Ford super duty 3.31 rear end. Will it be a big mistake. ?

4x4ord wrote:

StirCrazy wrote:

lenr wrote:
Yes, I know the owner’s manual says to not use cruise when towing. I end up shutting cruise off going downhill letting it coast up a few mph.

realy? my manual says to use cruise control as that the only way the enging braking decending hills works. I think you need to read the manual again.

Steve

The Ford exhaust brake started out from 2011 to 2014 as poor. However, with enough engine rpm the 6.7 would hold back a decent size RV. It really doesn't matter whether you've set the cruise or not, what mattered was that the transmission was in a low enough gear to get the engine rpm up high enough to hold back the load. If you find yourself braking too much you need to slow down enough to get the transmission to drop another gear.
2015 and 2016 6.7's have a different turbo that provides much better exhaust braking but the principle is the same .... if the engine can't hold you back in 4th or 3rd you need to slow down enough to get the transmission to drop to 3rd or 2nd.

The Ford exhaust brake has not changed from 2017 until present. It still relies on high engine rpm to provide effective braking. The 2017+ system has a full on and an auto setting. The auto setting attempts to build only enough back pressure to hold the truck at the speed it was travelling at when the accelerator or brake pedal was last released. If the engine rpm reaches redline the wheel and trailer brakes come on periodically to slow the truck down a few mph before releasing again. The computer monitors the amount of automatic wheel braking being performed and determines an approximate temperature of the brakes. If the the brakes get hot it will stop automatic braking and warn the driver of the condition. When the cruise control is used on the Ford trucks with adaptive cruise control the wheel brakes are automatically applied and work in conjunction with automatic downshifting of the transmission and exhaust braking.

yup, I know how it all works, there actualy was no exhaust brake in the 11 to 14 models it just used the VVT which is why it was ok at best, but having said that it does hold my 5th wheel on a grade 6 hill no issues so it isn't that bad, on a grade 8 I need to tap my brakes every now and then. but the cruse control has to be on for it to work. if I dont have the cruse control on there is absolutly no engine or transmition braking , I dont know if this changed with the 2015 and up models or not. adaptive cruse controle wasn't an option in 2014 on the f350

Steve