BD Big Stack Clutch Pack

Published in the June 2018 Issue November 2018 Products

There are two fundamental ways to increase a transmissions clutch holding capacity 1) Increase the hydraulic apply pressure; or 2) increase the clutch capacity.

 BD Diesel has released its Big Stack OD clutch pack that is designed to increase the clutch capacity to reduce premature wear or clutch failure. The Overdrive clutch pack, which is located in the input drum is the perfect candidate for an increased number of clutches. 

The factory OD/UD and OD/Reverse reaction plates are made of inexpensive powdered metal. These plates were designed to handle stock pressure at full thickness. While they do perform okay with increased pressure at full thickness, when they get machined down to fit more clutches they bend significantly—so much in fact that it will only contact half of the friction surface it is trying to apply. 

The BD Big Stack consists of a few parts, the heart of it is the overdrive shaft. To increase the spline length on the shaft BD starts with brand new OD shaft and machine off the clutch spline section. BD then billet machine a longer spline and weld it onto the shaft.

 Price: $525. Website:


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