In this issue of Keep Those Trannys Rolling, we are going to take a look at a 2020 Ford F150 XLT equipped with a 5.0 engine and a 10R80 transmission that was experiencing erratic shifting, downshift clunks, shuddering, and chattering concerns after overhaul.
This vehicle came to our attention after the customer was referred to us by an out-of-state transmission shop. The transmission shop manager contacted us requesting assistance with one of their customers, who was on vacation in our area and was experiencing transmission concerns. According to the shop manager, the customer was experiencing erratic shifting, downshift clunks, shuddering and chattering while driving. After a brief conversation with the shop manager, we requested the customer’s contact information and a copy the repair order. We contacted the customer and set up an appointment to bring the vehicle in the next morning.
Next Morning, Vehicle Arrives
The next morning, the customer arrived at the shop bright and early. According to the customer, the transmission was overhauled a couple of weeks ago, just before going on vacation. The customer said the transmission concerns started with erratic shifting and downshift clunks, then eventually started shuddering and chattering during shifts. He said he contacted the original transmission shop, who then referred him to us for assistance. With the vehicle in our shop, we started by performing an initial inspection.
Initial Inspection
It was time to perform an initial inspection. We did a walk-around inspection of the vehicle and noticed a large trailer hitch on the rear. The vehicle was in good condition with no signs of damage. We performed an under-hood inspection, checking hoses, belts, wiring harnesses, connections, and fluid levels. Everything looked good under the hood. We raised the vehicle on the rack and inspected its underside. We inspected the transmission and drivetrain. Everything looked good there. After completing the initial inspection, we headed out for our initial test drive to see if we could duplicate the customer’s concerns.
Checking for Codes
After completing the initial inspection, it was time to head out for our initial test drive. Prior to heading out for our initial test drive, we connected our scan tool to the vehicle’s Data Link Connector (DLC) to scan the vehicle computer systems for codes. There were no codes in any of the on-board computer systems. With no codes in the vehicle computer systems, it was time to head out for our initial test drive to see if we could duplicate the customer’s concerns.
Initial Test Drive
With the scan tool connected to the Data Link Connector, to monitor transmission operation, we headed out for our initial test drive. We started our test drive through city streets, ranging from 25mph to 45mph. The transmission seemed to work properly. We then headed towards the freeway. As we accelerated up the freeway onramp, we noticed a chatter sensation during the up-shifts with tcc not applied. We continued down the freeway for several miles with no other concerns. After duplicating the chatter concern, it was time to head back to the shop to diagnose this chatter concern.
Back at the Shop:
With the vehicle back at the shop, we rechecked the transmission fluid level and condition. The fluid level was correct, and the fluid looked clean. We checked the vehicle’s computer systems for codes, and no codes were found on any onboard computer. We connected a pressure gauge to the transmission line pressure tap so we could monitor pressure and rise during the chatter sensation. With the scan tool connected to the Data Link Connector and the pressure gauge connected to the line pressure tap, it was time to head out for another test drive to see if we could diagnose this chatter concern.
Duplicate to Diagnose
With the scan tool and pressure gauge connected to the vehicle, we headed out for another test drive. Again, we drove through city streets and then onto the freeway. The transmission began to chatter during the hard acceleration up the freeway on-ramp. We monitored the pressure and rise during hard acceleration and found the pressure and rise were within specification during the chatter sensation. With the pressure and rise within specification, we could eliminate pressure-related concerns, such as the filter, pump, pressure regulator valve, pressure control solenoid, and, more importantly, things outside of the transmission, such as mass air flow sensor (MAF), throttle position sensor (tps), map sensor(map) and accelerator pedal position sensor (apps). This puts our chatter concern inside the transmission. We contacted the original transmission shop and informed them that the chatter concern was an internal problem and the transmission would have to be removed, disassembled, and inspected. The original transmission shop authorized us to remove, disassemble, and inspect the transmission to address the chatter concern.
Remove, Disassemble and Inspect
With the authorization from the original shop to remove, disassemble, and inspect the transmission, we removed the transmission and disassembled it for inspection. During the disassembly process, we removed the valve body and air-checked the clutch components. All clutch components air checked with less than 35psi of air pressure, indicating that the clutch circuits were intact and capable of holding pressure. We vacuum-tested the new OEM valve body and found no concerns. 
The valve body looked good. With the clutches air checking at low pressure and the valve body being in good condition, it was time to disassemble the transmission case for further inspection. As we disassembled the transmission case, everything looked okay. We disassembled each clutch for inspection. During the individual clutch inspections, we found that the “F” clutch frictions (located in the CDF clutch hub) showed signs of slipping. During further inspection of the CDF clutch hub, we noticed that the “C” clutch had four (4) frictions and four (4) steel plates, the “D” clutch had five (5) frictions and five (5) steel plates and the “F” clutch had three (3) frictions and three (3) steel plates. After further research, according to Ford Motor Co., for the 5.0L application, the “C” clutch should have had five (5) frictions and five (5) steel plates, the “D” clutch should have had six (6) frictions and six (6) steel plates and the “F” clutch should have had four (4) frictions and four (4) steel plates installed. This was an indication that the incorrect CDF clutch hub was used during the overhaul process (Figure 1).
Concern Confirmed
After contacting our local Ford Dealership Parts department, we discovered that Ford produces three (3) different CDF clutch hubs, depending on vehicle and engine application. According to our local Ford Parts Department, the CDF clutch hubs are not interchangeable. We acquired all three (3) CDF clutch hubs from our local Ford Parts Department for comparison. During the CDF clutch hub comparison, we found that each of the CDF clutch hubs had the same external dimensions. The only difference between the CDF clutch hubs was the clutch snap rings grooves were in different locations, to accommodate the correct number of frictions and steel plates, depending upon vehicle application. The three (3) CDF clutch hubs applications are as follows:
- 2.3L & 3.3L Explorer and Mustang applications use four frictions and four steel plates in the C clutch, five frictions and five steel plates in the D clutch, and three frictions and three steel plates in the F clutch.
- 3.0L Explorer 5.0L Mustang/Explorer/ Aviator applications use five frictions and five steel plates in the C clutch, six frictions and six steel plates in the D clutch, and four frictions and four steel plates in the F clutch.
- 3.5L Expedition/Navigator applications use five frictions and five steel plates in the C clutch, six frictions and six steel plates in the D clutch and four frictions and 4 steel plates in the F clutch.
We installed the correct CDF clutch hub, according to application, and reassemble the transmission assembly. We installed the transmission assembly and filled it with the correct fluid. With the transmission installed and fluid levels checked, it was time to head out for another test drive.
Final Test Drive
With the transmission installed in the vehicle and the fluid levels checked, it was time to head out for our final test drive. With the scan tool connected to the Data Link Connector, we headed out for another test drive. Again, we drove through city streets and then onto the freeway. During the acceleration onto the freeway, the transmission worked perfectly. There was no chatter sensation at all. Everything seemed to be working properly. We continued driving the vehicle several times during the day and verified that the chatter sensation was gone. We contacted the original shop and discussed the CDF clutch hub concern. We contacted the owner of the vehicle and made arrangements for the vehicle to be picked up.
Well, there you have it. We were able to correct a shift chatter concern by installing the correct CDF clutch hub. During the overhaul, it would be recommended that you verify that you are using the correct CDF clutch cylinder for your application so you, too, can keep those Trannys rolling down the road.
