Part 2

Long Life to the 3-4 Clutch

   Let's work on the 3-4 stackup beginning with the apply plate. The apply plate on the right requires a steel plate on top of it. If you are using the thin HD Alto clutches in order to get 8 or 9 disks for added durability instead of the stock 5 plates. The thin steel will not apply evenly, depending on which direction the plate is installed it will cause either the inner 1/2 or the outer 1/2 of the disc to burn instead of using entire clutch surface area. The (late model) 4L60E trans has a combination apply plate that sits on the 5 legs & is a pressure plate also, GM # 8685044. This pressure plate allows for the most discs and a good even apply. It's highly recommended for performance & hard worked units.

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    When building late model units that use the 3-4 helper springs, make sure and check the height of them (shown below). The heat from a burned up 3-4 stackup reduces the spring tension and should be replaced with new ones, not too often can you reuse the helper springs. I like using the helper springs in the 3-4 pack, the quality & feel of the shift is better (my opinion for what it's worth) when you set the clearance between .050 to .070. on 700R4, on 4L60E Units .040 to .060. If you set the clearence to loose the computer will see it's taking too long to complete the shift. The later models prefer the .040 to .060 and in my opinion give a better shift especially when used with high energy frictions.

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The picture shown below is a snap ring from the reverse input drum that measures .062 instead of the stock .093 snap ring to get enough clearance out of a HD stackup. In order to use the snap ring, you have to cut aprox 1 inch off of the end of it, grind a small notch into the end so that a pocket screwdriver or whatever you happen to use,  can remove the snap ring easily

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   Make sure seat everything by applying air (aprox 75 lbs) before checking the clearances with a dial indicator.

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(click on image for large display)

 

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