Hrtbeat1 Posted January 7, 2009 Report Share Posted January 7, 2009 I've been putting parts together for a "Zippy" type shift kit. All Zippy's part numbers. Should I go with a metal pinned accumulator or the metal pinless accumulator? Also should I go with the same for both the 1-2 and the 3-4 or one of each? Quote Link to comment Share on other sites More sharing options...
southga03ss Posted January 7, 2009 Report Share Posted January 7, 2009 I've been putting parts together for a "Zippy" type shift kit. All Zippy's part numbers. Should I go with a metal pinned accumulator or the metal pinless accumulator? Also should I go with the same for both the 1-2 and the 3-4 or one of each? In 4L60E units it is common for the plastic or alloy forward accumulator piston to wear or crack. This causes a fluid loss, resulting is delayed engagement, slips, burned clutches and/or band. Repeated reciprocation of the accumulator piston causes the piston pin bore to wear. Fluid loss through the piston pin bore or cracks causes forward clutch to slip. After this wear reaches a critical point, fluid loss through the piston pin bore cannot be compensated due to lack of pump volume. The pinless forward accumulator piston kit eliminates these problems by eliminating the pin bore. Dual seals stabilize and completely seal the bore and provide a tight seal even after thousands of cycles. I just rebuilt my tranny and replaced all of the accumulator pistons with the pinless. They aren't that expensive so I believe if you are upgrading, you might as well go with them. And I believe the kit I got had the same pistons for 1-2 and 3-4. Quote Link to comment Share on other sites More sharing options...
blackbeast ss Posted January 7, 2009 Report Share Posted January 7, 2009 In 4L60E units it is common for the plastic or alloy forward accumulator piston to wear or crack. This causes a fluid loss, resulting is delayed engagement, slips, burned clutches and/or band. Repeated reciprocation of the accumulator piston causes the piston pin bore to wear. Fluid loss through the piston pin bore or cracks causes forward clutch to slip. After this wear reaches a critical point, fluid loss through the piston pin bore cannot be compensated due to lack of pump volume. The pinless forward accumulator piston kit eliminates these problems by eliminating the pin bore. Dual seals stabilize and completely seal the bore and provide a tight seal even after thousands of cycles. I just rebuilt my tranny and replaced all of the accumulator pistons with the pinless. They aren't that expensive so I believe if you are upgrading, you might as well go with them. And I believe the kit I got had the same pistons for 1-2 and 3-4. yeah the 1-2 3-4 pistons are the same and the foward is smaller Quote Link to comment Share on other sites More sharing options...
Hrtbeat1 Posted January 8, 2009 Author Report Share Posted January 8, 2009 yeah the 1-2 3-4 pistons are the same and the foward is smaller So I should also look for a metal foward accumulator piston? Quote Link to comment Share on other sites More sharing options...
southga03ss Posted January 8, 2009 Report Share Posted January 8, 2009 Yes. The aftermarket pinless pistons have many advantages over the stock. They are not made of plastic, you don't have to worry about the pin bore wear, they are double sealed, and the larger design prevents the piston from cocking inside the piston bore. I do have a question on these pinless accumulator pistons though as well. When I took my valve body apart, either the 1-2 or 3-4 stock accum. piston came with an inner and outer spring. The Pinless pistons I bought included only one spring, are you supposed to re-use the stock inner spring along with the aftermarket outer spring or leave it out? Quote Link to comment Share on other sites More sharing options...
blackbeast ss Posted January 8, 2009 Report Share Posted January 8, 2009 (edited) So I should also look for a metal foward accumulator piston? yes sir you got a total of 3 accumulator pistons Edited January 8, 2009 by blackbeast ss (see edit history) Quote Link to comment Share on other sites More sharing options...
zippy Posted January 9, 2009 Report Share Posted January 9, 2009 I use the pinned metal piston. Only the 1-2 has the problem. I've never seen a broken 3-4 accumulator piston and the forward piston I've only seen one broken. The 1-2 and 3-4 aren't the same, they have a different size pin. I'm not big on the pinless as I don't like the accumulator volume being reduced that much. Quote Link to comment Share on other sites More sharing options...
blackbeast ss Posted January 9, 2009 Report Share Posted January 9, 2009 I use the pinned metal piston. Only the 1-2 has the problem. I've never seen a broken 3-4 accumulator piston and the forward piston I've only seen one broken. The 1-2 and 3-4 aren't the same, they have a different size pin. I'm not big on the pinless as I don't like the accumulator volume being reduced that much. i was talking about the the pinless ones the 1-2 3-4 are the same,same part number on both Quote Link to comment Share on other sites More sharing options...
Hrtbeat1 Posted January 10, 2009 Author Report Share Posted January 10, 2009 I use the pinned metal piston. Only the 1-2 has the problem. I've never seen a broken 3-4 accumulator piston and the forward piston I've only seen one broken. The 1-2 and 3-4 aren't the same, they have a different size pin. I'm not big on the pinless as I don't like the accumulator volume being reduced that much. Thanks for your input Zippy! I knew there were three accumulator pistons, but I wasn't really sure which you were reffering to in your Zippy kit part list post. Quote Link to comment Share on other sites More sharing options...
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