46RE and 47RE Transmission Differences

[Allyn Boldt]

The 47RE transmission is supplied on the Cummins and V10 Rams. While
browsing through my 1997 Service Manual, I read the differences between the
46RE and the 47RE transmissions. I thought the news group might be
interested.

Overdrive clutch discs
46RE - 4 discs
47RE - 5 discs

Direct clutch discs
46RE - 8 discs
47RE - 10 discs

Front clutch discs
46RE - 3 discs
47RE - 4 discs

Rear clutch discs
46RE - 4 discs
47RE - 4 discs

Front band adjustment from 72 in. lbs.
46RE - Back off 2 7/8 turns
47RE - Back off 1 7/8 turns

Rear band adjustment from 72 in. lbs.
46RE - Back off 2 turns
47RE - Back off 3 turns

The 47RE and 46RE have a temperature thermistor in the transmission. The
thermistor and Powertrain Control Module (PCM) causes an overdrive (OD) to
3rd downshift and engages the torque converter clutch if the temperature
exceeds 260 F. The optional heavy-duty service group (required on the V-10,
standard on 3500 models, and included with the Cummins) includes an
auxiliary transmission oil cooler (in addition to the radiator tank oil
cooler) and a transmission oil temperature warning light. The auxiliary
transmission oil cooler is 7 in. by 18 in.

From another source (this news group in the past) states that the diesel
overdrive (assumed to be the 47RH) has 6 square cut planetary gears in the
overdrive while the normal transmission (46RH ?) has 4 spiral cut planetary
gears in the overdrive.

As a side note in looking at my 1997 Owner's Manual, synthetic rear axle
lubricant is recommended if you pull a trailer for a significant number of
miles (SAE 75W-140 synthetic gear lubricant recommended). The previous two
gear lube changes at 12,000 and 24,000 miles showed significant discoloring
of the gear lube. I noticed that Mobil 1 synthetic gear lube is available
for about $8.00 per quart. Will use synthetic gear lube on next change.
Ford motor increased the trailer ratings on some pickups with a change to
synthetic gear lube.

If there are errors in this assessment of the 1997 Service Manual and
Owner's Manual, please respond with corrections and additions.