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Progressive rate springs for 2xx

John V said:
To quote a suspension engineer at Ford Motorsports in the UK referring to GroupA cars (steel bodied cars the size of Volvos) "Show me a progressive damper and I'll look at a progressive spring"
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:rofl: so not really worth it? i see they are $40 less than the IPD ones...
 
I am kind of curious since I just bought these springs and a set of Koni yellows. Shocks and struts are speed sensitive aren't they? Their job is to dampen the movement of the car and the suspension. The faster the wheel moves up and down...the more dampening is provided to control it. The slower the wheel moves up and down....less dampening is provided. Won't this compensate for the progressive rate springs?
 
Rhymenocerous said:
I am kind of curious since I just bought these springs and a set of Koni yellows. Shocks and struts are speed sensitive aren't they? Their job is to dampen the movement of the car and the suspension. The faster the wheel moves up and down...the more dampening is provided to control it. The slower the wheel moves up and down....less dampening is provided. Won't this compensate for the progressive rate springs?
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sort of, the difference is in the amount of absolute load versus the rate at which the suspension is loaded. any spring will (theoretically) respond with the same force and rate at which that force is applied to it, so yes, a spring will respond with the same force to a given set of bumps at different speeds. a damper will oppose more force the quicker the car is moving because of the valving inside a shock: only so much fluid can pass the valve to go from one side of the piston to the other.

the difference between a prog. rate spring is that the spring rate is higher (stiffer) at one end than the other, making the spring react differently to the amount of load it receives, not the rate at which load is applied (ie, great lateral forces due to hard cornering or longitudinal forces when braking). the problem i see with these is that when there is more suspension load, the higher spring rates will make the car seem either over- or under-damped, hence the criticism above.


thats my take at least.
 
Rhymenocerous said:
I am kind of curious since I just bought these springs and a set of Koni yellows. Shocks and struts are speed sensitive aren't they? Their job is to dampen the movement of the car and the suspension. The faster the wheel moves up and down...the more dampening is provided to control it. The slower the wheel moves up and down....less dampening is provided. Won't this compensate for the progressive rate springs?
Click to expand...

OK, anybody who knows me knows I's needs me tea to even see straight and so far I only has one cup in me so hang on,eh.
Separate the spring from the damper.

Think of spring "rate" (rate of what?0 like this:
Major D (the coil diameter) and minor d, the wire diameter both have a influence on rate, along with free length.
They influence rate because they affect how much steel is in the spring.

So we's have D, L and d, three fawkin variables.
Lets do and example where we remove some variables.

D=5.5", L= 14", and d=0.5", 10 coils.

Unwind the spring and stick one end in a vise (we're doing what i do a lot, backing up in aprocess to see how it sumpin simpler, I am a simple guys after all.)

With the spring now fixed horisontal its about 172.7" long

next to it we fix a spring which was d 5.5, L 14" and d 0.5 but had 15 coils.= 259" long

We go out and hand some dead weight on the end say one of those useless POS Lay-cock overdrive things which weighs lets say 50 lbs

The fact that the same weight hung on the same wire will deflect the longer on is pretty obvious and clear why.

WRT progressive we wind them with a lot more laps of wire at one end, which makes that portion of the spring--with the same D and d, softer.
In use when that softer portion cooil binds, the remaining spring is now a spring with effectivly less wire in it so its stiffer.
The "slope" and the transition point , the coil bind point can be fingered out but the question is what is you want to effect a change in say pre-load and hence ride height.
You shove some spacers under the seat and-----you merely compress the soft portion.
Ya gets poissed off and rip the shtuff apart and add a spacer again and set er down and its still the same height!!
Pissed you rip it apart and add a 4" spacer and the two 1' rubber spacers from earlier and reassemble and set it down.
Ahh car is .75" higher now. All is well.

Except you used up over 4" of the springs spring travel leaving only 4" spring travel for a damper with 8" stroke.

Give me a linear spring, please where I don't have to deal with the coming together of things i have no choice or input over.

I want another cuppa.
 
I gotcha John :) Makes sense.

But here a question for you. Lets say that the progressive spring is the perfect height you want for you application (no spacer necessary). Would you still prefer a linear spring in that case?
 
Cool. It does make sense. I guess i'll just have to crank up the konis a little to work better with the stiffer portion of the spring and drive so fast that the springs aren't in the soft part of the spring a whole lot.
 
I'm confooooosed. Somebody put this in order of preference, best to worst.

1. Progressive lowering springs.
2. Linear lowering springs.
3. Cut stock springs.
4. Leave it stock and spend your time/money on other things.
 
b4_ford said:
I'm confooooosed. Somebody put this in order of preference, best to worst.

1. Progressive lowering springs.
2. Linear lowering springs.
3. Cut stock springs.
4. Leave it stock and spend your time/money on other things.
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"Linear lowering springs". We call these standard springs. You select the stiffness you want, then find the required size to put the car at the ride height you want. Some of us use adjustable perches to set the height and allow for corner weighting (but who has the time)

"Cut stock springs". These are linear springs, that are stiffer than stock, and will lower the car. Probably not stiff enough, though.

"Progressive lowering springs". I didn't know anyone even made em! Kind of a bandaid, unless you really design the **** out of everything, include really fancy dampers (do the new MR damped cars use progressive springs?)

"Leave it stock...". **** that.
 
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