Ok, so how if at all do you any of you calculate the spring rates needed for your rigs. I have found that manufacturers, simply take the GVW of the axle the springs are to go on, and double it. Then they set ride hight. This leads to a spring that can handle sever loads, and sever bashing on the trail wit hthis load, but does not compress under the weight of the vehicle it self.

Case in Point, when I first bought Our EBronco, we slapped a Sky Jacker 5" springs, just to get it up for the time being. But this did not last long. we figured the front coils were around 300lbs per inch. :eek: :eek: :eek: . It beat he fawk out of you. so we were going to have custom springs made, and we figured a spring rate of 113lbs would give us what we wanted. But another option came about and we went another way. We are now running fox shock 2.0's with about 520lbs of Nitro. this gives us a spring rate of 75lbs at ride height. And with every inch it compreses; it gains another 35lbs or so. It rides like a champ now, but is mcuh lower than our original numbers.

Anyway, Just wondering what if any ratios or equations have been formed to get the right spring rates on Rock crawlers etc. I have my own, but I would love to see what you guys think. I find most people that buy coil overs, just get a basic set of springs, and leave it at that.

Anyway. I'll shut up now.

as long as your ackerman angle is ok you should be good to go! :rolleyes:

I am not asking if my rates work, I know mine do. I am just curious what others do. I know the aftermarket screws it up bad.

Man that's the highest psi I have ever heard of anyone using. So your setting the psi at 520 with the shock fully extended right. I have never used more than 200 psi in a nitro charged shock. Do the seals have more stiction at that high a psi. Seems like my shocks have a bit more when at 200 than at 140 so I can only imagine what it would be like at 520 not to mention when its fully compressed!

Jason :)

about a year ago I built a very simple spring rate gauge for setting up one of my Toyotas. I have a different combination of springs in each of my trucks, and I have one clear favorite. I wanted to see how my springs compared to stock 1985 sr5 springs. I found the following.

(keep in mind this is very approximate data)
Stock 1985 Toyota SR5.........................280lb/in
Rancho 44050 (jeep yj 2.5").................175lb/in
old Rancho 4" for toyota.......................300lb/in
used stock '70s waggoneer front..........200lb/in


So the best set of springs overall seem to be the waggys... because they have more leaves, and hold up better.

Second place goes to the 44050 ranchos... they are the best out of the box, and give the best lift... but they bend very easy because they use 3 thick leaves and are very soft.

I am a motocross racer, so from that perspective, we have a long way to go in wheelin' before we get to the level of technology that motocross suspension has achieved... but I think some things can be applied...

On a motocross bike, you want about 25% of your suspension travel to be "sag". on my toyota it's more like 33% of my travel that is used up as sag.

the reason for this is that my motocross bike must be stiffer to deal with high speeds and jump landings... while my truck must be softer to allow the wheel travel that I want.

A good way to compair springs on different trucks is by the natural frequency (in cycles per min)

CPM = Squareroot(wheel rate/sprung weight)

So what CPM are you running?

60-80 CPM = comfortable road car
80-100 CPM = firmer
100-125 = race car
all the way up to
500 CPM for a ground effect F1 car.

I take the loaded weight of the axle, deduct the weight of the axle tires and wheels, divide by 2 and divide that by 3. This has worked so far on the 5 or 6 trucks that we have applied it to. It has provided a nice ride and very good control with out coilovers

well, fox shcok 2.0's are a little bit different than most. and we dont run spring teh only hting holding up the truck is the front Shock. It is a baja type setup, minus a helper spring. Here is a pic. remember, the only thing holding up the front is air.

Originally posted by Brutpwr
Man that's the highest psi I have ever heard of anyone using. So your setting the psi at 520 with the shock fully extended right. I have never used more than 200 psi in a nitro charged shock. Do the seals have more stiction at that high a psi. Seems like my shocks have a bit more when at 200 than at 140 so I can only imagine what it would be like at 520 not to mention when its fully compressed!

Jason :)

here is a shot fronm the inside These were taken before the cross brace.

and just for fun an RTI shot. This is with basic 5" sky springs in the back. And stock Ford radius arms. Noting was done except the shock/airspring

Originally posted by YELLER BLAZER
I take the loaded weight of the axle, deduct the weight of the axle tires and wheels, divide by 2 and divide that by 3. This has worked so far on the 5 or 6 trucks that we have applied it to. It has provided a nice ride and very good control with out coilovers

This is actually pretty close to the way I do it, only I used PI in my formula for some silly reason. It's been a LONG time since I played with charged suspensions (motorcycle racing) so I would say I don't know jack about the nitro shiat.

However, KC, I had Way in my rig on the highway and a trail run, and he was quite shocked. I have it set up via the formula above. I think the most overlooked part of coil set up is the rebound dampenning. It seems that most people forget that when rebounding, a spring exerts the same PSI. This needs to be "damped" to prevent premature unloading. I know you are quite familiar with rover weight distribution, and I run progessive 260-300 front, with 300-340 rear. This gives me around 12-20% sag depending on load.
j