Replacement steel clutch plates, kit 031753B, for rebuilding the clutch packs in GM 4L80E and 4L85E transmissions from 1997 on.
If your 2500 or 3500 Silverado, Sierra, Suburban, Express or Savana came back from a long tow with a 4L80E that flares between gears, slips in fourth, or shudders as it picks up, the friction material is only half the story. Kit 031753B is a set of new steel clutch plates for the 1997-and-later GM 4L80E and the higher-torque 4L85E, made for the builder who has the unit torn down and found the old steels discolored, scored or no longer flat.
Every rotating clutch pack in a 4L80E is a stack that alternates friction plates with plain steel plates. The 4L80E uses five of these packs: overrun, forward, direct, fourth and intermediate, along with a front band and a rear band. When fluid pressure pushes the piston, the stack is clamped and the frictions grab the steels, locking one member to another. The steels are the hard, smooth half of that contact. They also soak up most of the heat generated while the pack is slipping into engagement, which is why they are the first place a hard-run unit shows its history. A steel that has been cooked turns blue or straw colored, can develop fine heat cracks, and often dishes so it no longer lies flat. A dished steel holds the frictions apart unevenly, so the pack clamps on one side first, and that is how a fresh set of frictions gets glazed in its first few hundred miles.
Heat is what kills these parts. GM's 2006 Silverado owner manual puts normal transmission temperature at roughly 180-200 F and warns that protection mode comes in around 265 F. Trucks that live near that upper number while towing are the ones that come in with blued steels. Our 4L80E common problems guide covers the towing-related clutch wear pattern in more detail.
Before blaming the clutches, rule out the electrical side. A failing pressure control solenoid or a bad speed sensor can make a healthy pack look like it is slipping, so read the EPC solenoid symptoms guide first if you have codes. Once the unit is apart, judge each steel on its own: lay it on a flat surface plate or a known-flat piece of glass and look for light under it, check both faces for bluing, scoring or hot spots, and measure thickness against an unused plate. Any steel that is discolored, out of flat or worn through its surface finish goes in the scrap pile. Reusing the old steels to save money is the most common reason a 4L80E rebuild comes back slipping.
This kit is listed for GM 4L80E and 4L85E transmissions from 1997 on. The listing names Chevrolet Silverado and GMC Sierra 2500/3500, Suburban and Yukon XL 2500, Express and Savana 2500/3500, and the Hummer H1. The 4L80E also showed up behind some Bentley, Jaguar V12 and Aston Martin DB7 engines; those units use the same internal clutch layout but check your old plates before you order. Plate count, thickness and tooth profile are what matter, so set one of your old steels beside the new ones and compare before you start a pack, or send us your year and VIN and we will check it for you. Everything else for the build is on our 4L80E parts page.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
It is listed for the GM 4L80E and 4L85E from 1997 on, in Silverado and Sierra 2500/3500, Suburban and Yukon XL 2500, Express and Savana 2500/3500 and the Hummer H1. Compare one of your old steels against the new plates before you build each pack.
Only if they are flat, the original thickness and free of bluing or scoring. In a unit that came in slipping or burnt, the steels are almost always heat damaged, and new frictions against a glazed or dished steel tend to slip again quickly.
No. This is the steel plate kit. Pair it with a friction set or an overhaul kit so every pack gets new frictions and new steels together.
DEXRON-VI. GM lists 7.7 quarts for the 4L80-E in the 2008 Express owner manual; fill, run it to operating temperature and check the level hot.
GM sets P0894 when it sees slip in the converter clutch and/or the fourth clutch while the converter is locked in fourth. Worn fourth clutch frictions and steels are one cause, a failing converter clutch is the other, so confirm which before ordering parts.
