Trimatic Automatic Reliability
Symptoms
Slipping under load, delayed engagement, harsh shifts, overheating. The Trimatic may also develop a shudder on light-throttle upshifts.
Cause
The Trimatic 3-speed automatic was Holden's own design, and it's adequate at stock power levels behind the six-cylinder engine. Behind the V8, particularly the 308, it's marginal. The clutch bands wear, the internal seals harden, and the fluid breaks down faster under the V8's greater torque output. Cars that have been driven hard or modified to produce more power overwhelm the Trimatic quickly.
Fix
A fluid and filter service ($100-150) can improve shift quality if the damage isn't too far advanced.
A shift kit ($200-400 installed) firms up shifts and reduces clutch slippage.
For a full rebuild, budget $1,200-2,000.
For V8 cars making more than stock power, consider a TH350 or TH400 conversion, both are significantly stronger than the Trimatic and bolt in with adapter kits.
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