Spring Rates

[oldroydsr4]

Hi all,

I found this on the e30 tech forum.

Thought it may help a few guys here




Spring---------------------Front(lb/in.)-------------Rear(lb/in.)

Stock 325i*-----------------------106------------------------245
Stock 325is*----------------------118------------------------265
Stock 325ix*----------------------106------------------------308
Stock M3*-------------------------114------------------------314
Stock M3--------------------------140------------------------250
Dinan Sport-----------------------172------------------------300
H&R OE Sport---------------------180------------------------380
H&R Sport-------------------------180------------------------380
H&R Sport (29664)---------------200------------------------285
H&R Race-------------------------315------------------------ 570
H&R Coilovers***----------------340------------------------380
Eibach Pro-Kit--------------------102-------------------------277
Eibach Race----------------------160-------------------------445
Ireland engineering SIII--------315-------------------------570
Koni Coilovers-------------------342-------------------------407
Cosmo Coilovers----------------450-------------------------560
Tokico----------------------------165-------------------------265
TMS J-Stock**-------------------680------------------------1026
Alpina(est.)---------------------~200-----------------------~350
FK 60/60 cup kit-----------------379--------------------------379
Vogtland Standard***--------115/197-----------------------360
Vogtland CS***---------------137/200-----------------------400
Vogtland--------------------------225--------------------------360
Intrax-----------------------------126--------------------------250

[robzilla323]

so what would spec i need for a touring just for track day, not for road at all but firm enough for a good track day car.

[Morat]

There was also some debate on that thread as to whether the Eibach-Pro rates are correct, or if they have changed since the list was compiled....from the reports on this forum there isn't a lot to choose between the HnR and Eibach, but the spring rates seem to be significantly different on the list.

[UweM3]

so what would spec i need for a touring just for track day, not for road at all but firm enough for a good track day car.

how long is a piece of string??
What you may class as firm might be soft for somebody else.
For a track car only I wouldn't even start under 500lbs front.
What is the rest of the car like? Stripped, cage, brakes, tyres?
Your driving level/experience? Makes no sense to fit all out track suspension if you are still on the learning curve. Much more fun if you have suspension suitable for your driving experience.

[UweM3]

There was also some debate on that thread as to whether the Eibach-Pro rates are correct, or if they have changed since the list was compiled....from the reports on this forum there isn't a lot to choose between the HnR and Eibach, but the spring rates seem to be significantly different on the list.

I had some Eibach-Pro measured and they are 100lbs front and 277lbs/inch rear.
My M3 springs showed 100/280 on the spring Dyno.
At the moment I am running the softest Grp N spring rates 680/1030

[Jhonno]

The H&R's are known for being harder than the Eibachs

[UweM3]

The H&R's are known for being harder than the Eibachs

for occasional for track days and still be ok on he road setup I would use H&R race as well. Feels roughly the same as what you are driving right now. Don't know if you can get H&R race here or US only

[march109]

There was also some debate on that thread as to whether the Eibach-Pro rates are correct, or if they have changed since the list was compiled....from the reports on this forum there isn't a lot to choose between the HnR and Eibach, but the spring rates seem to be significantly different on the list.

Problem being manufacturers change spring rates withought feeding the info on, how often do most people actually ask the spring rates whem they purchase springs? most are looking to get the car lowered not actually handle any better or get scientific about it.

I believe different markets got springs marketed under the same names in different rates too.

As Uwe has done testing is the only sure fire way of knowing what your running.

[robzilla]

so if i was going to get some made could i use the tms j stock as a starting point (would i need to have the rears different from a saloon) and see from there, the car will be stripped and slicks with a cage, don't want to fork out on coilovers yet as they are still very expensive.any other thoughts?

[UweM3]

so if i was going to get some made could i use the tms j stock as a starting point (would i need to have the rears different from a saloon) and see from there, the car will be stripped and slicks with a cage, don't want to fork out on coilovers yet as they are still very expensive.any other thoughts?

make your own coilovers and buy 60mm springs. But for such hard springs you average Bilstein damper won't do it.

[Timbopbmw]

Christ i run 550lbs on my pbmw 318!

[Lloydie38]

On my 325 track car weighing 1020 I have the Bilstein sprintline kit - BUT because the car is lightened it sit's higher up than originally intended. It handles well but could handle better I'm sure if lowered further on quality springs...

Any advice which springs though..?

See below description of the above springs

Bilstein Sprintline Suspension Kit. Lowers by 40mm approx.
40mm

Car fitment
BMWType E30 323i/324 TD/ 325i. From: 10/82 > 12/90
The Sprintline kit consists of four Bilstein uprated Sports shock absorbers complete with lowered sports springs. These kits are individually developed for each model of car. Improving handling whilst maintaining excellent ride quality.

Please Note:
Bilstein Sprintline Kits contain yellow Apex Sport Springs.

[robzilla]

how would i go about building my own coilovers?? what shocks do i need to get if was going to change springs?

[UweM3]

how would i go about building my own coilovers?? what shocks do i need to get if was going to change springs?

how I did mine http://www.e30zone.net/modules.php?name ... highlight=

handpaper made a good conversion too. Used GAZ rear shocks which I think is a good idea with DIY converted front struts
Click here http://www.e30zone.net/modules.php?name ... highlight=

[superunknown]

any info on the spring rates for Apex?

[billgatese30]

Super unkown - Please reduce the size of you avatar please, it is currently far too large

Thanks

Chris (E30Zone Team)

[Rusty_McRusty]

I emailed Apex about their springs and got supplied with the following rates for a 318is ( P/ No. 20-1020)

29 N/mm front (166 lb/in)
52 N/mm rear (297 lb/in)

I have also been informed that the X Low kit (-60mm) is about the same stiffness, it just requires shortened shocks.

For a 6 I would assume slightly stiffer at the front in line with HnR

29663 - 4 pot - dia. 12mm front - 6 coils
29664 - 6 pot - dia. 12.5mm front - 6 coils

Both use dia 13.5mm rears - 6.5 coils

http://www.h-r.com/includes/download.ph ... /29663.pdf

http://www.h-r.com/includes/download.ph ... /29664.pdf

[Rusty_McRusty]

Eibach springs also show the information for their springs

http://performance-suspension.eibach.de ... ld=abe_www

Of note here is that there is an extra coil when compared to the H&Rs (7 vs. 6) and so they are ~15% softer up front but similar at the rear. As they are both progressive springs things get a little more complex (no. of close bound coils, deflection to rate change etc.) but until all the close coils are bound, that will be true.

Obviously more than spring wire diameter is required to calculate spring rate but it's a good comparison and does agree somewhat with the information up top.

[Rusty_McRusty]

HnR have confirmed that their 29663 springs (4 pot version of 29664 in post 1) are

Front - 33 N/mm = 188 lb/in
Rear - 50 N/mm = 286 lb/in

(@ 1 N/mm = 5.71 lb/in)

[Rusty_McRusty]

And for completeness, Eibach have confirmed that their spring rates for the 318is are

Front - 20 N/mm - 114 lb/in
Rear - 46 to 57 N/mm - 262 to 325 lb/in

I have gone for Apex springs now as I wanted a more aggressive setup than the Eibachs.

[zaust]

Has anyone worked out a good spring rate for the front with an m30 fitted, I have been told a figure but I think it is way to much. Looking at 70 kg over the normal fitted m20.

[UweM3]

And for completeness, Eibach have confirmed that their spring rates for the 318is are

Front - 20 N/mm - 114 lb/in
Rear - 46 to 57 N/mm - 262 to 325 lb/in

I have gone for Apex springs now as I wanted a more aggressive setup than the Eibachs.

hmmm, I had a BRAND NEW Eibach spring measured and it was linear 100lbs (for 318!)

[Rusty_McRusty]

Just relaying what Germany quoted. Perfectly possible that there are many different springs and the 318is is different to the 318 on the system, either way it's a lot less than the HnRs or Apex springs and it does show when pressing on, would indicate to me that the Eibachs are more for style and cruising than spirited driving.

[UweM3]

Just relaying what Germany quoted. Perfectly possible that there are many different springs and the 318is is different to the 318 on the system, either way it's a lot less than the HnRs or Apex springs and it does show when pressing on, would indicate to me that the Eibachs are more for style and cruising than spirited driving.

There are only two different E30 springs from Eibach. 4 cylinder or 6 cylinder.

the spring rate was the reason I sold the Eibachs, very good for a road car with a little bit lowering desired but not good for track work IMHO.
I was glad I got them measured before fitting, saved an aweful lot of time.

[Rusty_McRusty]

Ar, we're in agreement there, too soft for play time.