Scorched clutch plates in a hopped-up diesel's automatic transmission are as inevitable as tax hikes in California. Facing a $4,500 or higher invoice for a fully-built transmission is a major obstacle for many diesel enthusiasts.
BD Power has a solution that is both easy on the wallet and heavy on durability. Its Master Rebuild Kit provides all the necessary hardware to replace worn parts, improve clutch performance and increase the transmission's longevity without breaking your secret stash of performance funds.
The kit we installed on Premier Performance's truck came complete with the extra-capacity pan, plate packs for all clutches, flex band, complete forward clutch drum, billet input shaft, diaphragm spring, snap rings, front servo piston cover, overdrive piston retainer and triple-disc torque converter.
The triple-disc converter can be built for your stall speed preference.
This extra-capacity pan holds two additional quarts of transmission fluid, and dissipates heat better than the factory stamped pan. The extra fluid and improved cooling ability make a significant difference in the durability and longevity of the transmission components. Heat is a transmission's worst enemy.
Cam Hulse of Adrenaline Performance removes the valve body from the transmission housing.
Removing the front servo piston cover.
Hulse removes the pump from the transmission housing.
Next out comes the flex band, with definite signs of wear.
The front and rear clutch assembly comes out with the intermediate shaft. Most of the damage done to this truck's transmission is found inside the front clutch.
The steel plates of the front clutch had become so hot they warped pretty badly. All of the fiber on the clutch plates was worn off, too.
BD adds a fifth friction plate to the front clutch pack. The backing plate is machined to make room for the extra plates.
BD also adds a sixth plate to the rear clutch, compared to the factory's five plates. The backing plate is thinner and 0.005 is machined off of the piston for clearance.
The flex band was toast. The BD kit replaces the factory band with a Raybesto Pro Series band with Kevlar lining.
Left is BD's billet input shaft next to the stock shaft.
The billet input shaft has a larger shaft diameter, as you can see at the base of the splines on each shaft.
When an input shaft fails, it typically spreads the splines inside the hub, which causes the hub to crack. The crack lets the hub spread enough that the splines on the shaft destroy the spines inside the hub, letting the hub spin freely around the shaft. This is the most common failure. The shaft itself can outright shear into two pieces as well.
The BD kit replaces the band strut, band anchor and piston servo cover. The new piston servo cover has a tighter tolerance and also comes with an o-ring for a better fluid seal.
BD's kit includes a replacement gear train. It's not typical to replace this assembly on a rebuild, but BD has good reasons.
Hulse disassembled the gear train to show the difference between factory (right) and BD components.
BD has replaced all four thrust washers in the gear train with Torrington bearings, which require less fluid for lubrication and are far more durable. Plus, they don't create heat like thrust washers can under load. It's a high-quality feature for a budget-minded kit.
Hulse oils all of the new components as he assembles the transmission.
The tail section is removed so that the overdrive clutch assembly can be removed.
Like the other clutch packs, BD adds an additional friction plate set to the overdrive brake clutches. To fit the sixth friction plate, you have to remove the wave ring that sits atop the snap ring.
BD's overdrive retainer (left) is thicker and has an o-ring groove for better fluid retention.
The overdrive gear train houses a steel coil spring. It must be compressed in a press to remove the snap ring and disassemble the assembly. Adrenaline Performance disassembled it to inspect the parts and clean it thoroughly.
The overdrive direct clutches are replaced with Raybesto plates from BD.
Hulse repaints the housings on all transmissions that his shop rebuilds. Aside from looking clean, which he likes, the clean housings also make it easy to put back into the truck and spot any fluid leaks.
BD Diesel Performance