- Joined
- Apr 7, 2014
- Posts
- 1,176
- Reaction score
- 605
- Ram Year
- 2015
- Engine
- Hemi 6.4
Hell, the 66 is a 68 stuffed in a 545 case. Lol
Sent from my iPhone using Tapatalk
Well, sort of. It appears to be a bit of a hybrid, at least according to Allpar articles. This is from another forum post some time back:
Doing some reading on the 68 vs 66 from another Allpar article.
All three automatics have a one-piece case, electronic control, two stage hydraulic pump (which shuts the secondary side at higher speeds, for efficiency), and similar valve bodies. They all use three planetary gearsets, three driving clutches, three holding clutches, and an overrunning clutch. The 66 uses some parts derived or taken from the 545 (mainly in the front: torque converter and pump; overdrive, underdrive, and reverse clutches; and valve body), and some derived or taken from the 68 (low/reverse clutches, planetary gearsets, and 2C clutch).
The 68RFE and 66RFE automatic transmissions for Ram trucks
So, in comparing to the 68RFE it appears that 3rd and 5th would be the weakest link since the underdrive/overdrive and 4c clutches are not upgraded in the 66RFE. The low range and 2c clutches (1st and 2nd) are upgraded per the article. It's unclear (to me) if the 4c and UD/OD clutch assemblies from the 68 could be retrofitted into the 66RFE, but would seem like a logical place to start during a rebuild. Per Brandon, 4th would seem to be the best gear on the dyno since no clutches are engaged. I will have to follow up with HF to see what his actual concern is.