Shift improvement kits are considered mainly for improving performance. However, they also give an AODE/4R70W greater longevity because they reduce and even eliminate slippage, allowing clutches and bands to engage with a minimum of deterioration. And while clutches and bands are making solid engagement and doing their jobs, more power is getting to the drive wheels.
This Tech Tip is From the Full Book, FORD AOD TRANSMISSIONS: REBUILDING AND MODIFYING THE AOD, AODE AND 4R70W. For a comprehensive guide on this entire subject you can visit this link:
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Few companies know more about shift improvement than TransGo, which has been serving automatic performance enthusiasts for more than a half century. The SK AODE Shift Kit by TransGo, designed for the AODE and 4R70W/4R75W, is engineered to eliminate slippage, harshness, and excessive wear in your AODE/4R70W-series transmission. Shift kits reduce wear and tear by firming up and improving shift timing via increased line pressure.
“Line pressure” is transmission tech talk for hydraulic pressure made by the front pump, which is driven by the spinning torque converter, which is tied to the engine’s crank-shaft and flexplate. When the engine is running, your transmission’s hydraulic system is alive with line pressure.
A shift improvement kit is engineered to change line pressure control strategy, which means how clutches and bands engage and with how much control pressure. When line pressure is channeled into the valve body, it becomes control pressure. Because shift improvement kits vary, it is important to understand the differences. There are mild street shift improvement kits that increase control pressure to give you a firm shift and yield more transmission life. There are tow-vehicle shift kits that not only firm the shift, but allow your transmission to go further in a given gear range before upshift occurs. And there are all-out race-oriented shift improvement kits that jar your teeth, smacking clutches and bands with super-firm engagement for uninterrupted power transfer to the rear axle.
The TransGo SK AODE Shift Kit approach to shift improvement is based on a tremendous amount of research and development. TransGo says it developed this kit due to repeated complaints about shift quality from AODE and 4R70W performance enthusiasts. Excessive slippage and parts breakage led TransGo to develop a system that increases line pressure and shift timing, along with reduced harshness at WOT.
The SK AODE Shift Kit changes the AODE/4R70W high-speed down-shift from 4-2 to 4-3-2 before the engine and torque converter have time for a runaway that ultimately shatters the one-way roller clutch. This kit also improves clutch fluid loss that damages the overdrive band and forward clutch.
While your AODE/4R70W is apart, TransGo recommends using its special forward clutch sealing rings with the chamfer side away from the fluid feed hole.
Whether you are using a TransGo shift improvement kit or another from B&M, TCI Automotive, LenTech, Baumann Engineering, or Performance Automatic, follow the instructions to the letter and never mix up the kits interchange components from one kit to another. Each is unique to its manufacturer and has been developed to operate accordingly.
When it is time to road-test your vehicle, take note of the shift-points and vehicle speed. Watch the shift-points during throttle tip-in. Observe the downshift-points and the harshness. You should not be able to feel downshifts if the shift improvement kit has been properly engineered and you have installed it correctly.
Step 1: Disassemble Valve Body
Remove the cover plate, taking note of where each bolt is. Take pictures as you go regard-less of what you have for detailed instructions. You need to know how it all went together before it is taken apart. Lay everything out as it came out of the valve body and take detailed pictures.
Step 2: Remove Shift Valve Assembly (Critical Inspection)
Remove the shift valve assembly. Inspect the shift valves, also known as shift solenoids SS1 and SS2. Replace the seals on both valves.
Step 3: Remove Converter Clutch Solenoid
Remove the MCCC. Replace the seals. While you’re holding this part, closely inspect the solenoid and valve. Look for discoloration at the solenoid, which indicates overheating and warrants replacement.
Step 4: Lift Off Cover Plate
Remove the valve body cover plate and inspect the passages for contaminants. This is the time to take pictures of this side of the valve body before ﬂipping it over and disassembling the other side.
Step 5: Inspect Valve Body
The valve body inspection reveals a complex maze of passages. This is the side facing the pan with the filter and solenoids. There are no check balls in this side.
Step 6: Remove Stiffener Plates
This is the plate that faces the transmission case. Take pictures as you go and be mindful of where fasteners go. Remove these stiffener plates, which are also ﬂuid passages.
Step 7: Lift Off Separator Plate
Carefully remove the separator plate, making sure you do not disturb any of the check balls and other small parts inside. Take pictures of the check ball locations and examine the passages for contaminants.
Step 8: Remove Valve Body with Separator Plate
Once the separator plate is removed, examine the valve body passages and take a picture before disassembly begins. Take note of where all the check balls and other small parts are located (arrows).
Step 9: Remove Filter Screen
Remove this tiny filter and either replace or reuse it. If reused, it must be cleaned. This filter is designed to trap contaminants and keep them out of the valve body passages and valve assemblies.
Step 10: Remove Drainback Valve
This drainback valve is temporarily removed during shift kit installation. The drainback valve is there to keep ﬂ uid from leaving the torque converter and overfilling the transmission sump.
Step 11: Inspect EPC Relief Valve
TransGo provides an EPC pressure relief valve, which corrects uncontrolled line pressure if there is an electrical malfunction, sticking EPC valve, or cross-leakage. It also prevents accidental neutral and reapply that can break the one-way roller clutch or stub shaft. The paper clip is used for installation only and is removed once the EPC relief valve is installed.
Shift Accumulator Installation
Step 1: Install 2-3 Shift Accumulator
TransGo says if you have an aluminum piston and the hole in the small end is deeper than the large end you should use the blue spring. If the hole in the large end is deeper, use the washer with the red spring, then install the spacer in the large end. If you have a steel piston, use the blue spring.
Step 2: Install 2-3 Shift Accumulator Washer and Spacer
If you have an aluminum accumulator and the hole in the small end is deeper than the big end, use the blue spring without this washer. If the hole in the big end is deeper, lay this washer in the accumulator piston and use the red spring. If the hole in the bottom of the aluminum piston is deeper than the small end, use the thicker spacer TransGo has provided in the kit at the bottom of the accumulator piston, but not inside the piston.
Step 3: Install Proper Spring
If you go with the solid spring and the blue spring per TransGo’s instructions, lay the washer in first (as shown here).
Step 4: Install 2-3 Shift Accumulator Cover and C-Clip
Once you have the right combination of 2-3 shift accumulator springs and washer/spacer in the bore, install the cover and verify the proper seating of the C-clip.
Step 5: Install Tapered Orifice
Discard the factory’s thimble-shaped filter and install one of two provided tapered orifices included in the kit. You want a snug fit but you don’t want distortion, so be very careful when driving this orifice in place.
Separator Plate Modification
Step 1: Mark Separator Plate
Drill/modify the separator plate per the included TransGo illustration. Keep in mind no two shift improvement kits are engineered the same way, so don’t think you’re going to outsmart the teacher on this one.
Follow your manufacturer’s instructions closely and mark everything carefully before you drill. (Illustration Courtesy TransGo)
Step 2: Modify Plate Holes
Enlarge the holes per the marking (here to .93 inch) and TransGo instructions with drill bits provided. This is why you must mark the separator plate and circle the holes beforehand. You will learn from the instructions where to drill and what size to drill with the drill bits included in the kit. TransGo provides four bits in this kit: .125, .076, .063, and .055 inch. However, police and taxi applications need .093 to .096 or .076 to .086 inch, depending on which kit you have.
Step 3: Clean Up Holes
Chamfer each hole with a larger drill bit for a clean passage before moving on to the next hole to be drilled. This can be a needle-in-a-haystack environment, which is why you should drill and clean up these holes one at a time.
Step 4: Install Orifice Plug
Install the aluminum orifice plug. Squarely hit the plug with a hammer so it is ﬂush, which secures the orifice plug. This task is nothing more than resizing the hole in the plate.
Step 5: Drill Orifice Plug
Drill the orifice plug with the .055-inch drill bit provided. This resizes the .076-inch hole to .055 inch. This level of modification almost makes you wonder why they just don’t include new pre-modified separator plates.
Step 6: Continue Separator Plate Modifications
Modifications vary depending upon the engineering level of your AODE or 4R70W unit type. This is why sometimes kit manufacturers want to know your vehicle identification number or build date when you order the kit.
Step 7: Wash Separator Plate
Wash the separator plate once all modifications are made. Closely examine your work and make sure all holes have been cleaned up and have smooth edges. Make sure these holes and the plate are free of debris.
Valve Body Modification
Step 1: Mark Valve Body for Modifications
Carefully mark the valve body for modification per the TransGo instructions. Double-check the instructions before making any modifications. These modifications mandate extreme attention to detail and a steady hand. Mark and check twice, cut once.
Step 2: Modify Overdrive Servo Regulator Valve
One type of overdrive regulator valve has no hole in the separator plate, which is when you reuse the original spring. If there is a hole in the separator plate, install the blue spring. Also install the provided bushing in this location.
Step 3: Remove Overdrive Servo Regulator Valve
Remove the overdrive regulator valve and lay it out in the order it was installed. Take pictures as you remove each valve assembly.
Step 4: Inspect Overdrive Servo Regulator Valve
Type 1 and Type 2 valve bodies are determined by check ball location, which is confirmed in your TransGo instructions. If your Type 1 valve body separator plate does not have a hole “A,” reuse the original spring. If it does have a hole “A,” install the blue spring from the kit. If you have a Type 2 valve body, install the bushing (arrow) from the kit, keeping the original valve and spring.
Step 5: Install Overdrive Servo Regulator Valve
There are two potential overdrive regulator valve configurations, depending upon your application. One application calls for using the original spring. The other calls for using the blue spring in the kit.
Step 6: Reinstall Overdrive Servo Regulator Valve Retainer Clip
Reinstall the overdrive regulator valve retainer clip. Air check the valve operation using compressed air. The valve should move back and forth with air pressure application.
Step 7: Remove Main Pressure Booster and Regulator Valves
Remove the main pressure booster and regulator valve assembly and lay these parts out on your work surface. Take pictures of these valves as they came out of the valve body.
Step 8: Remove Main Booster Sleeve, Valve, and Regulator Valves
Here’s the main booster sleeve, valve, and regulator valve as factory installed with a blue spring. The TransGo kit offers options, depending on anticipated driving conditions. The specifics are in the instructions. Replace the blue spring with TransGo’s white spring.
Step 9: Verify Idle Booster Spring Application
This is the TransGo police/taxi main booster/regulator valve configuration with a white idle booster spring and special booster valve with factory booster sleeve. Unless you’re building an AODE/4R70W for police/taxi operation, this valve requires no modification. However, it should be removed for cleaning purposes when the valve body is disassembled.
Step 10: Drill Hole
Drill a .043 to .055-inch hole at the main booster/regulator valve location. Double-check the proper drilling location before you drill. Thoroughly wash the valve body and blow it out with compressed air before reassembly.
Step 11: Reinstall Main Pressure Booster/Regulator
The main pressure booster/regulator valve and sleeve installs per TransGo instructions. Check the valve and sleeve for smooth operation with compressed air. Compressed air acts on the valve as ﬂuid would in actual operation.
Step 12: Reinstall Main Pressure Booster/Regulator (CONTINUED)
Install the pressure regulator valve, then the spring, followed by the small booster valve and the aluminum pressure regulator valve piston.
Step 13: Install and Seat Booster/ Regulator Clip
Install the main pressure booster/regulator clip and check it for smooth operation with compressed air. All valves should be checked for freedom of movement and operation this way. Then install the retaining clip.
Bypass Clutch Control Valve Modification
Step 1: Remove Bypass Clutch Control Valve
Beginning with this retaining clip, remove the bypass clutch control valve. Organize this assembly on the bench as it came out and take pictures.
This is the bypass clutch control valve as it is installed at the factory. Inspect each of these parts for unusual wear and scoring and replace as necessary.
Step 2: Modify Bypass Clutch Control Valve
Reinstall the bypass clutch control valve piston exactly as it came out, using compressed air to check the valve function. Use transmission ﬂuid on each of these valve assemblies to ensure freedom of movement and proper function.
Step 3: Install Bypass Clutch Control Valve Spring
For 1991–1995 AODE/4R70W applications, reinstall the factory spring. For 1996-up, use this orange spring. For all applications, use the TransGo lockup bushing provided in the kit.
Step 4: Reinstall Bypass Clutch Control Plunger Valve
Reuse the small bypass clutch control plunger valve with the rest of the valve assembly. This plunger fits into the bushing.
Step 5: Reinstall Bypass Clutch Control Valve Clip
Check the bypass clutch control valve for smooth operation using compressed air. Seat it properly and reinstall this clip. Coat the parts with transmission ﬂuid.
Solenoid Pressure Regulator Valve Modification
Step 1: Inspect Solenoid Pressure Regulator Valve
This is the solenoid pressure regulator valve. On the left is the factory configuration. On the right is the TransGo valve with the orange spring. TransGo suggests using the stock spring with the new valve to establish smooth operation, stroking the valve piston at least 50 times with slight side pressure. The valve must fall in and out of the bore smoothly, without any resistance. Once free movement is established, install the valve using the TransGo orange spring.
Step 2: Modify Solenoid Pressure Regulator Valve
Here’s the TransGo solenoid pressure regulator valve piston with the orange spring ready for installation. Verify a smooth fit and use transmission ﬂuid as a lubricant.
Step 3: Install Solenoid Pressure Regulator Valve and Spring
Here’s the solenoid pressure regulator valve and spring installed in the valve body. Check the valve for proper operation using compressed air and give it a dose of transmission ﬂuid for smooth function. Seat the valve and spring, then install the clip.
Step 1: Turn Over Valve Body and Drill Holes
Use caution here, because it is easy to drill in the wrong location. Flip the valve body over and locate the back side of the main pressure booster/regulator valve, which is across from the manual shift valve. Drill two .125-inch holes through this wall. Again, do not attempt this with the valves installed, and always wash out metal debris and blast with compressed air.
Step 2: Install Cover Plate (Torque Fasteners)
With a clean valve body, install the cover plate. Remember, the valve body has two plates: the cover (shown) and the separator. Make sure you have all bolts in their proper locations. Torque pin nuts with 13-mm heads to 140 to 160 in-lbs of torque. Torque the smaller 10-mm bolt heads to 80 to 100 in-lbs. Keep in mind this is in-lbs and not ft-lbs.
Step 3: Install Check Balls and Filter (Documentation Required)
Install all the check balls and the filter screen. Note all the correct check ball locations and the drainback valve (upper left-hand corner). This is where the photos you took come in handy. You don’t want to miss any check balls or have any of them in the wrong location.
Step 4: Install Separator Plate and Gasket
Wipe down the separator plate and gasket to ensure all dust and debris is gone. Even finite dust can cause irregular plate mating and warping. Install the plate and gasket.
Step 5: Inspect and Install Stiffener Plates
These stiffener plates not only provide structural integrity, they also provide ﬂuid passage through the valve body. Check for clean contact surfaces and install the plates.
Step 6: Tighten and Torque Stiffener Plates
Seat, tighten, and torque the stiffener plates to 71 to 97 in-lbs. Keep in mind this is in-lbs, not ft-lbs, which is an easy mistake to make if you’re not paying close attention to what you are doing.
Step 7: Install Valve Body to Main Case Gasket
Check for debris between the main case gasket and the valve body during installation.
Written by George Reid and Posted with Permission of CarTechBooks