8L45 Transmission Rebuild & Repair in Glendale, AZ (GM)

Sun West Transmissions — Glendale, AZ. Free estimates, honest diagnosis and a 3-year / 40,000-mile warranty on qualifying rebuilds and replacements.

The GM 8L45: Eight Speeds for Smaller Engines

The 8L45 is GM’s lighter-duty rear-wheel-drive eight-speed automatic. It uses the same general architecture as the larger 8L90 but is sized for four-cylinder, turbocharged and V6 engines. GM introduced it in the mid-2010s to improve fuel economy and performance in midsize trucks and rear-drive cars.

Around Phoenix, the 8L45 is most common in the Chevy Colorado and GMC Canyon midsize pickups with the V6 engine, plus the Chevy Camaro and several Cadillac models such as the ATS, CTS and CT6, depending on engine and year. Sun West Transmissions in Glendale diagnoses these units and performs complete 8L45 transmission rebuild work when internal repairs are needed.

Colorado and Canyon Owners: What to Know

Midsize GM pickups are popular across the West Valley for commuting during the week and heading out on weekends. Many owners tow small trailers, carry dirt bikes or explore forest roads near Prescott and Payson. That variety of use, from Loop 101 commuting to slow off-road driving in summer heat, can be demanding on an eight-speed automatic.

The most common 8L45 complaints in these trucks include a shudder at light throttle, harsh or clunky shifts at low speed and occasional hesitation. GM addressed some of these concerns through service bulletins involving updated fluid and software, and in some cases torque converter replacement.

Common 8L45 Problems

Torque Converter Clutch Shudder

A vibration that feels like rumble strips, usually between moderate speeds and light throttle, is often tied to the torque converter clutch and fluid condition. Early treatment with an updated fluid exchange can help. A converter that has been shuddering for a long time may already be damaged.

Shift Quality Complaints

Harsh 1-2 or 2-3 shifts, clunks when slowing to a stop and busy shifting on grades can result from calibration, adaptive learning, valve body wear or clutch issues. A careful diagnosis keeps you from paying for a rebuild when a software update may help.

Slipping or Flare

Slipping between gears or RPM flare under load is a sign of internal clutch wear or pressure loss, which usually requires disassembly to repair.

Electrical and Module Faults

Like other modern GM automatics, the 8L45 has its control module inside the transmission. Module, solenoid and wiring faults can trigger warning messages and limp mode.

Our Diagnostic Approach

Modern eight-speed transmissions need modern diagnostics. At our shop on West Northern Ave, we:

1. Road test the vehicle to experience the shudder, shift or slip.
2. Scan for codes and monitor live data such as converter slip, gear ratio and fluid temperature.
3. Check fluid level using the correct temperature-based procedure.
4. Inspect fluid condition and look for leaks or debris.
5. Check for applicable service bulletins and software updates.

If the problem can be solved with fluid, software or an external repair, we’ll recommend that first. We only recommend a rebuild when internal damage is confirmed.

8L45 Rebuild: What’s Included

• Removal and complete disassembly of the transmission.
• Cleaning and inspection of planetary gear sets, clutch drums, shafts and the case.
• New clutches, steels, seals, gaskets and filter.
• Replacement of damaged bushings, bearings and hard parts.
• Valve body and internal control module inspection, with programming as needed.
• Torque converter replacement when worn or contaminated.
• Cooler flushing, correct fluid fill, adaptive relearn and a final road test.

What Drives the Cost of an 8L45 Rebuild

Several factors affect the price of an 8L45 rebuild: the vehicle model and engine, whether the truck is two-wheel or four-wheel drive, the extent of internal damage, torque converter condition and whether the control module needs to be replaced or programmed. We’ll also explain alternatives such as a remanufactured unit or a good used transmission if those make sense. Call for a free quote on your vehicle.

Qualifying rebuilds include our 3-year / 40,000-mile warranty with no deductible on covered repairs, and financing is available.

Protecting Your 8L45

Use the correct GM-specified fluid, follow a severe-service transmission service interval in Arizona heat and fix leaks early. If you tow, an auxiliary cooler helps. On four-wheel-drive trucks, we can also check your transfer case and differentials while the vehicle is in.

8L45 Transmission FAQ

Does my Colorado have an 8L45?

Many V6 Colorado and Canyon trucks from the later 2010s do, but it depends on the year and engine. We can confirm it by RPO code or VIN.

Will a fluid exchange fix my shudder?

It often helps if the converter isn’t damaged. If shudder returns, the converter may need replacement.

Can the 8L45 handle towing?

Within the vehicle’s rated limits, yes. Keeping fluid fresh and temperatures down is key in Arizona.