68RFE Gear Ratios and Specs: Exact Ratios, Clutch Chart, Axle RPM and Ratio Diagnosis

Ask ten people for the 68RFE gear ratios and you will get two slightly different answers. The Ram spec sheet says 3.23, 1.84, 1.41, 1.00, 0.82, 0.63 and 4.44 reverse. The ATSG manual says 3.23, 1.83, 1.41, 1.00, 0.81, 0.62. Neither one is wrong. They are rounding the same numbers two different ways, and once you see the real three-decimal ratios, the difference goes away.

This page is the reference: the exact ratios, the clutches applied in each range, the axle ratios Ram paired with the 68RFE, what the numbers mean for engine rpm on the highway and crawl ratio off-road, and how the TCM uses ratio math to set the gear ratio codes you end up chasing. If you are not certain the unit in front of you is a 68RFE, start with our 68RFE identification guide.

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68RFE Gear Ratios: The Exact Numbers

When Dodge introduced the 6.7L Cummins and the 68RFE for the 2007 model year, its media release published the ratios to three decimals: 1st 3.231, 2nd 1.837, 3rd 1.410, 4th 1.0, 5th 0.816, 6th 0.625, and called out a 5.16:1 ratio spread. Ram's later spec sheets, including the 2024 Ram 2500/3500 Heavy Duty sheet, round those to two places and list reverse as 4.44. Raybestos Powertrain's 68RFE reference lists the same rounded figures, the version most parts catalogs use.

Gear	Exact (2007 release)	Ram spec sheet	ATSG chart	Step to next gear
1st	3.231	3.23	3.23	1.76
2nd	1.837	1.84	1.83	1.30
3rd	1.410	1.41	1.41	1.41
4th	1.000	1.0	1.00	1.23
5th	0.816	0.82	0.81	1.31
6th	0.625	0.63	0.62	—
Reverse	—	4.44	4.44	—

That clears up the discrepancy. 0.816 rounds to 0.82 but truncates to 0.81; 0.625 rounds to 0.63 but truncates to 0.62; 1.837 rounds to 1.84 but truncates to 1.83. The ATSG chart truncates, the Ram sheets round. Same gearset. The step column is our arithmetic from the exact ratios, and it tells you something useful: the 1-2 shift is the biggest rpm drop in the box, about 43 percent. It also lines up with Raybestos naming the overdrive clutch pack as a common 68RFE failure point: OD is applied in 4th, 5th and 6th, the gears a towing truck lives in. A tired UD or 2C circuit, meanwhile, shows up first as a flare or bang on the 1-2, so a light 1-2 flare on a loaded truck is worth investigating before it becomes a slipping complaint.

Which Clutches Make Each Ratio

The ratios come from three simple planetary gearsets. ATSG notes all three use six-pinion carriers to handle diesel torque, and that the gearsets were chosen to give the 68RFE a deeper first and reverse than its RFE relatives. The unit reaches every ratio by applying two friction elements at a time, plus one freewheel, the low sprag. From the ATSG clutch application chart:

• Park / Neutral: low/reverse (L/R) clutch only.
• Reverse (4.44): reverse clutch plus L/R clutch.
• 1st (3.23): underdrive (UD) clutch, held by the low sprag. ATSG notes the L/R clutch stays on in 1st only while output shaft speed is below 150 rpm.
• 2nd (1.84): UD plus the 2nd (2C) clutch.
• 3rd (1.41): UD plus the 4th (4C) clutch.
• 4th (1.00): UD plus the overdrive (OD) clutch. Direct drive.
• 5th (0.82): OD plus the 4C clutch.
• 6th (0.63): OD plus the 2C clutch.

Two things fall out of that list. First, UD is applied in 1st through 4th and OD in 4th through 6th, so the 4th gear ratio is the handoff point, and ATSG notes the shift into 5th and 6th only happens after the transmission has completed the 4th gear shift. Second, 4th is also the limp-in gear. Per ATSG, when the TCM shuts off the transmission control relay the hydraulic system alone gives Park, Reverse, Neutral and 4th in Drive, and 2nd in the "2" or "L" position. ATSG adds that trucks with Electronic Range Select do not get the 2nd gear limp-in, because the lever has no "2" or "1" position. A truck that launches in direct drive at 1.00:1 feels like it is starting in third. It is not slipping, it is protecting itself.

What the Ratios Do on the Road

Gear ratio alone does not tell you how the truck drives. Multiply by the axle ratio for the overall ratio, then by tire size for engine speed. Ram's 2019 and 2024 Heavy Duty spec sheets list the 68RFE with 3.73 axles on single and dual rear wheel trucks and 4.10 on dual rear wheel trucks. Earlier trucks had more choice: the 2008 Ram technical specifications list 3.42, 3.73 and 4.10 for the 2500 and 3500.

Engine rpm with the converter clutch locked is mph × axle ratio × gear ratio × 336 ÷ tire diameter in inches. Using a 33.2-inch tire, a common LT275/70R18 size on these trucks, and the exact ratios:

Axle	6th @ 65 mph	6th @ 70 mph	5th @ 65 mph	Overall 1st
3.42	~1,410 rpm	~1,510 rpm	~1,830 rpm	11.05:1
3.73	~1,530 rpm	~1,650 rpm	~2,000 rpm	12.05:1
4.10	~1,690 rpm	~1,810 rpm	~2,200 rpm	13.25:1

Put that next to the engine. Ram rates the standard-output 6.7L at 850 lb-ft at 1,700 rpm behind the 68RFE on the 2019 and 2024 sheets; the original 2007 engine was 650 lb-ft at 1,500 rpm. A 3.73 truck in 6th at 65 mph is sitting right around 1,500 rpm, at or just under the torque peak. That is fine empty. With a heavy trailer on a grade, the truck will want 5th, and forcing 6th with the converter locked at low rpm and high load is how you cook the OD clutch and the converter clutch. Use tow/haul, or hold 5th with Electronic Range Select, which Dodge introduced with the 68RFE specifically so drivers could pick the gear for the load. Our 68RFE towing guide covers the temperature side of that.

Tire size changes everything above. Go from a 33-inch to a 35-inch tire and every rpm figure drops about 6 percent, the speedometer reads low, and the TCM's shift schedule no longer matches road speed. Recalibrate the tire size in the vehicle configuration after any tire change, or the shift and TCC apply points will be off.

Crawl ratio and reverse

Four-wheel-drive 68RFE trucks use BorgWarner 44-series transfer cases with a 2.64:1 low range, per Ram's 2019 spec sheet. Low-range crawl ratio is 1st × axle × 2.64: about 31.8:1 with 3.73 gears and 35.0:1 with 4.10s. Reverse is deeper than first on this box, 4.44 against 3.23, so backing a trailer uphill in reverse is easier on the 68RFE than on the Aisin.

68RFE vs AS69RC Ratios

Ram used the 68RFE behind the standard-output Cummins and the Aisin AS69RC behind the high-output engine, and Ram's own spec sheets show how different the two boxes are geared:

• 1st: 68RFE 3.23 vs AS69RC 3.75
• 2nd: 1.84 vs 2.0
• 3rd: 1.41 vs 1.34
• 4th: 1.0 vs 1.0
• 5th: 0.82 vs 0.77
• 6th: 0.63 vs 0.63
• Reverse: 4.44 vs 3.54

Same top gear, same axle offerings. The Aisin has the deeper first and a wider 1-6 spread; the 68RFE has the deeper reverse. If someone swaps one for the other, the TCM calibration has to change with it, because every ratio the controller expects between 1st and 5th is different. For everything else that separates them, see 68RFE vs Aisin AS69RC.

How the TCM Uses Ratio Math (and Why You Care)

The TCM does not know what gear it is in. It calculates it. ATSG describes the 68RFE input speed sensor reading a tone wheel on the input clutch housing and the output speed sensor reading the park gear teeth; the TCM compares the two to determine gear ratio, speed ratio error, the clutch volume index and converter clutch slip. Input rpm divided by output rpm should come out at 3.23 in 1st, 1.84 in 2nd, and so on. When the measured ratio does not match the commanded gear, the TCM sets a gear ratio error code, P0731 through P0736, one per gear plus reverse.

That gives you a simple scan tool check on any shift complaint: log input and output rpm, divide, and compare to the table. In 4th the numbers should match almost exactly. If they drift apart under load, a clutch is slipping. If one speed sensor drops out entirely, the ratio goes to nonsense and the truck drops into limp mode. ATSG notes both sensors are the same part and interchange, and a new one reads about 535 ohms at room temperature. Our guides to 68RFE speed sensor symptoms and P0736 reverse ratio walk through both failure types.

68RFE Quick Spec Sheet

• Type: six-speed, fully electronic, three planetary gearsets, one overrunning clutch (low sprag), electronically controlled converter clutch.
• Friction elements: UD, OD and reverse clutches in the input housing; 2C, 4C and L/R holding clutches (ATSG).
• Pressure switches: five (L/R, 2C, 4C, UD, OD), close at 23 psi and open at 11 psi (ATSG).
• Temperature strategy: upshifts to 5th and 6th are delayed below 40 F (4.5 C) and above 240 F (115 C) (ATSG).
• Fluid: Mopar ATF+4 only. The 2008 Ram fluid capacity sheet lists an overhaul fill of 15.6 to 16.6 liters (33 to 35 pints). Service fill after a pan drop is much less; see our fluid type and capacity guide.
• Applications: Ram 2500/3500 with the 6.7L Cummins from the 2007.5 launch; the standard-output diesel box through the 2024 model year.
• Engine ratings behind it: 350 hp / 650 lb-ft (2007 launch) up to 370 hp / 850 lb-ft (2019-2024 standard output).

The Short Version

1. 68RFE ratios: 3.23 / 1.84 / 1.41 / 1.00 / 0.82 / 0.63, reverse 4.44. Exact: 3.231 / 1.837 / 1.410 / 1.0 / 0.816 / 0.625.
2. ATSG's 1.83 / 0.81 / 0.62 are the same numbers truncated instead of rounded.
3. The 1-2 shift is the largest step (1.76:1). 4th is direct and is also limp mode.
4. Factory axles were 3.73 or 4.10 on 2019-2024 trucks; 3.42 was also offered on early trucks. About 1,530 rpm at 65 mph in 6th with 3.73s on 33-inch tires.
5. The TCM calculates gear from input and output speed. Divide the two on a scan tool to confirm a slip or a sensor fault.

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Frequently Asked Questions

What are the 68RFE gear ratios?

The 68RFE ratios are 3.23 first, 1.84 second, 1.41 third, 1.00 fourth, 0.82 fifth and 0.63 sixth, with a 4.44 reverse, per Ram's Heavy Duty spec sheets. Dodge's 2007 launch release gives the exact values as 3.231, 1.837, 1.410, 1.0, 0.816 and 0.625, a 5.16:1 spread.

Why does ATSG list 68RFE ratios as 1.83, 0.81 and 0.62?

ATSG truncates the exact ratios to two decimals, while Ram's spec sheets round them. 1.837 becomes 1.83 or 1.84, 0.816 becomes 0.81 or 0.82, and 0.625 becomes 0.62 or 0.63. It is the same gearset either way.

What rpm does a 68RFE Ram turn at 70 mph?

It depends on axle ratio and tire size. With 3.73 gears and a 33.2-inch tire, a 68RFE truck in 6th with the converter locked turns roughly 1,650 rpm at 70 mph. With 4.10 gears it is about 1,810 rpm, and with the older 3.42 option about 1,510 rpm.

What gear is 68RFE limp mode?

Per ATSG, limp-in puts the 68RFE in 4th gear, which is 1.00:1 direct drive, when the selector is in Drive, and 2nd in the 2 or L position. Trucks with Electronic Range Select do not get the 2nd gear limp-in. The truck feels like it is launching in a high gear because it is.

Is the 68RFE geared the same as the Aisin AS69RC?

No. Only 4th (1.0) and 6th (0.63) match. The AS69RC has a deeper 3.75 first and 2.0 second, while the 68RFE has the deeper reverse, 4.44 against 3.54. Both were offered with 3.73 and 4.10 axles, per Ram's spec sheets.