 446KC26 Retainer, shift plunger spring 3 107KD258 Spring, inner, reverse shifter plunger 4 699KC352 Reverse shifter 5 411KC221 Plunger, outer, reverse shifter stop 6 411KC33 Plunger, inner, reverse shifter stop 7 107KD254 Spring, outer, reverse shifter plunger Whenever the transmission shift cover is disassembled for any reason, install the new reverse shifter if it has not already been installed. SB-323-006 Page 5 of 9
6 Shift Rail Interlock Pins The shift rail interlock balls used in the previous T2060A transmission shift covers were changed to a cylindrical interlock pin. This change will provide smoother shifting and eliminate shift hang-ups. Because of the dimensional differences between the interlock balls and the cylindrical pins, the shift rail interlock pins have been changed to a longer pin. 7 Figure 6 Current Shift Rail Interlock Pin and Previous Shift Rail Interlock Ball Figure 7 Current and Previous Interlock Pins SB-323-006 Page 6 of 9
Countershaft/Mainshaft Improvements Whenever the transmission is disassembled for reasons such as damaged gears or worn countershaft spacers, the sixth speed washer, countershaft front and rear spacers and the countershaft third speed gear should be replaced with the components outlined in the chart below. These components, which will improve shift quality and reliability, will change the mainshaft gear end plays to the revised dimensions as follows: 8 0.023 0.039 between second and third speed gears 0.020 0.035 between fourth and sixth speed gears Figure 8 T2060A Countershaft and Mainshaft Component Changes Key Qty. Part No. Description Replaces 1 1 228KD236AP200 228KD236AP215 228KD236AP230 Spacer, mainshaft, size to achieve 0.020 0.035 end play between 4th and 6th gears. P equals spacer thickness 223KD241 2 3 31KD329B Spacer, countershaft, rear 31KD329A 3 3 757KB3359A Countershaft gear, 3rd speed 757KB3345 4 3 31KD332 Spacer, countershaft, front 31KD330 Do not intermix components. SB-323-006 Page 7 of 9
The T2060A Transmission Service Manual, 10-108, outlines the transmission reassembly for both the slow reverse ratio and the standard reverse ratio transmissions. With the slow reverse ratio transmissions, the mainshaft is assembled by sliding the shaft into the back of the transmission after first installing the countershafts and the mainshaft gears into the transmission case. With the non-current fast reverse ratio transmissions, the mainshaft gears are assembled onto the mainshaft outside the transmission and then installed into the transmission through the shift cover opening after first installing the lower-center and upper-left countershafts. To simplify assembly procedures of the fast reverse ratio transmissions, the following two modifications can be made so that the mainshaft can be installed into the transmission the same way it is for the slow reverse ratio transmissions: Install the countershaft rear spacers (part No. 31KD329B) with the large diameter facing second gear (facing the front of the transmission). Eliminate the snap rings and washers on the mainshaft between second and third gears. With these two modifications, the fast reverse ratio transmission can now be assembled by assembling the three countershafts and the mainshaft gears into the transmission case, and then installing the mainshaft from the rear of the transmission. Do not install the two upper countershaft rear bearings until the shafts are in place and timed correctly. Refer to the T2060A Service Manual, 10-108. SB-323-006 Page 8 of 9
9 Figure 9 T2060A Standard Reverse Ratio Transmission Modifications for Ease of Mainshaft Reassembly Mack Trucks, Inc. engages in a continuous program of testing and evaluating to provide the best possible product. This program naturally results in design changes and improvements. Mack Trucks, Inc., like other manufacturers, reserves the right to make these changes in design, or to make additions or improvements in its product without any obligation to install them on products previously manufactured. SB-323-006 Page 9 of 9