A/T - 125/125C Forward Drum Cautions

TSB 86-13 (Mar)

SUBJECT: 125 - 125C

FORWARD DRUM CAUTIONS:

There are three designs of the forward drum assembly, as shown in the figures. These drums can be interchanged , but the matched apply pistons must be kept with the drums. Keep the select snap ring on the splined end of the drum shaft with the transmission being serviced.

There are two areas where errors must be avoided:




1. Do not use the latest design "no check ball" drum (Figure 3, # 5) with apply pistons from earlier designs (Figures 1 & 2, # 1). There will be no checkball or bleed to exhaust the fluid left under the piston after clutch release.

2. Always use a waved steel next to the apply piston. The first two designs will have a harsh forward engagement without the waved steel, but the third (latest) design has a more serious effect. A flat steel next to the apply piston in the latest design will cover the bleed holes (Fig. 3, # 6) in the apply piston. Then the fluid left under the piston after clutch release can't exhaust. A tight clutch pack will worsen this condition. Don't leave out the fluid displacement insert (Fig 3, # 4), for it helps to displace trapped fluid.

Conditions 1 and 2 above can cause early clutch failure, but also other serious problems. Centrifugal force can cause the trapped fluid to build pressure under the apply piston and force it outward against the clutches.

This will apply the clutches at some unusual times -- such as when the the engine is raced in neutral or park.

The most common complaint is that the wheels lock after a hard back-up, when the throttle is released.

To date, the only injuries reported have been some stiff necks.

Feasibly, someone could be standing in front of a car and racing the engine (as in a cooling system flush) and the transmission could jump into drive.

If the vehicle was carelessly left in neutral -- someone could get hurt!