Koni STR.T + coilover?
Thread Starter
4th Gear Member
Joined: Nov 2007
Posts: 1,337
From: NJ / MA
Koni STR.T + coilover?
alright, so here's my question:
can Koni STR.T's be matched with coilovers, and if so what spring rates for backroad fun/every day driving?
also would like to match the spring rate for a TA/PHB setup... Maximum Motorsports couldnt give me any info and didnt recommend the STR.T for rear coilovers because of the increased spring rate required by a TA setup.
this is all based on budget... the STR.T's fit the bill perfectly, but i'm afraid they'll be too soft for a TA setup? how much would it affect my setup if i went with a TA/PHB setup out back, with somewhere between a 225 to 300 # spring up front, coilovers on the STR.T's, and rear springs to match? would i have to worry about the ride sucking or would it damage the strut or what?
what rate springs would suit a "fun" everyday backroad driver with Koni STR.T's?
can Koni STR.T's be matched with coilovers, and if so what spring rates for backroad fun/every day driving?
also would like to match the spring rate for a TA/PHB setup... Maximum Motorsports couldnt give me any info and didnt recommend the STR.T for rear coilovers because of the increased spring rate required by a TA setup.
this is all based on budget... the STR.T's fit the bill perfectly, but i'm afraid they'll be too soft for a TA setup? how much would it affect my setup if i went with a TA/PHB setup out back, with somewhere between a 225 to 300 # spring up front, coilovers on the STR.T's, and rear springs to match? would i have to worry about the ride sucking or would it damage the strut or what?
what rate springs would suit a "fun" everyday backroad driver with Koni STR.T's?
6th Gear Member
Joined: Feb 2007
Posts: 7,635
From: state of confusion
Is this about coilovers all around or just on the rear?
On the newer S197 chassis, STR.t's seem to be OK with springs up to about 50% stiffer then the OE springs, which covers the majority of "lowering springs" and obviously any C/O springs that provide a similar wheel rate.
I think we need to think in terms of wheel rate here, since moving to a C/O out back on your car involves a change in the spring's motion ratio (you need less C/O spring rate for the same wheel rate as the conventionally located spring being swapped out) but not the shock motion ratio.
With the TA/PHB setup, springs tend to be stiffer partly because the bind that's inherent in the converging/triangulated setup even in bump mostly goes away and partly because the rear roll center is lowered. If you're willing to stiffen the rear sta-bar slightly (assuming that you can), you shouldn't need quite as much rear spring as if you were trying to make up all of the "lost" rear lateral load transfer with the springs. In that case, where you get some help from the springs and some from the bar, you wouldn't need quite as much damping.
Somewhere I have a list of Mustang spring rates, just not on this computer.
Norm
On the newer S197 chassis, STR.t's seem to be OK with springs up to about 50% stiffer then the OE springs, which covers the majority of "lowering springs" and obviously any C/O springs that provide a similar wheel rate.
I think we need to think in terms of wheel rate here, since moving to a C/O out back on your car involves a change in the spring's motion ratio (you need less C/O spring rate for the same wheel rate as the conventionally located spring being swapped out) but not the shock motion ratio.
With the TA/PHB setup, springs tend to be stiffer partly because the bind that's inherent in the converging/triangulated setup even in bump mostly goes away and partly because the rear roll center is lowered. If you're willing to stiffen the rear sta-bar slightly (assuming that you can), you shouldn't need quite as much rear spring as if you were trying to make up all of the "lost" rear lateral load transfer with the springs. In that case, where you get some help from the springs and some from the bar, you wouldn't need quite as much damping.
Somewhere I have a list of Mustang spring rates, just not on this computer.
Norm
Thread Starter
4th Gear Member
Joined: Nov 2007
Posts: 1,337
From: NJ / MA
Ah ok. Do you mean a stiffer sway bar? Mms says with a ta/ phb set up the spring rate should be 100lbs less in the rear than the front. So I guess what I need to find is the stock equivalent to match c/o on all 4 corners. Then I can add 25-50% and I think that would be suitable for my needs? Then I could try it with a stock sway and upgrade later to help with the "lack" of spring until I can upgrade to koni yellows and up the spring Rates.
6th Gear Member
Joined: Feb 2007
Posts: 7,635
From: state of confusion
Yes, but it's really the other way around with "sway bars" being technically incorrect slang for stabilizer bar (abbreviated variously as "sta-bar"/"stab-bar"/"stabar", and which is itself probably short for "roll stabilizer bar"). "Sway" is not the same motion as roll - I think "sway" has more to do with towing trailers than taking corners.
Here's a link that ought to be helpful . . .
http://www.miracerros.com/mustang/t_wheel_rate.htm
I have a minor argument with its treatment of the effect of the angle - its sine function should also be squared just like the length ratio is.
There is a relationship between front and rear wheel rates and the car's weight distribution that leads to an inherently better ride over certain kinds of road unevennesses (involving pitch, or "flat ride" behavior). "100 lbs less" may be a rough approximation for some cases, but I don't have enough information here yet to know what combination of spring rates and configurations that it applies to. If you call MM again after spending a little time with the miracerros link and finding out a little about "flat ride", I'd suggest trying to speak with Jack Hidley.
Worst case by doing the rear springs first and not trying to recover all of the "lost" roll stiffness with them is that you'll understeer a bit more. If/when you find that to be the case, then close in on your setup with a rear bar (here's where adjustable sta-bars are at their best - they enable you to more closely find what works best for you (which might not be what works best for me or anybody else you might ask).
Norm
Mms says with a ta/ phb set up the spring rate should be 100lbs less in the rear than the front. So I guess what I need to find is the stock equivalent to match c/o on all 4 corners.
http://www.miracerros.com/mustang/t_wheel_rate.htm
I have a minor argument with its treatment of the effect of the angle - its sine function should also be squared just like the length ratio is.
There is a relationship between front and rear wheel rates and the car's weight distribution that leads to an inherently better ride over certain kinds of road unevennesses (involving pitch, or "flat ride" behavior). "100 lbs less" may be a rough approximation for some cases, but I don't have enough information here yet to know what combination of spring rates and configurations that it applies to. If you call MM again after spending a little time with the miracerros link and finding out a little about "flat ride", I'd suggest trying to speak with Jack Hidley.
Worst case by doing the rear springs first and not trying to recover all of the "lost" roll stiffness with them is that you'll understeer a bit more. If/when you find that to be the case, then close in on your setup with a rear bar (here's where adjustable sta-bars are at their best - they enable you to more closely find what works best for you (which might not be what works best for me or anybody else you might ask).
Norm
Thread Starter
4th Gear Member
Joined: Nov 2007
Posts: 1,337
From: NJ / MA
ah ok... makes sense. i'm doing some numbers now. email from MMS states that basically, for anything lower than 225lb front C/O springs, they recommend going with a stock location spring. after doing some numbers, it makes sense now, H&R super sports = ~135 C/O spring rates for the rear rate. (i just did a bit of multiplication and division using the numbers in that link, mult by .5, then divide by 1.1) and using coilovers isnt really worth it until probably 150-200+ lb rates.
figure i'll go with a 150 out back, on the Koni STR.T, see how i like it, if not im sure i could sell em. then i can match Koni STR.T's up front on a 250lb spring. this would match what MMS says they recommend for the 100lb difference between front and rear.
worst case scenario i could upgrade struts and springs later, or as you said, go with a stiffer sta-bar (been refering to it as a sway bar, but only because its the only thing i've ever heard it called, but i have now been corrected
)
figure i'll go with a 150 out back, on the Koni STR.T, see how i like it, if not im sure i could sell em. then i can match Koni STR.T's up front on a 250lb spring. this would match what MMS says they recommend for the 100lb difference between front and rear.
worst case scenario i could upgrade struts and springs later, or as you said, go with a stiffer sta-bar (been refering to it as a sway bar, but only because its the only thing i've ever heard it called, but i have now been corrected
)
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