8HP70 Transmission Cooler 2015

A 2015-or-newer Dodge Charger or Challenger with the 8HP70 eight-speed can run its transmission fluid hot, especially with a HEMI that sees drag strip passes, road course laps, towing a light trailer or summer traffic. If you are watching transmission temperature climb on a gauge or logger, or you want insurance before adding power, this is the TCI Max-Cool transmission cooler kit, part number 824105. It is a bolt-in auxiliary cooler built for these cars, with the brackets, hoses and thermostatic block already sized for the job.

What this cooler kit does on an 8HP70

The Mopar 8HP70 already has a factory cooling circuit, but it is controlled by a thermostatic valve that restricts flow to the cooler until the fluid reaches roughly 180 degrees F. Below that point the fluid is routed past the cooler so the transmission warms up quickly. That is good for economy, but under hard use the fluid climbs fast, and if that valve ever sticks closed the transmission loses its cooling entirely. TCI's kit adds a second heat exchanger fed through its own thermostatic cooler block, which also opens at about 180 degrees and then sends fluid through the added core. The thermostat in the block is removable, so a dedicated track or drag car can run full-time flow through the exchanger for maximum cooling.

The kit includes the heat exchanger, -6AN hoses cut to length with fittings, mounting brackets, the thermostatic cooler block and the remaining fittings and hardware. The exchanger measures about 7.19 by 1.25 by 23 inches.

Symptoms of an 8HP70 running too hot

• Transmission temperature climbing steadily during repeated launches, track sessions or long grades
• Shift quality that gets softer or flares when the fluid is hot and returns to normal when it cools
• A transmission overtemperature warning or the car protecting itself with reduced performance
• Dark or burnt-smelling fluid when the pan is serviced
• Fluid temperature that never drops on the highway, which can point to a stuck factory thermostatic valve

How to confirm before you buy

Log transmission fluid temperature with a scan tool through a drive that reproduces the problem. A steady climb under load that recovers at cruise points to cooling capacity; a temperature that stays high even at light cruise points to a stuck factory valve or a blocked cooler, which should be fixed first. Check the fluid level hot, since a low 8HP shifts poorly at any temperature. Our Charger 8HP common problems guide covers the faults these cars are known for, and the Charger shift problems guide helps separate heat-related shift complaints from software or valve body issues.

Fitment

TCI lists kit 824105 for the 8HP70 in 2015-and-newer Dodge Challenger and Charger models. Not every Charger or Challenger uses the 8HP70; depending on engine and year, these cars were also built with other ZF eight-speed versions, so read the transmission tag or send us your year, engine and VIN before ordering and we will confirm. The kit is designed for these specific cars, so a Chrysler 300, Durango, Grand Cherokee or Ram with an 8HP70 is not covered by this listing. Every 8-speed part we carry is on the ZF 8HP parts page.

Install notes

• TCI describes the kit as bolt-in with no cutting or welding. Mount the exchanger with the supplied brackets where it gets clean airflow, and route the -6AN hoses away from exhaust heat and moving parts.
• Opening the cooling circuit loses fluid. Top up with ZF LifeguardFluid 8, the fluid ZF approves for the 8HP, and set the level hot with the engine running at 30 to 50 C fluid temperature.
• If the fluid is dark or the car has high miles, service the pan and filter at the same time; the 8HP70 pan, filter and fluid kit covers that job.
• After the first drive, recheck the level and inspect every fitting for seepage. Decide whether to keep or remove the block thermostat based on how the car is used; street cars benefit from keeping it.

Which cars does the TCI 824105 cooler kit fit?

TCI lists it for the 8HP70 eight-speed in 2015-and-newer Dodge Challenger and Charger models. Confirm your car has the 8HP70 by checking the transmission tag or sending us your VIN.

Does this replace the factory transmission cooler?

No. It adds a second heat exchanger with its own thermostatic block, so the factory cooling circuit stays in place and the added core provides extra capacity once the fluid is hot.

What temperature does the kit start cooling?

The thermostatic block opens at about 180 degrees F. The thermostat is removable if you want constant flow through the exchanger for track or drag use.

What comes in the kit?

The heat exchanger, -6AN hoses cut to length with fittings, mounting brackets, the thermostatic cooler block and the installation hardware.

Do I need to add fluid after installing it?

Yes. Some fluid is lost when the circuit is opened and the new core and hoses hold more. Top up with ZF LifeguardFluid 8 and set the level hot using the ZF fill procedure.

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