The 845RE — commonly called the 845RFE — is the eight-speed automatic that Ram paired with the 3.6L Pentastar V6 in every Ram 1500 from 2013 through the current Classic generation. It is also found in the Dodge Charger, Chrysler 300, Dodge Durango, Dodge Challenger, and Jeep Grand Cherokee with the 3.6L V6. Based on the ZF 8HP45 design, Chrysler licensed the architecture and builds their version at the Kokomo, Indiana plant with beefed-up internals including additional friction plates beyond the original German specification.

The eight-speed design delivers excellent fuel economy with a wide ratio spread that lets the V6 cruise at low RPM on the highway. But the 845RE has specific failure points in the valve body, torque converter, and clutch packs that we see regularly at Top Notch. We rebuild these with upgraded components that address every known weakness in the original design.

The Failures We See Most on the 845RE

1. Valve Body and Mechatronic Assembly Failure

The 845RE integrates the transmission control module directly into the valve body as a single mechatronic unit. That means a valve body problem and a TCM problem often look identical from the outside. The solenoids inside this assembly fail hydraulically rather than electrically, which makes diagnosis tricky because they can test electrically normal while leaking fluid internally. When the solenoids lose their internal seals, you get erratic shifts, hunting between gears at highway speed, harsh downshifts, and delayed engagement.

The converter pressure regulator valve bore is another documented wear point on the ZF 8HP platform. As that bore wears, the regulator valve sticks or rattles, and your lockup clutch engagement becomes inconsistent. We address this with oversized replacement valves that restore factory-spec sealing and a shift recalibration kit that corrects clutch apply timing across all eight gears.

2. Torque Converter Shudder

The TCC lockup clutch on the 845RE is controlled by a pulse-width modulated solenoid that varies the engagement duty cycle for smooth lockup at cruise speed. When the friction material glazes from heat, you get a vibration at 40 to 50 miles per hour under light throttle that feels like rumble strips. A failed coolant bypass valve — a known related failure on this platform — can push fluid temperatures past 230 degrees, which oxidizes the ATF and strips its friction-modifying properties. Once that happens, the converter clutch cannot engage cleanly and starts shedding material into the hydraulic system.

We replace the factory converter with an upgraded unit featuring higher-quality friction material and improved clamping force that eliminates the shudder pattern.

3. Clutch Pack Wear

The 845RE uses multiple clutch packs working in combination to achieve its eight forward speeds. The underdrive clutch pack handles first through third gear engagement and takes the most abuse in stop-and-go driving. The overdrive pack manages seventh and eighth gear and wears under sustained highway cruising. When either pack starts slipping, you see gear ratio error codes and the transmission may drop into limp mode locked in a single gear. Debris from worn clutch packs contaminates the valve body and accelerates solenoid wear, creating a failure cascade that gets worse the longer you drive on it.

What Goes Into a Top Notch 845RE Rebuild

A dealer typically installs a Mopar remanufactured unit built to original factory specifications. That means the same valve body tolerances, the same converter design, and the same clutch material that failed in the first place. Our rebuild addresses the root causes:

• Valve body reconditioning with oversized converter pressure regulator valve and shift recalibration kit for corrected clutch apply timing
• Full solenoid testing using a dedicated test manifold to identify hydraulically failed solenoids that pass electrical testing
• Upgraded clutch packs using high-temperature friction material that exceeds OEM specifications for heat resistance and longevity
• Upgraded torque converter with improved friction material and higher clamping force
• New torque-to-yield valve body bolts — these are single-use fasteners that must be replaced every time the unit is opened. Reusing them causes oil leaks and valve body movement
• Fresh ZF 8 and 9 Speed ATF — the 845RE does not use ATF+4. Using the wrong fluid accelerates seal degradation and clutch wear
• TCM reprogramming with Quick Learn procedure to calibrate clutch engagement to the fresh packs

Every 845RE rebuild is backed by our 3-year warranty and we offer financing to keep the repair manageable.

Frequently Asked Questions: 845RE Transmission

My Ram 1500 shudders at highway speed. What is it?

On a 3.6L V6 Ram with the 845RE, highway shudder is almost always the torque converter lockup clutch. The friction material wears under sustained partial engagement and loses its ability to lock smoothly. A failed coolant bypass valve can accelerate this by allowing fluid temperatures to climb past safe operating range. The converter needs to be replaced, and the valve body should be inspected for contamination from the failed clutch material.

Is the 845RE the same as the ZF 8HP45?

They share the same architecture. ZF designed the 8HP45 in Germany, and Chrysler licensed it and builds their version in Kokomo, Indiana as the 845RE. The Chrysler version has additional friction plates for increased torque capacity. The two are functionally similar but not identical in every internal specification.

Does the Ram 1500 HEMI use the 845RE?

No. The 845RE is paired exclusively with the 3.6L Pentastar V6. Ram 1500 trucks with the 5.7L HEMI V8 use the heavier-duty 8HP70 or 8HP75 transmission. If you are unsure which transmission your truck has, call us with your VIN and we will confirm it.

How much does an 845RE rebuild cost?

A quality rebuild with upgraded clutch packs, valve body reconditioning, and a remanufactured converter typically ranges from $3,000 to $5,000 depending on the condition of the unit. We offer financing to make the repair manageable.

Vehicle Application Guide: 845RE Transmission

Note: The 845RE pairs exclusively with the 3.6L Pentastar V6. Vehicles with the 5.7L HEMI use a different, heavier-duty ZF 8-speed (8HP70 or 8HP75). We rebuild all ZF 8-speed variants.

Ready to Fix Your 845RE for Good?

Call Top Notch Transmissions today at (817) 386-7592 to schedule a diagnostic. We offer free estimates, a 3-year warranty on all rebuilds, financing to fit your budget, and free towing anywhere in DFW.