coasting with the 68RFE

[EricBu12]

Does anyone know if any damage or a detriment to the 68RFE transmission by putting in neutral on freeway coasting downhill?. . Have done it a few times on slow surface streets and haven't noticed any ill effects. . Even when putting back in drive while coasting.

 

[HBarlow]

Using that Georgia overdrive for improved economy huh?

 

[JHumphries]

In Washington State it is illegal to coast in neutral in a pick-up or less. It is illegal to coast with the clutch in or in neutral in an OTR.
As far as detrimental, the trans is still being lubed by the pump, but with the the engine at idle, the flow rate might be too low.
As far as putting it back in drive, I don't know the programming of the transmission: i. e. what gear it starts out in when placed in drive. I would assume that the computer would be smart enough to not try to shift in to first at 70, but some of the stupid things being done by vehicle computers still amazes me.
I'm no expert by any means. I know just enough to get myself in trouble. I have a pretty good understanding of mechanics though.

 

[sag2]

As long as the engine is idling no real ill effects as long as your not doing it for long periods of time. If you are trying to save fuel, my guess is the payoff is not that great. With the electronically controlled transmissions like the RFE's the converter is unlocked and engine braking is minimal on decel. So for my money, I would just drive it as is.

One 68RFE overhaul is going to cost far more than you could save in fuel in a lifetime if were all wrong.

 

[EricBu12]

Like I said, I have done the coasting on 45 mph roads. Salt Lake City has long gradual side hills. I can coast down these roads for a good mile or more. . when I put it into drive again, it is always at the right gear for the speed.

Since the truck at 65 mph is 1500 rpm, a idle speed of 750 with no tension on the gears should be OK I would think as you said, the pump is still turning so the lube with my deep pan on should be OK for a short run I would think. I plan on doing it on steep long downhills in Wyoming on I-80 that is around 2 miles or so in length.