With nothing found in the transmission that could be blamed for the slip complaint, the valve body was disassembled for inspection.
Subject Matter: Allison 1000/2000/2400
Critical Wear Areas & Vacuum Test Locations
Over the years, the Allison® 1000/2000/2400 valve body has had four versions. This article is written to help identify each version. The first two versions are five-speed and the last two are six-speed valve bodies. The information will explain casting number and separator-plate combinations that work correctly together.
The Technically Speaking article in the June issue of Transmission Digest was an article called A Twist of Fate. The subject matter was the effects produced when an AS68RC transmission’s stator shaft turns in the pump cover. The article briefly mentioned a similar issue with the Allison 1000/2000 transmission. This comment prompted several people to call asking for more information about it.
In ATSG’s “Shifting Great in 2008” technical-training seminar we covered a complaint of TCC shuttle or surge with GM’s medium-duty trucks using Allison 1000/2000-series transmissions. This complaint usually occurs after converter replacement.
Since the release of the Allison 1000/2000/2400 series transmission, four basic torque-converter configurations have been used. TC-210, TC-211, TC-221 and TC-222 can be found in Group 21 of the Allison Parts Book, and these four converters all have different stall torque ratios and “K” factors. Over the years several revisions have been made to the torque-converter assembly process for all four converters, and each time a change was made, a new part number was assigned. None of these changes had an effect on the performance or functionality of the torque converter. Different generations of each of the four converters are completely interchangeable with other generations of the same type.
Have you ever found yourself chasing a “phantom” TCC drivability problem in a GM vehicle that uses the Allison 1000/2000/2400 series of transmissions?
If you have, there’s a good chance that the root of your problem turned out to be the torque converter. No earth-shattering news there, but what is unique is that the problem was likely on the outside of the converter, not the inside.