I need a little education

[ms60ocb]

I starting to look MDTs to replace my F350. A F450 has the increased braking but is marginal on GVWR

I haven't got all the models Memorized but thinking along the line of Freightliner M2 or Int 4300 (maybe the LP model) with something like a Sports Chassis.

Every two years I've done Colorado so Long Pulls. The Fifth Wheel is my home and I would like to carry more tools.

Presently the scales say I'm pulling over 20,000 pound and like to drive close to 70 when the speed limits are 80 & 85.

What engine should I be wanting, what Automatic Transmission with what rear end ratio. Then your Low Profile trucks 19.5 tires which I can live with.

I think with the LP trucks, the Fifth Wheel sets on top the frame and the standard loading dock height the hitch sets between the frame.

I have done some searches and haven't communicated with those who, "BEEN THERE - DONE THAT'.

Was in Livingston last spring and saw lots of HDTs and a few MDTs but didn't talk to anyone as I wasn't looking.

Thanks Clay

[grumpydoc]

If you plan to pull a heavy rig up big hills out west at highway speed I believe you will need at least a 12L engine to be happy and safe. That translates to either an HDT or a Freightlliner M2 112 with the Detroit DD 13 engine. I previously had a FL M2 106 with the small 7.2L engine pulling a 22K rig. It was fine except on steeper grades. Would get down to 35 or 40 mph on 6-7% grades. With our new M2 112 pulling our current 27K rig we can run 65-70 all day although on the steepest grades we will get down to 55 mph. If we run 62 ish we can usually get 7-8 mpg but at 70 it drops down to 6. The biggest knock on the MDTs is their cost, new will be in the $175K or more(maybe much more) range. Of course the advantage of new is the warranty and its NEW! For a lot less money a nicely finished HDT(used) RV hauler can be had. This cost differential explains in part the popularity of the used HDTs on the forums. For those who will not or can not buy a used HDT the options become very limited, a potentially marginal class 4-5 truck like the F 450/550 or the expensive MDTs. If your budget can stand the challenge I would recommend the M 2 112, recognizing that others will have different opinions. Best Wishes, Jay

[GeorgiaHybrid]

We currently have a Freightliner M2-112 with a 13 liter Detroit Diesel with 450 HP and 1650 lb-ft of torque in front of an Allison 4000 series 6 speed auto. It is a class 7 truck with a 30,700 GVWR but that is a little deceptive as is has a 23K rear and 13.2K front axles under it. You will need to get a special license to drive it depending on the state you are in because of the weight and the fact that is has air brakes (in Georgia that means you have to pass a 20 question test with 15 right). Ours also has air suspension, air ride cab and air ride seats and with 4 doors, can haul a few people around while pulling a load without any issues.

 

Mine will run a LOT faster than I want to pull a trailer and will climb a long grade with ease. Having a true 2 stage Jake brake (not an exhaust brake) makes for a very pleasant experience on long downgrades (505 braking HP on tap) with the knowledge that those big air brakes will also keep you out of trouble. If you are going to be in this part of the country in 3 weeks, join us at the ECR and you are more than welcome to take ours out for a drive to help you decide.

[NH2]

Back in '06, I ordered an International 4400 DT570 9.3L engine with an Allison 6sp. tranny & 3.70 axle gears. Our trailer weighs 21K and the truck w tool adds another 16+K the total load. Ours is a 4400LP with 22.5" tires. We have a 3 position engine brake; not just an exhaust brake.
I'm not dismissing the recommendations of previous posts. As we all know, the "no replacement for displacement" rule holds true. I will let you know that I'm completely satisfied with the performance of our setup 96% of the total miles we've driven. Would I like more oomph during the other 4%? Sure. Some of the long, steep climbs we've experienced have slowed us to the 40-45mph range.
I can tell you that I didn't pay anywhere close to the $175,000 posted above—maybe half that—but a new MDT crew cab does cost more than a used HDT.

Good luck with your search,

Mark

[hemsteadc]

Then your Low Profile trucks 19.5 tires which I can live with.

I would recommend you get the 22.5". Call me delusional, but the bigger diameter tires turn fewer revs per mile and that adds to the comfort and smoothness. My Cummins 8.3 ISC does a fine job with 14.5k pounds behind me, but I do not pass anyone on grades. I don't care - I'm never in a hurry and if a dually pickup passes me that's ok. He can gloat all he wants.

 

My goals were comfort, safety, and beauty.

[Jack Mayer]

There is no substitute for torque out in the mountains. If you are looking new then Grumpydoc's advice is very good. The M2-112 is a very good solution, especially if you want a more "conventional" vehicle with four doors. And there are some very nice conversions out there on that chassis. You WILL be over $170K for sure, for anything that is more than the basics (on a -112).

 

For that range of money it is worth considering a NEW Volvo 630, 730, or 780. In MY OPINION, it is a more flexible solution in that you can do more things with it than the -112. That does not mean it is the right solution for YOUR needs, though. A NEW Volvo 780 with a hauler deck, drom box and optioned for RV use is going to be in the $170 range. This will be a lifetime truck. It will be able to piggyback a smart, a golf cart, a motorcycle, a CanAm, and most trikes. As well as many other things. It can be used very easily as a motorhome for week-long trips - depending on how many people/animals. But for a couple it is very doable for up to a week with all the comforts except a shower.

 

Lots to think about.....

[scranton21]

We have a 2003 Freightliner SportChassis with a Caterpillar 3126B engine (300 HP) and Allison auto 6-speed transmission. GVWR is 19,500 and it hauls our 17,500 lb. (fully loaded) DRV Mobile Suites with no problem. We haven't tried some of the steeper/longer grades such as Towne Pass on US190 through Death Valley, but we've been all over the country and taken many passes and it has enough torque (I believe 800 lb.ft. at 1500 rpm) to get us up most anything. Obviously it won't be as powerful as the HDT's discussed above, but the MDT's are simpler and less expensive to maintain (e.g., no air brakes) and, depending on what you haul and the state you're licensed in, may not require a CDT or equivalent. We've been very happy with it.

 

As it happens, we want to downsize, and we're eager to get a Jeep to get further out and about, so we're planning to switch to a smallish motor home. We expect to do that in the fall. At that time, we'll be selling the truck. If your timing is such that it could work for you and you have any interest, we're happy to share further information offline looking toward a possible sale. In any event, you can contact us offline at scranton21@gmail.com.

 

David & Kathy Scranton

[ms60ocb]

Thanks for the comments as it has help me.

I did a little tire kicking and found out the Sports Chassis is Freightliner specific and there other similar manufacturers. We are getting older, and find the Freightliner M2-106 is much easier to climb into than the M2-112.

I have been running some numbers and maybe some decision soon but used 4 door vehicles are hard to fine. If I should go new on decision of question is air or hydraulic brakes. Pro and con for me are go for air but for resale would people shy away because of the Air Brake endorsement required for a non-CDL license. Towed weight is almost 21.000 lb.

Thanks again

Clay

MS 38PS3

[grumpydoc]

Clay, special requirements for licensing are state specific. In VA and KY were we have lived there are no special requirements for FL M 2 trucks with air. So before you write off air brakes check state requirements were you might decide to declare residence. There are advantages to having air in my opinion so I would suggest looking into it. We didn't find the M2 112 significantly harder to climb into than our 106 and DW has had two knees replaced! If you can get by with the smaller engine in the 106 you may find there are more units available both new and used than the 112s. And possibly a little cheaper too. Best Wishes, Jay

[GeorgiaHybrid]

Clay, some states are crazy, by the letter of the law in Georgia, I can drive the M2-112 with a regular, class C license when the trailer is hooked up. Running bobtailed, I would need to have a class E license but any cop worth his salt understands the "no special license for an RV section" of the code and they consider this my "RV Hauler". Not hard to get that license either, just an affidavit that I had driven for a specified number of miles or time and a 20 question written test that you need to answer 15 right. Vision has to be 20-40 in ONE eye. The test was very easy and had the airbrake endorsement as well. I am allowed to drive anything on the road (non commercial) except hazardous material and double trailers.

 

I have not had an issue getting anyone into the 112 except for my dad. It took him a little effort but then again, he is 93 years old with two knees replaced (twice each) and one hip replaced. He had the right to be a little slow.

[davejobes]

19.5 tires ride like a buckboard wagon compared to the 22.5's. In the Rocky Mtns with steep grades & less oxygen, a HDT would hold speed better. But if you have no time schedule, the MDT will work just fine and still surpass any 350, 450, or 550. As per gear ratio, there are formulas that mechanical engineers use, but now with the internet there are sites where you plug in the numbers and it will spit out a proper gear ratio. I went to the "differential section" on anythingauto.com and plugged in the numbers for you. 4x4 websites have these calculators too, cause those guys are always changing their tire sizes.

The numbers it gave me for 22.5 tires (37.3" tall)...full economy/best MPG 4:30 gear, for both good economy and good towing 4:88 gear, and for all out towing power 5:30 gear. These ratios keep the engine at the proper RPM within it's torque range (1600 to 2200 rpm @ 65mph) 1600rpm being the 4:30, and 2200rpm being the 5:30 @ 65mph!

I have 4:88 gears. I love my cruise control and set it @ 1800 RPM in 6th gear (6-speed auto), not worrying what MPH I'm doing...FYI: 1800rpm is about 62-63mph on level highway. 1800 is at the lower end of the RPM torque curve, which gives me great economy, the turbo holds about 12-15 psi boost, and still plenty of RPM rise for climbing hills & building boost (set @ 23psi max boost).

If you have a MDT and want more SAFE power. The injectors can be upgraded by SWAMPS Diesel, or you could add a water/meth injection, or some kind of tuner (people call a chip). The tuner may raise your EGT's (exhaust Temps) too high though?

Hope this helped with some of the education you are looking for.

[cactus]

Clay, some states are crazy, by the letter of the law in Georgia, I can drive the M2-112 with a regular, class C license when the trailer is hooked up. Running bobtailed, I would need to have a class E license but any cop worth his salt understands the "no special license for an RV section" of the code and they consider this my "RV Hauler". Not hard to get that license either, just an affidavit that I had driven for a specified number of miles or time and a 20 question written test that you need to answer 15 right. Vision has to be 20-40 in ONE eye. The test was very easy and had the airbrake endorsement as well. I am allowed to drive anything on the road (non commercial) except hazardous material and double trailers.

 

I have not had an issue getting anyone into the 112 except for my dad. It took him a little effort but then again, he is 93 years old with two knees replaced (twice each) and one hip replaced. He had the right to be a little slow.

G-Hybrid,

He might be a little slow but damned sure worth waiting for

E.P.

[Morelli]

I have a SportChassis Freightliner M2-106 with a Cummins ISL9 engine. With engine stock, Allison TVR3200 transmission, 4.66 axle ratio, I pull a 30,000 lbs trailer with equipment with no issues at all. Yes on 7% grade hills we slow down but then so will a semi. I talked to the factory before getting our truck and had them show me currenty customers using the truck in the same fashion as me, they did and they have a chunk of people running 8.3L and 9.0L at 30,000 lbs gross trailer loads.

 

When I looked at the DD13 model, used, it has good pricing, new, you get slapped with additional taxes so beware. The 9 liter does extremely well !

 

If I had to do it over again, I would the exact same choice again. Extremely happy with the M2-106 !

 

Here is an example on some trailers I use and equipment I move around: