The RAM 1500 with the 5.7L Hemi runs either the 545RFE (older applications) or the 8HP70/8HP75 ZF 8-speed (2013+ Ram 1500). Both are capable transmissions. Both can develop a shudder complaint under load — and the two units have different root causes that lead to very different repair paths if you don't understand the distinction. The 545RFE is a Chrysler unit — 5-speed automatic used in the RAM 1500 and Durango with the Hemi. It requires Mopar ATF+4. The shudder on a 545RFE under moderate to heavy acceleration is almost always torque converter clutch shudder from degraded ATF+4. The TCC on this unit locks up aggressively under load, and when the fluid's friction modifier chemistry has degraded, the clutch engagement becomes inconsistent — grab, slip, grab, slip — which is the shudder you feel. The code P0740 (TCC circuit) or P0741 (TCC performance) accompanies this in most cases.
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Mopar ATF+4
SearchCorrect fluid for the 545RFE in pre-2013 Hemi RAM 1500 and all 45RFE applications. If your RAM has the 5-speed automatic, this is what goes in for a shudder service. Pick up 8 quarts for two drain-and-fills spaced 300 miles apart to adequately address a TCC shudder complaint.
Check Prices & ReviewsBlueDriver Bluetooth OBD2 Scanner
$89.95Reads Chrysler-enhanced codes on both the 545RFE and the ZF 8HP applications. Confirm P0740 or P0741 before starting a shudder repair, and monitor live TCC slip on a test drive after the fluid service. Also identifies the transmission type in the vehicle information — critical for confirming whether you have the 5-speed or 8-speed before ordering fluid.
Check Prices & ReviewsLucas Oil Transmission Fix
$14.87For 545RFE Hemi trucks showing TCC shudder with otherwise borderline ATF+4 condition, Lucas Trans Fix added to a fresh ATF+4 service helps recondition TCC clutch surfaces during the relearn cycle. Use only with the 545RFE — do not add to a ZF 8HP application without verifying compatibility with ZF-spec fluid.
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