Should I attempt to overhaul my own automatic transmission?

Special Tools:

In my opinion, the bare minimum tools, you need to overhaul an automatic transmission should include an air compressor, clean bench space, solvent tank, steam parts washer (the only way to get a case clean), complete bushing driver set, automatic transmission clutch spring compressor, a host of specialty tools for the particular automatic transmission you are working on (for ring sizing, spring compressing, measuring clearances, loading components into the case, etc.), various snapring pliers (depending upon the unit you are working on), feeler gauges, 0-6" calipers, micrometers, depth gauge, straight edge (an accurate one for checking flatness.... not a school ruler.... ), inch pound torque wrench, foot pound torque wrench, a few good manuals on the transmission you are working on (by having more than one, you will have a better chance of finding the information that you need), and, obviously, all of the common hand tools (wrenches, sockets, screwdrivers, hammers, pliers, etc.). Now, if you do not have all of these tools, and a few more, it would definately be more expensive to go out and purchase these tools than it would be to have a couple of transmissions rebuilt.

Schooling, and Experience:

In most cases, transmission rebuilders have worked many years at a transmission shop, first as an R&R person (Remove and Replacement of transmissions), and then on to apprenticeship, working along side an experienced rebuilder. Overhauling transmissions, in many cases, requires, not only, following the book on the rebuilding procedures, but, also, knowing when to modify, or update a particular problem area, as well as knowing interchangeability of various transmission components. For instance, during an overhaul or a 70R4, I include the tips outlined in my "700r4.htm" article, as well as many other procedures that are not mentioned in any Chilton's or Motor's transmission manual. Most transmission rebuilding manuals assume that the user is a qualified transmission rebuilder, and so, also leave many of the more obvious (to an experienced rebuilder) details out. In addition, diagnosis requires a great deal of experience, and understanding of automatic transmission components, and their particular function, to know "what's wrong with this picture" when looking at a subtlely failed component, or to know what to look for when diagnosing a particular complaint. Another example is with the AXOD and AXODE transmissions and their particular problem causing a "no drive" condition, or "falling out of gear" condition when coming to a stop. You could overhaul this transmission, completely "by the book", following every instruction to the letter, and have the exact same problem when you are through. Being an experienced transmission rebuilder, I know that the AXOD's have an aluminum apply piston, in the forward clutch, that tends to crack, and I replace it with a steel piston, even if it is not cracked. This crack can be hard to see, and many people overlook this detail. The book only mentions how to disassemble, and reassemble the unit with no mention of "updating" sensitive components. In addition to reading books, periodicals, etc., I also spend a great deal of time going to seminars, and hand's on training classes, to get the kind of "updating" information required to completely fix the customer's complaint, in addition to going through the motions of a transmission overhaul.

---

Written by Ken Bachellerie. Copyright © 1997. All rights reserved. Do not duplicate or redistribute in any form, without permission from the author.