[CJ Lagos]

Not sure where to pick this up but my post seems like a good place to start :flipoff2:

Can anyone comment on my spring setup for a 14" swayaway?

Corner Weight is 886lbs. Currently running 250/300. Notes: Suspension is too soft and bottoms out if I don't use the stop rings(136# primary), but if I set the stops a few inches above ride height the spring rate jumps from 136 to 300 and is very jarring, I need something in the middle. Currently the ride height is set 8" into the shock and I want to try 9" or 10".(Goat what are your front shocks setup for at ride height?)

First attempt at a starting spring selection:

Primary: 250#/16"
Secondary: 350#/10"
Keeper Spring: 3.5" free length
Primary Rate: 146#

Travel/Rate/Force:
0/0/0
1/0/0
2/0/0
3/0/0
4/146/73
5/146/219
6/146/365
7/146/510
8/146/656-secondary on stops at 8.5"(10/2 +3.5 for tender)
9/250/854
10/250/1104 (~ride height)
11/250/1354
12/250/1604
13/250/1854
14/250/2104

Thoughts:
-Will the 250# spring rate be enough for only 4" compression from ride height and allow a decent ride? Too stiff? Maybe a good excuse to get the air bumpstops?
-This combo gives me a ride height of ~25.5" which is what I want.
-If I find 4" isn't enough I can always lower the ride height adjuster 1-2" to fine tune. (But then ride height might be too close to transistion point?)
-The 16" main coil looks like it comes close but won't bind.
-The springs won't be loose at full droop.

Ideas/Comments? (Please double check force calcs, I think it may be wrong after the secondary coil hits the stops @ 8.5")

Thanks,
CJ

 

[TONY K]

Is the rig stable around corners (sidehills) now ?

Could it be better ?

How far apart are the shock mounts on the frame side and axle side ?

What front axle are you using and where are the shock mounts located on the housing ?


With the vehicle sitting on flat ground, what are the compressed messurements of the top and bottom coils ?



All of this is important if you plan to change coil rates.

tony k

 

[CJ Lagos]

Is the rig stable around corners (sidehills) now ?

Could it be better ?

It seems stable except going downhill off-camber which i account now to the low primary rates

How far apart are the shock mounts on the frame side and axle side ?
What front axle are you using and where are the shock mounts located on the housing ?

2.5ton rockwells. Shock mounts on axle are about 6" in from wheel mounting flange. They lean in at the top, about 5*. When I built my suspensions I payed very close attention to clearances. I put the axle as far up into the frame as I could fit it(made changes to a couple things to accomdate this). Then I built the shocks mounts the same distance apart as the compressed length of the shock. This way I am positive there are no clearance issues anywhere throughout travel and The rig is as low as it possibly can go.

With the vehicle sitting on flat ground, what are the compressed messurements of the top and bottom coils ?

886/250=3.544. 14-3.5=10.5
886/300=2.95 14-3=11

I made a cool spreadsheet to calculate all the forces and to tell ride height. It takes into account the preload adjuster, the stop rings, etc. I'll have to post it.

CJ

 

[TONY K]

2.5ton rockwells. Shock mounts on axle are about 6" in from wheel mounting flange. They lean in at the top, about 5*. When I built my suspensions I payed very close attention to clearances. I put the axle as far up into the frame as I could fit it(made changes to a couple things to accomdate this). Then I built the shocks mounts the same distance apart as the compressed length of the shock. This way I am positive there are no clearance issues anywhere throughout travel and The rig is as low as it possibly can go.

How many inches are the shock mounts apart from each other on the frame and axle housing ? Basicly measure from the center of shock eye on the drivers side to same location on the passenger side.

How wide are the housings from center of king pin to center of king pin ?

I assume the rear axle is steering axle also ?

I assume we have coilovers on all 4 corners ?

Same specs for front and rear shocks ?


Do you have any pics of the suspension ?

Do you have some thread left on the body to lower the rig ? You said that you wanted 9-10" of shaft in.

A stiffer spring rate would also require some thread on the body.



The rockwells should have you glued to the earth so if it feels bad on downhills then I would conclude that weight transfer is lifting or link angle is causing jacking.

With that much unsprung weight and wide axle set, I'd go after a 50/50 split on the shocks and keep the centerline of the axle housing from moving very far. Limit trap the center of the diff only.

Moving the shocks out on the diffs could get you a softer rate by increasing axle but gain stability with the wider shock location. That should alow you to back the jam nuts way off.


The rate of compression you are getting on the coils at rest are perfect and the tender is taking up the slack fine.

Really think shock location will be the answer. Let me know what the messurements are.

thanks

tony k

 

[CJ Lagos]

Hey Tony,

My front shock mounts are 49.5" wide on the axle and 36.5" wide on the frame. They lean in at an angle of 13*. The distance from kingpin to kingpin on the axle is 58.5" and WMS to WMS is 69.25" The shocks are as far out on the axle as they can go. To be honest, I'm just ignoring the angle correction in determining the spring rates...a 13* lean will only lower the spring rate by 3%.

With the springs I mentioned in the first post the ride height adjuster will be all the way at the top for a ride height of 25.5. If I think that is too low I can adjust it down an inch or two to fine tune. That seems ideal to me. I'm mainly interested in hearing opinion on the springs like if the transistion is in the right place, any better ideas?

I'm changing my front suspension over the next few weeks so pics won't help very much. I'll post one of my rear suspension though because I've got to figure out the spring rates for that too. 600lbs corner weight in back. The rear has 117% anti-squat, 29.82" high roll center and the roll axis slopes at -0.33 degrees.

 

[TONY K]

Everything by the numbers looks great. Shock angle looks fine. Can't really tell much about weight transfer but that is likely the feeling you have on downhills.

It's important to have a balanced rig. You don't want the rear outworking the front suspension in travel. Basicly the rear gets to 75% of it's travel before the front really starts to work.

I'd guess that you have a max of 150 lbs of gas in the cans.

Increase the gas pressure to 250+ lbs and back the nuts off about 3/4" more.

The higher lbs of gas will also make the valve respond faster and that normally makes the hard hit a lot softer.

You could increase top spring rate a little but I don't think it would help you enough.



The other thing is changing the shock valving.

1. If you feel the hard hit only when the coil slider reaches the nuts, then stiffen up the shock a little on compression and rebound.

2. If you think the hard hit is from just the rate of the compression stoke and not from the jam nut/ slider impact, then go a little soft on the compression valving only.

I don't know what vavling you have now but I'd say most likely # 1

Hope this helps


Tony k

 

[CJ Lagos]

I agree that balance is important. Mine works pretty well as is. I know exactly what you mean though. I also use a swaybar in the back which helps.

I have no idea what my valving is unfortunately. I plan to re-valve the shocks after I get the spring rates selected. Do the spring rates effect how you valve the shock? That probably should be another thread.

Thanks Tony,

CJ

 

[TONY K]

Spring rate to valve lap is important if you are going fast but not that important for rock crawling.

It is important to get the right compression/rebound to get a Rock crawler to "stick" rather than explode off on a launch or keep under control on a bumpy road.

Do you know what pressure of gas you have in the shocks ?

The higher the pressure the more controlled spring rate you gain and the valve in the shock works faster so the rig always feels more under control. More gas would slow the impact to the coil slider.


tony k

 

[CJ Lagos]

I've always run 200psi in the res. I Need to start keeping a closer eye on those.

 

[Ed A. Stevens]

Not sure where to pick this up but my post seems like a good place to start :flipoff2:

Can anyone comment on my spring setup for a 14" swayaway?

Corner Weight is 886lbs. Currently running 250/300. Notes: Suspension is too soft and bottoms out if I don't use the stop rings(136# primary), but if I set the stops a few inches above ride height the spring rate jumps from 136 to 300 and is very jarring, I need something in the middle. Currently the ride height is set 8" into the shock and I want to try 9" or 10".(Goat what are your front shocks setup for at ride height?)

First attempt at a starting spring selection:

Primary: 250#/16"
Secondary: 350#/10"
Keeper Spring: 3.5" free length
Primary Rate: 146#

Travel/Rate/Force:
0/0/0
1/0/0
2/0/0
3/0/0
4/146/73
5/146/219
6/146/365
7/146/510
8/146/656-secondary on stops at 8.5"(10/2 +3.5 for tender)
9/250/854
10/250/1104 (~ride height)
11/250/1354
12/250/1604
13/250/1854
14/250/2104

Thoughts:
-Will the 250# spring rate be enough for only 4" compression from ride height and allow a decent ride? Too stiff? Maybe a good excuse to get the air bumpstops?
-This combo gives me a ride height of ~25.5" which is what I want.
-If I find 4" isn't enough I can always lower the ride height adjuster 1-2" to fine tune. (But then ride height might be too close to transistion point?)
-The 16" main coil looks like it comes close but won't bind.
-The springs won't be loose at full droop.

Ideas/Comments? (Please double check force calcs, I think it may be wrong after the secondary coil hits the stops @ 8.5")

Thanks,
CJ

This looks much better than having the 350# spring as the primary (your older setup): the final rate, the transition into the static height, and the ride height itself.

The 250#/in rate is working against the sprung weight, and should feel more reasonable than the older setup 146#/in.

You will not know till you run it and test it.

I cannot check the math until I can get into my office. I read the transition is at ~730#? This requires the 350# secondary to be stopped at ~2.1" of travel.

The total corner weight (886#) compared to the total compressive resistance (2104#) is ~2.4:1. This is reasonable with a bumpstop in the last inch or two as a secondary spring to take the forces off the shock mounts.

How does the total 2104# compare to the older setup? If it was/is bottoming the shock, rather than hitting the spring rate transition hard, a bumpstop is cheap insurance. You do not mention the rear corner weight but you will seldom stand more than 3/4 of the total vehicle weight on a front corner (for very long). The addition of a bumpstop to add resistance in the final few inches will essentially provide a second transition 0/146/250/???.

When you state it feels unstable off-camber downhill, does the body roll or the axle(s) try to lift or slide a tire, how does it feel unstable?

Is the feeling a rigid front or rear suspension (no suspension movement after a certain angle), or does it feel as if one end is jacking higher and getting tippier (the front or rear feels like it wants to roll sideways)? Is the problem spring or suspension?

Is the instability static (very slow or stopped on the brakes) or dynamic (only when crawling down over rocks and holes with shock travel movement)? Is the problem spring or shock valving?

I have been off-line for a while. With luck, I'll get back into the office today and can run some numbers (customer's compressed project schedules, to take advantage of Christmas plant shutdowns, make this time of year busy).

Try it and see how it feels.

Happy Trails!

 

[CJ Lagos]

Thanks for responding Ed!

I suspect my force calculations are off once the slider hits the stop rings. I've been calculating the block load of the secondary spring using the primary spring rate(instead of the individual spring rate). From your numbers, this is what I thought you had done. I'm sure total forces are higher than what I posted...either way, the forces with my old setup are significantly higher.

I'm not going to worry about the instability I mentioned as it hasn't been a huge problem(just one of the few flaws I can come up with of my current setup). I've noticed it once or twice in certain situations that might make any vehicle unstable. I'm changing the front suspension along with the springs so I'll see what happens.

The rear corner weight is 600lbs. I have no problem running bumpstops, I already have a pair mounted but would really like to try the air cans.

CJ

 

[TONY K]

Your rear corner weight is the same as our Razors. About 600 lbs.

Someone was asking me questions after following a few theads on this board.

This is a good example to explain something for the people watching this.


How can 2 rigs that have the same corner weight each have such different spring rate requirements ?


Shock location on the axle housing.

When the shock is angled in a little it does change the spring rate some but overall makes very little difference in the overall spring rate.

Mounting the shock on the axle housing all the way at the tire vs mounting it 3" closer in from the tire could be the difference between a 150/200 rate (and that feels stiff) like the Razor vs a 250/300 rate (sound like its too soft) on CJ's.



Good thread.

thanks

 

[CJ Lagos]

Your rear corner weight is the same as our Razors. About 600 lbs.

Someone was asking me questions after following a few theads on this board.

This is a good example to explain something for the people watching this.


How can 2 rigs that have the same corner weight each have such different spring rate requirements ?


Shock location on the axle housing.

When the shock is angled in a little it does change the spring rate some but overall makes very little difference in the overall spring rate.

Mounting the shock on the axle housing all the way at the tire vs mounting it 3" closer in from the tire could be the difference between a 150/200 rate (and that feels stiff) like the Razor vs a 250/300 rate (sound like its too soft) on CJ's.



Good thread.

thanks

Hey Tony,

That's funny how the rear corners are the same(of course I don't have a motor near the back of mine). I currently run a 100/150 in back and have tried 150/200. The 150/200 gives me an incredibly uncomfortable ride. I have no idea what my valving is and I think they might be setup for pre-runners which could explain part of the problem. My shock mounts are as far out on the axles as I could get them and I also run a rear swaybar which makes up for the seemingly soft springs.

Thanks,
CJ

 

[Ed A. Stevens]

Not sure where to pick this up but my post seems like a good place to start :flipoff2:

Can anyone comment on my spring setup for a 14" swayaway?

Corner Weight is 886lbs. Currently running 250/300. Notes: Suspension is too soft and bottoms out if I don't use the stop rings(136# primary), but if I set the stops a few inches above ride height the spring rate jumps from 136 to 300 and is very jarring, I need something in the middle. Currently the ride height is set 8" into the shock and I want to try 9" or 10".(Goat what are your front shocks setup for at ride height?)

First attempt at a starting spring selection:

Primary: 250#/16"
Secondary: 350#/10"
Keeper Spring: 3.5" free length
Primary Rate: 146#

Travel/Rate/Force:
0/0/0
1/0/0
2/0/0
3/0/0
4/146/73
5/146/219
6/146/365
7/146/510
8/146/656-secondary on stops at 8.5"(10/2 +3.5 for tender)
9/250/854
10/250/1104 (~ride height)
11/250/1354
12/250/1604
13/250/1854
14/250/2104

Thoughts:
-Will the 250# spring rate be enough for only 4" compression from ride height and allow a decent ride? Too stiff? Maybe a good excuse to get the air bumpstops?
-This combo gives me a ride height of ~25.5" which is what I want.
-If I find 4" isn't enough I can always lower the ride height adjuster 1-2" to fine tune. (But then ride height might be too close to transistion point?)
-The 16" main coil looks like it comes close but won't bind.
-The springs won't be loose at full droop.

Ideas/Comments? (Please double check force calcs, I think it may be wrong after the secondary coil hits the stops @ 8.5")

Thanks,
CJ

Follow Up:



Old Set Up #1

"Corner Weight is 886lbs. Currently running 250/300. Notes: Suspension is too soft and bottoms out if I don't use the stop rings(136# primary)"

W/(I am assuming you have been running) a 3.5" travel tender coil?

Travel Rate Combined Force with Tender/Preload
0 0 0
0.5 0 0
1 0 0
1.5 0 0
2 0 0
2.5 0 0
3 0 0
3.5 0 0
4 136 68
4.5 136 136
5 136 205
5.5 136 273
6 136 341
6.5 136 409
7 136 477
7.5 136 545
8 136 614
8.5 136 682
9 136 750
9.5 136 818
10 136 886
10.5 136 955
11 136 1023
11.5 136 1091
12 136 1159
12.5 136 1227
13 136 1295
13.5 136 1364
14 136 1432

Ride height between 8 & 9 inches into the shock.
Low 136# rate for the entire travel.
Soft 1432# total at full bump.

---

Old Set Up #2; w/ stop Rings limiting the 250# secondary @4" compression (a SWAG on the stop ring setting).

Travel Rate Combined Force with Tender/Preload
0 0 0
0.5 0 0
1 0 0
1.5 0 0
2 0 0
2.5 0 0
3 0 0
3.5 0 0
4 136 68
4.5 136 136
5 136 205
5.5 136 273
6 136 341
6.5 136 409
7 136 477
7.5 136 545
8 136 614
8.5 136 682
9 136 750
9.5 136 818
10 136 886
10.5 300 1036
11 300 1186
11.5 300 1336
12 300 1486
12.5 300 1636
13 300 1786
13.5 300 1936
14 300 2086

A better force at full bump, but the 136/300 transition is probably hard.

---

New Set Up #3:

"Primary: 250#/16"
Secondary: 350#/10"
Keeper Spring: 3.5" free length
Primary Rate: 146#"

W/ secondary spring travel stopped at ~2.1" travel.

Travel Rate Combined Force with Tender & Secondary Travel Stop
0 0 0
0.5 0 0
1 0 0
1.5 0 0
2 0 0
2.5 0 0
3 0 0
3.5 0 0
4 146 73
4.5 146 146
5 146 219
5.5 146 292
6 146 365
6.5 146 438
7 146 510
7.5 146 583
8 146 656
8.5 250 781
9 250 906
9.5 250 1031
10 250 1156
10.5 250 1281
11 250 1406
11.5 250 1531
12 250 1656
12.5 250 1781
13 250 1906
13.5 250 2031
14 250 2156

886# ride height force ~8.5-9" deep into the shock (can be moved with the adjuster rings if the secondary transition is fine, and you can live with cutting the secondary coil shorter to make room).

146/250#/in transition ~.5" before the static load, keeping the spring rate firm at speed, and not as radical (170% increase vs. 220% increase).
The new spring stack stiffness rate at ride height, the difference between 136#/in and 250#/in (~180% increase) with the corner weight on the spring, should significantly improve the roll stiffness on side hills, and the ability to react to holes and whoops at speed. The major component working to keep the unsprung weight (the tires and axles) following the ground in fast whoops is the spring rate. If the springs cannot quickly push the tires into the holes, the tires will not bite, and the tires will be loosely topping the whoops rather than driving the vehicle forward. Shock action will also not travel enough for the chassis to gain full benefit of the reactive dampening. It's not that big of a deal on the straights but it makes a big difference cornering in rough conditions at speed.

Force at total travel 2156#, with less chance of bottoming than either of the older set ups.

---

The actual forces will be slightly higher, due to the tender coil force at full compression, although you are on the right track. The little I get to read indicates you have the basic concept down, and that you know the choice of coil stacking and stop selection is as important to the effective spring rate as the raw spring selection.

Test feedback will be appreciated.

What Tony K mentions about shock mount spacing (actually spring mount spacing) having an impact on the spring rate choice is true. Inboard axle mounts typically demand stiffer rates, due to the reduced leverage suspending the body about the roll axis. This is a good point to illustrate that what works for your set up may not work well for someone running the same corner weight and roll axis with more inboard (or outboard) spring mounts. Each component of the design (weight, spring mounts, roll axis) has an impact on the roll stiffness and the resulting spring selection.

HTH, and the cut/paste from Excel is not too hard to read?

Happy Trails!