When should you upgrade to eight (8) or ten (10) clutches in your powerglide transmission?

In a racing powerglide transmission, the high gear drum is an important area to consider when doing high performance upgrades.  In OEM applications, the high gear drum is stacked with 4 to 5 friction and steel clutches.  Our quick tip guide details the method for cleaning up the OEM drum and preparing it for a racing setup.

Using standard thickness clutches and a standard height clutch hub, six (6) friction and steel clutches can be installed in an OEM powerglide high gear drum.  However, this capacity can be increased to eight (8) clutches using a machined piston and thinner .060" steel and friction clutches. 

Using an aftermarket drum and taller clutch hub, you can achieve an even greater 10 clutch capacity.

While the ten (10) clutch capacity drum set up provides the most clutch surface area, the additional cost and clutch drag may not be best for all car setups.  BTE recommends the following guidelines for racing powerglide clutch setups:

• For cars under 3600 lbs and/or 700 horsepower and 600 ft lbs of torque, 5 or 6 friction/steel clutch packs are recommended
• For cars between 725 horsepower / 625 ft lbs of torque and 1600 horsepower and 1200 ft lbs of torque,  8 clutch packs are recommended
• For any applications making more than 1650 horsepower and 1250 ft lbs of torque, BTE recommends a 10 clutch pack setup

These recommendations are assuming the transmission line pressure is at least 220 lbs.