July 2007 Archives - Transmission Digest
Japanese Transmissions, American Cars

In the past, manufacturers of low-volume vehicles such as Rolls Royce and Jaguar used GM transmissions and A/C systems rather than design and develop their own. The trend has enlarged and continued so that the automakers looking to cut costs and increase efficiency are relying more on their tier-one suppliers to design and develop complete components such as transmissions and transfer cases. This has created a growth in units of a common design now showing up in many different vehicle platforms, from U.S.-built to imported brands.

Toyota Matrix U341F

In rebuilding today’s transmissions one has to be very careful with the small parts that come in these valve bodies, such as checkballs, solenoid filters, springs and relief valves. These small parts might seem insignificant, but they play a vital role in the function of the transmission. Many rebuilders dread rebuilding valve bodies with all these intricate parts that are so easily misplaced or lost. On the 50-42LE found in many Volvo, Daewoo and Saab vehicles, if the valve-body filters are installed incorrectly they can cause problems such as no reverse or lockup issues.

Volkswagen’s Direct-Shift Gearbox Part 3

Although the DSG 02E transmission contains 11 solenoids, they could be placed into three categories: gear actuator, pressure control and TCC. This article covers the first group and part of the second, and next month’s article will cover the rest of the second group and the third.

July 2007 Issue

Issue Summary:

Before and after a rebuild, the transmission may experience premature failure of the reverse, direct or coast clutch.

The vehicle owner may complain of a delayed reverse and/or flare on the 3-4 shift and may feel bind-up in reverse and 4th. The unit may failsafe with a code for incorrect 4th-gear ratio.

After a rebuild, the converter clutch may not operate, possibly producing code P0741, “converter clutch slippage detected.”

BMW vehicles may exhibit a delay of two to 30 seconds from Park into Drive during the first cold start in the morning.

The malfunction indicator lamp is illuminated with code 55 or P0735 stored for “Gear Ratio Error in 5th Gear.”
There are no complaints of slipping or poor drivability.
Some vehicles may suddenly exhibit a bind-up on the 1-2 shift.

Myth Busters

In parts 1 and 2 we looked at the results of chassis-dyno testing conducted on torque-converter modifications by Sean Boyle’s students in the automatic-transmission course at Southern Illinois University. The testing was done on an MD-250 Mustang chassis dyno, and the test vehicle was a stock 2000 Dodge Durango RT equipped with a 5.9-liter gas engine and a 46RE transmission.

Déjà Vu All Over Again

When GM introduced the stamped-steel drum for the THM 200 transmission, it presented technicians with some new challenges. The 200 direct drums would crack where the inner liner (where the piston lives) was joined to the outer shell. The weld that holds the two members of the drum together is subject to pivotal flexing each time the clutch is applied. Over time, this flexing action will cause a crack at the weld.

Aggressive Street-Level Marketing

I’ve fielded way too many phone calls lately from shop owners who tell me that their wholesale and fleet business is off.

As Bob Cherrnay always said, “You don’t have to be an Indian to read signs.” The reasons should be obvious. The problem is that too many owners have had their heads in the sand for too long.