Need Help With Spring Selection

[John Galbreath Jr.]

I am re-springing the Single Seater. It rides horrible on the Perimeter Roads and even worse when I tried the Jump Track at Morris Mountain. Here are the facts:

Weight without driver: 3783.

Left front: 1,081
Right front: 1,063

Left rear: 806
Right rear: 833

The spring that have been on it since I got it are:

150/125 front and 125/125 rear.

Springs I have in my posession:

300 - 2
250 - 2
200 - 2
175 - 2
150 - 2
125 - 6

Unspring weight, front and rear are close to the same as same axels, same steering.

Dana 60 - 525 (Off Pirate 4x4)
39" Krawler on my beadlock, moderate mud on lugs weighs 131 x 2 = 262
Truss and steering estimate: 80

That is 867 per axel or 433.5 per corner. I'll use 435 for this.

Front left
1,081 - 435 = 646 sprung weight
646 - 300 - 250 = 96 short

Right front
1,063 - 435 = 628 sprung weight
628 - 300 - 250 = 78 short

Left rear
806 - 435 = 371 sprung weight
371 - 200 - 175 = 4 over

Right rear
833 - 435 = 398 sprung weight
398 - 200 - 175 = 23 over

Am I doing this right? What do y'all think before I start taking the coilovers off.

 

[John Galbreath Jr.]

I just went back and re-weighed it with me sitting in it.

Strange results I think. I weigh 175.

Left front - 1,127 - 1,081 = 46
Right front - 1,098 - 1,069 = 29

Left rear - 850 - 814 = 36
Right rear - 903 - 840 = 63

 

[BamaTJ]

John,

Corner weights are a good start, but you really need the exact sprung weights instead of estimates. Your current setup is way too soft, so expect to go up in spring rate. Here is how you get exact sprung weight:

Let each end go to full droop so there is no tension on the springs and you can move them freely. Take the measurement of each spring with no tension on them. Right them down and then set it back down on the tires and give the cage a good shake to settle it all out. No measure each spring again and right down those lengths. Then do the math, I will use your front springs and some made up numbers to show you.

150lb Spring - 14" uncompressed and 11" compressed = 14.0-11.0=3.0x150 (Spring rate). Total is 450
125 Spring - 14" uncomprssed and 10.5" compressed = 14.0-10.5=3.5x125 Total is 437.5
Add the two together and divide by 2 for your sprung weight for that corner. Good idea to do it seperately for each corner as they are all a bit different.
437.5+450=887.5/2 = 443.75 So this is your total sprung weight.

Hope that makes sense. Your corner weights are close to mine, so I bet your sprung numbers are close also. A 100/300 or so is more in line for the front, but post up your numbers and I will work it out for ya.

 

[rock mafia]

I don't know any fancy formulars fo figurin sprangs, but wuch you gots is to soft.

Try 150/250 in front, 125/200 in the back. Set the dual rate stops a few inches above the bottom spring when it's sitting level at ride height.

 

[John Galbreath Jr.]

I don't know any fancy formulars fo figurin sprangs, but wuch you gots is to soft.

Try 150/250 in front, 125/200 in the back. Set the dual rate stops a few inches above the bottom spring when it's sitting level at ride height.

I have no stops on my coilovers, they were taken off before I got them.

 

[John Galbreath Jr.]

Reply per Matts formula. I removed the front bump stops, as it sits on them at ride height, which would change the spring rates. I then took off the limit straps and took the front coilovers off the mounts to let them extend. Took the unsprung measurements. Rear, just had to take off the limit strap and could pick it up enough on the lift to take all pressure off the tender coils. Here are the results.

Now I have double the numbers, and double the confusion :****:

Left Front
T - 14 - 10.0625 = 3.9375 x 125 = 492.19
B - 13.9375 - 11.1875 = 2.75 x 150 = 412.5

492.19 + 412.5 = 904.69 / 2 = 452.345


Right Front
T - 13.75 - 9.5 = 4.25 x 125 = 531.25
B - 13.9375 - 10.75 = 3.1875 x 150 = 478.125

531.25 + 478.125 = 1,009.375 / 2 = 504.6875


Left rear
T - 13.875 - 12.625 = 1.25 x 125 = 156.25
B - 13.75 - 12.5 = 1.25 x 125 = 156.25
156.25 + 156.25 = 312.5 / 2 = 156.25


Right rear
T - 13.625 - 11.5625 = 2.0625 x 125 = 257.81
B - 13.875 - 12.25 = 1.625 x 125 = 203.125
257.81 + 203.125 = 460.935 / 2 = 230.4675

 

[BamaTJ]

John that is crazy how much heavier the right is than left. If you truely wanted a fine-tuned setup you would need to spring each corner different since they are pretty far off weight wise. That said, that is a lot of work and money for minimal benefit. My setup is based on what you have on hand, not necessarily what is best overall. If you find you wanna make some more changes then you can buy the springs you need. This is what I would do.

Front
125 or 150 on Top
300 on Bottom

Rear
125 Top
Either 150, 175 or 200 Bottom (Maybe try 175 first and take it for a spin and decide if you need to go lighter or heavier)

I would also look at ordering spring stops for your coilovers, that will allow you to take advantage of the dual rates. Call Jimmy/Joe at EOR, he is a full service Bilstein dealer and can get parts. Also make sure you have the proper N2 Charge in your shocks. I would run 200psi front and 150 psi rear.

 

[jeep46]

not to impose, but the fact that the front sits on the bump stops at ride height, wouldnt that make the rigs rige rough

 

[BamaTJ]

not to impose, but the fact that the front sits on the bump stops at ride height, wouldnt that make the rigs rige rough

Yeah, not much to do about that except raise the ride height up. Mine has an inch before it hits the bumps and it rides ok

 

[draggbody]

get the bumps out of the equation... you might also try lowering the pressure in the bumps as well... you also need the secondary stops to get it right...


http://f-o-a.com/calculator.html

matt i think a 300lb sprin is high... i run 175/250 in the front and 100/200 rear.... 4600lbs total 2860 front and 1740 rear

 

[BamaTJ]

It is all in how you set it up. I have played with it a lot on both of my rigs and have found that is is good for crawling and cruising around here to have a heavy primary and soft secondary. For KOH type stuff, it is better to have both springs in a middle area and not have a ton of seperation in the rates.

 

[Toddy]

With out the stop the lower rate spring will do all the work. Get the stops first then start playing.The stop will let the lower spring work.

Toddy

 

[jtreeves1]

are coilovers don't have stops on them even the new ones

 

[BamaTJ]

Lots of coilovers don't come with the hardware kit, you have to buy it extra. Usually includes stops, spring slider, retainers, etc. All the stuff you need to put coils on. If you don't have stops then you are only using your man spring, so no benefits of dual rates are being achieved. For the Bilstein's it is about $50 extra, but if you have all the other stuff then just order the threaded spring stops on their own to save money

 

[John Galbreath Jr.]

Update, when I took it apart, the spring rates were different than I remembered.

F 125/175
R 125/150

So, I decided to update the numbers using Matts formula.

Left Front
T - 14 - 10.0625 = 3.9375 x 125 = 492.19
B - 13.9375 - 11.1875 = 2.75 x 175 = 481.25

492.19 + 481.25 = 973.44 / 2 = 486.72


Right Front
T - 13.75 - 9.5 = 4.25 x 125 = 531.25
B - 13.9375 - 10.75 = 3.1875 x 175 = 557.8125

531.25 + 557.8125 = 1,089.0625 / 2 = 544.531


Left rear
T - 13.875 - 12.625 = 1.25 x 125 = 156.25
B - 13.75 - 12.5 = 1.25 x 150 = 187.5
156.25 + 187.5 = 343.72 / 2 = 171.86


Right rear
T - 13.625 - 11.5625 = 2.0625 x 125 = 257.81
B - 13.875 - 12.25 = 1.625 x 150 = 243.75
257.81 + 243.75 = 501.56 / 2 = 250.78

That is a total sprung weight of 1769. Still cannot believe the numbers, I see no way the single seater can be that far off left to right.

So after all this. Rock Mafia seemed to have the most logic, no math.

I don't know any fancy formulars fo figurin sprangs, but wuch you gots is to soft.

Try 150/250 in front, 125/200 in the back. Set the dual rate stops a few inches above the bottom spring when it's sitting level at ride height.

So I bumped it up a little cause DragBody did and went 175/250[tarzan nut swinging yell].

Rear I went with Rock Mafia at 125/200.

I rolled the O rings down on the bump stops and when I got back. Left front had 1" left and right had 1/2", so the front did not bottom out.

Rear did bottom out a little in a couple of washes, so I went up to 150/200.

I have not ridden with new rear. I think I am closer now.

As to the stops, I am going to stay without them for now. Easier for me to change up as I don't have a nitrogen setup.

So now:

F - 175/250
R - 150/200

 

[BamaTJ]

I think your left rear was a typo, doesn't compute and cannot be that heavy.

Without stops you will always be running on the total combined spring rate and will never get the benefits of dual rate. So if you have a 150/200, your rate will always be 175. It is worth it to add the stops so you can get one of the major benefits out of your shocks.

 

[John Galbreath Jr.]

I think your left rear was a typo, doesn't compute and cannot be that heavy.

Without stops you will always be running on the total combined spring rate and will never get the benefits of dual rate. So if you have a 150/200, your rate will always be 175. It is worth it to add the stops so you can get one of the major benefits out of your shocks.

Fixed.

 

[Toddy]

And you can fine tune you rates with the lower stops. And you can change springs just as easy wih the stops and without them.

Toddy

 

[John Galbreath Jr.]

And you can change springs just as easy wih the stops and without them.

Toddy

How, won't the springs have to come off the top (remove shrader valve) with the stops on. The plasitc keepers will n ot go over the stops, will they? Guess I need to look at some at XRRA this weekend.

 

[BamaTJ]

How, won't the springs have to come off the top (remove shrader valve) with the stops on. The plasitc keepers will n ot go over the stops, will they? Guess I need to look at some at XRRA this weekend.

You put the stops above the plastic spring sliders so it will not effect anything except your ride They are just two threaded collars, nothing to them.

Bilstein also makes a jounce shaft bump for their shocks now. If you don't have air bumps on the back you can install these bumpers on the shaft and it will keep the shock from bottoming out and make it ride much better. I have a nitrogen setup you can use also, you really need to go through them and check pressures. Since you have some older shocks you may want to take them off and send them to bilstein for servicing next time you have a few weeks without rides.

You can see the spring stops in this pic.

And here is the shaft bump