Full sealing set of gaskets, lip seals, O-rings, and sealing rings for rebuilding a GM 4L80E or 4L85E, 1997 through 2011.
Searching for a 4L80E reseal kit for a 1997 to 2011 Silverado or Sierra 2500 or 3500, an Express or Savana van, a Suburban or a motorhome chassis? This is the WIT gasket and seal kit that crosses to interchange numbers KP34900FX, W34002EA and 80000733. It is the soft-parts half of a rebuild for the later 4L80E and 4L85E, aimed at the owner whose truck leaks at the pan and servo covers, engages slowly when cold, or loses its grip once the fluid is hot, but whose clutch packs still measure good.
From 1997 on, the 4L80E kept the same basic layout of overrun, forward, direct and fourth clutches plus the intermediate and rear bands, but GM revised the hydraulics; Sonnax groups the later units under different valve body castings from the 1991-1996 versions. Each clutch is applied by fluid that passes gaskets, crosses sealing rings on the turbine shaft, center support and pump stator, and then pushes a piston sealed by lip seals or O-rings. When that rubber hardens from years of heat, part of the apply pressure leaks away before it reaches the piston. This kit replaces the case and pump gaskets, lip seals, O-rings and sealing rings. It has no frictions, steels, bushings or filter, which keeps the cost down when the plates are still serviceable.
If the pan is full of friction material, a reseal alone will not hold. That calls for a full kit with plates, such as the 4L80E master rebuild kit with frictions and steels.
Transmission Digest recommends breaking a 4L80E complaint into hydraulic, electrical and mechanical causes and checking line pressure against a test sheet with the port locations and the clutch and band apply chart. Electrical faults come first: our 4L80E pressure control solenoid guide shows how a weak EPC solenoid mimics a seal leak. If line pressure is correct at the tap but one range still slips, the leak is downstream in that circuit, and new seals are the cure. Transmission Digest also traces overdrive clutch failures in this unit back to the overrun and coast clutch area, so look closely at that drum when it comes apart.
The listing covers the 1997-2011 4L80E and 4L85E: Chevrolet Silverado 2500 and 3500, Suburban and Express; GMC Sierra, Yukon and Savana; and the Hummer, Workhorse and other commercial and motorhome chassis that run the same unit. It is not for 1991-1996 transmissions, which use different sealing parts; those need an early kit from our 4L80E parts page. If you are unsure which half your unit falls in, send us the year and VIN and we will confirm it.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. This kit is for 1997-2011 4L80E and 4L85E transmissions. The 1991-1996 units use different sealing parts and need an early kit.
It crosses to interchange numbers KP34900FX, W34002EA and 80000733.
No. It contains gaskets, lip seals, O-rings and sealing rings only. Add frictions, steels, bushings and a filter if your unit needs them.
Only if the cause is pressure loss through hardened seals. If line pressure is low at the tap, check the pressure control solenoid first; if the plates are burnt, you need a full rebuild kit.
GM's 2005 Express owner manual lists 50,000 miles for vans over 8,600 lb GVWR or in severe service, and 100,000 miles under normal use.
