Symptoms:

  • 1-2 Flare
  • 2nd Slip
  • 5-6 Flare
  • 6th Slip
  • B1 band burned
  • Gear ratio & solenoid codes
  • Erratic shift timing
  • Harsh shifts

Cause:

Oscillation of the B1 band control valve causes bore wear, allowing critical pressure loss that prevents proper hydraulic actuation of servo and B1 band.

Correction:

Recover hydraulic control and renew shift performance by reconditioning the bore and installing Sonnax oversized B1 band control valve kit.

Warning:

Required tool kit F-39741-TL48 is no longer in production. Check with your distributor for availability.

TF-80SC, TF-81SC

Oversized B1 Band Control Valve Kit
Part No. 39741-48K

Also fits Volvo (AM6); Opel (AF40); Peugeot (TF80); Saab (AF40/6); LandRover (TF80); Ford (AF21) & Mazda (AW6A-EL).


You need this if... View Instructions Find a Distributor

The B1 band in Aisin AW TF-80SC and TF-81SC transmissions is applied in 2nd and 6th Gears in conjunction with other clutch packs. As the B1 band control valve oscillates and strokes over time, bore deterioration results which prevents proper hydraulic control of the B1 band. This can cause flares, harsh shifts, slipping, erratic clutch apply timing, ratio codes, and a burnt B1 band. Reconditioning the bore and installing Sonnax oversized B1 band control valve kit 39741-48K restores normal shift operation and feel by re-establishing the hydraulic integrity of the B1 circuit.

  • New spring matches OE calibration
  • Hardcoat anodized aluminum valve combats premature wear
  • Annular grooves help center valve in bore to reduce future side-load wear
  • Valve
  • Spring

Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.

Aisin AW TF-80SC Valve Body Layout

Aisin AW TF-80SC Valve Body Layout

Aisin AW TF-81SC Valve Body Layout

Aisin AW TF-81SC Valve Body Layout
  • TF-80SC, TF-81SC Oversized B1 Band Control Valve Kit 39741-48K
  • TF-80SC, TF-81SC Oversized B1 Band Control Valve Kit 39741-48K

You need this if...

Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.

TF-80SC, TF-81SC Oversized B1 Band Control Valve Kit Vacuum Test Locations