coilover spring rate question

[68ford]

So I had my eb sitting at perfect ride height, but then I charge all 4 4 front shocks and it raised 1.5 inches and I can't lower it because the coil adjuster is up as high as it will go.
I'm running 250 over 30 coils now.
Anyone have experience in changing springs in 50 pound increments and remember how much height change it made?
Not sure if I should go down to 250 over 250 or down even more to 200 over 250 or maybe Just go shorter top spring length?

 

[treihesse]

There are a ton of factors.
How long is the shock? How much up and down travel do you want?

The adjusters need at least 1inch of preload on them.

200x250÷450 will give you spring rate
Lets say you want 5" up travel on a 12" shock and you have 900lb corner weight.
900÷7= your needed rate to hold up the track at that height.

 

[treihesse]

I run around 250 under 200 rate

 

[Mountain Ram]

I think I have 175/200 in the front and 150/200 in the rear on my crawler, but I am running 16" shocks and have no driving experience in it yet.

 

[treihesse]

Yeah broncos dont weigh as much as people think. Unprung weight vs sprung weight is a big diffrence

 

[Yeller]

its really hard to guess what springs are really needed without weighing both the sprung and unsprung weight at the axle. Most race car chassis shops can do this service for you for a minimal charge, way cheaper then paying freight 20x shipping springs back and forth. I buy all of my springs (and shocks too) from Goatbuilt.com Drew has over 10 years of engineering back ground in coilover technology and really knows his stuff.

Get it weighed and you'll be much happier with the end result and no more guessing.

 

[68ford]

I just need it to be 1.5 in lower. Adjusters are all the way up. It is like preload because I do not use all the 14in shock because it's on the back side of the axle and the 14in bypass is on the front. Thinking dropping to 200 over 250, don't thing going down to 250 over 250 from 250 over 300 Will lower it 1.5 inches. Both springs now are 14 inch long.

 

[Yeller]

14" shock should have a 16" and 12" spring so the follower and/or the spring can't get caught under the end of the shock body.

get the rig finished, load it like you expect it to run and get it weighed, it saves sooooo much grief and aggravation. Not getting it weighed is like buying your wife a wedding dress on your own and not only expecting it to fit perfect and her to like it.

 

[ntsqd]

Build one of these and you can weigh it yourself with a beam torque wrench. Make the ratio of the lever lengths (to the pivot pin in the wrench's handle) 10 to 1 and it gets both easy to lift and easy to know what the weight on each corner is. 90 ft-lbs @ 10:1 means 900 lbs corner weight. If you need more resolution change the beam length ratio to less than 10:1

Weighing process requires a helper. Set it up with the beam just slightly above level and lift the tire. Place a sheet of paper under the tire & set it back down. Have helper gently pull on the paper while you slowly lift the tire. When the paper slips free take your reading on the wrench.

 

[68ford]

14" shock should have a 16" and 12" spring so the follower and/or the spring can't get caught under the end of the shock body.

get the rig finished, load it like you expect it to run and get it weighed, it saves sooooo much grief and aggravation. Not getting it weighed is like buying your wife a wedding dress on your own and not only expecting it to fit perfect and her to like it.

Just got home and looked, bottom is 16 long but the top is 14 long.
King said they would trade my springs since they are new.

 

[treihesse]

Thats hiw they should be. 2 inches longer for your bottom. I would drop your rate and you need pre load regardless of how much travel your using..

 

[Mountain Ram]

Total height of both springs should average to the travel length of the shock. In others words, the top should be 2" shorter (12") and the bottom should be 2" longer (16"). But I don't think this will fix your problem- your springs are still too HGH of a rate.

 

[Vcyota92]

It's really easy to figure out. At your ride height measure how long both springs are. For example You have 250/300lb springs. The combined spring rate of those is 136lb. So say between the two springs it is compressed 5 inches, you take 5x136= 680lb. That is a corner weight you can now use. So if you want the springs compressed a inch lower you would do 6/680=113lb. Then just play with a spring calculator to see what rate will get you to or close to that number