• Welcome to the Contour Enthusiasts Group, the best resource for the Ford Contour and Mercury Mystique.

    You can register to join the community.

BAT kit spring rates, other options < $600

The equation for spring rate is k=(d^4*G)/(8D^3*N) where d is the wire diameter, G is the modulus of rigidity (~11.2*10^6 psi for steel), D is the diameter of the coil (center to center on the wire), and N is the number of active coils.

the problem your going to have calculating it is that most springs for the contour are progressive not linear.

honestly, your better off saving your money for a little bit longer and getting a set of coilovers. either Konis/GCs or Ksports/D2s. the advantage of the GCs is that you can easily change spring rates just by ordering new 2.5" diamter springs in the correct length. also, you can keep the ride height up closer to stock so your not messing with the suspension geometery too much and moving the roll center too far from the center of gravity.
 
Can you explain to my non-engineering ass what the ^ & ~ mean in the equation?

It's not that I couldn't come up with the money, but I can't justify spending THAT much. Hell, I think $600 is too much but that seems to just be the nature of this particular beast.

The stock springs are linear aren't they? Those are the only ones I would even THINK about cutting but I'm expecting that I won't be able to get a decent spring rate AND ride height out of them.
 
if you cut the stock springs down, you will need stiffer shocks...otherwise the car will bounce all over the place. You can't beat a set of progressive springs...they take the bounce out of the ride and inspire confidence in the corners. G.
 
SicSE said:
Can you explain to my non-engineering ass what the ^ & ~ mean in the equation?

It's not that I couldn't come up with the money, but I can't justify spending THAT much. Hell, I think $600 is too much but that seems to just be the nature of this particular beast.

The stock springs are linear aren't they? Those are the only ones I would even THINK about cutting but I'm expecting that I won't be able to get a decent spring rate AND ride height out of them.
Click to expand...

^n means to the n-th power

~ I believe in this usage, denotes a rough estimate of a number.
 
SicSE said:
Can you explain to my non-engineering ass what the ^ & ~ mean in the equation?

It's not that I couldn't come up with the money, but I can't justify spending THAT much. Hell, I think $600 is too much but that seems to just be the nature of this particular beast.

The stock springs are linear aren't they? Those are the only ones I would even THINK about cutting but I'm expecting that I won't be able to get a decent spring rate AND ride height out of them.
Click to expand...
^ means to the "X" power. so ^3 is the same as cubed and ^2 is squared.

~ means exactly what it means anywhere else, "approximately"
 
Thanks guys. Two more Q's;
What is/how do I determine the modulus of rigidity?
Where exactly do I start, to count the active coils?
 
For steel G=(~11.2*10^6 psi)

The parts of the coils that touch the mounts at each end are not active. Also any coil that is stacked (bottomed out) would not be active.
 
Looks like cutting a coil off the stock fronts is only gonna bump spring rate about 30psi... so much for that. I guess I'll be chasing other Ford OEM possibilities. It's crazy to me that no one has already done this.

Does anyone know the rate of the springs in the BAT kit, or where I could find the rates since their site doesn't list them?
 
striker2 said:
For steel G=(~11.2*10^6 psi)
Click to expand...

Oh god no! Solids class all over again.


To the OP- if you can't swing more than $600, I would suggest that you not do anything for now. Getting the springs and struts is just one step. You're going to want to replace some stuff while you're under there (as I found out) which will probably cost about as much as any budget spring/strut combo you might come across.
 
biminiLX said:
What?
Stop regurging BS.
I cut my factory front coils and if you went for a ride you would never know its not stock.
-J
Click to expand...
did you have stock shocks on there or after market ? oh, i speak from the experience of having had both setups..try not to be so presumptuous in future... G.
 
TX00SVT said:
You're going to want to replace some stuff while you're under there
Click to expand...
That was already taken care of before I put the engine back in. I'd love to get a complete poly bushing kit but no one seems to make one.

I can't believe so many people have bought the BAT kit without knowing the spring rates.
 
gorman said:
did you have stock shocks on there or after market ? oh, i speak from the experience of having had both setups..try not to be so presumptuous in future... G.
Click to expand...
I'll try and be less presumptuous if you post something correct. :rolleyes:
If the springs and struts are in good condition, tell me why the car will "bounce all over the place". As he mentioned, cutting the springs will not raise the rate by much.
And I kept everything stock, but they were low mile units (20k) in good condition.
Let me be presumptuous again---you cut some clamped out stockers and had a bad result.:help:
-J
 
my experience of cut down stock springs was a poorer result than using 2 inch lowered progressively wound springs. On fast roads at speed, the car would bounce at dips and humps in the surface. At slower speeds, 30 - 40 it was stable. I don't think anyone who first cut their springs and then fitted prog's would argue that stockies were any good at all. For anyone doing this.. i clamped the spring to the spring seats to eliminate bump steer and reduce the chance of the spring falling out...that is if you retain the stock legs. Done carefully, with insight to what you are doing...it is a useful experience...but it's not anywhere near as good a setup that you can have...G.
 
when i went back to the guy i was buying parts from, i told him the symptoms i was having. That is hitting drain covers, bumps, joins in the road surface... and losing grip and drifting wide, (especially cornering). He said that was bump steer. He also told me that clamping the shorter springs to the spring seats, on the stock legs, should help. So i clamped the springs and the bump steer disapeared. I may be calling that symptom bump steer and that may not be what you call it...does that make sense ? ..g.
 
gorman said:
when i went back to the guy i was buying parts from, i told him the symptoms i was having. That is hitting drain covers, bumps, joins in the road surface... and losing grip and drifting wide, (especially cornering). He said that was bump steer. He also told me that clamping the shorter springs to the spring seats, on the stock legs, should help. So i clamped the springs and the bump steer disapeared. I may be calling that symptom bump steer and that may not be what you call it...does that make sense ? ..g.
Click to expand...
Bump steer is where the tie rod is at such a sharp angle (from the car being lowered) that the factory geometry is thrown off not allowing proper control of the spindle. That is why they make bump steer kits which is basically a spacer for the tie rod to drop it back down to a flat level.

You effectively made it worse by clamping the springs (i.e. further lowering). What probably happened is you gained a whole bunch of camber out of that such that it makes the car "feel" stable.

I've cut coil springs before. The rule of thumb I always took into it was that a complete coil is about a 2" drop on a linear spring.
 
z06killinsbf said:
Bump steer is where the tie rod is at such a sharp angle (from the car being lowered) that the factory geometry is thrown off not allowing proper control of the spindle. That is why they make bump steer kits which is basically a spacer for the tie rod to drop it back down to a flat level.

You effectively made it worse by clamping the springs (i.e. further lowering). What probably happened is you gained a whole bunch of camber out of that such that it makes the car "feel" stable.

I've cut coil springs before. The rule of thumb I always took into it was that a complete coil is about a 2" drop on a linear spring.
Click to expand...
Hi z06killinsbf; thanks for that. I never questioned this problem after i cured it with the suggested fix. I didn't really lower the ride height with the clamps much because they were nowhere near strong enough to compress the springs. Curious how it worked though. So what angle is the tie rod supposed to be ? ..G.
 
You must log in or register to reply here.
Back
Top