Larry 1 #1 Posted May 7, 2014 I'm rebuilding a pair of EZT transmissions on a Toro 50" zero turn I bought on Craigslist for $450. I have one side opened up and decided to replace the pump because the pistons have a bit more play than I thought was new. The original pump has 7 pistons, each 13.4 mm dia. I bought a replacement pump and come to find it has 5 pistons, each 16mm dia. The motor side also has 5 pistons. I haven't measured them. The blocks measure the same diameter and height between old and new. Does it make any difference to performance to use a 5 piston pump? Some drawings call out the same part number for both pump and motor. I calculated the displacement will be nominally the same with either block. Is the 5 piston a correct replacement part for the 7, or did I grab an incorrect parts list online? ZC-DFBB-5W5A-3CPX Share this post Link to post Share on other sites
bmsgaffer 2,043 #2 Posted May 8, 2014 I don't know that model, but if the displacement is the same, there will not be any difference in performance. The more pistons the "smoother" the hydraulic fluid flows, but at 5+ I doubt you will notice at full throttle. They probably improved the design with 5 to reduce the number of moving parts to increase reliability and increase the size of the piston for strength and durability. Just my wild theory guess. Share this post Link to post Share on other sites
