DIY Expo Trailer Builders Q&A Thread

drsmonkey

Observer
For question #3, here is what I did...

My trailer is light ~1000lbs fully loaded, so keep that in mind.

I put a receiver just past the triangle on the tongue, then used an extra heavy and long receiver extension (built my own) then drilled holes at the lengths I wanted. On the road I set it longer for easier towing and backing. Plus the longer tongue length makes it easier to maneuver the trailer by hand.

When I hit a trail and air down I pull the pin, chock the trailer tires, put the jack down and lift just a touch to get the tension off, then back up the truck to shorten the tongue length. I put a stop in the tube so that it only goes back far enough to fit the pin into the short hole. I'm considering cutting a groove in the inner tube that locates either hole correctly, then using a pin through the outer tube to limit it so I can shorten and lengthen the tongue without having to unhitch.

I like it short on trail for a couple reasons... at the shorter length the trailer tires track the truck tires very closely so I don't have to watch the trailer wheel placement separately, I wish I knew exactly how to calculate that, but I just got lucky and hit on the right length. Someday I will measure the various lengths and see if I can figure out the math. The second thing I like is that I can turn the whole rig around in a lot less space. The trade off is that it is twitchier to back up (which can be both good and bad on the trail) and I have to be more careful about jackknifing.

Bonus from this system is that I can also easily throw on a 2" ball hitch so that I can use an ATV to maneuver the trailer in and out of the tight spots I have to store it on my property.

One of these days I'll have time to put together a build thread, but all my spare time goes into building the thing. I don't know how y'all do it. I'm about to start re-arranging some things on the tongue, re-configure the tailgate into a swinging door, rebuild the fenders with some storage, then design and build a pull-out kitchen. I don't have any time to take and post pictures too.
 

lacofdfireman

Adventurer
These are exactly the type of responses I'm looking for. There's a lot of good info for me to consider on here. Next up is figuring out my axle length that I need to buy so I took some measurements and wondering if you guys can help me figure out what size axle to buy since I'm not sure how they measure axles when you go to buy one. .

This is the info I have

Jeep width is 72" at widest body points. 70" outside of Drivers side wheel to outside of passenger side wheel. Back spacing on wheels with tires on is 7". Tires obviously stick out further than the rim.

So because I am using Jeep wheels and I don't want to have the centers machined out I will need 2" spacers on each side. So my back spacing minus the 2" spacer gives me 5" per side. Not sure how much room between side of tire and trailer should be but I'd assume 2-4" for tire squish. I want to build my trailer so the inside of the box is 48x 72". So with 2x2 tubing or 2x3 not sure what ill use yet that would make the trailer frame 52"wide at the outside corners. Then my back spacing of 7" minus the 2" wheel spacers would give me a 57" axle. Then add on 8" for tire clearance (4" each side between trailer and tire) which would give me a 65" axle total length? Does that sound about right? Or does it not even make sense?

So next who do I call and order the axle from and springs and hangers etc. I'd assume I'll buy 1500lb springs. Also would you say I'd need brakes? Is it best to order this all from the same place?
 

stomperxj

Explorer
These are exactly the type of responses I'm looking for. There's a lot of good info for me to consider on here. Next up is figuring out my axle length that I need to buy so I took some measurements and wondering if you guys can help me figure out what size axle to buy since I'm not sure how they measure axles when you go to buy one. .

This is the info I have

Jeep width is 72" at widest body points. 70" outside of Drivers side wheel to outside of passenger side wheel. Back spacing on wheels with tires on is 7". Tires obviously stick out further than the rim.

So because I am using Jeep wheels and I don't want to have the centers machined out I will need 2" spacers on each side. So my back spacing minus the 2" spacer gives me 5" per side. Not sure how much room between side of tire and trailer should be but I'd assume 2-4" for tire squish. I want to build my trailer so the inside of the box is 48x 72". So with 2x2 tubing or 2x3 not sure what ill use yet that would make the trailer frame 52"wide at the outside corners. Then my back spacing of 7" minus the 2" wheel spacers would give me a 57" axle. Then add on 8" for tire clearance (4" each side between trailer and tire) which would give me a 65" axle total length? Does that sound about right? Or does it not even make sense?

So next who do I call and order the axle from and springs and hangers etc. I'd assume I'll buy 1500lb springs. Also would you say I'd need brakes? Is it best to order this all from the same place?
When you order axles they typically want a measurement from wheel mounting surface to wheel mounting surface. Are you working on a JK? You may be able to find that dimension online somewhere. The most accurate way to measure this is jack up the back and have someone help you. Get 2 straight edges or anything straight and place them on the face of the wheel mounting surface. Whatever that measurement is minus your wheel spacers is the width you need. You also need to remember that you will need a minimum of 1.5" clearance between the inside of the tire sidewall and the frame rail. They also ask you what the spring perch center distance needs to be so all that has to be measured/figured out before you order.

If you want 48" inside dimension on your box then you need to figure out what material you are building the box from, add that, add the tire clearance, add the backspacing and wheel spacer dimensions

If your trailer is going to be anything over 1000-1200 lbs loaded I'd say get brakes. Its good insurance. I wish I would have done brakes on my teardrop and it was only about 1100lbs loaded.

Jess
 
I used these same Jeep Rubicon - Hard Rock wheels on my home made trailer a couple years ago. After I bought my axle and mounted it and got ready to mount my new wheels, I discovered that the wheels have a very deep offset. I had to order aluminum spacers so that the wheels could bolt on to the hubs and not rub. It's not any big problem and I've gotten along just fine. I just wanted you to know up front.
 
!CID__0516141459a.jpg!CID__20150516_102859.jpgI have one other thing I'd like to mention about the height of the sides and top of your trailer. I do not have an RTT on my trailer and I wanted to be able to see out my inside rear view mirror over the top of my trailer and I can. It's not any big deal and obviously I can also just use my outside rear view mirrors, it's just my personal preference. I sat in my vehicle and looked out the inside rear view mirror and lined up a line on the rear window and measured from there to the ground to help establish the top of my trailer box. I'm very pleased with the result.!CID__20150516_132608.jpg
 

jwiereng

Active member
A heavy tongue tows nicely. A light tongue can lead to a wagging trailer. A tongue that is too heavy messes up to handling of the Tow Vehicle.

I suggest you make the axle on a separate subframe and bolt it down after you make the trailer and get it loaded up. I've seen this on boat trailers. It allows you move the axle to lessen or increase tongue wieght.
 

1store

Banned
When ordering from the hub face to spring make sure it not to long . Some that are cutting down the HF TRAILERS then putting bigger tires stand a good chance of bending the axle . There's are the axles we use when we do a M 100 M416 conversion . The longer one is for steel wheels . The other one uses a spacer . The longest one from hub to spring is the most overhang that Rock will build.




The biggest thing to look at is the spring pad out
This for using jeep wheels not 0 off set trailer wheels
 
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Sb_Moto

Adventurer
Here is my limited knowledge on the subject and what I did.

1. When building a trailer do you build it around your axle? Meaning do you buy your axle first then decide trailer dimensions after? Or is it the opposite. Do you build up a frame and then order an axle to fit your frame.

I actually built around my vehicle. I found my hub to hub measurement on my vehicle and went from there. It was 65" so I could have chosen a straight axle of the side, but i ended up going with a Timbren setup and used some math to get the hub to hub to be 65" the same as the truck. If it matters to you then use the vehicle hub to hub. If not then design your trailer and then figure out how wide of a axle you need. You will probably have to change the design and axle length a couple times to get it just right so remember paper is cheaper than parts.

2. Frame building materials. I've seen everything from Square tubing to C channel to angle iron. Why did you do what you did and what size material did you use?

C channel is great for saving weight and mainly on road, but the general consensus appears to be 2x2 .120 for on road and 2x3 .120 for off road. The main area to focus on is the tongue and the design. I went 3x3 3/16 for the tongue with 2x3 .120 for a v brace. There is a guide around here somewhere that talks about tongue weight vs tongue design.


3. As far as the trailer tongue goes how long is optimal so you can basically jackknife without hitting tow vehicle? Also what size tongue material is used to fit your hitch on the trailer size?


Measure your tow rig from ball to corner of the vehicle. Then add 6" and bam.. Tongue length. As I said earlier 3/16 thick and either 2x2 or 3x3. I went 3x3 with a 2.5x2.5 insert to have multiple removable hitches (2" ball and Lock N roll).



4. How do you locate where to put your axle and axle hangers?

Short answer is math or 60% back on the main body. Long answer is to calculate COG using moments off a fixed point. It takes a long time, but can be well worth it. You can use excel to help so you can play around with adding different weights at different points and seeing what that does to tongue weight. Keep in mind deproach angles, and enough room for doors. You can check out my build thread for more info on this. I think my second post was a writeup on it.


5. What is the ideal size of an off road expo trailer for an RTT raised above the lid of the trailer? And how tall should the sides be?

100% personal preference. I would keep it as low as possible for COG reasons, but still give enough storage for stuff below.

6. What is the typical cost breakdown of a trailer build ie Axle cost, materials cost etc?


Lord knows.. I would say anywhere from $1000.00 to infinity. It all comes down to what options you want to go with. Go to Etrailer.com and that will give you a idea.

7. Where did you source your axle from and do you use brakes or no brakes?

If building new I would go ahead and do breaks. Its going to cost you probably 100.00 more, but in the grand scheme of things its worth it and a slight drag can be nice on a decent.

8. What size axle is best to use. Looks like most people buy a 3500lb. Where to buy?

3500 without questions. its not worth the money to skimp on the axle. If you go timbren you can go 2000hd which has the beefiness of the 3500 with 2000lbs "springs"

9. What size leaf springs? Where to buy

Trailer springs are shorter and they work, but if you can accommodate longer springs then they will give a better ride. Add shocks to it too.
 

lacofdfireman

Adventurer
So I have been set on building a 4x6 or 7 trailer. After playing around with a pvc pipe as an axle I've came to the conclusion that the max I can build would be 40-44" wide max. Here is a photo of the axle with PVC pipe as axle. Inside of blue tape closest to the represents 2" between tire bulge and frame.

ImageUploadedByTapatalk1456796916.154456.jpg

There is some perspective distortion on the photo. The edges of the tires from outer edge to outer edge is 72" which is the width of my Jeep Cherokee.

I figured I'll need 1 1/4" wheel spacers on my axle to clear my center cap since my wheels center hole is to small for an axle. So I figure my axle distance from wms to wms is 58".

Yes I know I need to lift my Jeep still. It's all in the mail and will be going on in the next few weeks. Wheels are 255/75 17's




Sent from my iPhone using Tapatalk
 
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1store

Banned
looks like you have it worked out could not ask for better.
A little thing on beam axles when you order it will be hub face to the center of the spring pads .On rubber band axles it's hub face to out side of flanges
The trailer I am building is 44'' wide on the frame
 
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colorado matt

Adventurer
So I have been set on building a 4x6 or 7 trailer. After playing around with a pvc pipe as an axle I've came to the conclusion that the max I can build would be 40-44" wide max..... So I figure my axle distance from wms to wms is 58".
very close to what is going on in my mind also ... shooting for 58" wms ... and looking like 44-46 spring centers ..... subscribing as I am full of questions also ...Matt
 

lacofdfireman

Adventurer
Ordered up my axle. I tried to go through abc trailers in Georgia as they seem to be popular on this website but their phone number was not right. Even on their website it sounds like some marketing call your making asking your age and a bunch midnight wacky questions. I went through a local dealer called Six States. I'm sure I'm paying more than I should at right around $400 for a 3500lb axle with brakes, springs and hangers but it will be nice to get this first one done. Hoping to build another trailer after I figure the first one out.

My goals with this first trailer are to build it with a RTT in mind even though I don't know the first thing about them. I'd like one that sleeps at least 3 and is roomy. I'm a big guy at 6'5" 260lbs so not looking for a pup tent.
 
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