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Hey guys, I'm new here and to the diesel world.
I bought an 06 mega cab with the cummins in it. As far as comfort and able to tow, its awesome but I am concerned with my gear ratio.
I have 4.10's vs the 3.73's. While towing I don't have a problem with them, especially in the hills, but it seems that it needs to shift. The rpm's a very high while towing or cruising @ 8omph. it redlines @ 3200rpm and if I were to drive @ 90mph the rpm's are almost redling, they'll be at 28-2900.
I read some posts about gas mileage, that is a concern of mine also. I only have 19k on it and while towing I get about 13-14mpg (only towing 6000lbs at the most. I figured that since I have the 4.10's thats why my mpg isn't that great, or will it improve?
Are there any other options for changing my rpm's while driving. I've already considered a gear swap and larger tires. My main reason for this question is because I've always been a gas guy till now abd I don't know that much about diesel. I heard that the higher the rpm the worse it is for the diesel since it mainly works off of low rpm torqu.

thanks for your help

-TRK
 

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Newbie Questions

TRK,

Several things: I assume you have an automatic transmission. You have to remember the trans is designed to shift when it recognizes a given set of parameters. If you put it in drive and start up a hill, there is only so much the engine can do. It sounds like you are nudging a shift point. The solution is to simply back off a little and the trans will stop wanting to shift. The best solution in a tough pull is to lock out the upper gears. You do this by placing the selector in the appropriate lower gear range. This allows you to bring the RPM up for the appropriate amount of power.

Next: Why the heck are you towing at 80 MPH? Car drivers never get it. The instant you hook something on the back of your car or truck you come under the same regulations that a large tractor trailer does. I'm in California. Commercial truck speed is 55 mph while cars can run 65 mph. I don't know where you are but in most states just like here you would be limited to 55 mph. Further, you immediately become lane restricted. Lanes are numbered from the inside out. The fastest is lane #1. On a 4 lane highway the slowest lane is lane #4. Therefore, you are restricted to lane #4 and allowed to pass in lane #3. You can get away with running lane #3 normally, due to on ramp traffic. It all depends on where you are.

Next: You are almost certainly towing with a ball hitch. Have you ever noticed that with the exception of house and office trailers, large trucks use 5th wheels and pintle hooks. Ball hitches are not designed for 80 - 90 mph towing. Bear in mind that 6,000 lb. trailer will turn you over and may kill you - slow the heck down, it is not a race.

Studies with large trucks show that frontal area is critical. Are you pulling a trailer with a large flat front. Above 60 mph a trade off happens. As you increase fuel to the engine more of it begins to go to pushing the air out of your way than actually making the truck go faster. A light truck towing a trailer is not streamline.

When you gear a conventional diesel you want it to cruise at 80% throttle. If your redline is 3200 rpm and your legal highway speed is 65 mph then you want to achieve 65 mph at app. 2560 rpm.

I would not start swapping gears. It is expensive and you might mess up at this point. Look, gearing is always a compromise. The 4.10 has greater gradability than a 3.73 with all factors equal. If you go to the 3.73 when you pull hills you may find yourself one or two gears lower in the trans. Speed may be app the same. It depends. When you spec a truck you want to spec it for what it does 90% of the time. You make do the other 10% of the time. Your truck will last longer and will do a better job for you.

I think your mileage will get better when you get your foot out of it. Remember: Dodge built that truck for general use, primarily highway at the average national speed between 65 and 70 mph. Try obeying your local speed limits for a while and then do a mileage check.

I have seen a lot of 4 wheelers upside down. It is almost always stupidity/speed. Live long!
 

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ya man you need to slow down. when you have a trailer on your truck your braking distance is increased a lot and you can role over very easily. there is a big response ability when towing. it sounds like you need to take a class on towing, to become a better and safer driver.

That truck is made to tow. but only the right way.
 
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