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02-18-2019, 04:20 PM
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#1
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Junior Member
Join Date: Mar 2016
Posts: 6
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Ram 2016 3500 6.7 Cummins
I recently bought a 2016 Ram 3500 dully with the Cummins 6.7 diesel. It is equipped with the stock 6 speed trans. I believe I read somewhere that when towing my 13k Keystone Sprinter I should lock out 6th gear. It is supposed to keep it in the proper power band and therefore get better fuel economy. Does anyone do this and does it help with fuel economy?
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02-18-2019, 04:37 PM
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#2
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Senior Member
Jayco Owners Club
Join Date: Dec 2001
Location: Rhode Island
Posts: 123
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It does not help mine with fuel economy. There is a reason to gear down and that is to keep the engine in the power band (1700-2000 rpm). Used on the flats gearing down is not necessary. Expect mileage between 8 and 13 but there are a lot of factors. Speed and headwinds being a couple that will kill mileage.
Have fun camping!!
__________________
2015 RAM CC LB DRW CTD 68RFE 3.73
SOLD-'01 Dodge Ram 3500 CTD HO
'04 Jayco 28.5 RKS
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02-18-2019, 04:40 PM
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#3
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Senior Member
Join Date: Mar 2017
Posts: 671
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Turn on the Tow Haul Mode and let it do its thing
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02-18-2019, 06:03 PM
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#4
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Senior Member
Join Date: Feb 2019
Location: Foley, AL
Posts: 256
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If you check the owners manual, you'll see that tow/haul does not lock out overdrive. Tow/haul changes the shift points. When I had a 5er, I set mine in tow/haul and put the engine brake on "auto". Enjoy the new truck.
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02-19-2019, 07:50 AM
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#5
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Community Moderator
Join Date: Aug 2018
Location: Full timing
Posts: 6,151
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Quote:
Originally Posted by mwaroley
I recently bought a 2016 Ram 3500 dully with the Cummins 6.7 diesel. It is equipped with the stock 6 speed trans. I believe I read somewhere that when towing my 13k Keystone Sprinter I should lock out 6th gear. It is supposed to keep it in the proper power band and therefore get better fuel economy. Does anyone do this and does it help with fuel economy?
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We tow a Road Warrior 427 (empty 16K, loaded 19500) we have a 2017 RAM 3500 dually I use the tow/haul in the mountains and it helps going into the hills and down out of them. When we hit flat ground, coast areas tow haul comes off. Fuel mileage is around 9-10 mpg goes up a little on flat ground maybe another 1-2 mpg not much more then that.
Mountains we have towed in are the Smokies, later this year it will be out west area.
What rear end do you have and which transmission are you using?
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02-19-2019, 10:14 AM
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#6
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Senior Member
Join Date: Mar 2018
Posts: 1,643
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I leave the tow/haul mode on any time I am towing larger than a 20ft boat.
The longer the torque converter spends between locks means heat in the fluid. Especially with heavy loads the transmission needs to shift quickly and the converter needs to lock to keep the fluid temps down.
I would suggest never towing something heavy while not in tow mode.
__________________
Professional mechanic.
2018 Ram 2500 HD Mega cab.
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02-19-2019, 10:31 AM
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#7
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Senior Member
Join Date: Jun 2006
Location: Dallas,OR
Posts: 4,584
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By stock trans I assume you have the 68RFE automatic? That is a very stout transmission.
For longevity, every time you start it turn on the EB. The only time it should be off is under low traction situations.
There is a button on the endmof the shift lever. If towing turn on tow/haul. Non towing on or off is totally up to you. It will make little difference in the way the truck drives. Learn where your torque curve is on the motor. When pulling im the hills use the gear selector to keep the RPMs in or near the middle of the torque curve. DO NOT let the motor lug down. Its almost the worst thing you can do for a diesel.
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Don and Lorri
Resident Dummy.
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02-20-2019, 09:32 AM
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#8
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Moderator Emeritus
Monaco Owners Club Texas Boomers Club
Join Date: Nov 2015
Location: Central Texas
Posts: 13,426
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Quote:
Originally Posted by 450Donn
By stock trans I assume you have the 68RFE automatic? That is a very stout transmission.
For longevity, every time you start it turn on the EB. The only time it should be off is under low traction situations.
There is a button on the endmof the shift lever. If towing turn on tow/haul. Non towing on or off is totally up to you. It will make little difference in the way the truck drives. Learn where your torque curve is on the motor. When pulling im the hills use the gear selector to keep the RPMs in or near the middle of the torque curve. DO NOT let the motor lug down. Its almost the worst thing you can do for a diesel.
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Driving with the exhaust brake on kills the gas mileage on my 2010 as every time you let off the gas, it slows down the truck and gives you very little coasting time.
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Dennis and Katherine
2000 Monaco Dynasty
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02-20-2019, 09:36 AM
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#9
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Senior Member
Join Date: Mar 2018
Posts: 1,643
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Quote:
Originally Posted by barmcd
Driving with the exhaust brake on kills the gas mileage on my 2010 as every time you let off the gas, it slows down the truck and gives you very little coasting time.
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You are correct. I have never understood driving with the EB on all the time, even when empty. There is virtually no coasting time.
The newer rigs like mine have a 2 stage EB. One setting is a speed maintainer and the other is full stop. Even the first setting gives you very little coasting time.
__________________
Professional mechanic.
2018 Ram 2500 HD Mega cab.
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02-20-2019, 10:30 AM
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#10
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Senior Member
Join Date: Dec 2010
Location: Oswego IL
Posts: 2,381
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OK to really answer your question the only time I lock out 6th gear is when I tow in the mountains with the 68RFE auto. This way I am at the top of the power curve between 1,800 and 2000RPM's, although full torque is developed at 1200RPM's. Why this is to keep the EGT's below 1300F when I am towing in the mountains with my truck. This also will speed up the engine RPM's to provide more fan cooling to the cooling components when the fan is turning at engine speed and engaged. I like to keep my transmission temps measured from the oil in the pan below 185F when towing.
__________________
Jim & Jill
Sold: 2010 318SAB Cougar:New: 2016 Cedar Creek 34RL. 2008 Dodge 6.7LCummins the original 6.7L engine, w/68RFE Auto
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02-20-2019, 10:31 AM
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#11
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Senior Member
Join Date: Dec 2010
Location: Oswego IL
Posts: 2,381
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Quote:
Originally Posted by mobilemike
You are correct. I have never understood driving with the EB on all the time, even when empty. There is virtually no coasting time.
The newer rigs like mine have a 2 stage EB. One setting is a speed maintainer and the other is full stop. Even the first setting gives you very little coasting time.
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My exhaust brake is on 90% of the time. What little fuel mileage I may lose is more than made up by the brake pad life I save.
__________________
Jim & Jill
Sold: 2010 318SAB Cougar:New: 2016 Cedar Creek 34RL. 2008 Dodge 6.7LCummins the original 6.7L engine, w/68RFE Auto
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02-20-2019, 12:27 PM
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#12
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Senior Member
Join Date: Mar 2018
Posts: 1,643
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Quote:
Originally Posted by jimcumminsw
My exhaust brake is on 90% of the time. What little fuel mileage I may lose is more than made up by the brake pad life I save.
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Sorry Jim.
If we use 60k life for brake pads and 15miles a gallon and $3 per gallon
If you lose 1 mile per gallon that cost you $750 in fuel.
if you save 10% or even 20% in pad life and a brake job is $1000 on your truck. You are losing $550 in fuel costs.
Cost per mile for brakes is so far below cost per mile for fuel you will never make it up by using less brakes.
__________________
Professional mechanic.
2018 Ram 2500 HD Mega cab.
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02-20-2019, 04:14 PM
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#13
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Senior Member
Join Date: Dec 2010
Location: Oswego IL
Posts: 2,381
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Quote:
Originally Posted by mobilemike
Sorry Jim.
If we use 60k life for brake pads and 15miles a gallon and $3 per gallon
If you lose 1 mile per gallon that cost you $750 in fuel.
if you save 10% or even 20% in pad life and a brake job is $1000 on your truck. You are losing $550 in fuel costs.
Cost per mile for brakes is so far below cost per mile for fuel you will never make it up by using less brakes.
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Will your assumptions are a little incorrect for my truck!
I had my first brake job on the front axle at 72+K miles for $375. The rear brakes were done at 99+K miles for $400. My fuel mileage for non-towing highway is between 19 and 21 MPG with the brake on. When towing in the tow/haul mode and brake is engaged (100%) my fuel mileage is between 10 and 12MPG's. With wind resistance being the biggest factor on my fuel mileage. City/town driving average is 13 to 14 MPG's. This is what others have reported when not using the Exhaust braking feature of their turbo charger on the Dodge/Ram trucks.
You lose more fuel mileage do to the regeneration process than you will ever lose with the exhaust brake use of the turbo charger.
Another benefit of running the exhaust braking feature on the VGT is longevity of the sliding Actuator from soot build up. That will lead to a costly replacement of the turbo charger. This is do to lack of exercising the sliding vane mechanism in the VGT when the exhaust brake feature is not used.
__________________
Jim & Jill
Sold: 2010 318SAB Cougar:New: 2016 Cedar Creek 34RL. 2008 Dodge 6.7LCummins the original 6.7L engine, w/68RFE Auto
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02-20-2019, 08:53 PM
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#14
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Senior Member
Join Date: Apr 2018
Location: Lee Center, NY
Posts: 250
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Quote:
Originally Posted by mobilemike
Sorry Jim.
If we use 60k life for brake pads and 15miles a gallon and $3 per gallon
If you lose 1 mile per gallon that cost you $750 in fuel.
if you save 10% or even 20% in pad life and a brake job is $1000 on your truck. You are losing $550 in fuel costs.
Cost per mile for brakes is so far below cost per mile for fuel you will never make it up by using less brakes.
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I'd be more worried about the cost of not stopping fast enough, or not at all.
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