GM 8L80 and 8L90 Reaction Carrier Cracks: Program N252517790 Explained

GM 8L80 and 8L90 Reaction Carrier Cracks: Program N252517790 Explained

If you own a 2025 or 2026 Chevy or GMC truck with the 8-speed automatic, there is a good chance GM has already mailed you a letter about your transmission. In October 2025 GM opened Customer Satisfaction Program N252517790, and the condition it covers is about as serious as a hard-part failure gets: the reaction carrier inside the transmission cracks.

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This is not a shudder complaint, not a software flash, and not a valve body. It is a broken planetary carrier, and the fix is a full transmission teardown. Here is what GM actually documented, what the failure feels like from the driver's seat, and what your options look like once the free repair window closes.

What GM Actually Said

The bulletin is short and blunt. Per GM bulletin N252517790 (released October 2025), certain listed vehicles equipped with 8L80 or 8L90 transmissions "may have a condition in which the reaction carrier cracks." The correction is equally blunt: "Dealers are to replace the reaction carrier."

The covered vehicles are:

  • 2025-2026 Chevrolet Colorado
  • 2025 Chevrolet Express
  • 2025 Chevrolet Silverado 1500
  • 2025-2026 GMC Canyon
  • 2025 GMC Savana
  • 2025 GMC Sierra 1500

The program runs until October 31, 2027, and per the customer letter included in the bulletin, the repair is performed at no charge until that date, after which "any applicable warranty will apply." Important detail for anyone shopping used: GM instructs dealers that involved vehicles "must be held and not delivered to customers, dealer-traded, released to auction, used for demonstration, or any other purpose" until repaired, and any affected Certified Pre-Owned unit gets de-certified until the work is done.

One line in the bulletin is worth reading carefully before you panic. GM states that "there are a small number of vehicles anticipated that will need this fix," and tells dealers not to stock the parts as shelf inventory because of limited initial availability. This is a targeted VIN-based program, not a blanket condemnation of every 8-speed.

What a Cracking Reaction Carrier Feels Like

The reaction carrier is a structural member of the planetary gear train. It holds the pinion gears and takes the torque reaction that lets the gearset multiply engine output. When a carrier cracks, the geartrain loses its fixed reference point under load, and the symptoms show up as mechanical, not electronic.

Reported failure indicators for this condition include shifting issues, difficult gear changes, harsh shifting, delayed engagement, clunking sounds, grinding noises, fluid leaks, jerking sensations, and a sudden loss of power (per MotorBiscuit's reporting on the program).

Grinding and clunking are the tells. A shudder at cruise or a lazy shift can be a hundred different things, but a metallic grind that changes with gear engagement points at hard parts. Gears Magazine makes the same point about this transmission family from the diagnostic side: with the 8L90 "you're never JUST diagnosing the transmission alone. You're also diagnosing the powertrain management system simultaneously." Their guidance is to scan every module for codes and check bulletins before assuming the transmission is mechanically finished, because harsh shifts are frequently a TCM programming issue and the 25-80 mph converter shudder is the single most common complaint on these units and is fluid-related.

Translation for an owner: harsh shifts alone do not mean your carrier is cracked. Grinding, sudden power loss, and metal in the pan do.

How to Find Out If Your VIN Is Covered

You cannot determine this from a service manual lookup, and neither can your dealer. GM is explicit: Investigate Vehicle History in the GM Global Warranty Management system "MUST always be checked to confirm vehicle involvement and MUST be in OPEN status" before any inspection or repair, and the bulletin specifically warns "DO NOT use Service Information with VIN search, as it will not verify the VIN eligibility for field actions."

Practically, that means one phone call to a GM dealer with your VIN. If the field action is open against your VIN, the work is free until October 31, 2027.

What the Repair Actually Involves

This is the part most owners underestimate. The reaction carrier is buried, so the transmission comes out of the truck and goes on a holding fixture.

GM's documented labor times for operation 9108063 tell you everything about the depth of the job:

  • Colorado / Canyon: 6.8 hours 2WD, 8.1 hours 4WD
  • Silverado / Sierra: 6.1 hours 2WD, 8.0 hours 4WD
  • Express / Savana: 5.5 hours

The published sequence removes the transmission to a DT-48989 holding fixture, drops the fluid pan (GM notes the pan gasket is reusable if undamaged), pulls the fluid pump, discards and replaces the park pawl actuator bracket bolts, repositions the output speed sensor and clutch input speed sensor, removes six case extension bolts and the case extension with its seal, then works down through the output shaft bearing, output shaft, output sun gear thrust bearing, and output sun gear before the output carrier and reaction carrier assemblies come out together.

Torque values from the bulletin, for anyone following along on a unit already apart: the two new speed sensor bolts get 4 Nm (35 lb in) on the first pass, then a final 45-degree turn. The two new park pawl actuator bracket bolts go to 40 Nm (30 lb ft), and GM requires verifying the pawl locks into the output carrier before the case goes back together.

8L90 Raybestos GPZ friction clutch pack for GM 8-speed transmission rebuild
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The Parts GM Specifies

The core part is the same across every covered platform: CARRIER ASM - REACTION, part number 24059373. Alongside it the bulletin calls out two park pawl actuator bracket bolts (11547864) and two sensor bolts (11548404) as new, discard-the-originals hardware, plus DEXRON HP fluid (19417577 in the US) as required. Platform-specific kits add transfer case and driveshaft boot clamps, a converter cover gasket, and cooler line seals depending on whether you are working on a Silverado, a Colorado, or an Express van.

Note that GM prints a standing disclaimer on these documents: their bulletins "are intended for use by professional technicians, NOT a 'do-it-yourselfer'." With the free window open through October 2027, there is no reason for an owner to attempt this. Let the dealer eat the eight hours.

Replace-While-You're-In-There: The Out-of-Coverage Rebuild

The calculus changes after October 31, 2027, or if you are working on an out-of-program 8L80 or 8L90 that spun a carrier on its own. Once a unit is on the bench and the geartrain is apart, you are already carrying the entire labor cost. Doing a carrier and buttoning it back up with 100,000-mile clutches in it is how a transmission comes back a year later.

If the unit is open, the short list is:

  • Frictions and steels. The 8L90 runs five clutch positions, and Raybestos Powertrain documents how deeply they overlap: C1 serves gears 1, 2, 7, 8 and reverse; C2 covers 1, 2, 3, 4, 5 and reverse; C3 handles 1, 3, 5, 6 and 7; C4 works 2, 3, 4, 6 and 8; and C5 runs 4, 5, 6, 7, 8 and reverse. Their GPZ module is specified as 4 C1, 3 C2, 4 C3, 5 C4 and 4 C5 plates. With that much overlap, no clutch pack in this unit is a low-duty pack. An 8L90 Raybestos GPZ friction clutch pack is the sensible replacement when the geartrain is already out.
  • Every seal and gasket. An 8L90 master overhaul rebuild kit bundles the frictions, steels, and the full gasket and seal set so nothing gets reused on a fresh build.
  • Filter and pan gasket. An 8L90 transmission filter with pan gasket is the cheapest insurance on the list, and the pan is already off.
  • Fluid. Stay on the DEXRON HP specification GM calls out. Gears Magazine ties the well-known converter shudder on this family directly to fluid, so this is not a place to improvise.

Everything for these units lives in our 8L90 transmission parts collection. If you are still sorting out which GM 8-speed you have and how the 8L45 and 8L90 differ, start with our 8L90 and 8L45 transmission guide.

Don't Confuse This With GM's Other Transmission Field Actions

2026 has been a busy year for GM transmission news, and the programs are getting mixed together online. The reaction carrier program is separate from GM's 10-speed control valve recalls, which cover 2022 full-size SUVs (43,732 vehicles) and 2020-2022 Silverado and Sierra trucks (1,055 vehicles) for a transmission control valve that wears and can cause harsh shifting or rear wheel lockup, with a TCM software remedy rather than a hard-part replacement (per Carscoops). Different transmission, different failure, different fix. We covered that one in detail in our GM 10-speed wheel lockup recall breakdown.

FAQ

Is N252517790 a safety recall?
No. It is a Customer Satisfaction Program, which is a voluntary field action rather than an NHTSA safety recall. The practical effect for an owner is the same: free repair, dealer-performed, through October 31, 2027.

My 2025 Silverado shifts harshly. Is my carrier cracked?
Probably not, on that symptom alone. Gears Magazine's guidance on this transmission family is that harsh shifts usually trace to TCM programming and are addressed by reprogramming with the latest software. Grinding noises, sudden loss of power, and debris in the pan are the mechanical tells. Call a dealer with your VIN either way.

What if my truck fails after October 31, 2027?
GM's customer letter states that after that date "any applicable warranty will apply." At that point you are into a normal repair decision: dealer replacement, a rebuilt unit, or a bench rebuild where you replace the carrier and refresh the clutches, seals, and filter while the unit is apart.

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