A/T - 4L60 No Reverse or Delayed Reverse

9220pontiac01

Bulletin Number:
91-7-42A
Reference Number:
277111
Publish Date:
4/92


Subject:
NO REVERSE/DELAYED REVERSE COLD (INSTALL LONG LIPPED REVERSE INPUT CLUTCH PISTON OUTER SEAL)

Models
Affected:
1989-91 FIREBIRD MODELS


This bulletin is being revised to include Figure 1. This bulletin cancels and replaces bulletin 91-7-42 issued 3/92. Please discard bulletin 91-7-42.

TRANSMISSION APPLICATION:
1989-91 HYDRA-MATIC 4L60 (MD8)

TRANSMISSION MODELS:
All

Bulletin Covers:

Some 1989-1991 HYDRA-MATIC 4L60 (THM 700-R4) transmissions may exhibit a 'no reverse' or 'delayed reverse' condition when outside temperatures are below zero degrees Fahrenheit.

Service Information:

A transmission is considered to have a delayed reverse condition if it takes longer than three seconds for the transmission to engage when shifted into the reverse range.





If a transmission has a 'no reverse' or 'delayed reverse' condition, inspect the reverse input clutch piston outer seal. Determine if the seal is a 'short lip' or 'long lip' design by comparing it to Figure 1. If it is a short lip design, replace it with a long lip seal contained in the service packages listed under Service Parts Information.

If the reverse input clutch piston outer seal is a long lip design, or the newly installed long lip seal doesn't alleviate the delayed reverse condition, the reverse input clutch housing may be out of round. Inspect the housing and replace if necessary.


Service Parts Information:

The long lipped seals are available in several service packages.

Description Part Number

Pkg - Overhaul Seals and Gaskets 8683958

Pkg - Overhaul Repair Complete 8683959

Parts are available at GMSPO.

Service Manual Reference:

Refer to the HYDRA-MATIC 4L60 Automatic Transmission Unit Repair Section of the appropriate Service Manual for instructions on installing the reverse input clutch seals.