FIRST-GENERATION DODGE AUTOS

I own a 1990 Dodge Cummins-powered pickup truck that also has Chrysler 727 automatic. I originally bought this truck for work, and even after all these years it still delivers 22 mpg on the highway. The Cummins is perfect, but the rebuilt 727 slips under heavy load during the summer. Is there a cure for this? I don’t drive the truck as much as I used to, but it’s in such good shape that I plan to keep it for a long time. Wayne Fowler Via Email

There is an article entitled “Locked Up” on page 86 of the October 2010 issue of Diesel World. This tech piece covers the 47RH, 47RE or 48RE automatics used in the 1994-07 Dodge diesel trucks. It appears that the stock clutch-apply line hydraulic pressures and related solenoids can use some improvement for higher-power applications. This illustrated step-by-step article shows how to modify the transmission to improve durability. Contact the magazine via email or visit us online

to learn whether that issue is still available.

Your best choice for a transmission upgrade may be the 47RH like that used in the 1994-95 Dodge diesel trucks. This is essentially the same transmission as your 727, but with a lockup torque converter. The RH is a non-electronic automatic, with shift points determined by an internal governor along with throttle angle inputs. Look for a transmission sourced from a diesel truck when browsing auto recycling centers. You may find gas versions of this transmission, but their governors will be calibrated for higher-rpm shift points that are used with gas engines, and some internal components won’t be as heavy duty.

This would be a custom installation, but one of the easier ones. Lots of help is available on the Internet for this type of conversion, but get back to us if you need specific details. The RH’S lockup torque converter will likely improve your Gen 1’s already great fuel economy, and lots of aftermarket performance upgrade support exists for the popular 47RH.