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Q: Modify 4 speed transmission to 6 speed.

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My car a 1993 Camry 300 SEi , 3VZ motor; mileage stands at 174542 km. It is a 4 speed automatic transmission with overdrive. Cruising at 120 km/h the rev counter stands at 3000 revs/min. I always drive with the overdrive selector on. What can I do to modify the transmission to drop the revs to 2000 revs/min at least. If not, what other types of 6 speed automatic gearbox can be compatible with my motor? The intention is to get lower revs at 120 km/h and bring down fuel consumption. Help me.

My car has 178542 miles.
My car has an automatic transmission.

Unfortunately, undertaking a procedure such as converting an existing 4 speed transmission to a 6 speed transmission would be a task that may exceed the cost of the car to undertake. As you may know, your transmission is a complex set of gears, clutches, synchronizers and solenoids that use hydraulic fluid that moves through a valve body that allows the change from one gear to the next.

Adding an additional set of gears to the existing transmission would require an enormous amount of fabrication that would be cost prohibitive. The same will be true in terms of modifying your drivetrain to be able to accept a different or later model 6 speed transmission.

The cost of the transmission, plus the amount of fabrication and labor required may far exceed the value of the car. I would recommend taking a look at some later model vehicles to determine a model that may fit your needs for fuel economy.

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