coil overs vs. air shocks

[LT.]

Well, it looks like I will be purchasing my own presents this year, again. So the question is what should I be looking at? Going with the air shocks would be cheaper and you still have all the adjustibility you could ever want. But the coil overs offer you adjustibility without the problems of leaking out the air and leaving you dead in the water. I am unsure of what to do. I like the air shocks because they are lighter, less parts, and a cleaner look. I like the coil overs becasue if all else fails and all the fluid leaks out you are still able to get off the trail. Air shocks are all the rage and are on all the compitition rigs. Coil are found on all the previous generation rigs. I just don't know which I should go with. They will be going on the beater.

LT.

 

[Tacoma]

I'd go w/coilovers on that pig.

I just don't trust the seals on air shocks, holdover from mt. biking I guess. Coils will at least hold you up on the way home.

 

[RockMonkey]

I've never used air shocks, but I had coilovers on my last rig, and on the rig I am currently building. I think they work better, especially on a trail rig that's not super light.

 

[I Lean]

Coilovers > airshox.

Airshox have the advantage of lower price, less weight, and easier setup. (because there's only so much you can do to adjust them)

Coilovers have the advantage of being much more tune-able, mostly because the spring function and the shock function are kept separate. Since there's so much more to work with, they can be more difficult to get set up--but will outperform an airshock every time when correct.

 

[Greg]

Weight may be a consideration, this is for the Ramcharger, correct? I know you've put it on a diet, but that's still a big vehicle. If you were really considering air shocks, you'll probably need 2.5" diameter shocks. Any idea how much that thing weighs, minus axles, tires & wheels?

 

[Bucking Bronco]

and once your at the cost of 2.5 you might as well go with coilovers

That being said I have never run coilovers but my buggy seems to preform great with air shocks

 

[notajeep]

Ditto. Love the SAWs, but have never ran coilovers.

 

[LT.]

Yeah, this is for the Ramcharger. I am not too sure what it may weigh right now. The problem is going to be that as I work on it and add things (like a roll cage) it is only going to get heavier. I think that the whole rig weighs in between 4000 and 4200 lbs. That may be a light estimate. It started out weighing in at 5000 lbs. I have removed the roof, windows, interior, heater, ducting, stereo, speakers, wireing, wipers, and motor, cut out the fenderwells, bumpers, sway bar, wheel wells, and some other things that I just can't remember at this hour. I have added one ton axles, 42's, and bead locked wheels.

I saw a fella run air shocks on a toyota pickup truck for the Top Truck Challenge a few years back from Canada. They seemed to work well for him. I am guessing that his rig weighed more than mine does now. That is one of the reasons I was looking at them. But for a trail rig I was concerned with the abilities of getting off the trail if I had a failure. That is what led me to think about the coil overs.

Is there something else y'all think that I should do instead of what I have suggested? Something that I may have overlooked? Please let me know.

LT.

 

[rondo]

I ran air shocks on the back of my jeep and when it blew out i was hosed. had to limp back to the trailhead at 1 mph and was a pita. i kinda thought i was saving $ but now i have a spare air shock, and you need your own nitro tank, etc well it's cheaper really to get coilovers.
and i think your ram is definitely too big for 2.0 air shocks.

 

[ChestonScout]

I say coilovers Rob.

With either setup you are probably going to desire a sway bar but its going to be worse with air.

I was considering air shocks for the back of the Scout for your same reasons but decided the Scout was to heavy back there. Im sure Im lighter than the Ramcharger especially when you get your cage.

Having said this. Check out the FOA coilovers. That is what Corey put on the front of the Durango and thats the brand of air bump that I bought. For the price, they are SWEET! The only difference between them and say a King is just a little bling. King polishes theres up nice where a FOA is a little dull. Still be the shiniest thing on your rig though. They are performing perfect for the Durango so far.

Seriously though. FOA is a newer company and their focus is to build a quality product and still keep prices low. They are what the Scout will be getting when its time. The only problem with them right now is they are busy. It will take a couple weeks to get the shocks after you order them. They have a ebay store that works the best. I got my bumps in 2 days. They are made in Vegas as well. You American you!

http://www.f-o-a.com/

What kind of suspension are you wanting in the rear? I think you told me once but I forget

 

[Seth]

I think that the whole rig weighs in between 4000 and 4200 lbs.

I going to guess that is real light. My CJ with a fiber tub and 40's weighs 4000 empty.

 

[Chevycrew]

my 1/2ton toyota on 38's is about 4500

 

[ChestonScout]

Another thing to consider is I know you are going to be doing some desert racing type wheeling.

Airshocks will get hot and lose their characteristics after awhile.

 

[LT.]

Right on, so coil overs it is. Y'all rock and I really think that y'all have the best ideas. I will be looking more into the FOA coil overs that ChestonScout has suggested. Now for spring rates. I was thinking somewhere between a 165 to 185 over a 200 (this is just for the rear). Any other thoughts? What about lower link materials. What would y'all suggest? Double sleeving the lower links or is there a better way? Double triangulated or do I just triangulate the upper links? Pros and cons to either? Or something else, trianglulated upper link, (i.e. three link), reverse triangulated, five link, what? I am almost set on either the triangulated uppers or a double triangulated. (I did a paper on a double triangulated suspension in college).

Thanks again,
LT.

 

[I Lean]

Right on, so coil overs it is. Y'all rock and I really think that y'all have the best ideas. I will be looking more into the FOA coil overs that ChestonScout has suggested. Now for spring rates. I was thinking somewhere between a 165 to 185 over a 200 (this is just for the rear). Any other thoughts? What about lower link materials. What would y'all suggest? Double sleeving the lower links or is there a better way? Double triangulated or do I just triangulate the upper links? Pros and cons to either? Or something else, trianglulated upper link, (i.e. three link), reverse triangulated, five link, what? I am almost set on either the triangulated uppers or a double triangulated. (I did a paper on a double triangulated suspension in college).

Thanks again,
LT.

Without knowing how much weight is actually on that rear axle, it's hard to guess spring rates--but just the same, those sound really low to me. A TJ Unlimited we just set up ended up with 250 over 300, both front and rear.

As far as the suspension goes--do a couple quick searches here, there has been quite a bit of discussion in the past that will be relevant.

 

[RockMonkey]

Your spring rate is going to be partially determined by where your ride height is in the travel of the shock too. So even if you knew exactly how much weight was on each shock, you still can't figure out the spring rates without knowing how much compression and extension travel you have.

 

[LT.]

Y'all have been great! Thanks for all the replies. I will search some suspension ideas here on this forum and see what I can come up with. I went to Poison Spyder Customs web site and they were saying that a fully loaded TJ would use 200 over 200 coils. The rear of my rig does not weigh that much so that is why I was thinking about the lighter coils. I guess that I really need to get the racer scales out and weigh that pig. Is there a guide as too how much a 14 bolt full floater with disk brakes should weigh? I copied this directly from the Poison Spyder Customs web page:
-Jeep Wrangler weighing near 4,800 lbs with a 60/40 weight distribution (this is going to be your average built jeep with 1 ton axles, 38" tires and additional weight from aftermarket components such as bumpers, winches cages, etc),
Front lower coil- 300 lb
Front upper coil- 200 lb
Rear lower coil- 200 lb
Rear upper coil- 200 lb


Thanks for all your help,
LT.

 

[LT.]

Your spring rate is going to be partially determined by where your ride height is in the travel of the shock too. So even if you knew exactly how much weight was on each shock, you still can't figure out the spring rates without knowing how much compression and extension travel you have.

Is there any guides to this? Travel vs. weight?

LT.

 

[Seth]

I have 2 250's and 2 170's that I took off. If the ratio works out I will sell them cheep.

 

[RockMonkey]

Is there any guides to this? Travel vs. weight?

LT.

Nothing that I've ever read. Here's how I do it:

Build all your links and set the axle at full compression. Make your shock mounts so that the shocks are at full compression (or maybe just a tiny bit of shaft showing) when the axle is at full compression. Install the shocks, and put any spring of a known spring rate on. You can do this with just one spring, with the adjuster spun way down. Put the weight of the vehicle on the shock. Measure the spring before you put weight on it (generally 14" if you're using a 14" shock), and after you put weight on it. This will allow you to calculate how much weight you are putting on each shock.

For example, if you put a 14" 300 pound spring on, and it measures 11" long after the weight is on it, you know there is 900 pounds of weight on that spring.

Now, measure the shaft of the shock at full extension. 14" shocks usually have about 14.5" of shaft showing at full extension, but measure yours to be sure. Now set your axle at whatever you want ride height to be, and measure how much shaft is showing. Lets say you measure 6.5" of shaft at ride height. That means you compressed the shock 8" (14.5 - 6.5 = 8)

So, if you have 900 pounds of weight to work with, and you want it to compress the springs 8" to give you the correct ride height, that means you need 112.5 pounds per inch total spring rate. 900/8=112.5

This formula gives you your total combined spring rate:

(S1*S2)/(S1+S2)=Rate
S1 is your top spring and S2 is your bottom spring.
You can also use this calculator
http://www.swayaway.com/calculators/swayawayCalc.php#step7

BUT you already have that 300 pound spring you used to test with, so ideally you'd like to use that for your bottom spring. I changed the formula a bit to figure your second spring rate if you already know your total spring rate (112.5 in this case) and your first spring rate (300 in this case). Here is that formula:
S2=(S1*rate)/(rate-S1)

Plugging in our hypothetical numbers...
S2 = (300*112.5)/(112.5-300)
S2 = 33750/187.5
S2 = -180
Take the absolute value of that, so to get our desired spring rate of 112.5, using the 300 pound spring we already have, requires us to buy a 180 pound per inch spring. I like to get a spring that is just a little softer than "perfect" so I have to put a little bit of compression on the springs to achieve my desired ride height. This keeps the springs in compression even with the shock at full extension, so the springs stay seated, and I don't need a tender. So in this example I would look for a spring that is 175 pounds per inch or so.

Here are all of the 14" long 2.5" ID (you'll need 3" ID if you go with a 2.5" FOA shock) coilover springs Summit Racing has:
http://store.summitracing.com/egnsearch.asp?N=700+4294925130+4294846689+4294787535+115+4294791373

...and here's the 175 pound spring we are looking for.
http://store.summitracing.com/partd...846689+4294787535+4294791373+115&autoview=sku

Done!