SIL 20-1K2K-20 Service Bulletin/Repair Instructions

SIL 20-1K2K-20

November 13, 2020

Page 1 of 2

SUBJECT:
Redesigned C1 Piston Sealring
MODELS AFFECTED:
1000 and 2000 Series Transmissions
Introduction:

As a continuous product improvement, Allison Transmission has redesigned the C1 piston sealring to improve the

installation of the C1 piston. The C1 piston and C2 piston previously shared a common sealring, P/N 29542809.

The redesigned C1 Piston Sealring P/N 29562692 was released in October 2019 to be used exclusively with the

C1 piston. The former C1 Piston Sealring P/N 29542809 continues to be used with the C2 piston. Refer to Table 1.

NOTE: Current C1 piston sealring was implemented into production on: 6/19/2020 (Indianapolis),

9/23/2020 (India), and 9/17/2020 (Netherlands).
Table 1. Pistons and Associated Sealring Part Numbers

Clutch
Sealring P/N
C1 Piston
29562692
C2 Piston
29542809
Identification:

The current C1 piston sealring can be identified by matching the C1 piston sealring to the C2 piston sealring. The

diameter of the current C1 piston sealring is smaller. In addition, a color indicator has been implemented to

the current sealring. The former C1 Piston Sealring P/N 29542809 is black and the current C1 Piston Sealring

P/N 29562692 is purple. Refer to Figure 1.

NOTE: Color indicator is meant for initial assembly and may fade over time. Piston diameter and unit

shipping date can be used to determine seal vintage in the field.
DH / SL8776EN
5285094
Copyright © 2020 Allison Transmission, Inc. All Rights Reserved.
SIL 20-1K2K-20

November 13, 2020

Page 2 of 2
Figure 1.

Table 2. Figure 1 Legend

Item
Description
1
Current C1 Piston Sealring 29562692
2
Former C1 Piston Sealring 29542809
Copyright © 2020 Allison Transmission, Inc. All Rights Reserved.

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