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 > F350 Super Duty vs 3500 Denali vs The Ike Pulling 30k lbs

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Cummins12V98

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Posted: 01/26/20 09:59am Link  |  Quote  |  Print  |  Notify Moderator

To have zero brake applications they need to be running at the speed they want to maintain then set cruise to say 5mph less but also lock the trans in the same gear you would have climbed that grade in. This will vary based on the grade and load. This takes a human to dial this in.

I easily maintained 30-35mph locked in 2nd gear on a several mile 14% grade at 33k combined simply by moving the cruise speed up or down with my thumb.

For the Cummins closer to 3k will give the best downhill braking.

Cool brakes along any big downhill grade = GOLDEN.


2015 RAM LongHorn 3500 Dually CrewCab 4X4 CUMMINS/AISIN RearAir 385HP/865TQ 4:10's
37,800# GCVWR "Towing Beast"

"HeavyWeight" B&W RVK3600

2016 MobileSuites 39TKSB3 highly "Elited" In the stable

2007.5 Mobile Suites 36 SB3 29,000# Combined SOLD

cummins2014

Utah

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Posted: 01/26/20 10:15am Link  |  Quote  |  Print  |  Notify Moderator

Cummins12V98 wrote:

To have zero brake applications they need to be running at the speed they want to maintain then set cruise to say 5mph less but also lock the trans in the same gear you would have climbed that grade in. This will vary based on the grade and load. This takes a human to dial this in.

I easily maintained 30-35mph locked in 2nd gear on a several mile 14% grade at 33k combined simply by moving the cruise speed up or down with my thumb.

For the Cummins closer to 3k will give the best downhill braking.

Cool brakes along any big downhill grade = GOLDEN.



Although I am not towing the weight you are , I have never had to lock in a gear, it does it automatically when I set cruise on the descent . Mine will hold the setting on the cruise within 5 mph over. If it takes shifting down it does it. If I want to come off a grade at say 45, I set it for 40, and that is where it stays at 45. It seems we are arriving at the same , with doing it a different way.

larry barnhart

wenatchee. wa usa

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Posted: 01/26/20 10:28am Link  |  Quote  |  Print  |  Notify Moderator

combined weight of 22,920 lbs towing we don't have an exhaust brake but the allison does the job for us. 30K noway. Happy for the guys that have it for safe towing the bigger loads.

chevman


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Cummins12V98

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Posted: 01/26/20 10:54am Link  |  Quote  |  Print  |  Notify Moderator

Human intervention is still important, example is when I see a grade ahead while using cruise control I drop a gear seamlessly instead of letting it drop a couple mph and then playing catchup.

Besides it gives you something to do when towing.

Bionic Man

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Posted: 01/26/20 11:11am Link  |  Quote  |  Print  |  Notify Moderator

Cummins12V98 wrote:

To have zero brake applications they need to be running at the speed they want to maintain then set cruise to say 5mph less but also lock the trans in the same gear you would have climbed that grade in. This will vary based on the grade and load. This takes a human to dial this in.

I easily maintained 30-35mph locked in 2nd gear on a several mile 14% grade at 33k combined simply by moving the cruise speed up or down with my thumb.

For the Cummins closer to 3k will give the best downhill braking.

Cool brakes along any big downhill grade = GOLDEN.


Does your truck have adaptive cruise control? Because if it does (and most of the new high trim trucks have it), the brakes will be applied automatically if you are using cruise.

I don't get the brake application part of the test. I guess they have to do something to measure, but it isn't unnerving to apply brakes going down a grade.


2012 RAM 3500 Laramie Longhorn DRW CC 4x4 Max Tow, Cummins HO, 60 gallon RDS aux fuel tank, Reese 18k Elite hitch
2003 Dodge Ram 3500 QC SB 4x4 Cummins HO NV5600 with Smarty JR, Jacobs EB (sold)
2002 Gulf Stream Sea Hawk 29FRB with Honda EV6010

rhagfo

Portland, OR

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Posted: 01/26/20 01:02pm Link  |  Quote  |  Print  |  Notify Moderator

Bionic Man wrote:

Cummins12V98 wrote:

To have zero brake applications they need to be running at the speed they want to maintain then set cruise to say 5mph less but also lock the trans in the same gear you would have climbed that grade in. This will vary based on the grade and load. This takes a human to dial this in.

I easily maintained 30-35mph locked in 2nd gear on a several mile 14% grade at 33k combined simply by moving the cruise speed up or down with my thumb.

For the Cummins closer to 3k will give the best downhill braking.

Cool brakes along any big downhill grade = GOLDEN.


Does your truck have adaptive cruise control? Because if it does (and most of the new high trim trucks have it), the brakes will be applied automatically if you are using cruise.

I don't get the brake application part of the test. I guess they have to do something to measure, but it isn't unnerving to apply brakes going down a grade.


I don’t believe that adaptive cruise was available on Ram until about 2018.
Well I think the brake application is just a measurement of how well or poorly the Exhaust brake Slows the decent speed.

On Edit: seems you can’t use the correct term r3tards as it isn’t politically correct even used correctly.


Russ & Paula the Beagle Belle.
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Cummins12V98

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Posted: 01/26/20 01:20pm Link  |  Quote  |  Print  |  Notify Moderator

Bionic Man wrote:

Cummins12V98 wrote:

To have zero brake applications they need to be running at the speed they want to maintain then set cruise to say 5mph less but also lock the trans in the same gear you would have climbed that grade in. This will vary based on the grade and load. This takes a human to dial this in.

I easily maintained 30-35mph locked in 2nd gear on a several mile 14% grade at 33k combined simply by moving the cruise speed up or down with my thumb.

For the Cummins closer to 3k will give the best downhill braking.

Cool brakes along any big downhill grade = GOLDEN.


Does your truck have adaptive cruise control? Because if it does (and most of the new high trim trucks have it), the brakes will be applied automatically if you are using cruise.

I don't get the brake application part of the test. I guess they have to do something to measure, but it isn't unnerving to apply brakes going down a grade.


No adaptive. Just my input.

4x4ord

Alberta

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Posted: 01/26/20 01:44pm Link  |  Quote  |  Print  |  Notify Moderator

Cummins12V98 wrote:

To have zero brake applications they need to be running at the speed they want to maintain then set cruise to say 5mph less but also lock the trans in the same gear you would have climbed that grade in. This will vary based on the grade and load. This takes a human to dial this in.

I easily maintained 30-35mph locked in 2nd gear on a several mile 14% grade at 33k combined simply by moving the cruise speed up or down with my thumb.

For the Cummins closer to 3k will give the best downhill braking.

Cool brakes along any big downhill grade = GOLDEN.




After appling a bit of physics to what you're experiencing I come away thinking your Ram must work similar to my Ford on cruise.... it applies the wheel brakes. Holding 33k on a 14% grade in second gear with 4.10 final gear ratio means about 1000 lbft at the crankshaft. If your engine is revving around 3000 rpm it would be producing about 575 reverse hp. The back pressure on your exhaust brake would need to be somewhere around 180 psi. So I think your truck must be automatically applying the service brakes.


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blofgren

Surrey, B.C.

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Posted: 01/26/20 07:17pm Link  |  Quote  |  Print  |  Notify Moderator

4x4ord, I know for sure that my truck does not apply the service brakes and I don't think Ron's truck does either but we'll see what his reply is. I know that for my truck it is rare that I need to use the service brakes towing my fiver in the steep mountain grades in BC as long as I'm in the right gear, which is usually 3rd in my G56 manual transmission. This is 1 gear lower than I climb tough grades in. I leave my exhaust brake on the FULL setting all the time, and don't use the variable setting.


2013 Ram 3500 Megacab DRW Laramie 4x4, 6.7L Cummins, G56, 3.73, Maximum Steel, black lthr, RAM 20k sliding hitch, Retrax, Linex, and a bunch of options incl. cargo camera
2008 Corsair Excella Platinum 34.5 CKTS fifth wheel with winter package & disc brakes

Cummins12V98

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Posted: 01/26/20 07:37pm Link  |  Quote  |  Print  |  Notify Moderator

4x4ord wrote:

Cummins12V98 wrote:

To have zero brake applications they need to be running at the speed they want to maintain then set cruise to say 5mph less but also lock the trans in the same gear you would have climbed that grade in. This will vary based on the grade and load. This takes a human to dial this in.

I easily maintained 30-35mph locked in 2nd gear on a several mile 14% grade at 33k combined simply by moving the cruise speed up or down with my thumb.

For the Cummins closer to 3k will give the best downhill braking.

Cool brakes along any big downhill grade = GOLDEN.




After appling a bit of physics to what you're experiencing I come away thinking your Ram must work similar to my Ford on cruise.... it applies the wheel brakes. Holding 33k on a 14% grade in second gear with 4.10 final gear ratio means about 1000 lbft at the crankshaft. If your engine is revving around 3000 rpm it would be producing about 575 reverse hp. The back pressure on your exhaust brake would need to be somewhere around 180 psi. So I think your truck must be automatically applying the service brakes.


It does not.

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