leversole Posted February 19, 2011 Share Posted February 19, 2011 Anyone have any experience pulling a 5th wheel RV with any truck like ours? (old Mack hobby trucks)There are a few websites which decribe crappy volvo conversions with all the bells and whistles and special fifth wheels, etc...What I am looking to do is use a standard fifth wheel (so the truck "looks" right)...curious about the height differences, truck spring stiffness (I read that our stiffer springs can crack RV frames), pin diameters, etc...THanks in advance.... Quote Link to comment Share on other sites More sharing options...
peterj Posted February 19, 2011 Share Posted February 19, 2011 You will need an air ride, double ossilating 5th wheel. Why, Look at the frame on a 5th wheel trailer. Most trucks use heavyer metal on the bumper than the RVs use for a frame!When you are side ways, making a turn, if the 5th wheel doesn't tilt to the side,the trailer frame has to give (bend).With a pickup, the truck spring will give a little, not on a big truck. The second thing is shock load. because of the stiff springs and heavy frame on the HD truck, any bumps go straight to the trailer. RV trailers use a standard 2" pin. They use a different 7 wire light plug. If you have to use a regular HD 5th wheel, you can get an air ride pin box for the trailer, but they are not cheep.It's not going to fall apart on the first trip, but it will not be long. Those trailers are made as cheep as possible. Some brake apart just being pulled by a pickup. They are going to brakup faster pulled by a class 8 truck.Pay now or pay later................. Quote peterjhttp://forums.aths.org/Instantforum2010/topic72786.aspx57 mack h67 Link to comment Share on other sites More sharing options...
jake Posted February 20, 2011 Share Posted February 20, 2011 leversole, I have had no trouble with my rig and have pulled it with my B Model for three years. It is an older trailer and is very well built. The guy we bought it from used to pull it all over with a newer Peterbilt. I put an electric brake controler in the B Model, changed the trailer socket to match the tractor, and I run 80 PSI in the steer tires and 60 PSI in the drive tires.It creates a lot of intrest wherever I go.We pulled it down to Huntsville, Al. in '09 and have been all over Minnesota and Wisconsin with it. Jake Quote Link to comment Share on other sites More sharing options...
Lmackattack Posted February 20, 2011 Share Posted February 20, 2011 I have never pulled a RV with a Semi but I would think a spring ride truck would be kinda harsh on the trailer. I would be more worried about the contence inside. I think a air ride hitch and lower the tire press would do the trick to soften the shock. when I bobtail to truck shows I sometimes lower all the tires to around 40psi and it reduces the bounce a little. Quote Link to comment Share on other sites More sharing options...
dockmen027 Posted February 20, 2011 Share Posted February 20, 2011 You will need an air ride, double ossilating 5th wheel. Why, Look at the frame on a 5th wheel trailer. Most trucks use heavyer metal on the bumper than the RVs use for a frame!When you are side ways, making a turn, if the 5th wheel doesn't tilt to the side,the trailer frame has to give (bend).With a pickup, the truck spring will give a little, not on a big truck. The second thing is shock load. because of the stiff springs and heavy frame on the HD truck, any bumps go straight to the trailer. RV trailers use a standard 2" pin. They use a different 7 wire light plug. If you have to use a regular HD 5th wheel, you can get an air ride pin box for the trailer, but they are not cheep.It's not going to fall apart on the first trip, but it will not be long. Those trailers are made as cheep as possible. Some brake apart just being pulled by a pickup. They are going to brakup faster pulled by a class 8 truck.Pay now or pay later.................I believe this is what Peter J is refering to. Quote Link to comment Share on other sites More sharing options...
BJsDad Posted February 20, 2011 Share Posted February 20, 2011 Jakebrake, on an older unit like yours I wouldn't be as worried about it, the newer units have Lippert frames that have been put together on a mass assembly line and very often the problems have been because of shoddy welds. The new trailers with their longer more aero nose caps have necessitated the use of longer extended pin boxes which which will cause problems on their own, let alone taking the twist of using the regular fifth wheel.Another option would be to replace the pin box with an air ride gooseneck hitch, you'll get no twisting stress on the trailer frame and you will lower the stresses put on the trailer frame without the extended pin box. Air Safe and a couple others sell air ride gooseneck hitches that will bolt on in place of the fifth wheel pin box. All you'd have to do is mount a plate across behind your fifth wheel plate for the gooseneck hitch, I've seen a few that mount it inside the frame rails so it can stay in place and is not as noticeable. Quote Link to comment Share on other sites More sharing options...
Rob Posted February 20, 2011 Share Posted February 20, 2011 I've plated and welded a few frames from campers manufactured during the 90's into the 2000's. They are much too cheaply manufactured given the weight they must carry and abuse of rolling down the highway. The ones with the extended pin box are terrible from my experience due to cantilever effect loading on the structure. I've wrapped the original weldment with a layer of 1/4" plate fabricated to fit and welded solid with adding additional gussests where the box meets the main frame. A lot of the frame structure of these things are only 11 guage rectangular tube with either 11, or 10 guage steel spars supporting the plywood floor. An air ride hitch will help a bit I think but the rest of the frame flexes too much and will bust out the welds when traveling fully loaded. Most of the trailers I've repaired have been pulled by light trucks. Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
Freightrain Posted February 20, 2011 Share Posted February 20, 2011 I've been pulling with my B model for 8 yrs now, but I did cut the springs down to 3 main leaves. It rides pretty nice with trailer on and it hasn't created any problems. BUT, my trailer is alot stouter then a regular RV version.I did break a spring a couple years ago, but they were the original leafs and with all the motion they got over the years took their toll. I then put 3 new leafs on both sides and still going strong. Well, not any more as I converted to air ride. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
fxfymn Posted February 20, 2011 Share Posted February 20, 2011 I've been pulling a fiver for a few years now, but never with a class 8 rig. I see a fair number of class 8 rigs pulling fifth wheel trailer, so obviously it is a viable option. Most RV "experts" and fifth wheel warranties demand an air ride hitch for any truck heavier than a one ton.Fivers are like everything else in life; you get what you pay for. If you want an inexpensive trailer to use infrequently you will have problems with all of the issues that have been raised here. However, if you are willing to spend more to go to what is commonly called a full time rig you will not have near as many issues. Go to a camping show and look at trailers made by Excel, one of the industries best, and compare them to any rig Forest River makes. You'll see what I mean. I'm not bashing Forest River, that's what I own, but Excel and a couple of others are way above them in quality.I would stay away from a rear kitchen model as these are notorius for scattering the kitchen stuff due to rough ride.Air pin boxes are not expensive. I put one on my rig for around $700.00. IMO an air box pin will not smooth out the ride from a class 8 enough, you will need an air ride fifth wheel, or some other way to make the truck's suspension less harsh like air ride suspension. There are some after market suspension kits such as More-Ryde for fivers which might help as well.If you are looking for a fiver now there is a used Excel on EBay right now that I'm pretty sure is going to be a bargain for somebody. Quote Money, sex, and fire; everybody thinks everyone else is getting more than they are! Link to comment Share on other sites More sharing options...
h67st Posted February 21, 2011 Share Posted February 21, 2011 Jakebrake and Freightrain, those are both sharp-looking rigs. What if you converted the drive axle suspension to air ride light Freightrain did? Would that make it ride smooth enough? Quote Link to comment Share on other sites More sharing options...
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