New Transmission Vs. Rebuilding

Transmissions regulate and convey power from the engine to the drivetrain, which puts them under constant stress. They are also incredibly complex, consisting of dozens of moving precision parts. This makes transmissions very susceptible to wear and tear. On top of that, many a car owner neglects to check their transmission fluid and perform transmission service as required. The result: lots of broken transmissions.

Once a car needs a new transmission, there's no avoiding the shop. Mechanics typically offer the choice of new or rebuilt transmission replacement. The most obvious difference for drivers is cost. A new transmission can cost three times or more than a rebuilt transmission, and may take up to a week to order. Rebuilds usually don't take longer than three days.

In addition to money and time, there is the reliability factor to consider. Rebuilt transmissions are more hit and miss, and depend on the quality of work done at the shop where drivers choose to get their car fixed. New transmissions have a full manufacturer's warranty, while rebuilds get warrantied by the shop that did the work.

This is very self-explanatory. New transmissions for a given car model are no different than the one put in it by the manufacturer when it was originally made. They are best tuned and best suited to the other components in the car and are new from the ground up--with no used components included.

Conversely, a rebuilt transmission doesn't come from the manufacturer and is done by individual shops, hence the inconsistent quality of work. The process sounds simple: the hard parts of the transmission, the case and core, are made of tough metal and rarely break. These can be used in the rebuilding process. Soft parts such as gaskets, seals, filters, valves and clutch components are replaced in a rebuild when necessary.

There are several grades of rebuilding a transmission, from simple replacement of specific, easy-to-get-to parts to complete overhauls. Of course, the more comprehensive the operation the more expensive it is. Ideally, mechanics should be able to identify the problem without too much investigation, which makes a basic rebuild possible. In any event, all degradable components and fluids must be replaced and refilled to manufacturer specifications.

There is also the issue of remanufacturing, often mistaken for rebuilding. The two aren't the same, although remanufacturing is somewhere between rebuilding and getting new. In remanufacturing, the transmission isn't worked on by regular mechanics. Instead, dedicated facilities replace every soft part, keeping only the core. This is a bit more comprehensive than an overhaul, but takes longer and costs more.