In 'da trans... To the gears... To the torque convertor...

We crack open the trans.  John pulled all the parts apart for inspection.  As it turns out, the internal friction plates had been worn down to nothing.  Without friction material, the transmission couldn't "grab" to transmit enough power throughout the gears.  When the car felt like it popped into neutral, that was the last of the friction materials wearing off.

But the friction plate wear was unusual.  All of the friction plates for all gears were completely burned up.  1st, 2nd and 3rd gears were gone.  Even the overdrive friction band that wraps around the transmission was complete burned up.  John pointed out that lower gears are often killed from either a lot of horsepower or from abuse.  But it's next impossible for a car to produce enough HP to fry all of the gears in the same manner.  All plates looked exactly the same.  This indicated a failure somewhere else.

<- These pics show the fried friction plates.  They are normally light brown.  These are black and burnt.

Internal Friction Plates...
Do you like regular or extra-crispy?

John continued to pull the trans apart.  He measured the pressure of the transmission fluid at different points.  He also tested pressure from the transmission fluid pump.  The fluid pressure from the pump was far below Mitsubishi specs.  THAT WAS THE PROBLEM---The transmission fluid pump failed, resulting in premature wear or the transmission.  In other words, there wasn't enough fluid to lubricate the transmission.  Without fluid, the entire transmission wore itself down.

Inside the casing (shown to the right), the transmission fluid pumped failed to produce enough liquid to push the hydrolic press against the friction plates (see plates4.gif -- The hydrolic press lies in the center of the friction disks).

We replaced the entire transmission--torque convertor, casing, gears, plates, pump--every thing had to go.  After replacing the entire trans, the car ran strong with no problems.

For more questions on DSM Automatic Transmissions,
go to About DSM ATs...   

The pump that wasn't puming...

Strong, but slightly damaged gears...