AS68RC Planetary 2006-12

If your Ram 3500, 4500 or 5500 chassis cab with the 6.7L Cummins and the Aisin six-speed is whining under load, has lost a range, or came apart with metal in the pan, the gear train is one of the first things a rebuilder inspects. This listing is a used, factory Aisin front planet carrier with its matching ring gear, pulled from an AS68RC and offered for 2006-12 units. It lets you replace a damaged front gearset with a genuine Aisin assembly instead of waiting on a new one.

What the front planet does in an AS68RC

The AS68RC builds six forward speeds from three planetary gearsets (P1, P2 and P3), three drive clutches (K1, K2 and K3), two holding clutches (B1 and B2) and one sprag. The front planet is the first gearset in that train. The carrier shown here is a six-pinion design, and it works with the ring gear in the photo to pass torque to the rear gearsets. Because the AS68RC sits behind a high-torque diesel in vocational trucks that tow and haul at their rated weight, pinion bearings, pinion shafts and thrust surfaces in this gearset see a lot of heat and load over a long service life.

Symptoms of a worn AS68RC front planet

• Whine or growl that changes pitch with road speed in particular gears, often louder when pulling a load
• Bronze or steel debris on the pan magnet and in the filter, especially pinion washer material
• Pinions that feel rough, gritty or loose when spun by hand during teardown
• Chipped teeth on the ring gear or pinions after a hard failure
• Ratio error codes such as P0730 when a gearset or the clutch feeding it can no longer hold the commanded ratio

Keep in mind that the AS68RC is well known for clutch problems, especially the K2 pack, which applies in 4th, 5th and 6th. A slip in upper gears is usually a clutch or hydraulic problem, not a gearset problem, so do not buy hard parts until the unit is on the bench.

How to confirm the gearset is the problem

Start with fluid level and condition, then scan for stored codes. A ratio code tells you that input and output speeds do not match the commanded gear, and our gear ratio code diagnosis guide walks through separating a slipping clutch from a mechanical fault. If the truck slips only when loaded, read our Aisin slipping under load guide first. Once the transmission is apart, check pinion end play, spin each pinion for roughness, and look for bluing on the carrier and ring gear. Measure overall end play and the thrust washers as you go; our thrust washer and end play guide covers what to look for.

Fitment

This is an Aisin AS68RC part. In Ram trucks the AS68RC was used from the 2007 model year behind the 6.7L Cummins in heavy chassis cab and commercial models, and it ran through 2012 before the AS69RC replaced it. The same Aisin six-speed family was used earlier in Isuzu, UD and Mitsubishi medium-duty trucks, which is why the listing range starts at 2006. Internal parts can change between revisions, so compare the pinion count, the spline count and the ring gear tooth count with your old parts before you install, or send us your year and VIN and we will check it. You can browse other Aisin parts on our Aisin transmission parts page.

Install notes

• This is a used part. Clean it, spin every pinion, and check pinion end play before it goes in.
• Replace the thrust bearings and washers in the gear train during the rebuild rather than reusing worn ones.
• A gearset that failed usually leaves debris through the clutch packs, solenoids and cooler. Pair it with an AS68RC master rebuild kit and flush the cooler and lines.
• Lube the pinions and thrust surfaces with ATF or assembly gel during assembly.
• Refill with the Aisin-approved fluid. Our Mobil 3309 case is a common choice for this unit.
• Check overall end play before the pan goes on, then let the TCM complete its adaptive learning with normal driving.

Which trucks use this AS68RC front planet?

The AS68RC was used in Ram chassis cab and commercial trucks with the 6.7L Cummins from the 2007 model year through 2012. The same Aisin six-speed was also used in Isuzu, UD and Mitsubishi medium-duty trucks. Match your old parts or send us your year and VIN to confirm.

Is this part new or used?

It is a used, factory Aisin front planet carrier and ring gear. Inspect it before installation by spinning each pinion and checking pinion end play.

Will a bad front planet set a code?

It can. If the gearset slips or breaks, the TCM may set a gear ratio code such as P0730. A whine with no codes is also common. Ratio codes are more often caused by a slipping clutch, so confirm the cause before you replace hard parts.

What else should I replace with the planetary?

Replace the thrust bearings and washers in the gear train, and rebuild the clutch packs with a master rebuild kit if the unit has debris. Flush the cooler and lines so old metal does not come back into the new parts.

What fluid does the AS68RC use?

The AS68RC uses an Aisin-approved ATF. Mopar ASRC and Mobil 3309 are the common choices. Do not use a general multi-vehicle fluid in this unit.

• Gear Ratio Codes (P0730) Diagnosis
• Aisin Transmission Slipping Under Load
• Transmission Thrust Washers and End Play
• Aisin AS69RC Problems and Service Guide