Transmission rebuilding is one of the most expensive car repairs a car owner can face. Most people don't know when to rebuild, how much it will cost, what to do during professional service, or how to be safe while working on all of the parts. But it doesn't take long to familiarize yourself with the basics of transmission rebuilding.
The transmission of a vehicle consists of many different parts--including gears, hydraulics, computer sensors and controls, and more. It's not a single mechanism. Rebuilding a transmission requires that you disassemble all of the transmission's components, figure out exactly which parts are causing the trouble, repair or replace the troublesome parts, and put everything together again. You therefore need to understand what all of the parts of the transmission are and how all parts of the transmission work before you take the transmission out of the vehicle and attack it.
Some shop owners claim that replacing a transmission requires specific certification or training. They tell you this as a way of promoting their own expertise (which admittedly is often founded), or to convince you to buy their services. But you don't have to be certified to work on your transmission. You simply need to have the patience and mechanical inclination necessary to tinker, follow instructions from the transmission manual and troubleshoot.
Car owners sometimes choose to rebuild their transmissions when it really isn't necessary. Seal leaks, for example, can cause transmission fluid to leak and gears to be sluggish, but this doesn't necessarily require that the entire transmission be taken apart and overhauled. A bad repair shop may take advantage of someone who doesn't understand how transmissions work and do a full rebuild in such a situation, but a good repair shop will tell the car owner when the transmission problem really requires full disassembly and repair. Always request an estimate from whatever shop you use, and request that the damage to each replaced part be explained and shown to you by requesting those parts back (they're yours, after all).
Because transmissions involve so many components, safety has to be a priority while rebuilding. Transmissions use special fluid to lubricate their components, for instance, and this fluid must be drained and replaced during disassembly and assembly. You should know how to dispose of this fluid properly, and wear goggles and gloves. Get someone to assist you in lifting the transmission in and out if you know that you can't heft it by yourself, and be careful of parts that appear corroded by rust or other substances.
Rebuilding a transmission can be very expensive if done by a professional, costing in the thousands of dollars. This cost varies depending on how many parts are replaced, how much the repair shop charges for labor, and what type of transmission the vehicle has. However, you often get what you pay for in this instance, because a good repair shop charges a little extra to get better parts and pay employees a decent wage for the work.
