'73 Compact Jr. Frame

[Emmit D. Acklin]

I need a place to carry my generater when I go way off the road, so I'm thinking of adding heavy 13 foot rails to my Compact Jrs frame. The excess, to be in front, will carry the generater, spare fuel, tools and any other incidental items that I'm inclined to accumulate, such as a tow-chain, and perhaps a Dutch-oven.
Any comments?

[Chester Taje]

I had a Compct J.I think if you do the extra beef up on first part of frame you should be ok

[Donna D.]

webguy added 18"-24" to the front of his Casita, rewelded the tongue...all to get more room to mount two bikes on the front of the Casita (on top of a tongue box holding the generator, etc). I'd love to show you the pictures, but the hacker deleted em

[Bigfoot Mike]

Actually I added 8 inches to the length of my Casita frame.

I will take some detailed photos of the frame and the bike rack and post them.

[Brian B-P]

I probably wouldn't add to the frame to this extent without carrying it all the way to the hitch coupler, to avoid creating a high-stress point at the end of the reinforcement. Something from coupler to axle location might act as a "bridge" to carry the generator, but I am only guessing here, not having even seen a Compact Jr. frame.

In any case, some real technical expertise is called for in any structural modification. In this case, if it is only an add-on perhaps it doesn't risk compromising structure, but it seems to me that it could be unnecessarily heavy - it would be a shame to lose the lightweight nature which is one of the best features of our trailers.

I'm not sure what the end result would be here: is the overall length going to be the same, but with added structure under the egg (body) and just ahead of it, or is this a lengthening of the frame? If weight is added ahead of the egg, it goes mostly on the hitch (tongue weight) rather than the axle - this might be okay, but would be a problem for some tow vehicles. If the axle-to-coupler length is extended, that would decrease the tongue weight, and the cargo would put it up again: some calculations (or just try and weigh...) would be required to see the end result.

[Pete Dumbleton]

I saw a 13' Scamp Deluxe on which the owner had welded up a steel "T", with a coupler welded onto the long end, which was welded right underneath the existing frame without even removing the original coupler -- Per some comments from a poster on the list who used to be in engineering for an egg factory, you would want to make sure that the crossmember of the "T" was behind, not on, the most stressed part of the frame -- Depending on your existing frame's makeup, it might make sense to have two crossmembers.

In the case of the Scamp I saw, the intent was to create enuf space for a two-bike rack (vertical mount). One advantage is that you would lengthen the distance between the hitch ball and trailer axle, which would result in less trailer sway affect on the tow vehicle and more control (less tendency to jackknife) when backing -- Of course, the sites will have to be marginally bigger, but that's not likely to be a problem -- Ferries may cost a bit more, also.

Likely you will also have to lower your hitch ball, making hitch and tongue closer to the ground and it will add some weight to the front, along with the generator, but the lever arm will be longer, so that will partially offset the tongue weight effect.

Be sure the new totals won't be exceeding the gross weights of the tires or the axle.

AFTERTHOUGHT: When we put stuf in the tow vehicle, by vehicle design the stuf tends to go in the back, sometimes upsetting the manf's original layout of the weights over the front and rear axle, which we know can be critical on FWD vehicles, but is still important on other vehicles. Consider moving some of the load, stuf like tow chain, to front of Jeep.

I was able to redistribute weight on my Dodge D150 pickup by putting toolbox in front seat floor, chains, etc., under hood plus HiLift Jack and spare tire in front of bumper -- The resulting balance was noticable not only in towing, but also when driving without the trailer behind.

[Donna D.]

Originally posted by Mike Sanders@Nov 13 2005, 10:13 PM
Actually I added 8 inches to the length of my Casita frame.

I will take some detailed photos of the frame and the bike rack and post them.

Well, guess I gave more credit than was due

Pics would be nice. I've really missed looking at a bunch of pictures.

[Emmit D. Acklin]

I'm sure you've seen the pictures of the boxes Charles Watts builds for his van, the one with the slide-in plastic trays. I use the same type box in my Jeep Cherokee, in fact I got the idea from him. However in my case; with the box in there, I have no rear seats! Getting rid of the box will let me have rear seats again.

Also I have tried carrying spare gasoline inside trailers, pickup campers, cars, and even the "topper" on my pickup, believe me it wont work unless you like fumes in everything. Once I carried what I thought was a closed gas can in the back of my pickup with a picnic basket. Gas fumes got in everything; cookies, sandwiches and even a closed loaf of bread. Bettie and I split a cold can of pork-and-beans for dinner that day.

My plan is to add heavy rails to the bottom of the exiting frame, without cutting it, all the way from the bumper to three feet beyond the front of the body of the camper. I will have to cut the spring hangers off and re-attach them to the bottom of the added on rail of course.

I will then have to cut the tongue off, move it forward three feet on the same heavy rails right up to the coupler. Then I will build some sort of box on that three foot extension to hold the generator, tools, spare gasoline and folding chairs. (And lots of things I will never need.)

This will move everything (weight wise) out of the Jeep to behind the hitch. I know this will add weight to the little trailer, but where I want to go only a 4-wheel-drive can take it there.

[Kurt & Ann K.]

Emmitt,
"Nuestra Casita" has a 6" lift via 6" thick-walled rectangular tubing used as a filler between the axle and original frame. Her tongue has been extended 24" to allow room for a 3000 watt generator concealed inside an aluminum diamond plate box, and an additional battery. The underside of the tongue extension is floored with expanded metal to save weight and allow the generator to breath. With 15" tires and wheels and nearly all mods possible, she weighs 4000 lbs. wet and ready to roll for a trip.
The reason for the lengthy discourse, it to warn about tongue weight. With box, propane converted generator, 2 propane tanks, and battery in it's box, the tongue weighs 600 lbs! Given the weight of the trailer the ratio is right at the upper limit of 15%. She pulls like a dream, but I'm always aware that there is a 2 ton weight behind the truck. She is equipt with a 750 lb WDH and sway control to be on the safe side.
Before actually beginning construction of a tongue extension, it would be prudent to weigh all additional materials and everything you desire to carry there to forecast the total weight.
One other word of caution, no matter how skilled a welder you are, unless you are a certified welder, find and use one so he has the liability. The last thing any of us wants to see, is a fiberglass TT rolling down the road separated from it's tongue! The possible ramifications in terms of property damage, injury to innocent parties, and destruction to one's personal finances is within the scope of all our imaginations.
PLEASE do it right, or forget this particular modification.
Stay safe and happy on the road
Kurt & Ann K.

[Emmit D. Acklin]

Good advice and well taken!

Thank you one and all for your concern, comments and advice.

The last thing I want is a quick disconnect at speed, such thoughts help keep me awake at night.

I could tell a few good stories of such things I saw on the Alaskan hi-way, AND ONE WAS MY OWN.

I LOVE THIS SITE!!!

[Shannon and Ross]

Emmit ~~ Here is a pic of ours....I don't know if this helps as I'm not a real technical person...

[Tom Trostel]

Emmit,
My Compact Jr. has had work done to the frame and since I've never seen another, I don't know how much it is different. My guess is that a previous owner wanted to strengthen the frame and raise the heigth of the hitch. There is a 2 inch X 1 inch steel beam welded under the original frame that runs from below the hitch to the front spring shackle. I see no evidence of cracks in the original, so I think it was just a precaution. The distance from the end of the hitch to the front fiberglass wall is 34" on my trailer. The hitch is about 10" higher than the bottom of the frame. Hope this helps. Tom Trostel

http://albums.photo.epson.com/j/ViewPhoto?...&p=73194432&f=0

[Brian B-P]

Now I understand that the intent is to extend the frame 3 feet, by cutting off the tongue, moving it forward, and adding supplemental frame rails.

It appears that the new rails will be the only structure in the area between the egg and original tongue, which I believe is the most highly stressed area of the tongue. Usually (meaning in most of our trailers but not the U-Haul) I believe that the tongue material is the same as the main frame rails; in many cases, it is actually the main rails bent into an A-frame, and in my Boler 1700 it is composed of separate pieces of the same dimensions, welded to the main rails.

I don't know what the existing frame material is in the Compact Jr., but it seems reasonable to guess that the extension material should suit a trailer of the new (higher) weight and new (longer) length, since heavier and longer both mean more frame stress. In my Boler (which is long compared to a stock Compact Jr., but perhaps comparable to the stretched version), the material is hollow rectangular tubing, 2" wide by 4" tall by 3/16" thick. (The Boler 1700 frame thickness measurement is courtesy of Benny K., from an earlier discussion.)

By my calculator, that means for the proposed supplemenatary rails there would be 2.25 square inches of steel tubing, 26 feet long, which would be 702 cubic inches of steel, or about 80 kg (180 lb) of steel. Of course it would be proportionately less if a smaller section were used. Maybe it would make more sense (although I realize that it would be substantially more work) to just make a new frame. I don't think that this is an unreasonable idea, since these trailer frames are quite simple. I would expect any custom trailer fabrication shop to be able to make the new frame, people have reported doing this quite cheaply in this and other forums, and if I were running a fabrication shop I would be much more willing to vouch for the integrity of a new frame than a radical modification to an existing frame.

For a compromise, how about making a new tongue out of the front of the new rails, and not using the old tongue at all? A new coupler is cheap, and any useful brackets and fittings (e.g. propane tank mount) could be reused.

The main motivation for thinking of the one-piece tongue is the stress where the tongue attaches to the rest of the frame. Just butting the cut-off tongue up to the nice strong frame rails and welding them would scare me: it seems to me that it at least needs some overlap. I have seen a two-foot frame extension in a heavy commercial truck (Class 8 highway tractor, I think a Mack) and it was done by cutting the C-channel frame and splicing in a channel sized to just fit inside the original frame channels, but thicker (since it's smaller) and overlapping two feet each side of the extension area - that's 6 feet of added channel (per side) for a two foot extension. I'll concede that some of that overlap is required because the connections are bolted (by many bolts), rather than welded. Following the same approach, the new rails for the trailer would need to overlap well into the area of the relocated tongue section, negating most of the benefit of reusing the original tongue structure.

In any case, new tongue or not, I don't see a need to go all the way back to the trailer bumper - or even any significant distance behind the axle - since the stresses on the frame back there are not related to the tongue loads.

Originally posted by Emmit D. Acklin@Nov 14 2005, 10:07 AM
This will move everything (weight wise) out of the Jeep to behind the hitch. I know this will add weight to the little trailer, but where I want to go only a 4-wheel-drive can take it there.

If the cargo is mounted close enough to the hitch, the weight will be carried mostly by the hitch, which is an even worse point for the Jeep than over the Jeep axle, since the hitch ball is well behind the axle. The hitch weight even makes load transfer off of the front axle to the rear, which is essentially why weight-distributing hitches (WDH) are used. I would do the math and work out the resulting axle load to see if it makes sense to move all of the stuff. I like Pete's idea of considering the reloation of some particularly dense cargo to the front bumper of the Jeep.

I think it's worth considering choosing the extension length and cargo locations to make the hitch weight low enough to keep the Jeep happy without a WDH, knowing that with four wheel drive there will be enough traction for occasional tough spots even with little of the trailer weight contributing to tow vehicle tire load.

Finally, a comment that belongs in any structural discussion: the remarks above are just my thoughts, provided for entertainment and discussion, and do not constitute a design or recommendation.

I realize that this has been rambling on too long, but perhaps it's better to post and take the flack for too much text than to not contribute anything at all. And in the desparate hope that this big pile of text will make more sense with a picture or two...

[Emmit D. Acklin]

Thank you all very much. I've been too busy to get back before. My Compact's frame is built entirely, tongue and all, using 1in X 2in X 3/16ths inch thick channel. The material I plan to use is 2 1/4in X 2 1/4in X 3/8ths inch thick angle iron, all the way to the coupler under the original frame. I have welded, off and on, for many years, and still have one welder I kept to play with.
Thanks again...this is a great site!!!

[Brian B-P]

One of the lost topics was about "thread killers": members whose posts seem to be the death of the thread, as no one else then responds. I was sure I had accidentally killed this thread, and I really don't believe that no one out there has anything better to say than my ramblings.

The original frame material for the Compact Jr. seems quite small, especially to me since I am accustomed to the 2"x4" box section frame of my Boler, although I suppose it is closer to what those more familar with the smaller trailers might expect. The C-channel choice is not surprising - lots of utility trailers are built with C-channel - but still somewhat disappointing. I had not realized when I first saw Tom's photo that the frame members are channel, rather than box.

If I am not a fan of C-channel, I like angle sections even less. Angle (and to a lesser extent channel) has low torsional stiffness and is not efficient in carrying bending stresses. Why not use box section? For the less weight than the 2.25"x2.25"x3/8" angle, I would expect 2"x2"x3/16" closed box section (square hollow steel tubing) to be stronger.

The 2.25x2.25x3/8 angle should be about 1.6 square inches in cross section, so 26 feet would be about 57 kg (123 lb) - less than with the size of tubing I used for an example, but still significant - I assume more than 10% of the weight of the whole trailer.

[Emmit D. Acklin]

At this point weight isn't an issue, but strength is. The cost is a factor also, I have on hand everything I need to do this job. You are correct about the inherent weakness of angle iron, and the merits of the box section material. I am using the angle iron because that is what I have on hand. I have just enough to do this one project. I'm not replacing the frame, just beefing it up to get me into, and out of a very rough area. I don't want to have to haul a welder into a place a log truck can not go.