Chrysler 68RFE 6-Speed Automatic (Cummins Diesel) · Chrysler/Dodge/Jeep/RAM · Expert rebuild service since 1987. Lifetime warranty. Free diagnostic.
2007–present RAM 2500/3500 with 6.7L Cummins diesel; the primary automatic transmission behind the Cummins in modern RAM heavy-duty trucks
| Configuration | 6-speed automatic with overdrive — Cummins diesel application |
|---|---|
| Gear Ratios | 1st 3.23:1 · 2nd 2.25:1 · 3rd 1.55:1 · 4th 1.00:1 · 5th 0.75:1 · 6th 0.67:1 · Rev 3.16:1 |
| Fluid Type | Mopar ATF+4 |
| Fluid Capacity | 14.5 qts total, 7.5 qts service refill |
The 68RFE overdrive clutch pack is severely undersized for the Cummins diesel torque output. This is the #1 known 68RFE weakness — OD clutch failure is nearly universal at 150k+ miles, especially with any performance tuning.
Symptoms: Slip in 5th or 6th gear; drops from OD on grades; worse under full load; eventually all OD engagement lost
The solenoid pack wears at high mileage under Cummins torque loads.
Symptoms: Limp mode; P0750-series codes; erratic shift quality
TCC failure under maximum Cummins towing loads — TCC slip causes overheating.
Symptoms: Shudder under load; TCC cycling; transmission temperature warning
Full disassembly. OD clutch pack replaced with upgraded Sonnax billet and Alto Red Eagle heavy-duty kit (standard rebuild kit is inadequate). Solenoid pack replaced. TCC replaced. All clutch packs replaced. Valve body rebuilt. Converter flushed.
ATF+4 every 25,000 miles for towing applications. The OD clutch upgrade is strongly recommended with any rebuild — stock OD pack will fail again. Add an auxiliary cooler and temperature monitor. Do not tune the Cummins beyond stage 2 without rebuilding the 68RFE with upgraded clutches first.
The stock 68RFE is the weak link in the Cummins diesel system — the OD clutch pack is undersized for the engine's torque. Rebuilt with upgraded Sonnax billet clutches, it's significantly more durable. Many Cummins owners prefer the Aisin AS69RC that was available as an option starting 2019.
If it's early-stage OD slip with good clutch pack pressure, a targeted OD clutch replacement is possible. Once the band and clutch material contaminates the fluid, a full rebuild with flushed components is required.
$2,200–3,000 for a stock rebuild. $2,800–3,800 for the upgraded Sonnax billet OD kit — we strongly recommend the upgraded build for any diesel towing application.
The Aisin swap is stronger but expensive and requires adapter plates. A properly rebuilt 68RFE with Sonnax upgrades is the cost-effective choice for most owners.
Mopar ATF+4. Critical — do not use generic ATF.
Free diagnostic, written estimate, lifetime warranty. Chicago's 68RFE rebuild specialists since 1987.
