4L80E Shift Kit 1991, new and ready to install. Fits the 4L80E. Ships fast from the USA.
The first 4L80E trucks are now more than 30 years old, and most of the ones still working have a tired valve body and a direct clutch that has been rebuilt at least once. If you are building an early unit from a 1991-1996 C/K 2500 or 3500, Suburban, G-van or Hummer H1, or a 4L80E for a swap, and you want it to stop slipping the 2-3 shift, this is the kit to put in it. It is a new TransGo 4L80E-HD2 reprogramming kit. The box is marked for 1991-on 4L80E and 4L85E models, and TransGo lists it for 1991 to 2013.
The 4L80E applies its direct clutch for third and keeps it on in fourth, so that one clutch pack has to hold engine torque in the two gears a truck spends most of its life in. TransGo's fix is to feed that clutch from two sides. A laminated triple separator plate adds a second oil feed and, per TransGo, triples the torque the third gear clutch can hold. The kit then recalibrates the pump, valve body and internal parts to run on a higher line pressure curve, so the shifts become firm and short instead of long and slipping.
On an early, high mileage unit the boost valve is usually the part that is wrong. TransGo says the boost valve bore is notorious for wear. Too little boost gives a soft 2-3 shift and direct clutch failure; too much can break the case, the direct drum and the piston. HD2 swaps in a hardened, wide land boost valve and bushing and adds an EPC boost pressure relief valve as a ceiling.
An early 4L80E with a code or a shift complaint often has an electrical cause. The A and B shift solenoids, the pressure control solenoid and the case connector should be resistance tested first, and our A and B shift solenoid guide lists the values from the GM tables. A firm or bang shift can also be an EPC fault, so work through the 4L80E harsh shift guide. If the electrical side checks good and the 2-3 still slips, the kit and a rebuild are the cure.
TransGo covers every 4L80E and 4L85E from 1991 on, including early units in GM heavy duty trucks, vans and the Hummer H1. The early valve bodies, accumulator housing and pressure control solenoid are different from late ones, and the TransGo instructions call out what to do on each design. Read them for your build before you drill anything. If your unit came out of a swap, use the ID tag on the case, or send your year and VIN and we will confirm. More parts for early units are on the 4L80E collection page.
| Fits | 4L80E 1991 |
| Part type | Shift Kit |
| Condition | New |
| Brand | TransGo |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes. The kit is marked for 1991-on 4L80E and 4L85E transmissions, and TransGo lists it for 1991 to 2013. Follow the instructions for the early valve body design.
It fits the transmission, not the vehicle. Any 4L80E or 4L85E from 1991 on is covered, whatever it is installed in.
They are early OBD-I codes that TransGo lists among the complaints the kit helps correct. Read the code with a scan tool and rule out electrical faults before relying on the kit.
Not for the hydraulic part of the kit. But if the direct clutch is already burned, the kit belongs in a rebuild, and the snap rings and return springs only go in with the unit apart.
Dexron VI, which replaces the original Dexron III. Check it hot.
