Towing ~8k with dx3 or XL

wfo9 · 06-09-2018, 02:59 PM

First off. I'm totally new to RVing.. I've never actually owned one, however I have owned just about every other money pit you can think of (race cars, off-road trucks, boats...)

I sort of know what I'm getting into from that perspective and I'm pretty self sufficient and and a quick learner when it comes to fixing things with a motor and wheels on it. But I admittedly know nothing about RVs and I'm a total newb who is more or less clueless, so I apologize in advance for possibly asking common knowledge questions. The thought of spending this much money on something I may not be 100% satisfied with is concerning....

I know I should probably start with a cheaper starter RV.. but my entire use case involves towing a 7500k trailer around with my rock crawler or on of my other vehicles on it.

I've got a million questions, but my top priority is towing and I ran across the Dynamax DX3 and it looks like it might meet our needs. What I'm questioning first, is what it will be like in terms of towing power. Is the 350hp 1K tq of the m2 106 enough or is the 112 a much better choice. I plan to spend some time in the mountains, but I will mainly be on moderate grades. I may eventually pickup up a lighter vehicle I can flat tow (jeep...) but I will still need to pull a trailer for many trips to events....

Another basic question I have is about dealers. I live in central Texas and the closest Dynamax dealer is either MHSRV near ft worth or holiday world near Houston. Anyone have experience with these two. I'm about 150mi from both.

Thanks for your time.

Webefine · 06-09-2018, 04:50 PM

I have a 2015 DX3 that I regularly tow 4 to 5,000 pounds through West Virginia with. I know it's not the 8,000 pounds you are talking about and it's not the mountains of Colorado, but I am always pulling grades of 5 to 9 %. I think the 350 /1000 does a good job but does slow down some on the steeper grades with a trailer on back but nothing terrible. Bottom line is the DX3 will handle 8,000 pounds just don't expect to pull every grade at the speed limit. That being said having the extra power of the M112 chassis would be nice but it comes at a price.

mikew968 · 06-09-2018, 06:50 PM

I currently tow 8000 lbs with a 6.7 and while it does pretty good I am looking for a DX3...thinking that will get the job done a bit better.

wfo9 · 06-09-2018, 08:37 PM

Follow up question. Anyone know when they started offering the 450hp engine in the XL. I ran across a used one that listed the hp at 350.

Is it just the same motor with a bigger turbo in the 112? I saw some mention of an option to upgrade the 350hp 106 8.9 motor cal to get the torque up to 1150. Is that something that comes on the 2019 models?

Gas-man · 06-09-2018, 08:43 PM

I'm in Austin and bought my force HD from Longhorn Rv. They worked with me the best on my trade in and we're very easy to deal with.
I usually pull just my rock crawler on my trailer, which is about 5600 lbs total. I have put a JKU on the trailer with the crawler a couple times. For me, it pulls fine. It really only struggles when I hit a stop light going up hill.

LTZ470 · 06-09-2018, 08:45 PM

You will not be happy with 350hp and 1000 ft/lbs of torque except on flat ground...I'm using an XL to pull my 4500# Jeep in tow and it is much more favorable, I owned a Freightliner Sportchassis M2 106 with 330HP 1000 ft/lbs TQ MBE 926 for over 10 yrs and 100,000 mile+...

The main thing I am really concerned about to be perfectly honest is the axle placement on the Dynamax versus Renegade...If I were going to pull heavy I would opt for the Renegade, the rear axle placement on the Dynamax's have a significant effect on two things the steering and the rear pitching, the rear pitches heavily on marginal road beds and this has to create severe amplitudes in the tow bar including heavier wear on critical load points...

LTZ470 · 06-09-2018, 08:49 PM

Same engine 8.9L Cummins in both DX3 and XL, the XL has a larger cooling system (radiator) and that allows Cummins to add bigger fuel injectors and turn the 8.9L up to 450 HP w/ 1250 ft/lbs torque...M2 106 frame is not designed for more than 1000 ft/lbs of TQ...the 1250 ft/lbs is the max for Allison Tranny though....

wfo9 · 06-09-2018, 10:10 PM

Quote:

Originally Posted by LTZ470

You will not be happy with 350hp and 1000 ft/lbs of torque except on flat ground...I'm using an XL to pull my 4500# Jeep in tow and it is much more favorable, I owned a Freightliner Sportchassis M2 106 with 330HP 1000 ft/lbs TQ MBE 926 for over 10 yrs and 100,000 mile+...

The main thing I am really concerned about to be perfectly honest is the axle placement on the Dynamax versus Renegade...If I were going to pull heavy I would opt for the Renegade, the rear axle placement on the Dynamax's have a significant effect on two things the steering and the rear pitching, the rear pitches heavily on marginal road beds and this has to create severe amplitudes in the tow bar including heavier wear on critical load points...

The shorter wheelbase is a concern... Does the 37RB models really have a 20" longer wheelbase or is that a typo.

DynaQuest XL Class C Motorhomes by Dynamax

Webefine · 06-09-2018, 10:31 PM

M2 106 is rated for 1150 torque as per Freightliner, so getting the retune that some of the members on here have done still keeps it in line with Freightliner specs.

FOURWHL · 06-10-2018, 06:56 AM

I regularly tow that exact setup on I70 Denver to glenwood springs (plenty of steep grades). The RV is totally acceptable in my opinion. Would another extra 100 horses be nice? Sure. Necessary? Absolutely not. I cant pull the long 7% grades at 40-45mph and am passing semis. Not going to maintain 65mph but it’s reasonable imo.

FOURWHL · 06-10-2018, 07:01 AM

Also I purchased at MSHRV as well. Had a great buying experience. They’ve got an awesome setup for PDI. I flew all the way down from Chicago. Only 150 mi I’d head there to take a look for yourself. They had way more in stock then a lot of the dealers

LTZ470 · 06-10-2018, 07:32 AM

Quote:

Originally Posted by Webefine

M2 106 is rated for 1150 torque as per Freightliner, so getting the retune that some of the members on here have done still keeps it in line with Freightliner specs.

Did not realize this, very good point, thanks for the correction...

LTZ470 · 06-10-2018, 07:34 AM

Quote:

Originally Posted by wfo9

The shorter wheelbase is a concern... Does the 37RB models really have a 20" longer wheelbase or is that a typo.

DynaQuest XL Class C Motorhomes by Dynamax

Yes sir they are 41' in length, don't know if the axle is repositioned on these, if not that would be additional over hand that would really not be good for a tow bar or trailer hitch...

ablarson · 06-10-2018, 08:06 AM

I’ve towed a 24’ enclosed with car from MN to TX and MN to TN. Cruise alert at 78 MPH. Slowed down a bit through the TN foothills but still plenty fast. Force HD

LTZ470 · 06-10-2018, 08:27 AM

Quote:

Originally Posted by ablarson

I’ve towed a 24’ enclosed with car from MN to TX and MN to TN. Cruise alert at 78 MPH. Slowed down a bit through the TN foothills but still plenty fast. Force HD

Were you using a hitch stabilizer sway bar setup?

ablarson · 06-10-2018, 08:29 AM

Nope. Barely even noticed it was back there.

LTZ470 · 06-10-2018, 08:38 AM

Quote:

Originally Posted by ablarson

Nope. Barely even noticed it was back there.

Wonder what the total weight of a Force compared to a DX 3 and XL is?

I am sure the Force is much lighter in weight when they leave the factory, did it have the 8.9L engine or 6.7L...

wfo9 · 06-10-2018, 10:41 AM

Quote:

Originally Posted by FOURWHL

I regularly tow that exact setup on I70 Denver to glenwood springs (plenty of steep grades). The RV is totally acceptable in my opinion. Would another extra 100 horses be nice? Sure. Necessary? Absolutely not. I cant pull the long 7% grades at 40-45mph and am passing semis. Not going to maintain 65mph but it’s reasonable imo.

Yea, that is pretty much my use case. I love Colorado, but realistically only make it out there once a year or so right now. Moab is another destination I plan to hit, but think the grades will not be as extreme.

How does it handle the trailer in terms of the wheelbase and the tail bobbing....? I've done plenty of towing, but never driven anything this big before.

This thread also got me thinking about the forceHD as an option with a friendlier price point and maybe a bit less weight.

Also, does anyone know approximate leadtime on a DX3 or ForceHD factory order. Ideally, I would like to get a dx3 or maybe even force HD with the 112 chassis and motor and from reading another thread it sounds like that can be ordered. But I'm also inpatient and want to start using it ASAP LOL.

Webefine · 06-10-2018, 11:27 AM

I don't think you can order a Force or a DX3 on a 112 chassis anymore, I think to get the 112 you have to go to the Dynaquest.

steverkemp · 06-10-2018, 11:55 AM

Quote:

Originally Posted by Webefine

I don't think you can order a Force or a DX3 on a 112 chassis anymore, I think to get the 112 you have to go to the Dynaquest.

Correct. I just tried. They did it for a little bit stopped because it impacted production efficiency in a negative way.

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