Towing in OD/ Jakebrake - Montana Owners Club

Drifty1 · 07-07-2009, 05:19 AM

I am new to the forum, so please don't beat me up too bad. Here is a little info on my rig. I have a 2007.5 ton Dodge 2500 crew cab sb Cummins with 3.73 and 6 sp auto. Our trailer is a 2002 3295 5th wheel. I would like to know what gear everyone with this truck is using to tow in. I have been using 5th and in tow/haul mode. My mpg runs about 10.4 in this gear. My rpms run about 2000 at 60 mph. I tried to run in 6th for a while on somewhat level grade and mpg when up to 12. The tran didn't seem to search to much in 6th, but I am worried about putting undue stress on tranny.
I would like some input on using Jakebrake when towing. It seems when in the tow/haul mode it is very agressive downshifting when slowing down,but I hope Dodge has this hard downshifting in their design.

ols1932 · 07-07-2009, 08:47 AM

I don't have a Dodge but I'm sure the following is true for any tow vehicle. Run in whatever gear that doesn't cause the engine to "lug." By that I mean that you can tell when the engine is having to really bear down and it feels like the engine is really having to "over work." I'm sure there are some technical terms that can be used for this, but I'm a simple man.

Orv

Trailer Trash 2 · 07-07-2009, 10:43 AM

I will agree with Orv, putting unneeded stress on the motor(Luging)doesn't help the trans and will cause temps to climb in your TV. if it starts to search and cant make up its mind which to pick, go down one gear, it will also lower the EG temp by a couple hundred degrees. you have plenty of power to pull any Montana, you can't even buy a GMC, or a Chevy with 4:10 gears any more, you are running the same thing they are along with many of the MOC dodge owners with your gear set up.

Art-n-Marge · 07-07-2009, 11:02 AM

Orv's simple description is definitely something to consider, however my owner's manual recommends using tow/haul when towing. I do not run without it when I am towing. I believe there are better ways to tune the vehicle like diesel/tranny tuners. Now taking advantage of tow/haul could shorten the life of the engine or tranny because of the reasons pointed out by Orv.

btw - is that a typo or are you describing your 2500 as a .5 ton? Your truck is actually a .75 or 3/4 ton.

The reality of it is you now own 10-11 TONS of hardware rolling down the road. You were not looking for economy when you decided to purchase a rig. TOW/HAUL is smart enough to adjust to medium to heavy loads. The fact you chose a diesel over a gasoline engine was a vast improvement towards MPG.

I also have the same problems you describe going downhill with tow/haul mode. I use more brake than I like to, because while the downshifting helps keep the truck slower it can cause very high RPMs which are also not good.

For braking I'd recommend looking for an exhaust brake that attaches inline with the exhaust and slows down the vehicle in that manner. Jake Brakes are different and installing them would be very expensive. Jake brakes use the compression of a diesel's cylinders to retard the engine to slow the vehicle down and makes a loud popping noise when doing so. An exhaust brake closes a flap that causes backpressure to the engine to slow it down and there is a less loud hissing noise when active. It is cheaper to add something to your exhaust pipe, than to add valves to an engine for a Jake Brake.

Don't be shy about posting. Like many others believe in the MOC and I paraphrase "The only dumb question is an unasked question".

Happy hauling!

bigmurf · 07-07-2009, 11:50 AM

If he has a OEM exhaust brake on a Cummins it is a Jake Brake brand. Cummins owns that name from Jacobs.

KTManiac · 07-07-2009, 12:35 PM

Quote:

quote:Originally posted by Art-n-Marge

......btw - is that a typo or are you describing your 2500 as a .5 ton? Your truck is actually a .75 or 3/4 ton......

......Jake brakes use the compression of a diesel's cylinders to retard the engine to slow the vehicle down and makes a loud popping noise when doing so. An exhaust brake closes a flap that causes backpressure to the engine to slow it down and there is a less loud hissing noise when active......

The 3.73 is the ratio of the pumpkin(s) (differential(s)). The Jake Brake is a standard factory item on the 2007.5 and newer diesels, and is indeed a vacuum operated flapper in the exhaust stream, right after the turbocharger. It is muffled by the remainder of the exhaust system, so it is not loud like on the big rigs.

Art-n-Marge · 07-07-2009, 01:35 PM

I'm still trying to understand Drifty1's terminology, a "2007.5 ton Dodge 2500 crew cab sb Cummins with 3.73 and 6 sp auto" translates to what? What does the '2007.5 ton Dodge' mean? mid year 2007? What does the "ton" mean. I thought a 2500 was a 3/4 ton. That's where I am puzzled.

The Jake Brake you describe sounds more like an exhaust brake if it flaps/stops the exhaust. I was getting confused so a quick check of the integrated brake offered on the Cummins turbodiesel is an EXHAUST brake not a JAKE brake. It is standard on dodge 3500 with a Cummins turbodiesel, but an option on the 2500 with a Cummins turbodiesel.

Getting back to Drifty1's issue on braking, a Jake Brake is not in the picture. I believe we are discussing exhaust brakes. If he already has an exhaust brake in his Cummins then that's a great option and highly recommended for use. If not, then he can price what it would cost to have the Dodge exhaust brake installed after the fact, or look for an aftermarket solution that fits somewhere in the exhaust pipe.

Many folks tend to interchange these two braking terms but that is not correct. A JAKE (Jacob) brake involves much more integration than a flap at the exhaust, because it includes extra valves in the engine used for retarding the engine at the cylinder. An exhaust brake is a flap. I have kept things simple, but hopefully someone can offer better details on the differences.

I think we are understanding what we are looking for, I just want to make sure we use the correct terminology.

02pullin · 07-07-2009, 01:47 PM

Quote:

quote:Originally posted by Art-n-Marge

I'm still trying to understand Drifty1's terminology, a "2007.5 ton Dodge 2500 crew cab sb Cummins with 3.73 and 6 sp auto" translates to what? What does the '2007.5 ton Dodge' mean? mid year 2007? What does the "ton" mean. I thought a 2500 was a 3/4 ton. That's where I am puzzled.

The Jake Brake you describe sounds more like an exhaust brake if it flaps/stops the exhaust. I was getting confused so a quick check of the integrated brake offered on the Cummins turbodiesel is an EXHAUST brake not a JAKE brake. It is standard on dodge 3500 with a Cummins turbodiesel, but an option on the 2500 with a Cummins turbodiesel.

Art

The split year difference your puzzled on is Trucks out after Jan of that year came with the 6.7 Diesel up to then it was the 5.9.

Art-n-Marge · 07-07-2009, 02:17 PM

Thanks for trying 02diesel but I am now aware of the mid-year engine change, but that's not what I am questioning.

I am confused on the word "ton" in the description since I thought a 2500 was a 3/4 ton and the expression being used is "ton". I originally thought he had concatenated the 2007 and the .5 ton.

I am just going to assume it is a misnomer and leave it at that.

The good news is we addressed he should use tow/haul because trying to save 1-2 MPGs is worse than saving the engine and tranny. And we recommend an exhaust brake for his TV if he does not have one.

kerry · 07-07-2009, 03:10 PM

Most people , and most mechanics, will agree that towing out of tow mode will not harm an engine or transmission on flat land. When in hill or mountains, and the transmission starts to search (shift between in and out of overdrive) you should switch to tow mode. The Dodge exhaust brake is more aggressive in tow mode. It still works in overdrive off. In my 08 5500 with the Asian trans, I can pick between OD on, OD off, and tow mode, exhaust brake on or off. The exhaust brake still uses engine cylinder pressure to help braking. Kerry

TLightning · 07-07-2009, 03:39 PM

I take the easy way out...and do what my manual says to do.

hookman · 07-07-2009, 03:44 PM

The Founder of Cummins Diesel also was the Founder of Jacobs Brake and is owned by Cummins. The original brake released the compression not allowing the engine to fire. This causes the noise you hear when the truck start to slow down. Chrysler wanted an Exhaust Brake so Jacobs developed a brake to work with the engine electronics and new transmission.
In January 2007 Dodge made a mid year upgrade to the new 6.7 Cummins with the Jacobs Exhaust Brake and the new 6 speed auto tranny.
Tow/Haul changes the shift points when you engage the tow/haul. This causes the more positive shifting or hard shift. If you tow in regular mode you will do more harm to the tranny then in tow/haul.

Drifty1 · 07-07-2009, 07:02 PM

Looks like I confused a lot of folk out there. My truck is a 2007 1/2 model year (3/4 ton),crew cab, 6.7 liter Diesel,6 speed automatic transmission,373 rear end gear ratio, with factory Jacob (aka Jake) Brand exhaust brake. The Jacob exhaust brake comes facory installed on all 6.7 engines from Cummins,but they are not active unless ordered as a option. You can also have the brake hooked up at the dealer. The .5 ton was a typo error.
Also I would like to thank you for all your feedback. I have no problem running in 5th gear at 2000 rpm. But I am going to try turning off the tow/haul mode when going down lower grade hills as I don't like the 3000 rpm downshifts. Unless going down a steep grade I never have to touch the truck brakes. The Jacob brake is a big help while towing (sounds cool also).

Art-n-Marge · 07-07-2009, 07:54 PM

Naw Drifty1, I was the only one confused. You got me hook, line and sinker when you threw the word "ton" in there.

From Hookman's post it appears the Jake Brake people are now doing exhaust brakes (maybe they always have, I just never ran into that information). Being owned by Cummins I would have thought they would have thrown a compression brake in their diesel, but I guess they went for the quieter, less expensive solution of an exhaust brake and probably what Dodge specified for their new 6.7L.

What I have seen explained is that a compression brake (Jake brake) is better at braking and efficiency because it's done at the engine's pistons., An exhaust brake closes down a flap beyond the engine and in the exhaust and energy is wasted. But again, an exhaust brake is quieter. I learned something, again.

Bob Pasternak · 07-08-2009, 04:18 AM

Bookman: FWIW, the actual way a Jake brake works on the big boys it changes the valve action. It actually makes a large air compressor out of the engine. When the Jake is on and trying to slow, the intake valve opens but it delays the exhaust valve opening 'til a few degrees BTDC, then opens it. That opening is the "pop-pop-pop" you hear when they're on. You might call it "explosive decompression". When Jakes were first used they were only about 30% efficient. A 250 HP engine only had about 75 HP brakeing effort. Now days, they're about 97% efficient. 500HP will get 485 HP brakeing effort to the wheels. And that will be multiplied in lower gears.

sreigle · 07-08-2009, 09:59 AM

I have essentially the same truck and towing about the same weight. This 3400 is only 260 lbs heavier than was our 2003 3295RK, per CAT scales. I let the truck decide what gear to use, most of the time. I put it in Drive with tow/haul and exhaust brake engaged.

Occasionally on a long hill I may choose to manually drop it a gear via the manual control on the gearstalk handle. 99% of the time I let the truck decide. Mostly I use that manual control to see what gear it is in. As you probably know, pressing it once turns it on and shows the current gear. Then pressing the UP part of that control and holding it takes it to the top and turns it off. Or pressing it repeatedly until the top.

Drifty1 · 07-08-2009, 10:25 AM

Thanks for the response sreigle. I see in your profile that you had a 3295rk. This is our first 5th wheel so I have a few questions that I be looking up on the forums. I will try putting in 6th and tow/haul next time out and see what happens.
Thanks again Larry in Olympia Wa.

sreigle · 07-08-2009, 04:32 PM

Larry, feel free to click the envelope icon on top of this post and email me. I'll try to answer any questions, best I can. I probably can't answer all, though.

Hookman, I was not aware Jacobs built the exhaust brake for the 6.7. However, when I bought my 6.7 in late May 2007, the exhaust brake is listed as standard equipment. There is no option, extra cost or not. It comes with the 6.7. I am not sure whether it has to be an automatic for that to be true. I'm not even sure the manual is still available. Perhaps it was an option when you got yours but changed by the time we bought ours.

Also, the exhaust brake on the 6.7 works on a different principle than a jake brake. It is a slider on the turbo shaft. I don't know exactly how it works other than it causes some restriction when it slides. And that it works very well and quietly, just a little purr like brand new mellow glasspacks (for those of us old enough to remember those).

helmick · 07-08-2009, 05:01 PM

Today I drove from Orange County, California to Las Vegas, Nevada. Have a Banks exhaust brake.
I went down several long grades, and nevar used my brakes or changed a gear on my Allison.

Art-n-Marge · 07-08-2009, 06:53 PM

hey sriegel,

According to the Dodge website, the 6.7L has the internal exhaust brake as standard on dodge 3500s. It is an option for the 2500s. I found that out when I was trying to figure out if it was a jake compression brake or exhaust brake.

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