TransGo 48RE-HD2 Reprogramming Kit Installation Guide

About the Kit

Fits: All 48RE transmissions, except hybrid Converted VB's.

Features:

• Faster and more line rise
• More line boost in 4th gear and lockup
• Increased flow to the Direct Clutch and Band Release
• Shifts that are clean and hold power

48-RE Application Notes:

• 8th VIN digit = C indicates a 48RE Transmission.
• 8th VIN digit = 6 indicates a 47RE Transmission.

Important Considerations:

• Exercise caution when swapping parts.
• 48-RE Channel Casting must use a 48-RE Separator Plate and is only used in trucks that originally came with a 48RE.
• This kit only fits OE 48-RE Valve Bodies (VB's).

Component Details:

• 48RE Separator plates feature a small balance hole.
• 48RE transmissions use a bushing with notches and a one-piece boost valve.
• 48RE Channel Castings have two holes that pass through the casting and connect on the backside.

Note for Existing SK 48RE Kit Users: If installing this kit into a Valve Body that previously had an SK 48RE kit installed, ensure all springs and plates are swapped out due to calibration changes.

Document Date: 07 April 2020

Installation Steps

Step 1: Seal Rings

If the transmission is disassembled, install the Seal Rings. This includes one small seal and two large seals. Note: Two smallest rings are not furnished in the kit.

Clutch Clearance Note: High Clutch Clearance less than .085” can cause a 2-3 Bind-up. A clearance of .085" to .095" is considered perfect. Adding plates to reduce clearance is not the correct approach.

Step 2: Front Servo Piston

Install the stock Front Servo piston with all apply levers. Install a new Thick washer as shown. Reuse the original Return spring.

Special Note: If using an aftermarket oversized Front Servo with an apply lever greater than 4.2, discard the original servo return spring and use the new White spring without the new Thick washer.

Front Band Adjustment: Set the front band snug with a short wrench, then back it off 1 1/4 turns.

Step 3: 2nd Accumulator

Install the new short plain lower 1-2 Accumulator spring as shown. Some models may use the upper spring; reuse it if equipped.

Step 4: Optional Rear Servo (for Maximum 1-2 Firmness)

If maximum 1-2 firmness is desired, install the Tapered Orange return spring with the large OD end into the servo piston. Install the new spacer inside the cushion spring as shown. Refer to Page 7, Step 4 for additional details. This step is not recommended for Towing or Work Trucks.

Note: The new Orange spring is designed only for original 48RE's smaller rear servo with a matching double wrap band.

Step 1 (Drilling): Drill Guide Plate Installation

Borrow two short screws from the Valve Body (VB) and mount the drill guide plate to the VB. Ensure the word "UP" faces UP and is positioned on the upper right-hand side. This process involves removing a small portion of the VB wall using a drill bit and a drill "depth-stop" spacer.

Drilling Preparation: Tighten the screws to prevent the plate from moving during drilling.

Step 2 (Drilling): Drill Depth Setting

Using the provided Wound Spacer, adjust the 3/16" drill bit into the drill chuck so that only .435" of the drill is sticking out of the spacer. This setting will prevent the drill from going too deep. Do not drill through the VB.

Step 3 (Drilling): Drilling the VB Wall

Using the Spacer as a stop, drill straight down into the designated hole with the 3/16" drill bit. Drilling is complete when the drill stop spacer contacts the guide.

Visual Confirmation: Drilling is completed, showing the wall removed.

Step 4 (Drilling): Finalizing Drill Plate Removal

Remove the Drill Plate and reinstall the two borrowed screws.

Multi-Disc Converter Installation Note

If installing a Multi-Disc Converter, SKIP Step 1.

Step 1 (Converter): Drilling for Lockup

Drill one or two holes (.076" - .082" diameter) down through the bottom of the most outboard passage.

• One Hole = Slightly firmer lockup
• Two Holes = Much firmer lockup

Step 2 (Converter): Valve Body Modification

Turn the valve body over. Using the edge of a large file, file a notch approximately halfway through the thickness of the partition. Clean the VB of all drill and filing debris.

Filing Detail: File a notch across the bore, side to side. Precision is not critical.

Tip: A large countersink bit in a cordless drill can provide a neater finish. Ensure not to go past 1/2 the casting web thickness. Do not use a drill bit in place of a countersink.

Step 3 (Converter): Lockup Bracket Installation

Install the new Lockup Bracket. Ensure to reuse specified parts.

Step 4 (Converter): Original Plate Check

Check the Original Plate. If its hole is smaller than .082", enlarge it to .082". If it is already larger, it is acceptable.

Step 1: Rooster Comb and Manual Valve

Remove the Rooster Comb. Discard the original manual valve, detent ball, and spring. Test fit the new bullet and spring in the VB for free movement. If necessary, remove any burr inside the bore created by wear from the original ball. Insert the New Spring and Bullet into the VB bore, using the Mumbly Peg tool to hold the bullet in place. Insert the New Manual Valve and reassemble the Rooster Comb. Ensure the Arm Tip is indexed into the manual valve. Remove the Mumbly peg tool.

Step 2: Manual Valve Position Adjustment

With the valve fully inboard (Park Position), the right edge of the Tapered land must be flush with the right edge of partition "A". A tolerance of .030" from flush is acceptable. To adjust, bend the Arm Tip with pliers.

Step 1: Boost Valve and Spring Replacement

Remove and discard the original Boost Valve and spring. Save the original bushing.

Step 2: New Boost Valve Installation

Install the SMALL end of the tapered Orange spring onto the New Boost Valve and install it into the VB. Reuse the original bushing and install it with the notches facing the plate. Verify that the boost valve moves freely before reinstalling the plate.

Note: 48RE Bushings have notches that must face the plate.

Step 3: Small Orange Spring Installation

Discard the original spring and install the New Small Orange Spring in its place.

Step 4: Part Throttle (PT) Body Components

Install the gold spacer into the part throttle body, then install the part throttle (PT) valve.

Step 5: Transfer Plate Installation

Install the new transfer plate between the Cover and the part throttle body. Ensure the transfer plate does not go on the spring side.

Step 6: Pin Installation

Using a pick and a small hammer, taper the top of the designated hole to help start the pin. Install the furnished pin into this hole using needle-nose pliers and a small hammer. File flush if needed. The PT Body must sit flush against the VB. If this hole is already plugged from a previous SK 48RE Kit, skip this step.

Step 1: Switch Valve Notch

Grind one notch on a slight angle to about the middle of the switch valve land. Reuse the original spring.

Step 2: TV Valve and Bore

For .420" OE TV Valve & bore: Install the NEW TV Valve & Blue Spring. Reuse your original TV Plunger and Sleeve.

If you have an aftermarket Oversized Valve & Bore: Reinstall the TV lineup with a factory Orange TV Spring.

Step 3: CHERRYBOMB Installation

Install the CHERRYBOMB carefully, aligning the stem UP through the hole in the plate when assembling the VB. The kit includes one Cherrybomb and six Check-balls (five 1/4" (.250) and one 11/32" (.343)).

Step 4: Optional 2nd Gear Feed Ball

This step is optional and only for achieving maximum 1-2 firmness, provided rear servo parts were installed per Page 2, Step 4. Remove this ball. This step is not for Towing or Work Trucks.

Shift Feel Considerations

When this kit is correctly installed in a good transmission and paired with a properly set up Torque Converter for efficiency, shifts will be short with a quick drop in engine RPM, engine tone, or a slight forward acceleration feeling. This is sufficient for long-term durability.

If the truck lacks a noticeable RPM drop, tone change, or slight forward acceleration feeling during shifts (described as accelerating through warm butter), and only the firmness of lockup is felt, investigate the Torque Converter efficiency, not the transmission itself.

FYI: Aggressively altering gear train engagement during shifts necessitates higher-cost parts.

Step 1: Lower VB Plate Placement

Place the Lower VB Plate on the bottom of the Channel Casting, using two VB bolts to align it.

Step 2: Lower VB Plate Drilling

A hole needs to be added to the small Lower VB Plate. Use the channel casting as a drill guide. Place the plate on the bottom of the channel, align it using two VB bolts, then flip it over. Use the rectangular passage as a guide to drill a .101" hole through the lower plate.

Note: This step involves two 1/4" Check-balls.

Step 3: New 48-HP Plate Installation

Install the New 48-HP Plate. No drilling is necessary for this plate.

Step 4: Orange Spring Installation

Install the new ORANGE spring in the designated location.

Important Note: Small Holes

Ensure these small holes are clean. Failure to do so will result in NO 4th gear and/or NO Torque Converter Clutch (TCC) engagement. DO NOT enlarge these holes. A .020" paper staple can be used to clean debris from the smaller of the three holes.

Step 1: Accumulator Plug Installation

Using a small punch, drive the aluminum Plug into the hole just below flush. If this hole is already plugged and the housing was cross-drilled from a previous SK 48RE Kit, skip this step.

Step 2: Tapered Plug Installation

Using a small punch, drive the tapered PLUG just below flush into the hole. If this hole is already plugged from a previous SK 48RE Kit, skip this step.

Step 3: Limit Bushing and O-ring

Install the New O-ring on the small end of the Limit Bushing as shown, along with the 3/16" Ball and White spring. The O-ring serves as a shim to compensate for casting variations, not for sealing.

Step 4: Transfer Plate Installation

Install the new transfer plate as shown between the lower VB and the Accumulator housing.

Step 5: Spring Replacement

Discard the original spring and install the new Red Springs.

Step 6: Vented Cover Installation

Install the new Vented cover provided.

Step 1: Solenoid Body Plate Assembly

Install the new plate against the channel casting, followed by the gasket and the solenoid body. Note: A 3/16" Check-ball is involved.

Step 2: PR Valve Shim and Spring Seat

Install the new shim and spring seat onto the PR valve before installing the new inner and outer PR springs. Ensure the flat on the spring seat has clearance from the casting. File the casting if necessary to allow slight rotation. Do not allow the spring seat to bind between the PR valve and the casting.

Step 3: TV Back Stop Adjustment

Adjust the TV Back Stop from the Plate to the inside of the bolt shoulder to .910" with the new TransGo TV Valve.

Step 4: PR Adjustment

Using a 3/16" Allen wrench, turn the adjusting screw clockwise until the spring seat is just flush against the inside edge of the spring retainer.

Line Pressure Specifications

48RE-HD2 Kit & PR Set to Flush Max Line:

• 1st-3rd gears: 145-Psi at Wide Open Throttle (WOT)
• 4th gear & Lock-up: 185-Psi at WOT
• Reverse: 310 WOT

Recommendation: While pressures can go higher, it is not recommended. Adjusting PR by 3 turns can result in maximum pressure in 4th & Lockup exceeding 200Psi, which is sufficient to cause damage. It is advised to leave the adjustment flush.