A/T - Delayed Forward Engagement/Servo Apply Lip Seals
Technical Bulletin # 238Date: 1994
Transmission: ATX
Subject: Delayed Forward Engagement, late 1-2, 2-3 spin-up, 3-2 slide/chatter, servo apply lip seals.
Application: Ford 83/on
The ATX unit can give you any or several of the above listed problems if the low/intermediate servo apply seal does not properly seal the apply oil. When this happens it usually is not a defective or damaged seal. It is usually the wrong seal.
There are two things you have to keep in mind when you are selecting the servo apply seal. You have to choose the correct seal diameter AND thickness. The inner part of the lip seal comes in two different thicknesses (figure 1).
Separate into two stacks, one with thick seals and one with thin. Make sure you do not accidently include the direct clutch piston inner seal in one of your stacks. You should have one thin seal that is considerably smaller than the rest. It is for the 1981-82 servo seal. If that is the year range you are working on, your search has ended. You have your seal. For 1983 and later models, read on.
See if one of your thick seals will go all the way into the piston groove. If so, then you know you have a wide groove piston. If a thick seal will not fit the groove, then you know you will need your thin seals.
Now for the next step:
Finding the right diameter seal for your piston and cover.
There is a large and a small diameter servo and cover. You can usually tell which one you have by a letter that is cast into the cover or piston.
The small servo parts will have an "E" (figure 2) and the large parts will have a "P" (figure 3). If your cover and/or piston do not have a letter use the largest seal that fits inside the cover bore without wrinkling. The correct diameter seal will have an extremely thin air gap between the seal and cover bore, or no air gap at all.
Here are two more methods to see if you have the right seal.
1. To make sure you don't have a thin seal in a thick groove use a piece of your gasket and seal kit card board (typically about .019" thick). Slip it between the seal and groove (figure 4).
One piece should fit snugly. If two pieces fit you have a thin seal in a thick groove (figure 5).
2. Consult the chart, which matches the number inside the seal lip with the servo type (figure 6)