Shade Tree Mech
Active Member
I see a lot of issues relating to the rear clutch in the A727. I.E. catastrophic burn-up. While reassembling, I found a lot of slop (over .080) between the piston and the Bellevue spring. I ordered a slightly taller piston from a source recommended by responders in a previous post. Upon assembling, I found something that distresses me. The Bellevue spring fingers grip a lip on the new piston as shown in the attached photograph. This lip on the new piston is not present in the original piston. I examined the contact edges of the spring and found that it is stamped and tumbled. No further treatment of the edges is done. There are some sharp edges at the ends of those fingers. Given that there is no clearance between the fingers and the lip of the new piston and that the circle radius of the fingers will decrease slightly when the piston is activated, they will dig into the lip and generate the aluminum powder that accumulates at the bottom of the oil pan. I want to do something that will mitigate this condition before continuing. My choices are: put the piston into the lathe and trim off a few thousandths from the radius of the lip, or round over the edges of the fingers. I'm leaning toward the edges of the fingers. What say the experts and speculators? Also, Should there be some clearance between the bottom of the spring and the top of the piston? Like say, .003?
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