How Do I Tell What My Spring Rates Are?

[cowie165]

Brilliant! Thanks Gary

Hi Mark; results as follows;

88/76 X 12 X 10.125 =  170 lbs per inch

98/66 X 12 X 7 = 270 lbs per inch

Cheers

[ferni]

That means the 70mm/95mm is ID not OD?

No coil plant I know of makes 12.5mm spring steel wire, are you sure it's not 12 mm or 13 mm?

If it is 95 and 70 ID and 12.5 mm then;

95/70 X 12.5 X 7.25 = 300lbs per inch

cheers

<{POST_SNAPBACK}>

Hi SK,

Sorry your right its meant to say ID not OD.

I used your spanner trick, the 12mm wouldn't fit on, and the 13mm fit on too easy, with a bit of gap, so i guessed 12.5mm.

If it is 300lb per inch, how does that compare to what you recommend for an R33 GTR daily driven, but trackeda few times a year.

[Sydneykid]

Hi SK,

Sorry your right its meant to say ID not OD.

I used your spanner trick, the 12mm wouldn't fit on, and the 13mm fit on too easy, with a bit of gap, so i guessed 12.5mm.

If it is 300lb per inch, how does that compare to what you recommend for an R33 GTR daily driven, but trackeda few times a year.

<{POST_SNAPBACK}>

Sometimes the thickness of the paint takes it 0.2mm over the actual wire size, so I reckon 12 mm might be the go. That would make the spring rate 255 lbs per inch. Which is OK for a road GTR front and the occasional track day.

Cheers

[twisted]

SK could you please calculate these for me.

Top ID: 88mm

Bottom ID: 78mm

Thickness: 12mm

# turns: 9.125

Top ID: 98mm

Bottom ID: 68mm

Thickness: 12mm

# turns: 8.5

Also without getting under the car to take measurements, would you know the spring rate for king springs, kdrl-102 and kdfl-101? Just trying to decide if i should trial the above springs in my 32 with biltein shocks instead of the kings. What spring rate would suit a daily driver driven with much enthusiasm?

Any help would be greatly appreciated. Cheers.

[Sydneykid]

SK could you please calculate these for me.

Top ID: 88mm

Bottom ID: 78mm

Thickness: 12mm

# turns: 9.125

Top ID: 98mm

Bottom ID: 68mm

Thickness: 12mm

# turns: 8.5

Also without getting under the car to take measurements, would you know the spring rate for king springs, kdrl-102 and kdfl-101? Just trying to decide if i should trial the above springs in my 32 with biltein shocks instead of the kings. What spring rate would suit a daily driver driven with much enthusiasm?

Any help would be greatly appreciated. Cheers.

<{POST_SNAPBACK}>

88/78 X 12 x 9.125 = ~185 lbs per inch

98/68 X 12 X 8.5 = ~200 lbs per inch

Not much different to the Kings spring rates, don't think you will notice it.

cheers

[twisted]

Cheers SK, thanks for the help

[Sydneykid]

Can we make this thread a sticky, please. It seems to be a big help to the guys and it drops off the page very quickly.

Thanks

Cheers

[Chris32]

Can you work this one out for me?

Front

Top outside: 81.25mm

Bottom outside: 81.25

Thickness: 11.90

# turns: 6.5

Rear

Top outside: 84.25mm

Bottom Outside: 84.25

Thickness: 12.6

# turns: 8.5

Thanks,

Chris

[Sydneykid]

Can you work this one out for me?

Front

Top outside: 81.25mm

Bottom outside: 81.25

Thickness: 11.90

# turns: 6.5

Rear

Top outside: 84.25mm

Bottom Outside: 84.25

Thickness: 12.6

# turns: 8.5

Thanks,

Chris

<{POST_SNAPBACK}>

Hi Chris,

The front is a 2.5" race coil, unlikely to be 11.9 mm, 12 mm is closest.

If so the spring rate is 750 lbs per inch (13.5 kg/mm)

The rear is also a 2.25" race coil, unlikely to be 12.6 mm, most likely 1/2" (12.5 mm).

If so the spring rate is 600 lbs per inch (10.8 kg/mm)

cheers

Edited October 17, 2005 by Sydneykid

[Chris32]

Hi Chris,

The front is a 2.5" race coil, unlikely to be 11.9 mm, 12 mm is closest.

If so the spring rate is 750 lbs per inch (13.5 kg/mm)

The rear is also a 2.25" race coil, unlikely to be 12.6 mm, most likely 1/2" (12.5 mm).

If so the spring rate is 600 lbs per inch (10.8 kg/mm)

cheers

<{POST_SNAPBACK}>

Cool, thanks

I would say you are right about the thickness of the coils, as they are powder coated etc

This is what I had on the car and will be replacing with the group buy kit. They are pretty firm on the road, hopefully the new suspension will be a bit more daily driver friendly. Not to mention, that its pretty hard to get grip on the rear with springs that firm, and with the ride hide down at 308mm!!

How will the group buy spring rates compare (don't need exact rates, just would be nice to know what to expect, PM me if you don't want it to be public knowledge)

[Sydneykid]

Cool, thanks

I would say you are right about the thickness of the coils, as they are powder coated etc

This is what I had on the car and will be replacing with the group buy kit. They are pretty firm on the road, hopefully the new suspension will be a bit more daily driver friendly. Not to mention, that its pretty hard to get grip on the rear with springs that firm, and with the ride hide down at 308mm!!

How will the group buy spring rates compare (don't need exact rates, just would be nice to know what to expect, PM me if you don't want it to be public knowledge)

<{POST_SNAPBACK}>

Pretty firm :lol: :lol: :lol:

They are almost 3 times what the Group Buy spring rates are. And they are pretty sporty, with reasonable comfort.

Cheers

[Chris32]

Good to hear, I am looking forward to getting them now!

[GTRgeoff]

Just measured up the "you-know-whats" mate and have the following

Front

OD top 126mm

OD bottom 94mm

13.4mm wire

8.75 turns

no signs of stack contact, ovoid taper to the bottom with the last 3 making most of the taper.

Rear

OD top 126mm

OD bottom 117mm

Wire top 5.25 turns at 11.7mm signs of contacting

Wire bottom 4.25 turns at 13.8mm

Ouch

Let me know if you think you need more detail. Shocks were fully soft on adjustment.

[Sydneykid]

Just measured up the "you-know-whats" mate and have the following

Front

OD top 126mm

OD bottom 94mm

13.4mm wire

8.75 turns

no signs of stack contact, ovoid taper to the bottom with the last 3 making most of the taper.

Rear

OD top 126mm

OD bottom 117mm

Wire top 5.25 turns at 11.7mm signs of contacting

Wire bottom 4.25 turns at 13.8mm

Ouch

Let me know if you think you need more detail. Shocks were fully soft on adjustment.

<{POST_SNAPBACK}>

Front = 290 lbs per inch

Rear = 100/555 lbs per inch

Progressive, the 11.7/5.25 coil is 100 lbs per inch and when it closes up completely (coil bind) the spring rate jumps to 555 lbs per inch (the rate of the 13.8/4.25 coil). Now that is ugly, my back aches just thinking about it.

cheers

[GTRgeoff]

Cheers mate. I was a bit shocked when I measured the rears to find such a huge rate imbalance front - rear. All still looks in good condition and maybe ok for regular track but the GTR is less track and more daily driver.

Suddenly all these rattles and squeaks have disappeared

[Sydneykid]

Suddenly all these rattles and squeaks have disappeared

<{POST_SNAPBACK}>

I can imagine

cheers

[neil_se]

Hi Gary, i think i measured these right, but i could be horribly wrong too.

Apexi N1 Pro coilovers if that helps.

FRONT

Wire OD= 12mm

Coil OD=90mm

# Turns=5

REAR

Wire OD=12mm

Coil OD=90mm

# Turns=7.2

Thanks.

Edited October 23, 2005 by neil_se

[Sydneykid]

Hi Gary, i think i measured these right, but i could be horribly wrong too.

Apexi N1 Pro coilovers if that helps.

FRONT

Wire OD= 12mm

Coil OD=90mm

# Turns=5

REAR

Wire OD=12mm

Coil OD=90mm

# Turns=7.2

Thanks.

<{POST_SNAPBACK}>

90-12-12 = 66 X 12 X 5 = 790 lbs per inch

90-12-12 = 66 X 12 X 7.2 = 460 lbs per inch

Oh my..............

cheers

[MerlinTheHapyPig]

90-12-12 = 66 X 12 X 5 = 790 lbs per inch      

90-12-12 = 66 X 12 X 7.2 = 460 lbs per inch  

Oh my..............

cheers

<{POST_SNAPBACK}>

could be worse.... have you seen the sort of spring rates some of the japanese D1 drivers are using??

http://maxe.ausgamers.com/d1gp/imamura_.jpg

http://maxe.ausgamers.com/d1gp/maeda_.jpg

http://maxe.ausgamers.com/d1gp/suenaga_.jpg

18k / 16k.....

anyway, back on topic.

won't different materials have different densities? If you are using the formula I think you're using, you need to use a modulus of rigidity, which is different for different materials.

[GTRgeoff]

But Youngs Modulus remains about 200GPa for Steel. Titanium alloys are from 100-110GPa.