SIL 22-WT-20
January 05, 2021
Page 1 of 4
SUBJECT:

3000 SeriesTM and 4000 SeriesTM Torque Converter Damper and Turbine Changes

MODELS AFFECTED:

3000 SeriesTM, 4000 SeriesTM, B300, B400, B500, T200, T300, T400, T500 Models

Introduction:
In the third quarter of 2020, running changes were introduced to all 3000 and 4000 series torque converter models.
Changes are limited to new part number damper and turbine assemblies. In all cases, top level torque converter
assembly part numbers and groups are unchanged.
These changes have no effect on torque converter performance with respect to stall speed, torque ratio, capacity,
K-factor, or damper performance.
Former part numbers will be completely cancelled and unavailable as service parts when service stock is
exhausted. These changes dictate that when installing either of the current damper or turbine assemblies into a
former torque converter, both the damper and turbine assemblies must be replaced simultaneously. Doing so will
functionally convert the former version torque converter to the current version. Proper matching of components is
ensured by a change to the spline count for the mating damper and turbine assembly.
NOTE: The 3000 SeriesTM damper and turbine hub have changed from 40 splines to 42 splines. The 4000
SeriesTM damper and turbine hub have/will change from 46 splines to 48 splines. Refer to Figure 1.

MC / SL8799EN

5327397

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SIL 22-WT-20
January 05, 2021
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Figure 1. Current 3000 SeriesTM (Left), Current 4000 SeriesTM (Right)
Table 1. Figure 1 Legend
Item

Description

1

Current 3000 SeriesTM — From 40 splines to 42 splines

2

Current 4000 SeriesTM — From 46 splines to 48 splines

NOTE: Two service kits have been released containing damper and turbine assemblies to aid in the
servicing of former torque converters. Refer to Table 4 and Table 5.

Part Identification:
Turbine Assembly: The 3000 SeriesTM and 4000 SeriesTM have one new turbine assembly part number each, P/N
29560418 and P/N 29560448, respectively (as shown in Table 2 and Table 3 that follow). Positive identification
of current versions from former versions may be made by spline count.
Damper Assembly: The 3000 SeriesTM has three new damper assemblies, each with a unique part number. The
4000 SeriesTM has one new damper assembly (P/N 29559893). Each damper model has its respective part number
etched into the cover plate of the damper. Positive identification must be made from the part number on the part.

Part Number Matching:
Refer to Table 2 and Table 3 to match turbine and damper assemblies to their respective torque converter model.

Copyright © 2021 Allison Transmission, Inc. All Rights Reserved.

SIL 22-WT-20
January 05, 2021
Page 3 of 4
Table 2. 3000 SeriesTM Former and Current Damper and Turbine Assemblies by Torque Converter Model
3000 SeriesTM Torque Converter Assemblies
Group
Number

TC Model

21-935

TC 411

21-934

TC 413

21-933

TC 415

21-932

TC 417

21-937

TC 418

21-931

TC 419

21-936

TC 421

21-970

TC 418D

21-973

*

Former Turbine
Assembly

Current Turbine
Assembly

29503979

29560418

Former Damper
Assembly

29544144

29560358

29557862

29564212

29560418

TC 421H

Current Damper
Assembly

29558613

* Note: 21-973 TC 421H began production with the current turbine and damper

Table 3. 4000 SeriesTM Former and Current Damper and Turbine Assemblies by Torque Converter Model
4000 SeriesTM Torque Converter Assemblies
Group
Number

TC Model

21-930

TC 521

21-929

TC 531

21-928

TC 541

21-927

TC 551

21-926

TC 561

21-958

TC 571

Former Turbine
Assembly

Current Turbine
Assembly

29506620

29560448

Former Damper
Assembly

Current Damper
Assembly

29542526

29559893

New Service Kits:
Two service kits have been released, one for 3000 SeriesTM and one for 4000 SeriesTM. Refer to Table 4 and
Table 5. These kits may be used to convert former versions to current configurations or to service current version
torque converters.
Each kit contains one turbine assembly and one damper assembly. The two released kits will service the most
common converter models. Please note the TC418D and TC421H models are not covered by these kits.
Service those models with individual turbine and damper assemblies.
Table 4. 3000 SeriesTM Damper and Turbine Service Kit
Service Kit
Part Number
29564138

KIT-CONVERTER, DAMPER & TURBINE ASSY, 3K

Qty

29560418

TURBINE-CONVERTER, ASSEMBLY

1

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SIL 22-WT-20
January 05, 2021
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Table 4. 3000 SeriesTM Damper and Turbine Service Kit (cont'd)
Service Kit
Part Number
29564138

KIT-CONVERTER, DAMPER & TURBINE ASSY, 3K

Qty

29560358

DAMPER ASSEMBLY-CLUTCH, LOCKUP

1

Table 5. 4000 SeriesTM Damper and Turbine Service Kit
Service Kit
Part Number
29564139

KIT-CONVERTER, DAMPER & TURBINE ASSY, 4K

Qty

29560448

TURBINE ASSEMBLY-CONVERTER, TORQUE*

1

29559893

DAMPER ASSEMBLY-CLUTCH, LOCKUP

1

*Part Number 29560448 is not available individually. Part is only offered in Service Kit Part Number 29564139.

Existing Service Kit:
Service Kit P/N 29548989 Seal and Gasket Kit will continue to contain former Damper Assembly P/N 29544144
until stock at the Parts Distribution Center (PDC) is depleted (projected date March 2021). At that time, kit P/N
29548989 will start to contain the new 3000 SeriesTM Damper Assembly P/N 29560358.

Service Specifications:
All specifications regarding service of the torque converter assembly are unchanged. Disassembly, assembly,
and bolt torque values are unchanged. For specifics, refer to the respective 3000 SeriesTM and 4000 SeriesTM
service manuals.

Copyright © 2021 Allison Transmission, Inc. All Rights Reserved.