Ultimate Diesel Builder's Guide - - Project Work Truck -

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.

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