6T50 Banner Rebuild Kit

If your GM front-drive six-speed has started slipping in reverse, flaring into third, or setting P0776, and the tag says 6T50 or one of its Gen 1 cousins, this is the soft-parts kit for the teardown. The 6T50 is the least common member of the 6T family; Wikipedia lists it behind the 2.0L turbo in the Buick Verano and the 3.0L V6 in the Captiva. This banner kit is built for first-generation units only, covering 2008-2011 6T40, 6T45 and 6T50 transmissions. It contains the overhaul kit (gaskets, metal clad seals, O-rings and seals) and a friction plate kit.

What the banner rebuild kit does in a 6T50

The 6T50 shares the 6T40 layout: an on-axis transaxle with clutch-to-clutch shifting and no bands. Six forward gears come from five clutch packs, the 1-2-3-4, 3-5-R and 4-5-6 rotating clutches and the 2-6 and low/reverse holding clutches, all controlled by the TCM on the valve body. When the frictions in those packs glaze or shed material, apply times stretch and the TCM keeps adding pressure until it runs out of adapt and sets a code. A banner kit renews every friction and every seal and gasket that holds clutch pressure, so each pack applies the way the TCM expects after the rebuild.

Symptoms that point to this kit

• No reverse, or a slip or flare in reverse or third gear
• P0776 stored in the TCM, the code GM ties to a broken 3-5-R waved plate on early units
• No forward movement after debris from that failure has spread through the unit
• Late, soft engagement into Drive or Reverse once the fluid is hot
• Dark fluid with friction material on the pan magnet, or leaks at the pan and case halves

How to confirm it before you buy

GM bulletin PI0780A was revised to add RPO MHK, the 6T50 code, so the same 3-5-R failure applies here. Scan the TCM, then check the build date: the bulletin covers units built on or before Julian date 11-015 (January 15, 2011). Our 6T40 and 6T45 wave plate failure guide explains how that plate breaks and what the debris does next, and the P0776 fix guide walks through the code. If the fluid is clean and the code points at one solenoid circuit, the problem may be controls rather than clutches.

Fitment

This kit is listed for Generation 1 6T40, 6T45 and 6T50 transmissions from 2008-2011. It is not for Gen 2 units. GM's PI0604C says most 2012 models moved to Gen 2, which uses a 4-5-6 clutch with a revised piston, a different friction plate count and re-marked frictions in every pack, so Gen 1 frictions are not a safe swap. The same bulletin lists a few 2012 exceptions that stayed Gen 1, including the 2012 Captiva Sport with the 3.0L (LFW) and the 2012 Cruze and Sonic with the 1.8L. Read the RPO code on the service parts label (MHK for the 6T50), check the build date, and send us your year and VIN if you are unsure. More kits are on our rebuild kits page.

Install notes

• Steels and pistons are not listed in this kit. GM recommends a new 3-5-R piston and waved plate any time the unit is apart, and any 3-5-R piston with notches must be replaced. Our bonded piston set covers that step. Reuse steels only if they are flat and not heat-blued.
• Clean the debris out of the whole unit and both case halves. GM says the pump fluid filter and the control solenoid filter plate must be replaced after a 3-5-R failure, so confirm you have both before assembly.
• The 1-2-3-4 piston return spring needs a compressor; the DT-47799 compressor set fits this family.
• Soak the new frictions in DEXRON VI before assembly, refill to the hot level at the check plug, and run the TCM adaptive relearn with a scan tool before the road test.

For the full parts picture on these units, see our 6T40 rebuild cost breakdown.

Will this kit fit a 2012 or newer 6T50?

Usually not. The kit is for Gen 1 units from 2008-2011. GM moved most 2012 models to Gen 2, which changed the 4-5-6 clutch and re-marked the frictions. A few 2012 models stayed Gen 1, such as the Captiva Sport 3.0L, so check your RPO code and build date or send us your VIN.

What comes in the 6T50 banner rebuild kit?

An overhaul kit with gaskets, metal clad seals, O-rings and seals, plus a friction plate kit. Steels, pistons and hard parts are not listed, so plan to buy them separately if your teardown shows damage.

Does a P0776 code mean I need this kit?

On a Gen 1 unit with no reverse or a slip in third, P0776 usually means the 3-5-R waved plate has broken and the transmission has to come apart, which is when this kit is used. Check fluid level and condition first, because a low level can cause slip codes too.

What else should I replace with it?

GM recommends a new 3-5-R piston and waved plate any time the unit is disassembled, and after a waved plate failure the pump fluid filter and control solenoid filter plate must be replaced.

What fluid does the 6T50 use?

DEXRON VI. Fill and check the level hot at the check plug, not by a dipstick.

Do I need a relearn after the rebuild?

Yes. Clear the old adapts and run the TCM adaptive learn procedure with a scan tool, then road test so the TCM can learn the new clutch apply times.

• GM 6T40 and 6T45 Wave Plate Failure
• 6T40 P0776 Fix
• 6T40 No Reverse Fix
• 6T40 Identification Guide
• 6T40 Rebuild Cost