Tie-down strap rating?

Does anyone know if the article on tie downs is online? I can't find it anywhere...

Looking for some new tie downs for my Spec Miata. Thinking of through the wheel tie downs.

Thanks.

Never mind. I Googled for a bit and found Mac's. Gave them a call and explained my needs and they suggested this Pro Pack with Through the Wheel straps:

http://www.macscustomtiedowns.com/product/262/ProPacks

Great service so far.

PSA: Always check your straps again during every stop. I actually had some jerk loosen all my straps once. God smiled and I suffered no damage but it sure made the point to check them every time I'm away from the trailer.

David

Yep. My straps actually came loose yesterday. Got saved by a guy honking to let me know. no idea how i screwed it up but i did...

Hum. I think I'm glad I read this thread. I'm headed to Lincoln on Sunday for Nationals. A friend let me borrow a trailer. I don't have a lot of experience with this stuff, but I bought some "better than the cheapest" straps at Harbor Freight. But they're only rated for something like 800 lbs. I want to say. I figured four of them was 3200 lbs. Car only weighs 2300. But I didn't really know if that was enough or not.

I like the idea of suspension stops. I'm going to do that. And I guess I'm going to get more straps.

When I trailered my ZX2SR I used four 2"/1500 lb. straps. First I had blocks at the front to help in locating the car on the trailer. I used the factory tie downs. The fronts were almost level, and out ward at an angle. On the rear, again using the tie downs, I crossed the straps with practically no rearward angle. The fact that I still had the parking brake was a plus. Towed all over the NE and never had the car move. Just my 2 cents.

fast_eddie_72 wrote: Hum. I *think* I'm glad I read this thread. I'm headed to Lincoln on Sunday for Nationals. A friend let me borrow a trailer. I don't have a lot of experience with this stuff, but I bought some "better than the cheapest" straps at Harbor Freight. But they're only rated for something like 800 lbs. I want to say. I figured four of them was 3200 lbs. Car only weighs 2300. But I didn't really know if that was enough or not. I like the idea of suspension stops. I'm going to do that. And I guess I'm going to get more straps.

I don't remember much of my high school physics, but it seems the fallacy of using your car's weight to determine strap rating on a 1:1 is that it ignores the force in motion. A rolling, falling, pitching car will exert greater force than its weight. Like when you slam on the brakes and the car's mass slams against the straps....

In reply to Basil Exposition:

Yeah, I figured that out when I actually gave it some thought. Ran all over the west side of Denver this morning and got four straps from four different U Haul places rated at 6,000 each. I feel pretty good about that, I think. I have the HF straps still, so I'll find somewhere to put them too just to have some kind of insurance.

iceracer and mguar make me feel a little better about it.

Keith, glad you asked this and sorry for the threadjack. Y'all may have saved me a big headache.

In the C-130 we plan for 10G forward and 4G aft. Probably a little overkill for towing, but if you cut in half- 5G fwd and 2G aft, for a 2500lb car, you'll want 12500lb restraints (which is two larger 10,000lb ratcheting cargo straps) holding the back of the car (assuming it's facing forward), and 5000 lb at the front of the car, which is two of the same straps. Cinch down the back, cinch the front, cinch the back again, then verify the front is good. Should compress your suspension a bit.

Here's some 10klb tie downs for reference. Nice and cheap.

http://www.northerntool.com/shop/tools/product_200344936_200344936

Or you can get the 5000lb, which are probably more useful for everyday loads.

Mac's video page is actually very informative. Check it out: http://www.macscustomtiedowns.com/tricks

Direct links to some goodies: how much material to wrap around: http://www.youtube.com/watch?feature=player_embedded&v=brnRh8XzV_8

Failure testing video (this will scare you...) http://www.youtube.com/watch?v=M4mKOB33vmk&feature=plcp

The basics: http://www.youtube.com/watch?v=btRWr3OO-hs&feature=plcp

I feel so smart now.

I asked the question more than four years ago, actually

I'm still tying my Miatas down the same way. Two crossed straps on the rear to the control arms or the rear subframe (usually the latter), two crossed straps to the front control arms. Works well and the car cannot move. The straps are actually from Home Depot but have a significant working load, something like 3000 or 5000 lbs each. As I noted earlier, quite a bit more than the rating for the tiedowns themselves. Even after a 4000 mile tow, everything stays tight and happy.

Ive towed countless cars with 2" wide straps. One around each front control arm or convenient forward point and one around the rear diff/axle and back to the trailer. Set the E-brake. Put it in gear or park. No issues.

93gsxturbo wrote: Ive towed countless cars with 2" wide straps. One around each front control arm or convenient forward point and one around the rear diff/axle and back to the trailer. Set the E-brake. Put it in gear or park. No issues.

I always leave my cars out of gear when towing them, especially the racecar. I may be needlessly paranoid, but I don't like the idea of the movement of the car on the trailer being constantly fed into the drivetrain while being towed. The racecar sees more miles in the trailer than on the track, and the components seem to wear and fail enough without adding the trailer miles.

In reply to Basil Exposition:

I'm kind of hoping you are not strapping it in a way that it is rolling back and forth putting stresses on the drivetrain. Suspension movement should have no effect on the drivetrain.

I put it in gear for the opposite reason. I have no intention that the wheels will be turning (even slightly), so I am not worried about drivetrain wear. However, if for some unknown reason I am wrong and have a strap failure or some other catastrophic problem, I'd like all the assistance I can get in stopping the momentum. I put it in gear, chock wheels, and leave the e-brake engaged.

In reply to 93gsxturbo:

I'm OK with the 2" straps, but control arms are not tie-down points. They are not capable of holding back 2000 lbs of car, and it's really easy to over-torque the straps and bend them.

A single strap on the rear axle is not enough. It has no redundancy, so if the only strap you've got fails, you have a battering ram weighing more than a ton coming through the back of your tow vehicle the next time you brake.

SVreX wrote: In reply to Basil Exposition: I'm kind of hoping you are not strapping it in a way that it is rolling back and forth putting stresses on the drivetrain. Suspension movement should have no effect on the drivetrain. I put it in gear for the opposite reason. I have no intention that the wheels will be turning (even slightly), so I am not worried about drivetrain wear. However, if for some unknown reason I am wrong and have a strap failure or some other catastrophic problem, I'd like all the assistance I can get in stopping the momentum. I put it in gear, chock wheels, and leave the e-brake engaged.

No, I don't let the car roll back and forth. But however tightly you strap down the car it is still going move. That's a lot of mass with a lot of jiggly and soft bits letting it move around, however minutely, including the rubber in the tires and stretching of the straps. The vibration of the trailer and these minute movements of the mass of the car are going to be transmitted through your drivetrain if you leave it in gear.

I agree that a single strap in the back is not a good idea. Not only do you lack redundancy, you have little to keep the rear end of the car from moving sideways.

I keep mine out of gear as well. Parking brake on.

SVreX wrote: In reply to 93gsxturbo: I'm OK with the 2" straps, but control arms are not tie-down points. They are not capable of holding back 2000 lbs of car, and it's really easy to over-torque the straps and bend them.

Are the ratchet straps really delivering more force to the suspension than threshold braking with nice hot Hoosiers on the car?

I just don't go into hulk mode when tieing down!

When I haul trucks I do it the same way one moves heavy equipment. 4 chains and load binders, I will crank them down and load the suspension, or go around the rear axles depending on brake line routing. With some nice chain and load binders, its not going anywhere.

codrus wrote:

SVreX wrote: In reply to 93gsxturbo: I'm OK with the 2" straps, but control arms are not tie-down points. They are not capable of holding back 2000 lbs of car, and it's really easy to over-torque the straps and bend them.

Are the ratchet straps really delivering more force to the suspension than threshold braking with nice hot Hoosiers on the car?

Absolutely. (partially dependent on the design of the control arms, etc.).

Under normal braking, there is nothing pulling perpendicular on the center of a control arm. The weight of the vehicle's forward momentum is being distributed across 4 wheels each attached to the car by 3 or more different attachment points, and the biggest force they will ever be subjected to is linear and forward.

In the example above, the potential weight shifting could be in an awkward direction, on only 2 members that were not designed for lateral force.

But you have to consider the worst possible case.

In a towing accident, the deceleration is huge, and the momentum is unpredictable. If the trailer is rear ended, the force will be toward the rear (contrary to the design parameters for the control arms). If the trailer is T-boned, the force is really random- all bets are off.

I realize the control arms are sometimes the best option, but that is going to depend on the specifics. Big A-arm, maybe. I'll bet I could snatch a single control arm right out of my Europa with a chain and a good pull by hand.

Strapping the wheels is a more distributed method than the control arms, and is more similar to the forces they would be subjected to in braking.

As the driver, it's your job to do your best to prevent stray flying cars.

Honestly it's one of those things where it's better to be safe than sorry. I personally have always went with www.ratchetstraps.com that have a 10,000 pound breaking strength per strap just because I would rather be safe than sorry and I don't want someone getting hurt by it. As for quality goes the best straps I've used are from www.lodimetals.com I just think this is one of those things when you have a car that you love you can't really put a price on it. I absolutely love my 2016 Plum Crazy Hellcat Charger and would do anything to not have it falling off a trailer. We've all spent a good amount of time to have our dream cars and it's not worth a hundred dollars or so. 

The canoe that never sinks!

You have to think about weight shift.  When you accelerate, the straps attached to the front of the car are 100% under load, the ones at the rear are slack.  The weight of the car is now more than 2000 pounds (F=M*A).  So, if you use (2) 1000 pound straps up front, you have just exceeded their capacity.  Same goes for braking.  

Assume your car can exert twice it's weight in force in any reasonable direction (if your trailer is upside-down you have bigger issues) then exceed that capacity by a 25% margin in each direction.  

In reply to pinchvalve :

Thread is 9 years old. 

I stop caring about strap strength somewhere between 2 and 3".  Coincidentally, i believe it's just two 3" straps that have held down every car i've ever moved on my car dolley, and i've put thousands of miles on that thing and never had one even come close to coming off. I've had straps come loose for various reasons, but never fail. On a dolley they do have the benefit of pretty much ideal connection points, laying flat against a squishy tire, etc.