Trimatic Flareup

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Page created by T Mar 16th 2014:

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LS V8 Trimatic from 5L VK Commodore. Flareup occurs inside the torque converter. Click to Enlargen.

Trimatic Flareup:


Flareup was a common problem in Old Holdens fitted with Trimatic gearboxes. Noticeable flareup occurred when a kickdown was forced from top to second due to the longer duration of a typical 2nd gear downshift. Flareup was a situation that caused a collapse of coupling inside the torque converter because the engine driven impeller was allowed to accelerate to an RPM  higher and in less time than that to which the stator and turbine could respond. The sensation was that the car was being slowed down by the kickdown, it was. There was also the accompanying sound of an hurricane occuring under the car because the torque converter had a fluid war occurring internally. Eventually things would settle down and the car would accelerate in second gear, then change back up to top gear again. On changing back to top the impeller, stator and turbine speeeds would become similar.

Flareup Cure:

Flareup is cured by running a taller diff ratio, a 3.08 or 2.78,  because the difference in speed between the impeller and the other 2 elements at kickdown is reduced. The kickdown is then greatly improved. There is no sensation of deceleration and no sound of hurricane emerging from the torque converter. There is also the benefit of "stator windup" meaning that the overall coupling of the transmission improves continuously as the stator accelerates up to impeller speed, simultaneously accelerating the turbine. Also the engine is not allowed to run up to redline without taking the roadwheels along for the ride. The engine keeps delivering to the road wheels throughout the entire kickdown process and through the 2nd gear operation.

The Impeller:

The Impeller is a large fan inside the torque converter that is rotated by the engine. Even though it is driven by the engine, the Impeller is located on the gearbox side of the torque converter.

The Turbine:

The Turbine is a large fan inside the torque converter that is rotated by the Impeller. The Turbine is on the engine side of the torque converter.

The Stator:

The Stator is a large fan inside the torque converter that is also rotated by the Impeller, but which improves the efficiency of the torque converter by the way it directs the flow of oil. The Stator is located in the centre of the torque converter, between the Impeller and Turbine. The Stator can be stopped when there is a large speed difference between the Impeller and the Turbine. It can also be accelerated as the the speed difference between the Impeller and Turbine decreases. 




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