diesel truck help can't decide what to get

[egon]

Found it but not factory installed. [img]/forums/images/icons/smile.gif[/img]

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OEM Dodge Ram Diesel Exhaust "Jake" Brake 05-Up Cummins



Fitment Guide
Year Model
2005-UP 2500
2005-UP 3500
none 1500

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Your Price: $1,325.00
Shipping: $10




Part # Availability
M82209823 Item ships from alternate warehouse in 3-5 days.



OEM Dodge Ram Diesel Exhaust "Jake" Brake 05-Up Cummins


Make your Cummins powered Ram like the big rig it is with an exhaust Jake brake from Jacobs & Mopar.
An electronically controlled valve is placed in the exhaust system to generate backpressure, slowing your engine, drivetrain and vehicle. A Jake Brake helps save on brake pad and rotor life, provides increased driving control when towing and/or driving in hilly areas and helps warm the cab in twice the time.

Designed and tested by Dodge, Cummins & Jacobs. Professional installation recommended.

For use on 2005-2006 Manual Transmissions and 2006 Automatic Transmissions.

Egon

[CJDave]

[img]/forums/images/icons/tongue.gif[/img] I drove the GM early diesels from day one, and those cars and pickups definitely did coast more than their gasoline-powered counterparts. A lot of what seems like engine braking is actually due to various parasitic loads both on the engine and in the drive train. Things like compressors, oil pumps, and vacuum pumps; it all takes HP to run and it does help slow the vehicle. I used to play the "no brakes" game in the mountains and use the air conditioning system as a grade retarder. I only cut in the compressor on downgrades so I got "free" air conditioning. [img]/forums/images/icons/crazy.gif[/img] PAT....did you know that before the advent of the Jacobs system the logging trucks had 11-inch brakes, two fifty-gallon barrels of water to drip onto the brake drums, and a lot of really nervous drivers? When those trucks went down a very long downgrade, the air through the engine often cooled it so much that if would not fire the fuel when the throttle was opened for the next upgrade. [img]/forums/images/icons/tongue.gif[/img]

[Gatorboy]

I hope you plan on keeping this truck for a long time to put on the number of miles required to offset the cost of the diesel engine over a gas one.

[tbolt]

Pat, I don't have a clue on the transmission braking either. I never heard of it until I was looking for a truck. All I know is with the push of a button the transmission is in this mode for towing, also by holding in this button it cancels overdrive. When in this towing mode, the truck seems to reach more rpms before changing and when deccelerating, it gears itself down like a manual transmission. Going down a hill with a heavy load you can actually let it hold itself back by just not accelerating. As far as the temperature of the fluids, I don't know but it must have a really good fluid cooling system, in the panel there are two temp. guages. One for tranny and one for engine. The tranny one stays real cool, towing or not.

[Nat]

I love my diesel Dodge, but this is the first automatic trans. I have had and will admit I don't like it much. It shifts fine and is no trouble, but I bought all the diesels to pull. I have had 5 dodge cumins starting in 1991 and all have been straight drives. This is my first auto. The thing I don't like about it is it doesn't shift when I think it ought to. I will not go into drive till you get to 43 mph no matter how easy I take off. It won't go into OD till you hit 50. It seems kind of stupid to me to run at 1800 rpms in 3rd gear at 40 mph just because the speed-o-meter hasn't said 43. These trucks build their top torque at 1600 rpms. I pull a 11,000 lb 5RV and it will pull it at 70 mph from NM to NC and never drop out of OD till I hit the backside of Black Mt. here in NC, and if anyone is familiar with it that is a tough pull. It has a lot of power and I get 11 MPG pulling that, and I have pulled it a lot of miles.
It still seems to me that it would upshift around 15/1600 rpms instead of an arbitrary number on the sp-o-meter. If I pull out of a rest area and start to accelerate it will pick up speed with the cars leaving at the same time, but it seem like I have to let off the throtle to get it to shift into OD, or keep my foot at the same place and it will stay at around 65 mph and in drive that puts the engine turning 2700. If it would shift sooner it would still accelerate with traffic, but the engine wouldn't need to turn nearly that many rpms and to me that would save fuel, save wear anr tear, and sound better, and I'd feel better about it. Other than that I couldn't be happier with it, and the 5,000.00 for the diesel upgrade is a no-brainer to me. Not only will it get better milage it will more than pay back when you go to sell, or trade it in. Aroung here you can't give a gas 3/4 or 1 ton away, but there is a line waiting to find a used diesel. HTH some, later, Nat

[tbolt]

This came from Allison website:
Q. Automatic Grade Braking - How does it work?
A. The grade-braking feature's primary purpose is to utilize engine braking to slow a heavy vehicle on steep grades in order to reduce wear on the traditional braking system. The method used to slow the vehicle is by overriding the PRNDL position, effectively pre-selecting the next lower gear range automatically. Because the transmission is electronically controlled and there is no mechanical linkage that needs to be moved for a pre-select downshift, implementation of this feature can be done completely in software with no hardware modifications.
This control feature takes into consideration several factors before commanding a pre-select downshift. These are the primary inputs to the Transmission Control Module (TCM):

Throttle position
(Service) Brake state
Vehicle acceleration/deceleration
Grade/Load
Vehicle speed
These factors are continually calculated to determine when a preselect downshift is commanded
Q. Automatic Grade Braking - When will I get a downshift?
A. There is no 'fixed' shift point for a 'grade braking downshift', however, the shift will never occur such that the engine speed following the shift exceeds GM Truck guidelines. Also, the shift will never occur without depressing the brake pedal.
Q. Automatic Grade Braking - What happens on ice if it downshifts and slips?
A. Grade Braking monitors the front and rear wheel speeds/slips and can determine if the vehicle is slipping. If this occurs, grade braking will be exited and the transmission will up-shift to the normal range depending on throttle position and output speed.

[Pat]

hudr, I am at a loss to explain your experience.

As regards the effort that is required to push the piston up on the compression stroke. You get that back (minus frictional losses) when the piston comes back down on the power stroke. This is true even if ALL fuel is cut off, not just reduced as in coasting.

All I can say is that in my experience, your experience is unique. I have never known of a normally aspirated gasolline engine of equivalent displacement that would out coast a diesel. Goes back to my comment about exhaust brakes being offered from several manufacturers for diesel application but I have never heard of one for a gas engine. The reason is... diesels don't have significant engine braking without an exhaust brake (or jake brake.)

[img]/forums/images/icons/smile.gif[/img] PaT [img]/forums/images/icons/smile.gif[/img]

[Pat]

Egon, I don't know what they did to the auto tranny to make it compatible with the exhaust brake for the '06 model but it sure wasn't allowed for the '97.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[egon]

I surely do not know either.

Seem to recall something about heavier duty components ???

I do know I will not have to look forward to owning one any time in the near future! [img]/forums/images/icons/frown.gif[/img]

Egon [img]/forums/images/icons/grin.gif[/img]

[Nat]

iT HAS TO DO WITH HOW LONG THE TORQUE CONVERTER STAYS LOCKED UP. The torque converter locks up at 50 mph in OD and stays locked up till it slows down to 42 mph then unlocks and the engine virtaully slows to an idle. There is an aftermarket chip you can buy for the 2004/5 that will keep the converter locked up longer so the brake can assist in stopping, but with the current setup it unlocks at to high speed to give almost any braking at all.
The GM Allison trans just shifts to a lower gear and then another lower gear as long as the engine rpm doesn't excede 4100 rpm's. If the hill is steep enough that the rpm's get to high it will upshift. They work pretty good. My son and his partner have a Dodge and a Chevy, both diesels and both autos and the Chevy downshifting works well, where-as the Dodge just coasts to a stop.
FWIW, a Jacob's engine brake closes the exhaust valves and the compresion stops it . They also make an Exhaust brake that has a butterfly that closes the exhaust pipe so that you have compresive braking. There is a big difference in the 2, but either will help save wear and tear on the brakes. HTH, later, Nat