Morin inspected the factory transmission internals and found that the damage was concentrated in the forward clutch pack, which was severely slipping. The clutch material was completely worn off the discs in the forward clutch pack, leaving that section of the transmission with metal-to-metal discs that would not propel the truck at all. The heat buildup from the slipping clutches also damaged the piston spring and seal, which were also replaced. The overdrive clutch pack also showed signs of overheating and burning, but not to the extent of the forward clutch pack. Fortunately for Uriah, there was no damage to the case or other major internal transmission components like the planetary gear sets. 2 This set of clutches is the low/reverse set with the new Raybestos blue clutch discs on the left and the original clutches on the right. Both sets use the same number of discs in this clutch pack, but the blue set is an upgrade over stock. 3&4 Here are the direct clutches with the new Raybestos discs on the left. Notice that there are six clutches in the Suncoast set compared to five in stock trim. This is possible because of the new thinner machined apply plate (left) compared to the stock unit (right). 5 Transmission specialist Dan Morin stacks the clutches and steels in the drum. This is done with each of the clutch packs alternating between steels and clutch discs. 6 As you can easily see, the clutch material has completely worn off the factory forward clutch set on the right. To handle more power, the Suncoast kit uses five Raybestos GPZ clutch discs while the factory used four. Not only did the slipping clutches fail, the heat also damaged the spring and the piston seal. 7 Morin installed the clutches and steels into the forward drum, aligning the discs and installing the machined apply piston that’s included with the Suncoast kit.
8 Then Morin joined the forward drum with the direct drum and installed the forward planetary gear set. 9 After the assemblies are aligned, Morin lowers them down into the transmission housing. 10 The band is installed next. 11 The intermediate clutch pack from Suncoast uses four Raybestos GPZ discs with thinner Kolene-coated steels, while the factory arrangement on the right uses only three discs with the thick steels. 12 Suncoast also included a machined center support that allows a snap ring to be used in the transmission to provide a more solid base for the center support to ride on inside the transmission. You can see the machined edges and snap ring on the support on the left compared to the factory support on the right.
13 The snap ring retainer is lowered into the transmission and then the Suncoast machined center support is installed. 14 The optional Suncoast four-disc coast clutch drum shown on the right is machined to fit the retaining snap ring more securely than the factory arrangement as shown by the arrows. Additionally, the Cnc-machined pressure plate and higher mounting position for the snap ring allow the coast clutch pack to double in size with four clutches as opposed to two clutches from the factory. 15 Morin installed the additional clutch discs in the modified Suncoast clutch drum. 16 Morin lowers the clutch drum down into the transmission housing to join the rest of the components in the transmission.
17 The last of the clutch segments for the transmission are the overdrive clutches and steels. Morin installed these in the trans and began the final assembly. 18 Morin installed the supplied converter pressure spring in the pump assembly to increase the line pressure in the transmission. Higher line pressure improves clutch application and holding power, which helps reduce slippage and, in turn, dissipate heat. 19 Once the pump was installed, Morin slid the input shaft down into the transmission assembly. 20 To wrap up the transmission rebuild, Morin installed the valve body assembly complete with the Suncoast and Transgo components as well as his own Swamp’s Diesel Performance valve body modifications.
For a skilled transmission builder like Morin, this build was fairly typical with burnt clutches in desperate need of replacement and an owner in desperate need of getting his truck back on the road. He flew through the installation of the new components with meticulous skill and knowledge of exact placement, alignment and operation. We followed along with the assembly of the Suncoast Xtreme rebuild kit, but due to space limitations we can only show you highlights. If you choose to remove the transmission yourself be sure to practice safe shop techniques. If you’re among the few who are bold enough to tackle the rebuild yourself, be sure to follow a service manual closely and work carefully through the rebuild process.
While we’re fairly sure that most diesel enthusiasts won’t run out and try to rebuild an automatic transmission on their own, we wanted to show you what makes a kit like the Xtreme Rebuild Kit from Suncoast, when assembled by a skilled technician, better than a standard factory-style rebuild from your dealer or local transmission shop. Even if you decide to “R&R” the trans yourself to save money you can still have a diesel performance shop like Swamp’s Diesel Performance build the transmission for you to make sure that your own 7.3L Power Stroke work truck can tow and haul whatever you need. Just be sure to tell them that your friends at Ultimate Diesel Builder's Guide referred you. UDBG
22 The Suncoast billet multi-disk torque converter will link the 7.3L Power Stroke engine to the 4R100 transmission and ultimately along to the rear wheels to transfer the power from the engine to the ground without slipping for many years to come.
21 After reinstalling the deep Mag-hytec transmission pan and moving the transmission to the work bench he installed the tail housing as well as the sensors and vent tube.