The B&M Shift Improver Kit, Part No. 70360, is designed for GM 4L60E transmissions manufactured between 1993 and 2006. Its primary function is to mechanically recalibrate the transmission to produce firmer, more positive shifts, reduce clutch pack heat build-up, and ultimately improve transmission life. This kit does not modify or alter shift point RPM in any range, as all shift point RPM and pressure control functions remain under the control of the Powertrain Control Module (PCM).
Function Description:
The kit aims to eliminate less desirable features of factory-calibrated shifts by allowing users to configure their transmission for two levels of performance:
- Heavy Duty: Suitable for passenger cars, street rods, towing vehicles, campers, motor homes, police vehicles, and taxis. This configuration provides improved transmission performance without a harsh shift feel.
- Street / Strip: Designed for dual-purpose performance vehicles used on both the street and track/off-road. This setting offers a firmer, more positive shift feel while still being suitable for daily driving.
The kit achieves these performance enhancements through modifications to the pressure regulator and separator plate, as well as adjustments to the accumulators. It includes various spacers, drill bits, and gaskets to facilitate these modifications.
Important Technical Specifications & Kit Contents:
The kit includes a comprehensive set of components for the modifications:
- Gaskets: Pan gasket, Gasket "C" (Case Side, 1993-2000), Gasket "V" (Valve Body Side, 1993-2000), Gasket "CA" (Case Side, 2001-2006), Gasket "VB" (Valve Body Side, 2001-2006). These are crucial for sealing and proper fluid flow within the valve body and separator plate.
- Plugs: Aluminum Plug, 1/4" DIA × 1/8". This plug is used to modify specific fluid passages in the separator plate.
- Filter Screens: Solenoid Filter Screens (1 Large + 1 Small). These are replacements for the existing solenoid filters.
- Snap Ring: Pressure Regulator Snap Ring. Used for reassembling the pressure regulator.
- Spring: Pressure Regulator Spring (Green). This is a key component for modifying the pressure regulator's function.
- Spacers:
- 3/8" Spacer - Red
- 3/8" Spacer - White
- 1/2" Spacer - Green
- 19/32" Spacer - Violet
- 5/8" Spacer - Yellow
- 3/4" Spacer - Blue
These spacers are used in various accumulator configurations to adjust shift firmness.
- Drill Bits:
- 3/32" (0.094) Drill Bit
- 1/8" (0.125) Drill Bit
These bits are supplied for drilling specific holes in the separator plate according to the desired performance level (Heavy Duty or Street/Strip).
- Anvil Plate: Used to support the separator plate when peening the aluminum plug into place.
Usage Features:
The installation process involves disassembling and reassembling parts of the transmission's valve body and accumulator system. Key steps include:
- Fluid Drainage and Pan Removal: The process begins with draining the transmission fluid and removing the oil pan and filter.
- Electrical Disconnection: Various electrical connectors for solenoids (EPC, TCC, PWM) must be disconnected. Specific instructions are provided for different model years (e.g., PWM solenoid removal for 1995+ models).
- Valve Body Removal: The valve body is carefully removed, requiring attention to screw lengths and locations, and the handling of check balls.
- Separator Plate Modification: The separator plate is cleaned, inspected for deformed check ball holes, and then drilled according to the chosen performance level (Heavy Duty or Street/Strip). An aluminum plug is installed and peened into place.
- Pressure Regulator Modification: The existing pressure regulator spring is replaced with the supplied green spring, and the assembly is reinstalled with a new snap ring.
- Accumulator Modification: This is a critical step where the choice between Heavy Duty and Street/Strip configurations dictates the specific spacers and springs used in the 1-2 and 3-4 accumulators. Detailed diagrams are provided for both 1993 and 1994-2006 models for each performance level.
- Reassembly: The transmission is reassembled in reverse order, with specific torque specifications for various screws (e.g., valve body screws to 120 in-lbs, detent spring screw to 200 in-lbs).
- Fluid Refill and Check: After reassembly, the transmission is refilled with fluid, and the fluid level is checked at various operating temperatures and shifter positions.
Maintenance Features:
The kit itself is a modification rather than a routine maintenance item. However, the instructions emphasize several maintenance-related points:
- Pre-installation Assessment: The kit is not a "cure-all" for ailing transmissions. If the transmission is already slipping, overheating, or shifting irregularly, it should be repaired before or during the kit installation.
- Cleanliness: A clean work area is essential, as transmission components are precision-fit, and burrs or dirt can cause issues.
- Documentation: Users are advised to take photos or notes of harness layouts, connector placements, and screw locations and lengths during disassembly to aid in reassembly.
- Part Organization: Immediately placing removed parts into separate containers is recommended to prevent loss or mixing.
- Filter Replacement: The oil filter should be inspected and replaced if clogged or if the transmission has accumulated 25,000 to 30,000 miles since its last service.
- Gasket Replacement: New gaskets are provided and should be used during reassembly to prevent leaks.
- Check Ball Inspection: The separator plate should be inspected for deformed check ball holes, which could indicate underlying transmission issues.
- Troubleshooting Guide: The manual includes a comprehensive troubleshooting guide for common issues that might arise after installation, such as inconsistent shift points, slipping gears, high/low oil pressure, and harsh shifts. This guide helps diagnose problems related to incorrect assembly, damaged components, or misadjusted linkages.
- Technical Support: B&M Performance provides technical support for assistance with installation or troubleshooting.
Safety Precautions:
- Always work safely, parking the vehicle on a clean, level surface.
- Securely support the vehicle with a lift or jack stands to prevent crushing injuries. Never work under a vehicle supported only by jacks.
- Allow the transmission to cool down to avoid burns, as operating temperatures typically range from 150-200°F.
- Prevent oil pan leaks by not overtightening pan screws.
- Ensure the pressure regulator snap ring is fully seated in its groove to prevent loss of line pressure.
The B&M Shift Improver Kit is designed for stock or moderately enhanced vehicles and is not intended for all-out racing applications. It provides a customizable solution for improving the driving experience and longevity of GM 4L60E transmissions.
To Next Page
Need help?
General
