DC-1000/2000 Improvements


The Allison 1000/2000 appeared in 2001 in many GM heavy duty trucks and later model Fords. Several improvements have been made with a few positive results. As popularity increases, rebuilders need to be aware of the factory short comings and capitalize on known improvements. This is one converter that should not be rebuilt as a stock OEM design. Known early warning signs will tell the story.

If impeller hub wear is even slight (2.293 is new, 2.2915 or smaller) the hub should be replaced. A pump failure or complete transmission failure could occur leading to a costly comeback. Excessive clearance between the hub and pump bushing can also lead to converter clutch malfunction. Neither you nor your customer can afford this. Use only a new flanged hub. Do not try a butt mount hub here.

There are many areas to inspect for problems. First take a very close look at the damper springs. Early units used in GM diesels commonly are found with broken or weakened springs. Even later converters, as shown in photo A, need careful examination. They may be hard to see but the larger outer springs do break. If the converter has metal contamination, remove and clean the damper assembly. This is a hiding place for debris such as clutch material and metal particles. If the clutch lining is to be replaced consider using a stronger carbon type liner instead of the OEM design. Heat is a real factor here and the paper type clutch is not a good choice. They are usually worn or burnt from excessive slippage. This brings us to the front cover. Hot spots indicate slippage and possible distortion of the front cover. You have a choice of resurfacing the clutch contact surface after careful inspection for cracking near the mounting pad area or replacing the cover with a new one piece billet. This is the preferred choice among rebuilders. It provides a stronger converter to flywheel mounting area that will not crack along with a clutch contact area that will retain integrity from friction and heat under severe use.

The newer units have better bearing than the 2001-2005 models. Shown in photo B is the latest improvement. Early converters should always have the bearing replaced. Testing them and inspection efforts will certainly lead to regrets. Replace them now and avoid a comeback.

As a last notation, inspect the outer most ring of dimples located on the impeller. Small nicks or indentations of the dimples can cause engine and or transmission malfunction do to erratic magnetic impulses DC-1000/2000 Improvements from the speed sensor. Properly rebuilt, this converter can add to your company an increased profit center.

Dennis Sneath
Midwest Converters
Rockford, Illinois

– Found in June 2008 Newsletter