eileeneh

Hi everyone, I'm trying to decide on a truck for towing a fifth wheel, and I love going to the mountains most. I decided to ask this question here because I am getting different answers, and perhaps you have the most up-to-date and accurate information. Some tell me I don't need an exhaust brake (the fiver is close to 8,000 lbs. DRY WEIGHT with no belongings inside, and I'm considering the Cummins 350, so there is no overweight problem to my knowledge). Others tell me I must have one for safety. There isn't one made to my knowledge for the Cummins automatic (which I what I definitely want). I don't know what to make of all this. I don't know for sure if I need one (I DO love places even as extreme as Bear Tooth Pass in Montana). And if I DO need one, I don't know what I'm supposed to get. I called the acclaimed Gayle Banks Engineering in CA and they don't have one for the Cummins. I'm trying to look into a Pac brake but they were not open today.

Can those of you with experience please shed some light on all this for me?

Thanks, Eileen

wannadiesel

The problem is that Dodge does not approve of exhaust brakes with the auto trans. PacBrake and Jacobs both make exhaust brakes that will work, but you will void the trans warranty. You'll also need a trans controller box to keep the torque converter locked up while the exhaust brake is engaged.

I think you ought to get a 6 speed with an exhaust brake. The pucker factor will be lower.

eileeneh

Thanks for responding. These are the kinds of things that worry me. I really detest shifting. I have to shift on my husband's Subaru and I hate it, and I used to have to shift my Honda. I don't want to have to pull a fiver, focus on the road and all that is involved with such a large vehicle, and shift on top of it! As a result, I don't know what to do. . . I don't like the noise and smell of the Duramax (EB not necessary on this, I hear). Do I FOR SURE need an exhaust brake on the Dodge? Any suggestions, anyone?

Thanks, Eileen

wannadiesel

Well, you can't get an exhaust brake for Ford or GM '04 and '05 models so it's not an issue on those trucks. I'm not saying it can't be done safely without an exhaust brake, but it will require paying close attention to your speed and careful use of the brakes. Personally I'd rather drop a gear and let the engine hold me back.

eileeneh

When you say drop a gear, you mean to downshift instead of braking, right? I know how to do that in my Toyota (always do it in the mountains). But I've heard there is something more complex with the diesels--that the brakes like quit working (they heat up terribly). I don't use my brakes much in the Toyota in mountains, but it's a tiny car and there aren't 9,000 lbs. behind me. I've also heard that one can use the trailer brakes and avoid an exhaust brake in that way. I've also heard that if an authorized dealer puts on an exhaust brake, it doesn't void the warranty, but I've also heard what you said--that is does. I'm not sure what's right in all this! Having no experience towing, I have nothing to use to evaluate the different answers. And I don't want to buy the wrong truck!!

Thanks, Eileen

wannadiesel

A diesel with no exhaust brake does not provide much engine braking. On a gas engine the throttle plate is closed when your foot is off the accelerator. This basically blocks air out of the engine and makes the wheels work hard to pull the pistons down against a vacuum, giving you the braking effect you feel in your Toyota. A diesel has no throttle plate so plenty of air comes in and there is no vacuum for the pistons to work against. The air in the cylinders acts like a spring. The wheels have to work to compress the air, but the air bounces back on the downstroke of the pistons, giving very little braking. The exhaust brake is a flapper valve in the exhaust pipe that basically closes it off, making the pistons compress the exhaust coming out of the engine and working against the wheels to slow the truck.

Trailer brakes are not the solution to the problem. They are designed to stop the trailer so the truck doesn't have to. You can't expect the trailer to hold the truck back on a long downgrade.

The warranty situation is why none of the exhaust brake companies are saying that you can install their product on a Dodge with an automatic.

Running without an exhaust brake you will have to keep your speed low and use the brakes carefully. On a steep grade with the trailer you should not let the truck speed get over 35-40 MPH. Downshift the automatic trans to low gear so you get what little braking the engine provides. Let the truck get to your max safe speed (you will have to determine this yourself, aim low until you get a feel for the rig), then brake firmly until you are 5 mph below your safe speed. Release the brakes and let the truck speed up, then brake again. Do this all the way down the hill. You'd have to do this in the Ford or GM as well.

eileeneh

Thank you. That was extremely informative--I learned a lot new. I feel like I can do what you are suggesting (I am pretty careful). However, I was told that the tow-haul button on the Duramax Allison eliminates the need for an exhaust brake because it somehow uses the transmission. Is this not true? The technician at Gayle Banks told me I would not need an exhaust brake on the Duramax, but I would on the Dodge (I didn't ask about the Ford because it is so noisy and stinky). Dick Reed, the major RV driving teacher, also said this. There must be something about the Duramax that is different. But I like the Dodge better. I am afraid to spend huge sums for a new Cummins when I don't know for sure that I will be OK on steep grades with it. The mountains are my favorite place. Is this the only solution?

Thanks, Eileen

wannadiesel

The difference between the Allison and the Dodge trans is that the Allison keeps the torque converter locked up (it's like a clutch, a direct connection to the wheels)when coasting in the tow/haul mode. This means that what little engine braking there is gets to the wheels. The Dodge unlocks the torque converter which means there's basically no engine braking, the inherent slip in the torque converter that allows you to stop in gear without killing the engine also lets that engine braking slip away.

The GM is going to be better than the Dodge going downhill, but neither would be as good as a gas powered truck. The Duramax doesn't provide any more engine braking than the Cummins, but the Allison transmission uses what there is more effectively. The diesels are way better up the hill and at the fuel pump though.

chipset

I tow a 24' aft cabin boat. I go through some very big hills. I had a gas powered truck, an Expedition, that struggled to pull it. So we went out and bought a diesel. So long at you are careful and tune your brake controller, you wouldn't have any problems with either truck.

The brake controller is made to assist in braking. If used properly, it can also help slow down the truck. I would recommend it for all situations, as there is no substitute for proper driving techniques.

Drive safe and in control, you'll be fine.

eileeneh

Thanks. I've been planning to buy a Master Brake (I think it's called) controller, which is supposed to be the best. I decided I should spend more and take as few chances as possible with that sort of thing.

Eileen

Rain Man

You can go to the post on the towing forum below this one and there are plenty of people using the 48re to tow fifth wheel trailers with. They will tell you strait how they are doing. I test drove an 05 Dodge with the automatic and it has a tow switch now but don't know what the function does. As to the Allison transmission in the GM trucks. The braking feature is good for an automatic but is no where near the braking that an exhaust brake gives. I just installed a Pac brake but have a 6 speed. I did notice on their web site that they offer a control module that has to be used in conjunction with the exhaust brake on the automatic as expained in previous post. From some of the post on the towing forum I see that many are happy with the towing.

eileeneh

Thanks Rain Man. I'll go and check it out. Eileen