Eleven sized POM drivers that press worn internal and speedometer bushings into a GM 4L80E, TH400 or TH350 case squarely without scoring the bore.
Worn bushings are the quiet killer in a high-mileage 4L80E. A Silverado 2500 that has towed for years, an Express van with a lot of idle time, or a TH400 that has been in a hot rod for decades will often look fine on the outside and still have bushings that let the shafts wobble and bleed off pressure. This 11-piece driver kit is made for replacing those bushings in GM 4L80E, 4L85E, TH400 and TH350 units, with drivers sized for the case, extension housing, pump, drum and speedometer bushing locations.
Inside a 4L80E the bushings are not just bearings. Several of them sit between rotating shafts and the passages that feed the clutches and the converter, so the clearance between bushing and shaft acts as a seal. When the stator support bushing wears, apply oil meant for the converter clutch leaks past, and Sonnax lists TCC slip codes, no lockup, overheated fluid and no overdrive among the problems a new stator support bushing helps cure. A worn case bushing lets the output shaft move and can walk out of its bore. Getting a new bushing in straight is the whole job. Drive it in with a socket and a hammer and it can cock, shave the bore or crush its own edge, and a crushed bushing has the wrong inside diameter before the truck is even back on the road.
These drivers are machined from POM (acetal) plastic rather than steel. Acetal is hard enough to drive a bronze or steel-backed bushing but will not gall the aluminum case or mark the bushing face. Each driver has a pilot that centers it in the bushing and a shoulder that locates it.
Pressure problems on a 4L80E are not all bushings. The EPC solenoid, the AFL valve and the boost valve can all drop line pressure too, and on diesel trucks an injection pump fault can fool the computer into commanding the wrong pressure. Read our 4L80E pressure control solenoid guide and the 4L80E common problems guide before you commit to a teardown. Once the unit is apart, measure each bushing against its shaft. Any bushing with visible scoring, missing material or an egg-shaped bore gets replaced, and with this kit on the bench there is no reason to reuse a marginal one.
Listed for the GM 4L80E and 4L85E (1991-2009 Chevrolet and GMC 2500 and 3500 trucks, Suburban 2500, Express, Savana and Hummer H1) and the TH400 and TH350 families those units grew out of. The cross-reference numbers listed for this set are 46626B, 46627A, 46629, 46640, 46630, 46627, 46627B, 46632A, 46631, 46633A, 46634A and 46635B. Bushing dimensions vary between some TH350 and TH400 parts, so compare the driver against the bushing in your hand before you start. If you are not sure which unit you have, send us the year and VIN. Replacement hard parts are in the 4L80E collection.
| Pieces | 11 bushing drivers |
| Fits transmissions | GM 4L80E, 4L85E, TH400, TH350 |
| Driver material | POM / acetal (non-marring) |
| Covers OEM numbers | 46626B, 46627A, 46629, 46640, 46631, 46632A, 46633A, 46634A, 46635B |
| Weight | 1.72 lb |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes. The kit is listed for the 4L80E, 4L85E, TH400 and TH350, which share many bushing locations. Some sizes differ between units, so fit the driver to the bushing before you start.
POM acetal drivers will not gall the aluminum case or mark the bushing face. They are tough enough for normal bushing installation, though a tight interference fit is better done under a press than with a heavy hammer.
Most builders replace every bushing that shows wear: pump, stator support, drum, case and extension housing. The stator support and case bushings get the most attention because they affect converter feed and output shaft support.
Yes. Excess clearance at the stator support bushing lets converter apply oil leak away, which can cause no lockup or TCC slip codes. A cracked converter clutch can cause the same code, so check both.
It is built for installation. You will still need a bushing puller or a cutter to remove the old ones without damaging the bore.
