Exhaust Brake

Thanks for the clarification on this.

Much appreciated!

Just a note on the 68RFE. The Auto-6 (the plus/minus buttons) controls the HIGHEST gear the trans will go to. It will still shift up and down, but will only shift up to and including the gear shown in the display. IOW, if you set it to show 4, then the trans will shift through 1st, 2nd, 3rd, AND 4th as required by current driving requirements. Also, the number in the display is NOT the current gear, it is the HIGHEST gear allowed. If you want to see what gear the trans is currently in, you will need something like an Edge Insight (at least on the 08MY, don't know about newer trucks with the info screen).

The Mad Norsky, if you are shifting into Auto-6 mode, what you are seeing then is the Auto-6 limiting to the highest gear you are currently in. So, if you are at a stop, then it will go directly to 1st. If you are cruising in 5th, that's what will display. The trans will still shift into gears below what is displayed as required. Again, my experience is from my 08MY, but I suspect newer ones will be similar.

As for selecting gears, I do it all the time, usually without even looking at the shifter (or display many times), even while moving. But then, I always use the Auto-6, except when using tow/haul, and even then I often engage Auto-6 mode. It allow me more control over the trans, and to a point to play "big-rig" ;).

Cheers!
Mike

Say, just an update for info.

Same situation as before, running around town 30 MPH tops, but this time tow/haul activated.

3rd gear.

Also for those using the plus/minus on their shift lever so as to see which gear you are in on the new Rams:

noticed that doing that on mine will immediately limit you to whatever gear you are currently in. It would show 2-2, showing limited to second gear.

So I just hit the plus button and it goes up to 2-6 and allows shifting through all gears.

For safety, I figure at a full stop is the best time to do this.

The Mad Norsky wrote:

Cummins12V98 wrote:
Running without TH in town at 30mph you will find your self in 6th gear.

Just thought I would mention that I did the above today with my truck.

Around town, without TH. 30 MPH.

4th gear tops.

And for those that complain about Ram not showing which gear one is driving in, just use that plus and minus toggle on the gear shift lever.

It will then show on your display.

Thanks for telling about the gear showing on the 13 and newer trucks. Mine does the same thing.

I will test mine later, its the 68RFE. Don't want false info spread on the internet!

The Mad Norsky wrote:

Cummins12V98 wrote:
Running without TH in town at 30mph you will find your self in 6th gear.

Just thought I would mention that I did the above today with my truck.

Around town, without TH. 30 MPH.

4th gear tops.

And for those that complain about Ram not showing which gear one is driving in, just use that plus and minus toggle on the gear shift lever.

It will then show on your display.

The OE exhaust brake and 68rfe transmission have been out for 8 model years now.

Isn't it amazing how many buyers don't read their owner's manual?

Cummins12V98 wrote:
Running without TH in town at 30mph you will find your self in 6th gear.

Just thought I would mention that I did the above today with my truck.

Around town, without TH. 30 MPH.

4th gear tops.

And for those that complain about Ram not showing which gear one is driving in, just use that plus and minus toggle on the gear shift lever.

It will then show on your display.

KATOOM wrote:

06Fargo wrote:
Why don't gasohol engines in pickups have exhaust brakes?

1st road trip with work F1 fitty ECO boost I thought truck go crazy! the trans shifted down to a 4000 rpm engine gear to hold downhill speed on cruise...

Even though both gasoline engines and diesel engines are piston/crank/compression/combustion engines, they're really nothing like each other and use completely different principles to function.

So without getting too technical..... Most gasoline engines use vacuum to fill the cylinder under atmospheric pressure. To achieve that vacuum gas uses an intake venturi throttle flap to regulate air flow at a given time. When the throttle is closed vacuum builds behind the flap and causes the engine to work against this vacuum, thus you feel deceleration. The higher the rpm's with the throttle closed, the higher the vacuum against the piston trying to suck in air flow. But since vacuum is only so strong the resistance is only so great. Before anyone jumps to conclusions too, even forced induction gas engines use this same principle system.

All that said, if you installed an exhaust brake on a gasoline engine you would find that the intake and the exhaust restriction would conflict each other and would result in very little gained in additional retarding power due to the fact that the intake flap is restricting most of the air and the exhaust flap is trying to restrict more air than what is barely being sucked in. So in order for the system to work at all you'd have to allow the intake some amount of air flow just to have the exhaust have something to pressurize. And since gasoline engines are very sensitive to air/fuel ratio, the system would have to incorporate some sort of an anti-fueling mode during that time when the throttle is partially opened a bit so you didnt run into a hyper-lean condition. You can see where this would be getting really involved and costly for the consumer. And really, to end most discussions about exhaust brakes and engine brakes mounted on gasoline engines, the bottom end structure and component system of a gasoline engine isnt strong enough to support the pressures and stresses it would face and will eventually result in failure.

Hope I didnt go off in a tangent and get too confusing.....

KATOOM I think your integrated throttle/exhaust brake would work on a gas engine - fuel cut off completely then link the opening of the throttle plate with the closing of the exhaust brake... course you would need an engine strong enough to pull enough weight to actually benefit from a retarder ;) :E

Cummins12V98 wrote:

It will come on when you let off all the time. It is slightly noticeable just driving around normally. When you let off and apply the brakes or descending a grade it senses what is needed and comes on stronger as required. Now the newer RAM's 13 up have two EB settings that I am looking forward to. Full on and auto. For the EB to work the best the TH should be on. Th makes the trans go into lockup sooner and keeps the trans in the proper gear for your speed. Running without TH in town at 30mph you will find your self in 6th gear. Then when you want to accelerate the engine boggs until the trans downshifts.

If your truck is going into 6th at 30mph, there's a problem in the software. 5th should be the highest at that point. And even then, the engine will be lucky to turn at anything greater than about 1200RPM is the TC is locked.

The Service Manager at Dave Smith Motors told me three things to make my truck perform and last. Run the hell out of it, leave the TH and EB on at all times.

Hmm, he's right about 2 of 3. But, you don't need TH all the time. In fact, you probably DON'T want to run TH unless you're actually hauling or towing a heavy load. What you should be doing it using your Auto-6 controls to limit the trans to 4th and below for city driving. Here's what I do with the Auto-6 system:

1st: parking lots, slow moving areas (max 10kph or 5mph)
2nd: rare use, maybe the old slower construction zone (max 20kph or 10mph)
3rd: construction zones, some off road (max 40kph or 20mph)
4th: city driving, most off road (max 60kph or 35mph)
5th: slower highway driving (max 80kph or 50mph)
6th: higher speed highway (max: whatever the truck can do)

In fact, the only time I don't use the Auto-6 is when I have TH engaged, and THAT only happens if I'm pulling the big trailer. Even then, I sometimes find that the trans "forgets" it's in TH mode and reverts to normal operation, usually after driving for a time at a constant highway speed.

Now, this is for a 2008 MY, but I would assume that newer trucks operate in a similar fashion.

Sometimes, I wish my truck had the Auto-Stick feature the DW's 2006 Pacifica has.

Cheers!

06Fargo wrote:
Why don't gasohol engines in pickups have exhaust brakes?

1st road trip with work F1 fitty ECO boost I thought truck go crazy! the trans shifted down to a 4000 rpm engine gear to hold downhill speed on cruise...

Even though both gasoline engines and diesel engines are piston/crank/compression/combustion engines, they're really nothing like each other and use completely different principles to function.

So without getting too technical..... Most gasoline engines use vacuum to fill the cylinder under atmospheric pressure. To achieve that vacuum gas uses an intake venturi throttle flap to regulate air flow at a given time. When the throttle is closed vacuum builds behind the flap and causes the engine to work against this vacuum, thus you feel deceleration. The higher the rpm's with the throttle closed, the higher the vacuum against the piston trying to suck in air flow. But since vacuum is only so strong the resistance is only so great. Before anyone jumps to conclusions too, even forced induction gas engines use this same principle system.

All that said, if you installed an exhaust brake on a gasoline engine you would find that the intake and the exhaust restriction would conflict each other and would result in very little gained in additional retarding power due to the fact that the intake flap is restricting most of the air and the exhaust flap is trying to restrict more air than what is barely being sucked in. So in order for the system to work at all you'd have to allow the intake some amount of air flow just to have the exhaust have something to pressurize. And since gasoline engines are very sensitive to air/fuel ratio, the system would have to incorporate some sort of an anti-fueling mode during that time when the throttle is partially opened a bit so you didnt run into a hyper-lean condition. You can see where this would be getting really involved and costly for the consumer. And really, to end most discussions about exhaust brakes and engine brakes mounted on gasoline engines, the bottom end structure and component system of a gasoline engine isnt strong enough to support the pressures and stresses it would face and will eventually result in failure.

Hope I didnt go off in a tangent and get too confusing.....

Sport45 wrote:

Cummins12V98 wrote:
You can do what you want with your truck. I always turn on EB and TH after starting the truck. Service MGR at Dave smith Motors suggested I do so all the time. Head West coast Chrysler Warranty person says to do so.

Fact is line pressures are higher in TH and it keeps your engine rpm's up and trans in the proper gear for the speed you are driving. When driving thru town without TH and you apply the go pedal and you are in 6th you are adding stress to your torque converter. Keeping EB on with TH makes the Service brakes last longer. Turbo stays working better.

I'm looking forward to the experience and appreciate your insight. I don't see where using the EB could hurt anything.

In your experience, with the EB on does the truck start slowing down when you let off the go pedal? Or does it act just like the EB is off until you get on the brakes?

It will come on when you let off all the time. It is slightly noticeable just driving around normally. When you let off and apply the brakes or descending a grade it senses what is needed and comes on stronger as required. Now the newer RAM's 13 up have two EB settings that I am looking forward to. Full on and auto. For the EB to work the best the TH should be on. Th makes the trans go into lockup sooner and keeps the trans in the proper gear for your speed. Running without TH in town at 30mph you will find your self in 6th gear. Then when you want to accelerate the engine boggs until the trans downshifts.

The Service Manager at Dave Smith Motors told me three things to make my truck perform and last. Run the hell out of it, leave the TH and EB on at all times.