Talk to me about trailer design

With recent purchases I've realized that I need a lower trailer.  What I thought I wanted was a deck so low that I could crank the tongue up and the rear just hit the ground like a tilt trailer but without the complications.  I think that would be too low and drag.  Let's get specs out of the way.

My lowest angle of approach is 11 degrees.

I want it 7x16 feet with no dovetail.  

Two 3.5k axles with brakes hoping to keep the trailer under 2k lbs for a load weight of 5k lbs max

If my level deck is 12 inches off the ground and I use 4 foot ramps around 11 degrees then the rear of the deck needs to be 9 inches high so I'm wagging the tongue jack would need to raise less than 6 inches.   

To get that deck height I would need 4 inch drop axles.  My biggest question is the steel to build the trailer.  I see a lot of angle and C channel being used.  My current trailer is 5 inches of C on top of another 5 inches of C.  By going to rectangular tubing I'm assuming it would be stronger and I could lower that height.  How do I figure out what size?

Torsion axles.  You can get the arms degreed to any angle you want to set ride height.

I used a trick today loading a '56 Caddy that I learned at the track. The Caddy bottoms out going up the ramps to get on the trailer. The trick is to put ramps in front of the truck's rear wheels and roll up on them. Trailer nose goes up, rear deck goes down. Edit: That heavy bastard took enough weight off the rear of the truck when I started up the ramps  that I shoved truck, ramps and all until I put in 4wd and "park"

In reply to RonnieFnD :

I think I can get my deck height to where I want it without the extra expense.

In reply to NermalSnert (Forum Supporter) :

I've been using a similar method to load on my existing trailer.  When I babysat it, Brad the Challenge winning Bradley GT loaded pretty easy with the rear squatting.  The most recent purchase only weighs 1200 lbs so not so much squat.

Here is a idea 

https://m.youtube.com/watch?v=5dRU-3YiAsE

I found it on here when I McGoogled it

https://grassrootsmotorsports.com/forum/grm/making-a-lowering-deck-trailer-out-of-current-trailer/198304/page1/

In reply to MyMiatas :

Oh I've watched those.  I'm a KISS man.  Now this one got me thinking.

My car trailer is homemade and the axles are stubs from a minivan welded to the frame. There is no suspension at all so the deck is only about 10 in from the ground. I keep the tires soft and it has been hauling 3,500 lb of race car and pit cart around for years with no issues. And doesn't act like it has no suspension and doesn't beat up itself, the car or the tow vehicle. Was it Kas Kastner who said the secret to making a suspension work is not to let it?

In reply to bearmtnmartin (Forum Supporter) :

You know I've thought about that.  If I do wheel straps then the cars suspension should soak up the bumps.  How long is yours?  Dual or single axle?  Do you have issues with the rear rubbing on steep inclines?

My trailer is made with rectangular tube down each side. I think it's 2x6x1/8 wall. Cross pieces are 2x2, two 3500# axles. If you get serious about building a trailer I can go to the storage facility and confirm the tubing sizes and wall thickness.

I also built this one many years ago. The wheels are at the four corners of a subframe that pivots on a big bolt midway between the wheels. You can see it's built from 2x2 tubing to keep it light. I towed that Mini or a FormulaVee on it. The stub axles were from a K-car IIRC, and were bolted to the subframe, which had a four inch drop built into it. Resulted in a nice low deck. I towed with a Pontiac 6000 because the whole rig was light. You could build something similar, just scale it up.

A good friend built several car trailers over the years with mobile home axles cut, put through 3" holes in frame from both sides, and weld 'er up. No suspension so nice and low. Axle or wheel straps, and rides nice. Surprisingly so. 

Stampie said:

In reply to bearmtnmartin (Forum Supporter) :

You know I've thought about that.  If I do wheel straps then the cars suspension should soak up the bumps.  How long is yours?  Dual or single axle?  Do you have issues with the rear rubbing on steep inclines?

It's a tandem axle. I would would take photos but I'm not home for a few days. And yes our track is sloped so I have to be quite careful driving in and out but I'm happy with the trade off.

I have a low trailer as well (it has 4" or maybe even 6" drop axles with leaf springs).  I went to link to it here and see that you had posted a couple questions there I had not seen yet, Stampie.  https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/1989-car-hauling-trailer-refit/59467/page1/

I don't know the deck height at this time...it's something I've been meaning to measure.  The main structure is built from 2"x3" steel and 1"x2" steel tube.  The tongue is 2"x3" x about .160 wall.  The rest of the 2"x3" is roughly .108 wall.  The 1"x2" is in the .100-.120 ballpark for wall thickness (Looks like it's 14 gauge based on an early post in my thread). 

One thing about the tubing is that it rusts from the inside (Any metal will rust...but it's hard to stop/kill/prevent the rust inside the tubes).  If I built one out of tube in the future I'd cap all tubes and leave a cap screw hole somewhere to oil it annually or something.  I put vaseline inside a couple of the tubes I replaced on my trailer for this reason.  I don't know if it worked but it made me feel better ;).  Non-tubular steel (C-channel, angle, etc) will be easier to inspect/clean/prevent rust in theory.  Frankly, though...as humid as it is here and as fast as vegetation grows, a steel trailer parked outside doesn't have a fighting chance against rust.  I imagine your area is similar.  

A low deck and drop spindles means TALL fenders.  This means you usually can't open doors once the car is on the trailer.  I can still climb in and out through the windows of cars/trucks but it's not fun and not particularly good for the interiors and window trim of the cars I'm going in and out of Duke-Boy-Style.  

Ramps are a pain in the ass.  A little complexity in making a trailer tilt could pay off in not having to heft and handle ramps and potentially roll around on the ground messing with them as well.

I've been working on some designs for a replacement trailer as the one I have is reaching the end of its life. It's been about a year since I was heavy into designing a trailer, but it's getting to be the dark and cold time of year so I'll probably be at it again soon.  Steel prices killed my momentum last winter.    

I used 4 inch angle with 2 inch angle cross beams.  A 2X6 makes the deck as high as the trailer side.  I used 4 inch channel for the tongue.

I have 2 3500 pound axles and springs.  I have pulled a full sized Jimmy, tractors, etc.

Go for it. It is fullfilling to build your own even if it costs the same as buying one.

I've posted this before.  About 15" tall.  4" drop axle with brakes.  No ramps. Deck pivots ahead of axle.  Outlaw Bug is 3" off the ground, and just drives on.  Cost me about $1,500 in materials.  Tows 80+.

Rectangular box tube is the way.  I learned that from Deande Trailers in NJ...had one of their single axles years ago and then bought a similar two-axle home-built that Stan Whitney put together in a weekend.  Torsion axles, drop spindles, aluminum decking and fenders, etc.  Weighed around 700 lbs.  Towed Miatas and EF Hondas around for many years with a CX9 (check out the little teeny drawbar)

I have a bunch of pics, but here's just one.

If you do something with rectangular tube, you can slow the interior rust issue alot by squirting boiled linseed oil inside the tubes before you weld on the final cap. It will wick up and around the inside surfaces and hardens to seal the surface. Roll the tubes/assembly around to help spread it out if you can. This is a fairly old method used in aircraft with tubular engine mounts and fuselage structures.

In reply to Andy Hollis :

That looks like a single frame type build instead of a frame on a frame like I normally see.  What size is that tubing?

Watching this thread to see what you build. For years I thought about designing my own trailer to fit my particular needs, since my race trailer was overkill for hauling a Miata or VW GTI. The trailer probably weighs 80% ,or more of what the cars did, not really efficient engineering. What would have been "fit for purpose" was a trailer somewhere between the red one and the one I built to haul the Mini.

Stampie said:

In reply to Andy Hollis :

That looks like a single frame type build instead of a frame on a frame like I normally see.  What size is that tubing?

I no longer own it so not sure.  Went to a larger Trailex when the papaya car addiction began.  :)

I *think* the main rails are 2x6...but might be 2x4?

Here's another shot for more of the detail work.  I'll see if I can find Stan's original build thread.  David Whitener built a similar one modeled after this one.

OK stupid question time.  Would unhooking the trailer from the truck, raising it with the jack and deflating the rear trailer tires be easier than building a new trailer?  Admittedly I am a lazy idiot who has never unloaded anything so low a few block of would wouldn't fix.

In reply to porschenut :

You're pretty likely to shove the trailer around and make things very scary for yourself. 0 tongue weight with nothing holding down the hitch is not an experience you want to have, because you wind up with a 3500lb+ teeter totter

In reply to porschenut :

I've done it a few time moving junk. Will probably need to in the future. I can tell ya... TTO17 is correct. No one should ever try this ! 

In reply to porschenut :

It's a real thrill ride when an unattached trailer starts rolling down a hill when you are inside a non running car on top of it. 
 

Ask me how I know. 
 

Andy Hollis said:

Stampie said:

In reply to Andy Hollis :

That looks like a single frame type build instead of a frame on a frame like I normally see.  What size is that tubing?

I no longer own it so not sure.  Went to a larger Trailex when the papaya car addiction began.  :)

I *think* the main rails are 2x6...but might be 2x4?

Here's another shot for more of the detail work.  I'll see if I can find Stan's original build thread.  David Whitener built a similar one modeled after this one.

Looks like 2x4 to me, judging by where the front center spar meets the cross piece. It looks like the whole thing is built from 2x4 and 2x2 tubing, a nice simple design.