what pound springs are you track people running up front
#31
Rennlist Member
Way off.
Here's the valving that I collected from various sources. It's in Nm and R is for rebound and C is for compression.
944 HD INSERT FRONT - PN: 34-001042 - 1480R/1125C (NM)
944 HD 36MM SHOCK REAR - PN: 24-020527 - 2350R/1190C
944 TURBO CUP FRONT - 3800R/1500C
944 TURBO CUP REAR - 5650R/2180C
944 FIREHAWK FRONT - 6000R/1800C
944 FIREHAWK REAR - 4000R/2000C
Ideally, you would probably want to run the Bilstein Cups with HIGH spring rates and WITHOUT torsion bars. The H&R RSS kit that comes with 500 front, 800 rear spring says to take out the torsion bars and that running 800lbs rear is perfectly fine with the proper rubber mounts. I'm pretty sure the H&R RSS uses the Bilstein Cup shocks and struts as a starting place.
The misinformation for this topic on here is stunning.
Here's the valving that I collected from various sources. It's in Nm and R is for rebound and C is for compression.
944 HD INSERT FRONT - PN: 34-001042 - 1480R/1125C (NM)
944 HD 36MM SHOCK REAR - PN: 24-020527 - 2350R/1190C
944 TURBO CUP FRONT - 3800R/1500C
944 TURBO CUP REAR - 5650R/2180C
944 FIREHAWK FRONT - 6000R/1800C
944 FIREHAWK REAR - 4000R/2000C
Ideally, you would probably want to run the Bilstein Cups with HIGH spring rates and WITHOUT torsion bars. The H&R RSS kit that comes with 500 front, 800 rear spring says to take out the torsion bars and that running 800lbs rear is perfectly fine with the proper rubber mounts. I'm pretty sure the H&R RSS uses the Bilstein Cup shocks and struts as a starting place.
The misinformation for this topic on here is stunning.
Brian
#32
Rennlist Member
[QUOTE=robstah;9525404]How is that wrong? Those valvings come STRAIGHT FROM BILSTEIN. And saying that the shocks are setup for 300 front and what is an effective 126 rear (300lb coilover spring comparison) is so far off base it's not even funny.
The Bilstein Catalog is WRONG!!!!. They mixed up the names and the rear shocks. There are two setups. The front struts are exactly the same The Escort Cup are valved stiffer (600lb spring) they go with the coil overs. The Firehawks (300-400lb springs) go with the shocks. If you don't believe me just look at the numbers. Why would you put the stiffer rears with the weaker fronts?
As far as the rears are concerned ...Yes I know if you just do the math it doesn't work...But that’s how it was designed and it works very well. The rear shocks are very stiff in fact I asked Jack at Bilstein if I could use them with 29mm rear torsion bars and he said NO they would be too stiff.
The Bilstein Catalog is WRONG!!!!. They mixed up the names and the rear shocks. There are two setups. The front struts are exactly the same The Escort Cup are valved stiffer (600lb spring) they go with the coil overs. The Firehawks (300-400lb springs) go with the shocks. If you don't believe me just look at the numbers. Why would you put the stiffer rears with the weaker fronts?
As far as the rears are concerned ...Yes I know if you just do the math it doesn't work...But that’s how it was designed and it works very well. The rear shocks are very stiff in fact I asked Jack at Bilstein if I could use them with 29mm rear torsion bars and he said NO they would be too stiff.
#37
Race Car
Thread Starter
I will be running 18x10(255/35/18 tire) in front and squeezing 18x11.5 (285/35/18 tire) in rear
tires are just estimates as I havent bought them. The fronts and rears will be stretched a bit
tires are just estimates as I havent bought them. The fronts and rears will be stretched a bit
#38
Rennlist Member
Wow I missed this gem of a thread. As much as it pains me, I'm not going to bother contributing for fear of getting yelled at...oh and the fact that I've never personally used the Bilsteins!
Dillon, will the car be exclusively a track car? Mine is a dual purpose car and I run 350#/30mm setup with revolved koni yellows. Don't think this gives you much help but I can offer that this setup offers loads of fun on the track and is about as stiff as I would want to go for a street car. (You can use your g/f as a gauge -- if it's too stiff she'll let you know!)
Dillon, will the car be exclusively a track car? Mine is a dual purpose car and I run 350#/30mm setup with revolved koni yellows. Don't think this gives you much help but I can offer that this setup offers loads of fun on the track and is about as stiff as I would want to go for a street car. (You can use your g/f as a gauge -- if it's too stiff she'll let you know!)
#40
Rennlist Member
all i can add is that when i owned this car it had 525lb rear coil overs and 400lb front springs. I liked the balance very much on the track and was getting into the 1:42/1:43 range on the club course at Mid Ohio on street tires.
#41
Race Car
Of course, if you really want to get an opinion from someone who knows what they are talking about, you could call Racer's Edge and buy the springs there.
#42
Addict
Rennlist Member
Rennlist Member
The effective spring rate is equal to the spring rate times the displacement ratio squared, where the displacement ratio is defined as the spring displacement divided by the wheel displacement.
Numbers have been flying around in this thread, but let’s take the example, that the spring rate is 500 lb/in (which confusingly in common parlance is called 500 lb) and the wheel moves 1.25” for a 1” compression (or expansion) of the spring around its resting point. The displacement ratio then is 1”/1.25” = 0.8.
For a 1” movement of the wheel the spring changes height by 1/1.25” = 0.8”. Since the spring is very linear (non-progressive) it exerts a force of 500 lb/in * 0.8” = 400 lb on its mounting point. In this case think of the suspension as a lever for the spring and wheel mounting points and realize, that the wheel sees an effective 400 lb * 0.8 = 320 lb. So it takes 320 lb to move the wheel 1”, hence an effective spring rate of 320 lb/in.
In essence we have multiplied the 500 by 0.8 twice, which is the same as writing 500 * (0.8)^2 = 500 * 0.64 = 320, which is where the square of the displacement ratio comes from.
I hope this helps more than confuses.
Laust
Numbers have been flying around in this thread, but let’s take the example, that the spring rate is 500 lb/in (which confusingly in common parlance is called 500 lb) and the wheel moves 1.25” for a 1” compression (or expansion) of the spring around its resting point. The displacement ratio then is 1”/1.25” = 0.8.
For a 1” movement of the wheel the spring changes height by 1/1.25” = 0.8”. Since the spring is very linear (non-progressive) it exerts a force of 500 lb/in * 0.8” = 400 lb on its mounting point. In this case think of the suspension as a lever for the spring and wheel mounting points and realize, that the wheel sees an effective 400 lb * 0.8 = 320 lb. So it takes 320 lb to move the wheel 1”, hence an effective spring rate of 320 lb/in.
In essence we have multiplied the 500 by 0.8 twice, which is the same as writing 500 * (0.8)^2 = 500 * 0.64 = 320, which is where the square of the displacement ratio comes from.
I hope this helps more than confuses.
Laust
#45
Rennlist Member
Sorry to tune in late...
The front motion ratio is 0.91 and the rear is 0.63.
These are calculated by taking very careful measurements - I raised up the wheel exactly 1" and measured exactly how much the shock compressed.
Now, these measurements are probably a little different for early offset cars and cars with steel rear control arms...
The front motion ratio is 0.91 and the rear is 0.63.
These are calculated by taking very careful measurements - I raised up the wheel exactly 1" and measured exactly how much the shock compressed.
Now, these measurements are probably a little different for early offset cars and cars with steel rear control arms...