coilovers

rawkerstatus

Bought an X
Founding Member
Location
Santa Ana, SoCal
Alright guys, I'm at the point where I'm going to pick up some coilovers. They're coming from FOA 2.5 rod ,,,diameter. 14 inch length. My question is, what spring rate should I get? It will be a dual spring rate due to the length. I understood that a ball park should be about 350 upper and 300 lower. Does that sound about right?
 

TheFauxFox

Titan Swapped / SAS'd
Founding Member
Location
Huntsville, AL
Call them. Its what I did when I bought some from them.

They suggested 300/350 if I recall. I still have them in a garage somewhere.
 

TheFauxFox

Titan Swapped / SAS'd
Founding Member
Location
Huntsville, AL
Don't tease man lol

You didn't have to read this thread :angel:

Seriously, I think JD is who I spoke to about mine. They're extremely helpful. Just tell them what you're trying to do. It may help to have a few weight figures for your truck before you talk to them. Pirate's coilover bible may also be of use.
 

rawkerstatus

Bought an X
Founding Member
Location
Santa Ana, SoCal
Yeah i read a SAS build thread somewhere and that's what it recommends.I'm thinking that's the way to go. Then next question what type valving? not sure if to go with something firm or not.
 

TheFauxFox

Titan Swapped / SAS'd
Founding Member
Location
Huntsville, AL
Yeah i read a SAS build thread somewhere and that's what it recommends.I'm thinking that's the way to go. Then next question what type valving? not sure if to go with something firm or not.

I had been recommended medium compression and light/medium rebound. Looking back, I would do more research on that just as a second opinion. I never used mine so I couldn't tell you how they held up.
 

TJTJ

Skid Plates
Founding Member
Location
NJ
For a live axle, the rates are lower than for IFS. The rates for the rear axle will be close for the front.

You'll be raising the COG and will need stiffness to control sway off camber, etc....but you'll want something digressive for the shocks that will work with the coils, as part of the rebound/compression damping is FOR is the oscillation of the coils.

If you make the coils TOO stiff to allow full compression, you'll lose uptravel, and the tire rising on a rock, etc, will pick up that corner of the truck instead of rising the rest of the way up into the well. It will also ride hard and need a lot more damping to control bounce, etc.

I'd go soft on the suspension and count on the shocks to get the best of both aspects.

Otherwise, you'll "bow" a lot when braking, pitch up on acceleration, etc.
 
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rawkerstatus

Bought an X
Founding Member
Location
Santa Ana, SoCal
For a live axle, the rates are lower than for IFS. The rates for the rear axle will be close for the front.

You'll be raising the COG and will need stiffness to control sway off camber, etc....but you'll want something digressive for the shocks that will work with the coils, as part of the rebound/compression damping is FOR is the oscillation of the coils.

If you make the coils TOO stiff to allow full compression, you'll lose uptravel, and the tire rising on a rock, etc, will pick up that corner of the truck instead of rising the rest of the way up into the well. It will also ride hard and need a lot more damping to control bounce, etc.

I'd go soft on the suspension and count on the shocks to get the best of both aspects.

Otherwise, you'll "bow" a lot when braking, pitch up on acceleration, etc.

just the person i was waiting for. so had i talked to them and they also recommended the medium compression and light/medium rebound. but yes i am aware of the whole issue of being too stiff. i just dont want to have a lot of body sway.
 
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TJTJ

Skid Plates
Founding Member
Location
NJ
just the person i was waiting for. so had i talked to them and they also recommended the medium compression and light/medium rebound. but yes i am aware of the whole issue of being too stiff. i just dont want to have a lot of body sway.


You can't count on the coils to completely control sway on an off road rig, as if it can't lean over, it can't compress the suspension to follow the terrain, etc. You want the coils to support the weight, and the shocks to damp motion.

If you make is stiff enough to corner flat with just coils, it will be like a buck board off road.

The best way to work all of this out is to take some weights with one side up/down on the rig, calculate the center of gravity...

Then look at your roll centers, and see where they are relative to each other/the COG.

Drop an imaginary plumb bob down from the COG to the ground, and tip the rig onto nose dive, stall and all the way off camber positions, and see when the plumb bob swings OUTSIDE of the progressively smaller rectangle foot print made by the 4 tires.

THAT angle is "too far", and you roll if you exceed it. It can be different for P and D sides, etc.

For example, my COG on the 2001 was pretty close to a spot ~ 1' above my right knee.


If the roll center of the suspension can handle that, you can lean away w/o worrying about it...even if it drives like a drunken master. (Higher RC means less lean in turns typically, but can make you slide laterally in hot corners/not weight the loaded tires as much, etc. If COG and RC are in the same plane for example, you don't lean at all in turns, and so forth.)

If its all too high, you do need to worry about it,and, typically try to first consider your weight distribution and the roll center.

The F/R centers and the axis that results will be different typically, but setting up that balance also involves personal driving style.

The COG is the best starting point typically...as your roll center factors will probably be the least adjustable parameter....you want to know it mostly to simply help understand the leverage acting on the sprung mass.


Sooo....the best way is typically, for your situation, is to use the shocks to damp the sway instead of the coils.
 
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TJTJ

Skid Plates
Founding Member
Location
NJ
You have to consider natural frequencies of the springs and shocks together at road speeds. That's what will determine the ride.

Exactly.

As I mentioned a bit above, the part of the shocks extension and rebound work is damping the oscillations of the coils...and the harder the coils are oscillating (The stiffer) the stronger the shock's valving needs to be to compensate.

As recommended to you, you want a softer suspension to ride smoother and to allow articulation...so you need to select a shock/coil combo that work with each other, as well as the dynamics of the rig.

Other wise its like the guy who says "What's the best self defense round for a sidearm?" and is told to get 45 ACP...so he buys a few boxes of 45 ACP rounds.

But he has a 9mm Glock, and the rounds don't really work with it.

:D
 

rawkerstatus

Bought an X
Founding Member
Location
Santa Ana, SoCal
so it seems ill be buying these monday. after some research and derping around i'll be set on 2.5 14' coilovers with 300/350 spring rate and med/light medium valving
 
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