If you get either the Moog or TRW catalog, you will find all the important specs on coils that fit in all '66-'79 Broncos. They list inside diameter, wire diameter, installed height, load rating, spring rate in lb./in., and free height. With simple math you can figure out what spring you need to get the ride hieght your looking for. I've used these coils in the front and rear of cars and trucks. I've yet to see any change in the ride hieght of any of these vehicles so the "sagging" story is hard to believe.
Spring sag is a perfectly normal occurrence. It can happen no matter what brand. Lots of variables at work, but sag is just another simple fact of life. Glad you've never had it, but it's hard to believe you've never heard of it.
I've used Cargo Coils too, and for a short time we even sold them at WH.
All springs of any type are susceptible to sag. Some will, some won't, but it's all due to whatever circumstances you care to mention. My first set of Moog CC's did sag. Not a ton, and not right away. I used them very happily for a few years. These were only about 1.75" of lift, so when I lost over 1/2" I needed to get it back up and so changed the coils. But I considered that performance very acceptable.
The application of the ones I used were early F100 with 6-cylinder (I forget the part number). Since I was not looking for a tall lift they were perfect. Tried those same springs in a '78 Bronco once, and they lowered the truck almost to the bumpstops.
Same rules apply for our springs as any other vendor. My WH Rock Crawler set is over 20 years old now, and has settled "maybe" less than a 1/2". But at 3.5" of lift I'm not as worried about that quarter to half inch as I was with the shorter springs. Other customers have had varied results to report in that same time. Some of ours have sagged out over the years. But many more have not. Again, your results may vary.
As I've said before, no matter who makes them, all springs are still as much art as science. Metals differ per batch even when they're not supposed to. Probably other variables as well. I'm just happy that the various manufacturers can make them as good and as consistent as they do and that ours work as well and last as long as they do.
Try to find the specifications of any of the vender's springs. All you get is 2 1/2", 3 1/2", etc. lift. What exactly does that mean? What is the starting point? What's the spring rate? How much will more or less weight change ride hieght? How can specifications be a classified secret? They're springs, not missile guidance systems.
Why are you trying to put a negative spin on what is perfectly normal behavior?
And if they're so perfect, why doesn't Moog list the exact lift height for each vehicle that their springs could possibly fit then? That way you wouldn't have to look up the specs and make your own decision based on what you "think" might work best for you.
We and some of the other Bronco vendors have posted up our specifications many times here on the forums, as have our customers when they've had a chance. One thread even had a full chart.
They're not a complete secret, but for very good reasons neither are they generally advertised. As a good business practice we like them to remain ours for as long as possible. Anytime a business (the key word here) comes up with something new on their own that took time and effort (equals money) that you think is going to work better for your customers than similar products on the market, it's just standard practice to keep it under the radar as much as possible.
When you're talking about "stock" replacements like you're discussing with the Cargo Coils however, there is no secret right up front. They're using data that's purposely made public for just that reason. So the aftermarket can re-supply the public with replacement parts that are either up to, or better than the original stuff that the O.E.s no longer want to have in their system.
It's a completely different concept.
Our stock height replacements have an initial rate of 200 lbs, and a secondary rate of 300 lbs
The 2.5" coils have an initial rate of 200 and a secondary rate of 375.
If you need to know how many coils, what wire diameter and coil diameter, along with free and installed height, I have that info too. It's not a secret, I just didn't want to type it all up and most could not care less. As long as it lifts their Bronco close to the height that they expect, and they get the street ride and off-road flex that we claim, that other info is just something else to stuff into the noggin' and then forget.
Enquiring minds like ours need to know that stuff to keep us happy of course, but in the grand scheme of things, it's not always pertinent to everyone. So even after all these years and public discussions, it's still not likely to clutter up our catalog any time soon.
But any time any of you would like to know, just ask.
Paul
