How Do I Tell What My Spring Rates Are?

[Sydneykid]

hey Sk, can you please calculate my spring rate

front

Coil ID: 69mm top & bottom

Wire ID: 12.5mm

# of coils: 9.0 evenly spaced

335 lbs/inch (6.0 kg/mm)

rear

Coil ID: 71mm top & bottom

Wire ID: 11.5mm

# of coils: 9.125 evenly spaced

245 lbs/inch (4.4 kg/mm)

Thanks heaps

Cheers

Gary

[9krpm]

Thanks Gary

[Dan_J]

after rates for these

Coil ID = 60/60 mm

Wire OD = 10 mm

# of Coils = 6.5 turns

thanks SK

no chance a simple excel doc can be made to make calculating easier on yourself and quicker for use?

Edited August 4, 2009 by Dan_J

[Sydneykid]

after rates for these

Coil ID = 60/60 mm

Wire OD = 10 mm

# of Coils = 6.5 turns

thanks SK

350 lbs/inch (6.3 kg/mm)

no chance a simple excel doc can be made to make calculating easier on yourself and quicker for use?

Nope, the formula is complex and requires some knowledge to use correctly. Plus it took many years to perfect, so no one is going to give away that sort of intellectual property.

Cheers

Gary

[Luke@WSP]

after rates for these

Coil ID = 60/60 mm

Wire OD = 10 mm

# of Coils = 6.5 turns

And just for shits and giggles, the length of steel required for that spring would be 1.44meters

Edited August 26, 2009 by Luke@WSP

[warps]

I'm curious to see how you work out the spring rates, Gary. I have a spreadsheet (derived from my engineering text books many years ago) which I use successfully, and it gives me much lower values than what you're quoting. Also, I note a few people have given you the spring OD, rather than the ID.

Not having a go at all. Yes, the formula is complex to the layman, but there aren't a lot of variables that can change. The modulus of rigidity is the only variable that can change, and that is pretty constant for carbon steels and alloy steels (although Stainless is different, but I don't think many of us use stainless springs, do we?)

I've just checked my calcs on two springs i have here, whose rates I know (from catalogues and shop manuals) and my calcs were very close with both of them (in fact my numbers were a bit on the high side if anything)

Also, I haven't read the ful 18 pages of this thread, but you should use the number of ACTIVE turns of the spring, not the total number of turns. That is, the number of turns that aren't in contact with the spring seat, as the metal in contact with the spring seat doesn't actually do anthing.

Again, not having a go at all, just interested to hear some real world experience. I'm happy to take this to PM, as I'm not one to try and jeopardise your business.

So you know I'm not just another internet hack, I'm a qualified mechanical engineer, with over 20 years experience and run my own consulting company. No, I don't design or make springs for a living, but have had to do several spring calculations to confimrm the correct operation of products I've been involved with over the years (most recently a major claim against a manufacturer who supplied some spring operated brakes that weren't performing to spec)

[Sydneykid]

I'm curious to see how you work out the spring rates, Gary. I have a spreadsheet (derived from my engineering text books many years ago) which I use successfully, and it gives me much lower values than what you're quoting. Also, I note a few people have given you the spring OD, rather than the ID.

Yep, just take the diameter of the wire away twice from the OD and you get the ID. But you know that so, you were just testing me right?

Not having a go at all. Yes, the formula is complex to the layman, but there aren't a lot of variables that can change. The modulus of rigidity is the only variable that can change, and that is pretty constant for carbon steels and alloy steels (although Stainless is different, but I don't think many of us use stainless springs, do we?)

Yep, but dead coils, sacrificial coils, progressive wire diameter, conical coils, beehive shapes etc all make the inputs complex. As you know the skill and experience is realy needed in the input, not so much in the formulas themselves.

I've just checked my calcs on two springs i have here, whose rates I know (from catalogues and shop manuals) and my calcs were very close with both of them (in fact my numbers were a bit on the high side if anything)

OK

Also, I haven't read the ful 18 pages of this thread, but you should use the number of ACTIVE turns of the spring, not the total number of turns. That is, the number of turns that aren't in contact with the spring seat, as the metal in contact with the spring seat doesn't actually do anthing.

Yep

Again, not having a go at all, just interested to hear some real world experience. I'm happy to take this to PM, as I'm not one to try and jeopardise your business.

All I am doing is offering a no cost service in my spare time, not that there is a lot of that available. The only reason I have been doing it for over 4 years, is because I just hate guys guessing or not knowing their spring rates

So you know I'm not just another internet hack, I'm a qualified mechanical engineer, with over 20 years experience and run my own consulting company. No, I don't design or make springs for a living, but have had to do several spring calculations to confimrm the correct operation of products I've been involved with over the years (most recently a major claim against a manufacturer who supplied some spring operated brakes that weren't performing to spec)

Excellent, we should catch up somewhere, have a beer (or, as the guys know, a Jack Daniels for me) and talk technical.

Just so you know I'm also not another internet hack, I have been working with suspension on race cars for over 30 years (yes, I am that old), I hold a diploma, a degree and a masters. I designed the first 400 coil spring part numbers to start, from scratch the Whilteline Springs program in the late 90's. I actually have no idea on the number of swaybar designs that I have engineered, maybe 600 or so. I also, again started from a zero base, the Whiteline alignment products range, including the first ever caster/anti lift kits for WRX's. I worked for Jaguar for 5 years as Motorsport Manager including the successful 1984 and 1985 Bathurst campaigns. I was with the Holden Dealer Team at Bathurst in 1979 which Brocky won by 6 laps. I was also in the team in 1980 when he won by only 1 lap. Just to show the old guys still has it, earlier this year I was Team Manager and Race Engineer at the Bathurst 12 Hour where we came 1st and 2nd in Class. That'll do, I could go on for pages, best to stop now.

I'm serious about the catch up and a drink

Cheers

Gary

[aDrew_C]

I got some springs which have markings on them 62 180 008 and 62 200 006, now from measuring the first two relate to IN Dia and height respectively in mm, so the last numbers I'm guessing refer to spring rate (8kg/mm and 6kg/mm), which is not what these springs were meant to be.

My measurements are:

FR:

Coil ID top and bottom - 62mm

Wire OD - 11mm

# of Coils - 6.5

RR:

Coil ID top and bottom - 62mm

Wire OD - 11mm

# of coils- 7.5

The # of coils depends how you look at it but this is close enough to give me a good idea of whether I was sent the right springs or not. Thanks for any help Gary!

[lawler]

165 lbs/inch (3 kg/mm R33 front standards)

Cheers

Gary

Any idea what they would be with a coil cut off them?

also dose anyone have the measurement or specs of whiteline r31 springs? then I need to know what the spec would be with a coil cut off them

Plz no one flame about cutting coils being dodgy and to just buy good springs. there's a good reason for me to be asking.

I didnt cut them but they seem to be a good rate so I want to know what specs to be after when/ if I change

Edited November 29, 2009 by lawler

[loffe]

You can try play with this...

Lofa_Springrate.xlsx

One tricky thing is how many active turns the feather really has.

Edited January 11, 2010 by loffe

[Dan_J]

once again i'm after rates

Coil ID - 60mm

Wire OD - 12mm

# of Coils - 8

thanks

[R32Abuser]

From what I can tell, Sydneykid no longer operates regularly on these forums. Hence all the rates which have been asked have been left unanswered.

Using the engineering text books I have and used to build racecar suspension, I can calculate you rates. If you need a quick answer, just send me a PM and Ill plug it into my spreadsheet and give you an answer as quick as possible.

For example:

Dan J

Using the inputs you gave me the spring rate is 7.08 kg/mm or 396.5 lb/in

Cheers,

David

[stimps]

Ok ive read most of this thread, luv it, and i am looking for advice.

Got a r32 gtst, very hard, very low. Im looking for a good set of new coilovers, for the whole cars springs and all.

The rides too hard, the shocks are shagged,

Decided im getting beilstens but as for the springs, have no idea what to ask for.

I want a soft ride! City driving, brissys shit streets, no track.

So what is stock spring rates for this car??

[stimps]

Awww comon

[Rolls]

Ok ive read most of this thread, luv it, and i am looking for advice.

Got a r32 gtst, very hard, very low. Im looking for a good set of new coilovers, for the whole cars springs and all.

The rides too hard, the shocks are shagged,

Decided im getting beilstens but as for the springs, have no idea what to ask for.

I want a soft ride! City driving, brissys shit streets, no track.

So what is stock spring rates for this car??

I would aim for ~4kg max at the front for a street car, rear I am not too sure, fix your roll with sway bars, not stiffer springs. Perhaps post a thread asking this specific question as I don't think many people still read this thread.

Also don't lower the car too much, it stuffs up the geometry.

Edited June 27, 2011 by Rolls

[sonoramicommando]

I have this Tein S Tech spring instruction (in Japanese), from what I can tell, it lists both front & rear as 2.2. (c.f. S tech soft, front 2.9-3.2 & rear 2.2-2.9 and medium 2.8-4.2 & 1.8-3.6)

[TrikkBen]

SydneyKid, are you still doing this?

If so I would like to no roughly what my rates are.

Just Fronts at this stage. Done in-car so sorry for the OD measurements.

Wire OD - 12.28mm

Top of Coil OD- 127.7mm

Bottom of Coil OD- 90.61mm

Starts to taper smaller at the 5th coil down.

No. of Coils- 9.125

Also, seeing as I have read a few other suspension threads and you seem to be the "guru", would you mind looking at these pictures and telling me if its Mono tube and also are those grooves under the seat the circlip grooves I have read about?

Also there's a reference picture there for the Coil taper.

Whole Strut.

http://i888.photobuc...en/be1c40df.jpg

Taper.

http://i888.photobuc...en/3360d864.jpg

Grooves?

http://i888.photobuc...en/0cf19255.jpg

Thanks SK

Ben

Edited February 1, 2012 by TrikkBen

[TrikkBen]

Bumpage? No SK anymore?

[R32Abuser]

SydneyKid, are you still doing this?

If so I would like to no roughly what my rates are.

Just Fronts at this stage. Done in-car so sorry for the OD measurements.

Wire OD - 12.28mm

Top of Coil OD- 127.7mm

Bottom of Coil OD- 90.61mm

Starts to taper smaller at the 5th coil down.

No. of Coils- 9.125

Also, seeing as I have read a few other suspension threads and you seem to be the "guru", would you mind looking at these pictures and telling me if its Mono tube and also are those grooves under the seat the circlip grooves I have read about?

Also there's a reference picture there for the Coil taper.

Whole Strut.

http://i888.photobuc...en/be1c40df.jpg

Taper.

http://i888.photobuc...en/3360d864.jpg

Grooves?

http://i888.photobuc...en/0cf19255.jpg

Thanks SK

Ben

Ill calculate your spring rates when I get home. At work and my spreadsheet etc. is not on this computer.

[TrikkBen]

Awesome mate thank you.

Ben