M/T - 4-3 Downshift/1-2 Upshift Gear Clash
File In Section: 07 - Transmission/TransaxleBulletin No.: 00-07-29-001
Date: September, 2000
Subject:
4-3 Downshift Gear Clash, 1-2 Upshift Gear Clash When Cold (Replace Affected Gear, Synchronizer Ring, Synchronizer Assembly and Transmission Fluid)
Models:
1999-2000 Chevrolet Tracker with 5-Speed Manual Transmission (RPO M59)
Condition
Some customers may comment on gear clash under the following shift conditions:
^ Downshifting from 4th to 3rd gear
^ Upshifting from 1st to 2nd gear
This condition primarily occurs with a 4-3 gear downshift. However, careful diagnosis may reveal a 1-2 gear upshift condition, particularly when cold or on an initial drive-away.
Correction
A new synchronizer spring service kit, P/N 91176347, has been released to reduce this condition. This kit includes two new springs for the 1-2 synchronizer (larger) and four springs for the 3-4 and 5-R synchronizer (smaller).
Complete manual transmission replacement is not necessary for this condition. This new spring kit and transmission fluid replacement should aid in reducing this condition and improve overall shift performance and feel.
In order to properly correct the 4-3 gear clash condition, the following components must be replaced:
3rd Gear Clash
^ The 3rd gear, P/N 91175252
^ The 3rd gear synchronizer ring, P/N 96058173
^ The 3-4 gear synchronizer hub and sleeve, P/N 96068499
^ The 3-4 gear synchronizer hub inserts (3 required), P/N 96066873
4th Gear Clash
^ The 4th gear, P/N 91174539 (1 .6L) or 91174538 (2.0L)
^ The 4th gear synchronizer ring, P/N 96058173
^ The 3-4 gear synchronizer hub and sleeve, P/N 96068499
^ The 3-4 gear synchronizer hub inserts (3 required), P/N 96066873
1. Install the above components along with new synchronizer springs in the 1-2, 3-4, and 5-R synchronizers.
2. Reassemble the transmission and fill the transmission to the appropriate level with GM Synchromesh Transmission Fluid, P/N 12345349.
If after careful diagnosis you find a 1-2 gear clash condition, replace the following components:
^ The 2nd gear, P/N 96058162
^ The 2nd gear synchronizer ring, P/N 96058172
^ The 1st and 2nd gear synchronizer hub and sleeve, P/N 96068498
^ The 1st and 2nd gear synchronizer hub inserts (3 required), P/N 96066873
Replacing each of the synchronizer springs requires the disassembly of the transmission mainshaft gears in order to access the 1-2 synchronizer.
Refer to the Manual Transmission - M59 (Tracker) sub-section of the 2000 GM Transmissions Unit Repair Manual (TURM) for transmission disassembly/assembly procedures.
Parts Information
Important:
^ Use the new synchronizer springs provided with kit P/N 91176347. Do NOT use the synchronizer springs, P/N's 91174260, 91174261, and 91175908 currently listed in the GMSPO catalog. These springs do not adequately prevent the gear clash condition.
^ Use Synchromesh Transmission Fluid, P/N 12345349, when refilling the transmission. Do NOT use GM Goodwrench(R) Synthetic Manual Transmission fluid, P/N 12346190, listed in the Service/Owner's Manual. This fluid does not adequately prevent the gear clash condition.
Parts are currently available from GMSPO.
Warranty Information
For vehicles repaired under warranty, use:
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