Clutch Piston Snap Ring Removal
On the internal clutches, the snap ring is retained by a metal lip or posts on the spring retainer. It is necessary to push the outer edge of the spring retainer down about 1/4 inch to remove the snap ring. The ATSG manual shows a nifty tool to do this but a variety of home made devices could do this. It could be as simple as using a nearly empty mylar shipping tape spool, as I did one night. Or a small board with 4 or 6 long screws paced in a circle. I fabricated one out of a 4 inch diameter thin wall steel tube that was 2 ½ inches tall. A section of the sidewall was cut out so the tube could be bent to 3 ½ inch diameter. Basically, ovals were cut out of each side for viewing and tool access. That left nearly a complete ring on the top, so the device stayed in one piece, and two half moons on the bottom. A vertical column on each side supported these wide feet, much like the one pictured in the manual. This design is easily bendable to fit different diameters. The compressive force is supplied with two bars pulled together with a long bolt. The top bar is 5 inch and threaded for the long bolt. The bottom bar is 3 1/4 inch with a clearance hole for the bolt.. It takes very little effort then to remove the snap ring. Once you have removed the ring, the need for the retainer becomes obvious. Care should be taken when the rubber sealing rings are removed to note the direction of the sealing lip. Put them in backwards and you won't have much of a seal. Great care must be taken when reinstalling the snap ring. Visually inspect that it is properly seated. Push down on the edges of the retainer and the snap ring to see that it is all the way in. This was considered such a problem that they redesigned the retainer into a continuous lip instead of the posts in later versions.
The clutch plates, friction and steel are easily removed prior to the piston removal. The snap ring has a small lip on one end which can be caught with a small screwdriver. This is followed by a thick pressure plate and the alternating friction and steel plates. There is usually the same number of each but if the transmission has been rebuilt before, there may be an extra plate (.070 inch) to take up some slack. A clear sign to install new friction plates. This is the poor boys adjustment instead of installing a thicker snap ring. When the clutches are installed, you are looking for a clearance of about 70 thousandths (.055-.079 inch) between the snap ring and the pressure plate for all three clutch packs. You not only have to push down on the clutch pack to make this measurement but lift up on the snap ring New friction plates should be soaked in transmission fluid at least an hour before assembly to insure proper thickness.
Overdrive clutch had a retaining ring thickness of 0.0681 and I had about 40 thousandths clearance with all used plates. Installed three new steel clutch plates (which were slightly thinner, Allomatic) with the old friction plates and got the required minimum clearance. This was the rebuilt drum from Transtar Industries and doesn't use a full complement of springs (install three springs and skip a spring) . One down, two to go.
.Reverse-high clutch had a retaining thickness of 0.0681 and I had less than 40 thousandths clearance with all used plates. Again, installed six new steel clutch plates (which were slightly thinner, Allomatic) with the old friction plates and got the required minimum. This was from the transmission rebuild in 96 and wasn't checked too closely. Two down, one to go.
Forward clutch, the one with the rubber cushion, had a retaining ring thickness of 0.0819 and had more than 110 thousandths clearance on all used plates. But then, just how do you measure that when you are gauging against rubber. The interesting part was that this clutch had 5 friction plates and 6 steel plates. Although the friction plates showed no more wear than the others, this drum had the most friction material sediment. All friction and steel plates were all replaced. This time I was able to install six of each and still have the minimum clearance. This piston has the largest surface area of all the clutches and uses the flat sealing rings that don't have any install direction. For this piston, only the two bars and the screw were needed of my home made tool for removal.
The tightness of two of these clutches were probably the cause of the fluid blackening the first six months of operation after the rebuild in 96. Glad I found a use for the steel clutch plates, though it was never the purpose I imagined.
This transmission is rumored to be out of 94 4x4 and so far from what I've seen it has all the right parts. 
