Mike the Mechanic: Dyno Testing a Remanufactured Transmission and TestBox

There are plenty of companies that rebuild transmissions.

Once a transmission is rebuilt, however, few companies perform testing to ensure the transmission will work properly and reliably. Centranz performs dyno testing on every remanufactured transmission for internal pressures and leaks. “We test the transmissions on the dyno for at least three hours. We make sure that all transmissions meet factory pressure specifications at operating temperatures,” says Mike Cullen, shop supervisor.

A dyno is a machine that holds a transmission while driving the front pump with an electric or diesel motor by way of a special adapter. A dyno has numerous gauges that monitor all pressure readings in the transmission. Normally, the transmission is operated through the gears manually, which ensures the clutch packs are being applied correctly. For most companies in the remanufacturing industry, this can be an ordeal involving a controller that’s a mess of wires, ports and switches – if they opt to test their rebuilt transmission at all.

TEM-Co's TestBox

TEM-Co’s TestBox used for Dyno Testing

Centranz uses a device developed by owner Ellis Gorden, and a team of engineers. This device is called TestBox. TestBox’s original purpose was to serve as a complementary tool to a dyno, automating the process of running through the gears and checking electronic solenoids. “What we had previously was essentially a dumb box,” says Jill Rogge, electrical engineer at Centranz. “(TestBox) is much more sophisticated. One universal TestBox with different ‘smart’ cable harnesses will run many different vehicle and transmission types. This saves our customer time, money and space.”

It wasn’t long before TestBox’s application moved beyond Centranz’s headquarters and onto job sites. Six years ago, an official with the Missouri Department of Transportation (MoDOT) identified a need for TestBox in the field.

Every winter, MoDOT salt trucks break down due to salt damaging transmission sensors. The availability and price of a tow truck is prohibitive: there are only a couple in the state capable of towing such a heavily weighted-down vehicle and the cost to do so can run in the thousands of dollars. MoDOT needed something that could override the OEM controls to the transmission, moving the vehicle safely off the road to a repair facility.

“If a transmission stops working because of a sensor, connector, harness or solenoid, Test Box allows you to move the vehicle elsewhere for further diagnosis,” Ellis says. “It allows you to get some clarity from a cloud of questions about what might be wrong with the transmission.”

Rather than the need to test transmission sensors individually from beneath the vehicle, Test Box, via a single connector, provides comprehensive data on each sensor, which can be crosschecked with a manual to determine whether the sensor is good or bad. TestBox is configurable to a range of transmissions, both on highway and off highway.

“A whole mining operation can shut down because of one stalled vehicle,” Jill says. “TestBox minimizes such an issue.”

The TestBox, a key element of Centranz’s test methodology, has proven useful outside of the shop, serving industries such as construction, mining, municipality, and fleet vehicles. Centranz’s testing protocol, unique in its industry, assures Centranz customers that remanufactured transmissions will be returned fully-functional and ready for service.