When I start my rebuild and I have the high gear drum assembly on the bench I simply give it a visual inspection. The outer diameter of the drum should be smooth and look consistent. If it has signs of hot spots or some scoring it can be put in a lathe and cleaned up. If it takes more than .010” to clean it up I would replace it. They are not expensive and companies like TCI, BTE, or Mike's Transmissions have them.
 This photo shows how we measure the high gear clutch pack clearance. We feel there should be .060” to .100” clearance to reduce friction when you are in low gear. We try to stay near the .100” with 7 or 8 frictions and slightly tighter with 6 or less frictions. |
 One little “trick” for engines running under 8,000 rpm or lower horsepower engines you can leave every third spring out under the high gear spring retainer to speed up the high gear apply. |
Next thing to do is to remove the large snap ring that holds the sun gear pressure plate on the high gear drum. It is a simple operation and requires nothing more than a screwdriver and some patience to get it removed. Once the plate is removed you can measure the high gear clutch pack clearance. Doing this is easy and requires nothing more than a good quality dial caliper. Push down against the clutch pack and measure from the ledge that the sun gear cover plate sits on to the surface of the top clutch.
On this transmission it was .095”, which is right where I like to see it. I took the steels and frictions out and it had 6 frictions and 7 steels. I measured each one and it had the thicker (.098”) Raybestos frictions and thicker (.070”) steels. I used the thinner frictions (.065”) that are available and a mix of the thin (.060”) and thick (.070”) steels to get 8 frictions and 9 steels in the high gear clutch pack and end up with the same clearance of .095”. I soak any new frictions for at least 30 minutes in RTF (Racing Trans Fluid) before installing them so they are not “dry” when you make the initial startup.
There are several high gear clutch hubs available and while
the aluminum one will save some weight it wears out rather quickly and
I would recommend a new steel clutch hub. The one I use from TCI has lightening
holes drilled in it and will last several seasons.
There are some small items that need to go into the high gear assembly.
Pay attention when you are disassembling it and getting it back together
correctly will be easy.
Items to check before setting the high gear drum into place are the ‘wedding
band” and pinion thrust bearing. If they look good, coat them with
lube and assemble.
Note: When assembling the high or reverse clutch packs it is acceptable to run two steels against each other but DO NOT run two frictions against each other.
Low Band and Valve body:
 This is the bottom view of the band adjuster bolt and the components that retain and adjust the low band. The shaft from the accumulator and how it holds the other side of the band is shown in this photo. |
I take the new drum out of the RTF it has been soaking in for an hour or so. Since you took the pieces out that held the band in place I won’t go over those details. Install the band adjusting screw (I recommend a new billet screw to prevent flexing) into the case and be sure to put a little anti-seize on the threads. After that is in far enough to hold the larger band retainer it is time to install the servo. Don’t worry about adjusting it yet, we’ll do that later.
