BlueMule
Junior Member
2017 2500 bought new with 6.4L and 66RFE, 98k miles. Leveled with 37's, factory 4.10 gears swapped out at tire upgrade to 4.88's. Regular oil changes with synthetic, one spark plug change, no other fluids changed yet. No towing, only hauling some firewood occasionally. About 2-3k miles ago it would downshift violently from 5th to 4th during gradual/easy deceleration due to coasting or gentle braking all the time (to the point it was predictable). Regular downshift during rapid deceleration due to hard braking and it shifted fine. During rapid acceleration (from dead stop, passing, etc) it would have a pause and then a violent upshift. I don't beat on it much, so this happened a fraction of the time compared to the deceleration shifts. I schedule a dealer check up and before it goes in, the shift issues clear up. Dealer can't find anything. I put somewhere around 1000 miles on it and it's back to the shifting issues again.
I see the 66RFE posts on here with the valve body issues. Are these the symptoms indicative of VB issues?
I see the 66RFE posts on here with the valve body issues. Are these the symptoms indicative of VB issues?