Chassis for 5x8 Hybrid Off Road/Highway

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Chassis for 5x8 Hybrid Off Road/Highway

Postby eagle24 » Tue Jul 17, 2018 7:22 pm

I'm planning to build a chassis from 2" sq tubing (1/4" wall). I'll use some 1"x2" tubing for cross bracing under the floor. There will be a spine running underneath from rear to tongue. Tongue will be braced back underneath the body frame. Hitch receptacle on rear of the spine. Here's where I need to be checked: I'm planning to use a 2000# axle over sprung with 1200# leaf springs and shock absorbers. 58" spring centers and 76" hub face to hub face. Wheels are Aluminum 15x7 with -6 offset. Tires are P235 75/R15 off road (they measure 9-1/2" wide unmounted. Can anyone tell me if you think the 76" hub face to hub face measurement is right for the wheels and tires? Also, any issues with the Axle/Springs/Shocks setup I'm planning? My second option would be 1200# Timbren Axle-less suspension. $670 vs $200

Greg
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Re: Chassis for 5x8 Hybrid Off Road/Highway

Postby Ottsville » Tue Jul 17, 2018 8:42 pm

Whether that is the right axle spacing depends on the design of the trailer, which you haven't given measurements for. Maybe post a drawing of your design?

2x2x1/4 tubing is probably overkill for what you are building with the exception of your full length tongue. You should take a look at some of the builds over on ExpeditionPortal if you are going with an off-road design. You'll see some other ideas over there.
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Re: Chassis for 5x8 Hybrid Off Road/Highway

Postby Ottsville » Tue Jul 17, 2018 8:49 pm

Also, with off road use and those size tires I would consider going to a 3500# axle. You will get larger diameter spindles and brakes.
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Re: Chassis for 5x8 Hybrid Off Road/Highway

Postby eagle24 » Tue Jul 17, 2018 10:40 pm

The design is basically like a Oregon Trailer Terradrop except no hatch. The trailer frame width will be 60", but the exterior 1/4" ply will lap over the trailer frame, so the finished width will be 60.5". 76" face to face on the hubs will give me 7-3/4" from the side of the trailer to the hub face on each side. I'm guessing the tires will be about 1/4" wider mounted and inflated, so just shy of 10". The -6 offset on the wheels puts the mounting surface just over 1/4" inboard of center. So, if my math is correct, the tires should be shy of 5" inboard from the hub face leaving 2.75" minimum clearance on each side.

I wondered if the .250" wall tubing was too heavy. I can get some .125" wall tubing. I guess once the plywood bottom is attached, it provides a good bit of strength to the frame. I want to keep it as light and simple as I can. I was debating whether I need brakes. My tow vehicle is a 2016 Toyota Tacoma 4-door 4x4. My normal fishing trips are 225 miles one way. The off road stuff is mild and infrequent. More than anything, I just like the look of the overland trailer designs.

Thanks for your input, and keep it coming. I'd like to iron out this chassis in the next few days and get everything ordered.

Greg
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Re: Chassis for 5x8 Hybrid Off Road/Highway

Postby KTM_Guy » Tue Jul 17, 2018 11:34 pm

2X2X1/4 is over kill. 1/8" is probably over kill to, but unless you can find 12 gage it's probably the best bet. I have heard people using 14 gauge but it seems a little thin to me but I tend to over build.

1200# is very light for an offload build. Even with 1/8 tube. I'm using Timbren 3500# with 2000# springs. It's their HD offload axle with 4" lift. I haven't weighed it yet but just one side with brake drum is heavy. I think when I'm all done I'll be pushing the 2000#, and I was thinking I would be in the 1200-1400 pound range.

Nice thing with the Timbrens you don't need to worry about how wide the axle is.

What is the backspace on the wheel? Also know if you are going with breaks you need a 66MM or 2.60" ( or larger) bore in the wheel to fit the spindle.

As far as leaf springs vs Timbren vs torsion axle, it's like asking which oil to use. They all have their good points and bad. My next build will be with torsion axles probably.

For me when I was planing my build I had images in my head of pulling the camper on any trail or mountain pass in Colorado or spending a week or two in the desert. It sounded good, I now say I was drinking the Overland Kool-aid. We like green and blue trails and forest roads. It's not fun to my wife if she is white knuckled all the trip or trashing the Jeep. So have a realistic idea on where you want your trailer to go and build to that.

Todd
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Re: Chassis for 5x8 Hybrid Off Road/Highway

Postby Ottsville » Wed Jul 18, 2018 6:02 am

Here is a thread that talks about determining axle length. One of the best suggestions I saw was to tape out a mock up of your frame on a garage floor to get a solid idea of how things will lay out.

https://www.expeditionportal.com/forum/ ... th.195579/


KTM_Guy wrote:
For me when I was planing my build I had images in my head of pulling the camper on any trail or mountain pass in Colorado or spending a week or two in the desert. It sounded good, I now say I was drinking the Overland Kool-aid. We like green and blue trails and forest roads. It's not fun to my wife if she is white knuckled all the trip or trashing the Jeep. So have a realistic idea on where you want your trailer to go and build to that.

Todd


This is so true. Like jacked up pickup trucks, most people will never take a trailer anywhere a manufactured trailer couldn't go and are just caught in the need to look cool. Be honest with yourself about your needs.
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Re: Chassis for 5x8 Hybrid Off Road/Highway

Postby eagle24 » Wed Jul 18, 2018 7:52 am

Ottsville wrote:Here is a thread that talks about determining axle length. One of the best suggestions I saw was to tape out a mock up of your frame on a garage floor to get a solid idea of how things will lay out.

https://www.expeditionportal.com/forum/ ... th.195579/


KTM_Guy wrote:
For me when I was planing my build I had images in my head of pulling the camper on any trail or mountain pass in Colorado or spending a week or two in the desert. It sounded good, I now say I was drinking the Overland Kool-aid. We like green and blue trails and forest roads. It's not fun to my wife if she is white knuckled all the trip or trashing the Jeep. So have a realistic idea on where you want your trailer to go and build to that.

Todd


This is so true. Like jacked up pickup trucks, most people will never take a trailer anywhere a manufactured trailer couldn't go and are just caught in the need to look cool. Be honest with yourself about your needs.


Thanks! I think my math is correct on the hub to hub measurement. I calculated it pretty much the same way as in that thread. What I'm not real sure about is how much clearance between tire and trailer. Surely 2-1/2" is plenty.
Last edited by eagle24 on Wed Jul 18, 2018 8:08 am, edited 1 time in total.
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Re: Chassis for 5x8 Hybrid Off Road/Highway

Postby eagle24 » Wed Jul 18, 2018 8:07 am

KTM_Guy wrote:2X2X1/4 is over kill. 1/8" is probably over kill to, but unless you can find 12 gage it's probably the best bet. I have heard people using 14 gauge but it seems a little thin to me but I tend to over build.

1200# is very light for an offload build. Even with 1/8 tube. I'm using Timbren 3500# with 2000# springs. It's their HD offload axle with 4" lift. I haven't weighed it yet but just one side with brake drum is heavy. I think when I'm all done I'll be pushing the 2000#, and I was thinking I would be in the 1200-1400 pound range.

Nice thing with the Timbrens you don't need to worry about how wide the axle is.

What is the backspace on the wheel? Also know if you are going with breaks you need a 66MM or 2.60" ( or larger) bore in the wheel to fit the spindle.

As far as leaf springs vs Timbren vs torsion axle, it's like asking which oil to use. They all have their good points and bad. My next build will be with torsion axles probably.

For me when I was planing my build I had images in my head of pulling the camper on any trail or mountain pass in Colorado or spending a week or two in the desert. It sounded good, I now say I was drinking the Overland Kool-aid. We like green and blue trails and forest roads. It's not fun to my wife if she is white knuckled all the trip or trashing the Jeep. So have a realistic idea on where you want your trailer to go and build to that.

Todd


Todd, Is your trailer going to have a kitchen galley? You might be right that I can't get it done and be in the 1200# range, but keep in mind that mine will basically be a 4x5x8 box on a trailer frame. I'll have a window a/c, Fantastic Fan, 2 small windows in the doors, electrical converter/charger, battery, and that's about it. You do have me thinking about how much weight I might put in as far as cargo (gear) goes. I like the idea of a heavier axle, but I don't want to go too heavy with the springs and beat the trailer to death with a stiff ride. My off road will be mild and probably infrequent. Mostly will be camping in parks with camper sites.

Greg
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Re: Chassis for 5x8 Hybrid Off Road/Highway

Postby tony.latham » Wed Jul 18, 2018 10:35 am

My 5x10 weighs 1300 pounds empty and I have never felt the need for trailer brakes with my 2007 and now 2016 Tacoma.

And I too think the 1/4”chassis is gross overkill. Put that in your tongue. Weight on or off road is not your pal.

Me and the U.S. Army put Dexter Torflex axles under our trailers. Each is manufactured for the weight of the specific trailer.

Tony


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Re: Chassis for 5x8 Hybrid Off Road/Highway

Postby Ottsville » Wed Jul 18, 2018 10:54 am

eagle24 wrote: I like the idea of a heavier axle, but I don't want to go too heavy with the springs and beat the trailer to death with a stiff ride. My off road will be mild and probably infrequent. Mostly will be camping in parks with camper sites.

Greg


You can buy a 3500lb rated axle without springs and put whatever springs you would like on it. Some people even use jeep springs or ford ranger springs to get a longer spring and the benefits that brings.
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Re: Chassis for 5x8 Hybrid Off Road/Highway

Postby working on it » Wed Jul 18, 2018 12:37 pm

eagle24 wrote:
KTM_Guy wrote:2X2X1/4 is over kill. 1/8" is probably over kill to, but unless you can find 12 gage it's probably the best bet. I have heard people using 14 gauge but it seems a little thin to me but I tend to over build.1200# is very light for an offload build. Even with 1/8 tube. I'm using Timbren 3500# with 2000# springs. It's their HD offload axle with 4" lift. I haven't weighed it yet but just one side with brake drum is heavy. I think when I'm all done I'll be pushing the 2000#, and I was thinking I would be in the 1200-1400 pound range. ...

... Is your trailer going to have a kitchen galley? You might be right that I can't get it done and be in the 1200# range, but keep in mind that mine will basically be a 4x5x8 box on a trailer frame. I'll have a window a/c, Fantastic Fan, 2 small windows in the doors, electrical converter/charger, battery, and that's about it. You do have me thinking about how much weight I might put in as far as cargo (gear) goes. I like the idea of a heavier axle, but I don't want to go too heavy with the springs and beat the trailer to death with a stiff ride. My off road will be mild and probably infrequent. Mostly will be camping in parks with camper sites....
tony.latham wrote:My 5x10 weighs 1300 pounds empty and I have never felt the need for trailer brakes with my 2007 and now 2016 Tacoma. And I too think the 1/4”chassis is gross overkill. Put that in your tongue. Weight on or off road is not your pal. Me and the U.S. Army put Dexter Torflex axles under our trailers. Each is manufactured for the weight of the specific trailer....
  • Here's a helpful link I found that sums up the axle question-points better than I could: http://lamartrailer.net/spring-vs-torsion-utility-trailer-axles-whats-the-big-deal/, but I have other points to cover, so....
  • My TTT, meant for eventual "semi-offroading". started out on a derelict 50"x 60" frame, of 11 or 12 gauge tube, with a short & bent tongue, and a circa-1250 lb axle...definitely not what I wanted nor needed, but I was on a low/no, <$500 budget build (I concealed all cost overruns from the wife for almost 2 years). But, I did extend the frame with welded-on 12 gauge steel tubing, and used a 3" x 3" x 3/16" x 6' long tube, to make a new tongue (45" sticking out forward of the frame rail, 29" welded to 3 cross-members, with additional 12 gauge spine running the length of the frame, welded to the tongue beam for max strength). I built the superstructure above, of 3/4" plywood, which made the whole framework more rigid, due to the monocoque construction. It should've sufficed, for off-road structural strength, but soon appeared a hidden flaw.
  • I did, later, have a spring hanger tear loose from the original frame (it was installed improperly, or it wouldn't have), which revealed to me that I would need thicker gauge frame-rails to mount a heavy-duty 3500 lb axle, which I saw as necessary to carry my increasingly heavy trailer, if ever I was to go off-road. To repair/reinforce the frame-rail, and to mount new spring hangers/springs/axle, I made an assembly to encapsulate the weak rails, out of 1/4" angle, with 3/15" flat bar on the other side as a load-spreader, and installed the 3500 lb Dexter axle into the same spot as my original axle had been.
  • I used 3000 lb-rated leaf springs, knowing that my TTT was at 1500+ lbs already -and now at 2000 lbs-, and would need extra load capabilities), and rode very stiffly, so I made an active bumpstop device that always modifies/absorbs suspension travel, so the ride became quite smooth. Later on, I changed my tires from ST bias-ply 205-75D-14 to LT (27 X 8.50R14LT), with some more sidewall flex than ST's, so the ride became smoother, still (I always use the recommended max. cold air pressure, on my trailer tires).
  • Adding brakes or not? I think it's a good idea for any trailer, even a 1000-pounder (if towed by a small vehicle). My squareback, at 2000 lbs now, will certainly need them for tow-ability behind a smaller vehicle than my 2500HD Chevy, so since I plan to get a SUV to use later on, I ordered the new axle with brakes. When I replaced both axles on my race-car tandem hauler, I upgraded to 4 brakes from 2, which helped my HD truck stop it much better. Always get brakes!
  • In summary, since you're starting your build, I think that you might best use the 2" x 1/4" square tube for tongue, spine, front & side frame rails, with the tongue welded to the spine and 3 cross-members (as I did), get a 3500 lb axle with brakes, and upscale your springs t 1750-2000 lbs at least (though you're trying for a minimalist cargo load, I did too, at first aiming for 1k lbs total trailer weight; I have added so much later, that it's now double the goal weight...you might accumulate more gear later on, so more load-bearing capacity, now, will be better than adding later). The 58" spring center/76 hubface measurement will work' Dexter insisted that my asked-for overhang wasn't enough, so they increased it to 15 inches, due to the included brakes.
  • my axle data.JPG
    my axle data.JPG (40.27 KiB) Viewed 1004 times
    axle overhang info, for ordering an axle.JPG
    axle overhang info, for ordering an axle.JPG (143.42 KiB) Viewed 1004 times
2013 HHRv "squareback/squaredrop", semi-offroad, 4x8 TTT, 2150 lbs
  • *3500 lb Dexter EZ-Lube braked axle, 3000 lb.springs, & active-progressive bumpstop suspension
  • *27 x 8.5-14LT AT tires (x 3) *Weight Distribution system modified for single-beam tongue
  • *100% LED's, GFCI outlets, 3x fans, AM/FM/C *A/C & heat, Optima AGM, inverter & charger(s)
  • *extended-run, on-board, 2500w generator *Coleman dual-fuel stove & lantern, Ikea grill, vintage skillet
  • *zinc/stainless front & side racks *98"L x 6" rooftop rod & reel carrier tube
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Re: Chassis for 5x8 Hybrid Off Road/Highway

Postby eagle24 » Thu Jul 19, 2018 10:45 am

This is a sketch of the trailer I'm building. You guys have convinced me to go to a 3500# axle with brakes. I'm waiting on the wheels so I can have the tires mounted and measure the offset before I have the axle built. This trailer will not have a hatch/galley, only a simple cabinet for storage in the rear. I'm thinking 67/33 for the axle placement rather than 60/40. Any thoughts on that?

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Re: Chassis for 5x8 Hybrid Off Road/Highway

Postby working on it » Thu Jul 19, 2018 12:51 pm

eagle24 wrote:This is a sketch of the trailer I'm building. You guys have convinced me to go to a 3500# axle with brakes. I'm waiting on the wheels so I can have the tires mounted and measure the offset before I have the axle built. This trailer will not have a hatch/galley, only a simple cabinet for storage in the rear. I'm thinking 67/33 for the axle placement rather than 60/40. Any thoughts on that?

Image
  • That same 67/33 front/rear ratio works for my TTT, after struggling to achieve it for several years. Your design calls for using evenly distributed loading, with a 67/33 weight bias built-in from the start; my TTT began life with too much frame in the rear, and not enough length forward of the center-line of the axle, causing the heavily-loaded rear to make the tongue weight nearly nil.
  • I goofed when adding 12" forward and 24" rearward to the originally 60/40 ratio'ed, 50" x 60" small trailer I converted; I should've added a proportionate length to maintain the favored "magic ratio", but I had created a 54.6/45.4 ratio instead. And, I compounded the error by putting all my really heavy items at the time (generator, battery, cooler, Aquatainer, Coleman gear + fuel) back there, while the only heavy items forward was the spare tire (bolted to the front wall), and a small overhead shelf behind the front slope of the roof. I think my first actual weighing of the tongue weight was zero lbs.
  • I had left room on the tongue for a tongue box, but couldn't find one at the right price, and the right shape I wanted, so in the interim, I compensated by using a Husky diamond-plate (black) toolbox, bolted to the tongue. I moved the battery into it, plus as many tools, spare parts% hardware that I could fit into it (shielding the battery terminals, of course). That made my tongue weight 40 lbs. Again, I compensated for that by carrying heavy camping gear inside the cabin, and making a Weight Distributing arrangement, using only one spring-bar, instead of two,and the hitch head as I used it, for pulling my big trailers.
  • I finally bought a nice tongue box, mounted it to a sliding platform (for blocking-in the spare, and to gain added tongue weight), stuffed the battery & spares from the earlier box, then added lots more electrical supplies and tools, until it was full. I finally reached 10% tongue weight, and the added 3 feet of tongue box forward of the cabin, made the EFFECTIVE balance ratio become 67/33, as well.
  • ms paint measuring exercise.JPG
    ms paint measuring exercise.JPG (345.01 KiB) Viewed 950 times
  • Recently, prior to my last trip, I added a single shelf on a rack over my front slope/tongue box, which doesn't change the ratio in terms of length, but it certainly added more tongue weight. After I returned from that trip, I added a second shelf to that rack, which added more tongue weight, now at 253 lbs (trailer total weight is 1989), when loaded up. Now, I don't have to carry heavy gear inside the cabin (now on the racks, or in the truck bed), and I might not have to use the WD hitch system anymore (it's almost impossible to back up while using it on a short trailer), also due to recently adding a drop-shank, to lower the ball height.
  • tongue weight, total weight, lower-center-of-gravity as calculated 5-17-18.JPG
    tongue weight, total weight, lower-center-of-gravity as calculated 5-17-18.JPG (31.11 KiB) Viewed 950 times
  • So, by starting out with an elongation of frame proportionally in front of your axle, you'll probably need less, or none, adjustments to get your weight balance correct, for a safer towing experience, without having to make major alterations that I had to, to achieve the desired results.
2013 HHRv "squareback/squaredrop", semi-offroad, 4x8 TTT, 2150 lbs
  • *3500 lb Dexter EZ-Lube braked axle, 3000 lb.springs, & active-progressive bumpstop suspension
  • *27 x 8.5-14LT AT tires (x 3) *Weight Distribution system modified for single-beam tongue
  • *100% LED's, GFCI outlets, 3x fans, AM/FM/C *A/C & heat, Optima AGM, inverter & charger(s)
  • *extended-run, on-board, 2500w generator *Coleman dual-fuel stove & lantern, Ikea grill, vintage skillet
  • *zinc/stainless front & side racks *98"L x 6" rooftop rod & reel carrier tube
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Re: Chassis for 5x8 Hybrid Off Road/Highway

Postby KTM_Guy » Thu Jul 19, 2018 10:53 pm

I like the design, Looks cool, I saw the Oregon Trailer at Overland Expo a few years ago and liked it but it's a little to small for us.

We do have a galley on ours and that will add some weight.

How will you access the storage under the cabinets?

I like a tongue box for misc camp gear and the batteries and electrical stuff, but you might not have much weight in the back to offset the weight.

Will the AC go in the cabinet? Just remember you need to get rid of the heat it puts out.

Todd
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Re: Chassis for 5x8 Hybrid Off Road/Highway

Postby eagle24 » Fri Jul 20, 2018 7:49 am

KTM_Guy wrote:I like the design, Looks cool, I saw the Oregon Trailer at Overland Expo a few years ago and liked it but it's a little to small for us.

We do have a galley on ours and that will add some weight.

How will you access the storage under the cabinets?

I like a tongue box for misc camp gear and the batteries and electrical stuff, but you might not have much weight in the back to offset the weight.

Will the AC go in the cabinet? Just remember you need to get rid of the heat it puts out.

Todd


I'll probably just put some sort of lightweight door or access panel to the inside of the trailer. I'll use that storage for miscellaneous items that you don't regularly need. Maybe a cheap tool set, extra paracord, lightweight tarp, rope, electrical wire, tape, etc. Also, to access tail lights and rear marker lights if they need to be repaired or replaced. I might possibly put the AGM Battery there depending on the balance, but most likely it will be on the tongue.
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