Upgrading The Automatic Drivetrain


This page describes the options available for upgrading the manual drivetrain.  This includes the transaxle, axles, and brakes.  This page is very incomplete.

Transaxle Options

Technical details on these transmission are available on the Automatic Transaxle Specifications page.  You can click on each section title below for details on that transaxle.

The A413 Torqueflite Automatic Transaxle

The most common way to modify this transaxle is to stuff minivan parts in it (bearings, clutches, etc), install torrington bearings in the torque converter, and install a manual valve body.  The minivan parts will help the transmission handle the additional power output of a performance engine because they are designed to handle the loading of a heavy minivan.  The torrington bearings replace the thrust washers to increase the life of the converter.  The manual valve body disables the transaxless ability to shift automatically, giving the driver complete control over the shift points.

You may be wondering why someone would want to turn an automatic transaxle into a manual.  Well, the point of having the automatic is not for the lack of shifting, it's for the quick shifting that it can accomplish and the fewer number of shifts made possible through the torque convertor.  The transmisson switches directly from one gear to another without having to "pause" for a clutch or destroying syncros with power shifts.

The A604 Torqueflite Automatic Transaxle

This transmission has reliability problems to begin with.  As far as I know, no one has been able to keep one of these transmissions alive in a performance application.  One advantage to it is that it is a four speed with a lock torque converter.  This could, potentially, increase the efficiency of the drivetrain.


The proper axles for your vehicle depends on the vehicle.  Many vehicles have different wheel bases and therefore require different shafts.  Most manual and automatic axles are interchangeable for any given model year (except some L-bodies).  Vehicles equipped from the factory with a Turbo II engine usually received heavy-duty axles and CV joints (i.e. the Daytona Shelby) and these can be interchanged with other axles, as long as the transmission has the correct output shaft size.

Most stock axles can handle a lot of torque.  If you constantly break axles, you need to make sure that your engine is properly centered.  See the How To Center Your Engine page for more details.
Return to the Mini-Mopar Turbo Performance page


This page is maintained by Russell W. Knize and was last updated 02/05/99. Comments? Questions? Email minimopar@myrealbox.com.

Copyright © 1996-2003 Russ W. Knize