6.4 and 6th gear with 35s...

[Iron Outlaw]

I'm not sure if it was the latest transmission update, the rebuilt transmission or if my catback added that much torque (doubtful) but man my truck is driving like it never has. I had to rebuild my transmission and put in a borla catback at the same time. Before I got the trans rebuilt I let the dealer do all the recalls on the truck and included an updated flash for shifting. I put the 35" tires on last summer and ever since it never could hold 6th gear unless I was running over 70-75. Now its crusing along at 60 with no issues at all and letting the mds work. I'm guessing my mpg should go up pretty good too. I honestly didnt know the 66rfe could behave like a normal automatic. I was strongly considering regearing soon just because 6th gear was useless, but now I'm happy with how it is driving at least without towing a load.

 

[wyo2track]

Probably a combination of the tranny rebuild, new torque converter and updated flashing. Could it be your new torque converter is staying locked longer and the shifting flash may have increased pressure. Did your shop upgrade all the clutches?

Since the last program update I got on my truck, its running as good as it ever has. I took the Pedal Commander off 15 months ago when I had it in for them to look at the little blue smoke on startup and the additional recalls that kept coming. The truck takes off better than it ever has and I haven't had any blue smoke on startup since the last flash. And since that time I haven't put the Pedal Commander back on and it feels just fine to drive. I should sell that thing.

 

[Iron Outlaw]

Probably a combination of the tranny rebuild, new torque converter and updated flashing. Could it be your new torque converter is staying locked longer and the shifting flash may have increased pressure. Did your shop upgrade all the clutches?

Since the last program update I got on my truck, its running as good as it ever has. I took the Pedal Commander off 15 months ago when I had it in for them to look at the little blue smoke on startup and the additional recalls that kept coming. The truck takes off better than it ever has and I haven't had any blue smoke on startup since the last flash. And since that time I haven't put the Pedal Commander back on and it feels just fine to drive. I should sell that thing.

Yea the shop upgraded everything they could inside and I got a billet torque convertor. They also increased the pressure by 10 psi at idle which progressively gets higher with more rpms. That could be what's helping more than anything but now it holds 6th gear better than it did before I got the 35s.