Tow vehicle help - Page 3

Motor31 · 10-12-2007, 09:50 AM

It is not necessary to have an HDT to tow a larger MS unit. It's a bit of overkill in capacity for RV uses. The choice to go that large isn't just based on the capacity of the tow vehicle but the cost analysis as well. It is still cheaper to find a used but still very serviceable HDT for less than the cost of a 3/4 ton Pick up. That does not mean that your circumstances will be best served by that kind of vehicle. It works best for a full timer vs a part time RV'er.

What is important to have is enough truck to tow the trailer with while staying inside of the tow vehicles ratings for GVW and GCVW. There are several to choose from in models like the 450 / 4500 up to the 650 / 6500 (depending on brand) as well as the smaller "big trucks" like the Freightliner and International MDT's that are capable of handling the larger trailer that we love to use. It does make a difference in safety and comfort when you are towing inside the capacity of both the tow vehicle and trailer limits.

WildJohn · 10-12-2007, 02:07 PM

I agree completely Mike. Another point that is sometimes overlooked.. These trucks are designed from the ground up for driver comfort. EVERY time I drive mine I am amazed as to where the miles went.. trips I usually dread are over before I even realize it. And at times I am disappointed that they are over.. The cities just seem to be closer together for some reason.. I take her out to "stretch her legs" and when I get home I think.."Was that a long enough drive for her?" No matter how long it was.
Happy Camping... all the time
John

47hook · 10-15-2007, 12:08 AM

Posts of this nature usually include braking ability. After buying our 1st 5er, I sent an email to the axle/brake manufacture touching on this subject:

"Thank you for visiting the Dexter Axle website and sending us your question.

The Dexter brakes are designed to stop the maximum rated capacity for each axle series. For example: Dexter's 8000 pound brakes (12-1/4" x 3-3/8") are designed for stopping 8000 pounds. The stopping distance is a very complicated set of formulas based on many variables. I can fax the formulas to you and provide you with the sample brake torque output curve your particular brake (by size and type - electric or hydraulic). You would have to fill in your Static Loaded Radius of your tires, the number of brakes, the brake torque at a specific input (voltage or PSI), pounds of wheel load, the traveling velocity and the time that you are actuating the brakes in order to calculate your stopping distance. There is no simple table for all these variables.

The capacity rating of the running gear will be based on the weakest link of the whole system. The trailer designer may have selected a 7000 pound beam and bearings, but only selected our 6000 pound brake assemblies (instead of the 7000 pound brakes), and only put 2600 pound rated leaf springs on the axle. This would result in only a 5200 pound axle assembly rating, NOT including the wheel and tire rating. This example would have 6000 pounds of potential stopping force but only 5200 pounds of carrying capacity.

Christine Bachman
Application Engineer"

Pretty definitive, in My Opinion. The trailer brakes will stop what they are rated at. So will the TV. So, with my original TV, I had at a minimum of 9200#'s for TV, 16K for 5er = 25,200# capacity for a GW of under 24K. Overkill. Now, I have 11,400 TV, 16K 5er = 27,400#'s for about 25K. Overkill. And, no matter how much braking capacity you have, some fool will pull out in front of you and you may not have enough room to stop, even in your brand new Z06 Corvette. Now what? Let me know if you get those formulas and what you come up with. Oh, and let me know if your owner's manual lists your stopping distances. My old 92 Corvette, IIRC had some performance numbers but they had the disclaimer of being done by a professional on a race track. Leaves me out.

I am also, as so many of us are, waiting for a definitive law that covers what we are discussing: civil weight restrictions for RV's. Website? State and #? Anything? Or is it just an opinion, even those that have the best interest at heart for our fellow RV'ers.

Again, as I have said many many times. Not saying anyone should exceed anything. Know what you weight, what your limits are/capabilities, and be careful. You are much more likely to be hit by lightening or hurt in an auto accident than be in an accident because you are a touch overweight...your TV/5er...not you...

rverdlm · 10-15-2007, 09:56 AM

All that info on trailer brakes is very interesting, but the limiting factor is the 4 patches of rubber that meet the road. No matter how good the trailer brakes are (and IMHO regular trailer brakes are almost worthless) you're still trying to stop 18,000 pounds with 4 little patches of rubber. Your 6 to 8000 pound truck will have 4 or 6 or in my case 10 bigger patches of rubber.

Motor31 · 10-15-2007, 10:17 AM

This was interesting.

"The Dexter brakes are designed to stop the maximum rated capacity for each axle series. For example: Dexter's 8000 pound brakes (12-1/4" x 3-3/8") are designed for stopping 8000 pounds."

I have 8,000 lb axles on my rig. The rig weighs 18,500 so the brake capacity by their own statement is not up to the weight of the trailer. This would be more so for those who have an Elite since they are provided with a GVW of 20,000 lbs and still only have two 8000 lb axles.

That's all assuming that the trailer manufacturer contracted with Dexter to provide 8000 lb rate brakes on those 8000 lb axles and that they are working to full capacity with a fully functional set of wires and a brake controller that is sending sufficient signal to the brakes for electric brakes. Similar conditions will have to be met for the air over hydraulic brakes. Then other factors such as coefficient of friction for the tires, pavement as well as grade and curvature of the roadway will have to be taken into consideration as well as that the trailer is not certified to stop on it's own.

They are also did not give stopping distances for the unit or any indication of how well the brakes will stop the trailer. Technically, according to the wording they had there, as long as the trailer stopped sometime, the brakes are adequate.

rdunk · 10-15-2007, 12:28 PM

Double post deleted!

rdunk · 10-15-2007, 12:29 PM

Quote Motor31: ""The Dexter brakes are designed to stop the maximum rated capacity for each axle series. For example: Dexter's 8000 pound brakes (12-1/4" x 3-3/8") are designed for stopping 8000 pounds." I have 8,000 lb axles on my rig. The rig weighs 18,500 so the brake capacity by their own statement is not up to the weight of the trailer. This would be more so for those who have an Elite since they are provided with a GVW of 20,000 lbs and still only have two 8000 lb axles".
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Mike, I would assume that we need to be looking at weight on the axles, rather than weight of our trailer, relative to Dexter's axle rating stopping capacities. You and I have 4,000+ lbs of pin weight, which is not carried by the trailer axles, when towing. I assume the TV is responsible for stopping the weight it carries on its axles, which would include the pin weight.

If these "assumptions" on my part are right, then, we are pretty much ok with our 8,000lb axles, and what they have to stop.

Of course, this is why trailer mfgrs. can design in 7000lb axles for 16k GVWR trailers, and 8000lb axles for 18K GVWR trailers. Also, even when not towing, the axles should not be over weight, because the front jacks (and rear jacks) handle a significant share of the weight load.

FWIW!