Race Trailer Question

Ron Earp

Admin
I've a question for those knowledgeable about trailers. My race trailer has too much tongue weight. Way too much. We measured it on the scales yesterday at about 1600-1700 lbs of tongue weight. Way more than recommended for even a class V receiver, which I don't have. I only have a class four, and it is rated to about 1000 lbs with the load leveling system.

I routinely tow with the 1200 load leveling bars and my air bags pumped up to about 75 psi. Setup in this fashion the trailer tows great - nice and straight, no swaying, and stops easily thanks to the dual axle electric brakes.

But, the tongue weight is a problem. I can move some weight in the trailer but the general layout is fixed and things won't shift too much. The Z is a 50/50 F/R balance car so loading it backward has no effect. Loading it a little further rearward helps but I can only go so far.

I've come up with a couple of options. Move the two axles forward, or, add a third axle. Of these options adding a third axle is by far the easiest due to the under floor steel lockers that are already in place on the trailer.

So, what about a third axle? Think it'll help much with tongue weight? What about towing with a third axle? Some people have told me the trailer will be extremely hard to turn and park compared to a dual axle trailer. Is it really that hard?

Third axle pros: larger safety margin for an overloaded trailer, remove some tongue weight, more redundancy

Third axle cons: I bet fuel mileage will suffer, handling?

Anyone have experience with triple axle trailers they'd like to share?

Boundary conditions - must work with trailer as it is now. We're not cutting tire racks off, moving the box back two feet, lengthening the rear of the trailer, putting on goose necks, and so on.

BTW, the trailer looks like this:

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Ron Earp

Admin
Get a shell for the back of the pickup and load more stuff in there?

Nah.

Boundary conditions - must work with trailer as it is now. We're not cutting tire racks off, moving the box back two feet, lengthening the rear of the trailer, and so on.

The thing tows great as is, absolutely fabulous. All that tongue weight does that I suppose. And at the track it is great to work with for car support. Everything is exactly where you need it, at your finger tips. Really makes the track easy and the trailer gets multiple visitors and picture takers per event, people realize it works well. But I'm concerned that the receiver/hitch will fail and bad things will happen.

How much harder is a three axle trailer to handle than a two axle? If it is like the difference between a one axle and two axle, well then puh, that makes little difference. Fuel mileage, how much less? 3%? No big deal. 25%? That would stink.
 

Dimi Terleckyj

Lifetime Supporter
Hi Ron

Looking at the photo of the trailer, yes there is far too much weight forward of the wheels.

The best solution all round would be to stay with two axles not three and relocate them forward till you achieve the right hitch loading.

If too much weight is rearwards of the axles then this makes the trailer unstable with a tendancy to fishtail.

Weight forward stabilises the trailer but too much weight will cause structural failure of either the trailer or the tow vehicle.

The fix is never easy.

Dimi
 

Pete

Lifetime Supporter
how about moving the forward axle to the front and make it turning axle. Move the aft axle back.

Pete
 

Ron Earp

Admin
how about moving the forward axle to the front and make it turning axle. Move the aft axle back.

Pete

Guy at work suggested that but there is a lot to making a steering axle system that is beyond what I'm willing to do.

The best solution all round would be to stay with two axles not three and relocate them forward till you achieve the right hitch loading.

And it very well might be. But are three axles a "bad thing"? Lots of trailers in town have them, they aren't uncommon.
 

Trevor Booth

Lifetime Supporter
Supporter
Ron,
move the axles forward, 3 axle trailer will not necessarily increase fuel usage, 3 axles will however increase tyre wear. A trailer with a rearward weight bias will be unstable as Dimi has pointed out. What actually happens is that the rear wheels of the towing vehicle move laterally ( causing the sway effect) due to insufficient weight on the rear wheels of the towing vehicle.

You also need to be aware that in getting the balance of the trailer correct you may still have insufficent weight on the back wheels of the towing vehicle, especially so if the towing vehicle has no load in the rear.

What is also critical is that the suspension system on the trailer is load sharing. Independantly sprung axles will "see" diffferent loading which may well affect overall handling and varying tongue weights.
 

Julian

Lifetime Supporter
Firstly bear in mind that the recommended tongue weight should be no more than 15% of gross weight (and ideally around 12%), so assuming you have the typical car trailer with 2 x 5,200lb axles and even if its fully laden you are over that and the weight distribution on the trailer is too far forward, no matter what your hitch rating. I'd recommend you get a gross weight on the trailer and work on distribution from the above angle of % tongue weight.

There's being prepared, but how many tools are in that box? The T70 shouldn't be much over 2,000lbs and weight is over the axles, so what is all the weight?

I would not see a third axle as a solution on the trailer pictured, shifting the axles further forward would probably be the way to go IMHO.

Interesting your truck stance doesn't seem to be complaining too much.
 

Ron Earp

Admin
Interesting your truck stance doesn't seem to be complaining too much.

That is just the thing - the truck is fine with it with the leveling bars and air bags. Otherwise it flattens the truck. Flattened Jeff's 2500 Dodge Ram too. I only became concerned about it once we knew what the tongue weight was and paid attention to the max specs. Otherwise, everything is hunky dory.

Gross weight is high, around 7200 lbs but there is a lot of stuff on the trailer in that configuration - 2300 lb 260Z, 12 wheels/tires, 30 gals of gas in the fueling rig, that box is steel and has the air compressor, tool box, sleeping bunk, AC, two marine batteries, 1500 W inverter. The under deck steel storage lockers are 7ft x 2 ft x 1 ft and there are three of them, chock full of spares - drums, alternators, brake calipers, drive shaft, clutches, etc. two spare trailer tires on the rig, three fire extinguishers, spare car battery. Cooler and grill mounted on one side of the trailer. Stereo in the box, TV in the box, etc. It adds up.

Hell, I might just have my welding trailer man reinforce the hitch receiver and the trailer tongue and call it a day. Thus far the thing works great.
 

Julian

Lifetime Supporter
That is just the thing - the truck is fine with it with the leveling bars and air bags. Otherwise it flattens the truck.

I missed the reference to load leveling bars i.e. weight distribution by shifting some of the weight to the front axle. Have you weighed the truck with and without the trailer, preferably by axle to see what the weights are?
 

Dimi Terleckyj

Lifetime Supporter
Ron

The one thing that worries me is that you can go to all the trouble to reinforce the hitch and the towing tongue but that still does not address the main problem.

It also makes the trailer able to be towed only by a vehicle modified to do so.

Should wish to change tow vehicles for any reason this will make it very difficult in the trailer's current form.

Would it not be better to bite the bullet and fix the trailer and the cause rather than work on all the symptoms??????.

Dimi
 
Ron, is there room at the front of the truck bed for any of the accessories,possibly even moving the tires to a removable rack just in back of the cab?
 

Ron Earp

Admin
Would it not be better to bite the bullet and fix the trailer and the cause rather than work on all the symptoms??????.
Dimi

Yep, it would. If it even needs fixing. The trailer has been used all of last year with no problems at all. It is just when one of our buddies started thinking about it that we've discovered all these problems.
 

Kirby Schrader

They're mostly silver
Lifetime Supporter
Ron,

I pull a 24' enclosed trailer with my Lightning. I've hauled my GT40 to Road America and brought my Pantera back from Colorado with it. No drama except heavy cross winds get a little exciting...

I move the car until I get a 'good' tongue weight. What's good?
I don't use airbags, but I do use a load leveller. I can tell if the truck sits too low that I've got too much forward.
As Dimi said... if it is too little, it is NOT nice and bad things start happening.

I may be wrong, but there appears to be some room behind your car... can you not move the car further back and move more weight over the axles of the trailer?

Dunno for sure... can't really tell from the pic. You may not have that flexibility.

FWIW,
Kirby
 

Kirby Schrader

They're mostly silver
Lifetime Supporter
PS: Crummy picture, but you get the idea of my truck and trailer.
That's Mike Trusty driving his GT40 for the very first time at Jack's house back in July!
 

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Ron, perhaps add some more structure to your tire rack extending back to the rear of the trailer...and then shift weight back to the rear. In other words, a rack that goes all the way to the back of the trailer...you can strap stuff down to it (tires) shifting the weight rearwards. Side benefit of it is that you can lay a full length tarp over it when you're at the track and essentially have a covered and dry area to work on the car if necessary (or just keep the car and you dry).
 

Malcolm

Supporter
When I made my race trailer many years ago it was designed around my GTD. I got the C of G of the car from the GTD factory and then drew the plans around that. In effect it meant shifting the trailer axle positions to a place that works. And it worked very well. Crazy but quite stable trailer towing speeds are acheivable, but not recommended as fun! So moving the axles is worthwhile long term even if a pain to do now. I played around with moving the axles on my boat trailer, I ran a thread on that a while back maybe in November 2008 or around then. Again that was based on nose weight issues like you have here except the weights were a lot lower than you would accept! But my experimenting also showed that if you lower the tow hitch on the tow vehilce by a couple of inches it will reduce the tongue weight. Whether that would be enough for you I do not know. It helped me!

We are getting to see triple axle trailers here quite regularly now. We have them as our UK trailers are smaller than yours especially on the width so to get a good width, we use beaver tail traielrs with the wheels under the trailer bed. The wheels used are smaller diameter to keep height down but the handling concept should be a similar issue to the one you are thinking of. I haven't heard of bad handling characteristics whilst towing. But if man handling the trailer then yes I would guess it would be harder to turn, but no harder to push back or forth. Going back to my home made trailer, I got round the man handling issue by using the jockey wheel in such a way that when wound down, it lifts the front axle clean off the ground so that it means I now have a 3 wheeler to turn. Very easy. But if I remember correctly you guys don't use jockey wheels but a flat footed post up front. But also with the net weight of your trailer are you ever going to try and turn it by hand anyway? I use my garden tractor to pull my trailers about for storage and retrieval.

A third axle will do what you need it to and I think that when towing on the highways, with such a competent tow vehicle you will not notice any issues in turning. You will drag tyres around corners but for the amount you use the trailer and tyre wear, that should be an acceptable price to pay. So long as you don't leave tyre marks on the driveway at home.....
 
Ron,
Could you possibly make a storage box under the back of the trailer for heavy items that you are currently storing in the white box. My kids do that with all of their trailers that they haul.
I use your system as I have a very heavy speck tow unit and have been known to have over 2000 lbs of toung weight. That system keeps others from borrowing my trailers.
Also, did you weigh the trailer at the hitch or at the jack? that will make a big differance as to the actual weight on the truck.
Just my 2 cents
Mark
 

Ron Earp

Admin
Ron,
Could you possibly make a storage box under the back of the trailer for heavy items that you are currently storing in the white box. My kids do that with all of their trailers that they haul.

Already done, four of them, you can seem them peeking out under the trailer and the open tops to them. Weight at the hitch.

There isn't much room for moving the car. We did that the other day to the max aft limit and it helped by 150lbs or so, but not nearly enough. The Z is 50/50 so loading backwards is not any help.

http://www.gt40s.com/forum/race-track/28446-new-race-rig.html

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