BorgWarner 38014BW high energy rear band for the GM 4L80E and 4L85E, 1991-up, the band that holds reverse and manual low. Smooth lining design.
Your Silverado or Sierra 2500, Suburban 2500 or Express van pulls fine in Drive but will not back up, or reverse takes a long, mushy second to bite? On a GM 4L80E that points at two parts, and this is one of them. The BorgWarner 38014BW is the rear band for the 4L80E and the 4L85E built from 1991 on, made with a high energy, smooth lining. It is the band that holds the reaction member in reverse and in manual first.
The 4L80E grew out of the TH400 gear train, and like the TH400 it uses a single wrapped band around the rear of the gear set. When the rear servo strokes, the band clamps down and holds the drum stationary. In reverse the band works together with the direct clutch, so a slipping band gives you the same feel as a burned direct clutch: high RPM and little or no movement. In manual 1 the band applies again to give engine braking on a downhill grade. In normal Drive first gear the band is not on; the roller clutch carries the load instead. That split is exactly what makes the band easy to diagnose, as you will see below.
Backing a heavy trailer up a ramp or a hill is the hardest job this band ever does. Every hard reverse engagement puts heat into the lining, and once the lining glazes or the bonding lets go, holding power drops off quickly.
Not every no-reverse is the band. The direct clutch shares the reverse job, a leaking checkball in the valve body can starve the circuit, and the control module can block reverse if it sees a speed signal above about 8 mph during the shift. Our 4L80E common problems guide covers the other failures that come through the door.
A Sonnax TASC Force write-up in Transmission Digest lays out a clean way to split the problem. Check line pressure in reverse, 3rd, 4th and manual 1. If 3rd and 4th work, the direct clutch is holding, because it is applied in those gears too. If there is no engine braking in manual 1, the rear band or its apply circuit is the suspect. Unplugging the case connector forces maximum line pressure and a failsafe pattern, which rules the computer in or out. The last step is mechanical: lock the rear servo down with a modified cover and see whether reverse comes back. If it does, the band and servo are your problem. Truck owners chasing other shift complaints can also use our Silverado 2500 shift problems guide.
This band is listed for the GM 4L80E and 4L85E, 1991 and later. That covers the 4L80E found behind the gas and diesel engines in Chevrolet and GMC 2500 and 3500 pickups, the Suburban 2500, Express and Savana vans and the Hummer H1, plus 4L80E swaps into older trucks and hot rods. If your unit has an aftermarket heavy duty drum or a non-stock rear servo, compare the old band against the new one on the bench before you button it up. If you are not sure what you have, send us the year and VIN. You can see all of our 4L80E parts on the 4L80E collection page.
| Transmission | GM 4L80E, 4L85E |
| Years | 1991 and up |
| Part number | BorgWarner 38014BW |
| Position | Rear / reverse band |
| Lining | High energy, smooth lining |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Only if the band is the cause. Reverse uses the direct clutch and the rear band together. If 3rd and 4th gear work, the direct clutch is holding, so a no reverse plus no engine braking in manual 1 points to the band, its servo or the band apply circuit.
Yes. The 38014BW is listed for both the 4L80E and the 4L85E, 1991 and later.
Inspect and resurface or replace the drum it rides on, check the rear servo seals and apply pin, and fit a new filter and pan gasket. If the fluid is burnt, plan on a full overhaul kit and frictions.
No. The rear band sits around the rear of the gear train, so the unit has to come out and be torn down to reach it.
Use Dexron VI ATF. Soak the new band in ATF before installing it, refill, and check the level hot on the dipstick.
