needlern32724

If nothing is agreeable with DC, which then is the lessor of two evils? An engine brake or an exhaust brake?

I've just read, for a couple of hours, these forums. On this topic it seems that nothing yet has been approved by DC for use in slowing down a descending truck with heavy rv(13,500#).

Some say I do not need any kind of additional braking. I would feel better having something, in addition to my brakes.

Your input is appreciated. Bill

Maccandy

That is one of the reasons I got the 6 speed!

thejeepdude

Um, I don't think there's an engine brake available for the ISB cummins, only the bigger ones. Even if there is, the problem with the exhaust brake on the auto would still exist whether with an engine brake or any other kind of brake that applies before the tranny. Basically, the tranny can't handle the reverse [braking] torque for lots of continuous use. The problem is actually fixable, and an exhaust brake is definitely useable with the right mods. It's just that who wants to lose their warranty and spend aftermart $$'s on their tranny in a brand new truck when this SHOULD be certified from the factory?

needlern32724

Thank you thejeepdude. I'm brand new to trucks and diesels. Should I start a different message with something like: What is the best way to help slow down a truck towing a heavy rv (after down shifting and brakes) going down a mountain?

Whether or not its after market $'s. Bill

thejeepdude

Well you're right in assuming that after downshifting and brakes, exhaust brake is the next most important thing. How heavy a load are you towing? The nice thing about the 3rd gen trucks (like you 2004) is that they have the biggest disc brakes on the market, so you have a lot more stopping ability before an exhaust brake is "required". I know with careful driving I was able to lug about 10K through the CA sierras (lots of steep hills and tight turns) without too much trouble, even with my '99 which had absolutely crappy brakes compared to your '04. That said, an exhaust brake is definitely a nice luxury and gives you a much added margin of safety, especially in the event of mechanical brake failure. Personally, if I was towing all the time, I'd say screw the transmission warranty and have DTT fix the thrust washer problem, beef up the tranny a bit, and install the exhaust brake with no worries. The nice thing about your '04 is that it already has the capability to downshift while locked and maintain cruise control speed going downhill with the exhaust brake, even with a bunch of weight trying to push you down the hill. The main thing to remember, though, is that you have a truck with BIG brakes, and you're not going to hurt it using them. Just remember when slowing on long downgrades to use substantial pressure to take ~10mph off, and then let the brakes cool/rest until the grade speeds you back up and you can shave ~10mph off again. It's much harder on the brakes to do the "constant gradual braking to maintain exact speed" sort of thing. That's most likely going to result in fast brake wear and warped rotors.

Most of all, enjoy the new truck!

rmb93243

I read somewhere that Cummins had modified the 48re for 2004 to accept the Jacobs exhaust brake and still maintain the warranty. But I can't find the article, I think it was on the Cummins web site. I've only pulled less than 10K and these breaks work just fine with the trailer brakes.

thejeepdude

There were a couple magazines that published this information but it was later proved to be false. The inside scoop from DC is that it's still not approved, but I'm sure we'll know as soon as it is. I'm hoping for '05 approval... man I'm going through withdrawls not having a truck.

needlern32724

thejeepdude wrote:
Thanks again thejeepdude. I'm going to tow my 13,500 pounder through some smaller hills in Georgia, to start. From what you say I should have few to no problems mechanically.

If you or anyone else can, give me more input on the above quote. What (while going downhill) if I use the tow/haul to lock out the OD, then set my cruise control to say 30 mph, would that act in anyway to use the engine as a braking mechanism?
Bill

Lightman

WEll on my 2004, the cruise won't go on till 35mph At those slow speeds, I doubt you'd need an exhaust brake unless they were some seriously steep/long grades.....I mean the trailer has brakes too does it not...?

2ndcummins

Cruise won't work at that low speed. If you just give a little throttle it will give the same effect as cruise and you will feel the engine hold back. If TC is not locked the trans can overheat from shearing of fluid. This will happen with an e-brake also. Monitor trans temp.

needlern32724

Thank you Lightman and 2ndcummins.
Lightman, TT has brakes and I have a good brake controller.

2ndcummins,
Ignorance asking here. What have I done to not lock my TC?
Bill

2ndcummins

needlern32724, Sorry .... TC is "torque converter" ... When you are in fourth gear you can feel it lock up (no more slipping and rpm comes down). I believe yours is also able to lock up in 3rd. This lock up is a good thing. (saves fuel and reduces heat in trans). Next time you are going down hill solo (not towing) take your foot off the pedal (the right one ) You will feel very little engine hold back. Increase throttle a little until you will feel the engine hold you back. Weird but it works. Hope that explains it. Wheeeew!

69D100

I was on the phone a month or so ago with Dodge's engineering division, for another unrelated subject, and asked about the exhaust braking. Mopar is going to come out with an aftermarket exhaust brake only for the manual transmission. You could have seen an earlier post regarding that.

needlern32724

Thanks again 2ndcummins. Going to take the truck up to N.C. smokey mtns in a few days. Without the rv. Will practice techniques. Bill