Spring rates: Some in measured in K some in LB/In ?

[Al Grain]

Broadway Static is recommending 14-16k range in rear and 8K in front for my e91. Stock rates are 195 lb/in and 505 lb/in. Any idea why there's different metrics?

All the other manufacturers use lb/in, any way to convert this for a better understanding of the rates?

KW v1-v3 (non M3)
Front: 190-256 lb/in (progressive average)
Rear: 545-570 lb/in (progressive average)

KW Street Comfort
Front: 286 lb/in
Rear: 572 lb/in

KW Clubsport (non M3)
Front: 400 lb/in
Rear: 570 lb/in

M3 KW v3
Front: 285 lb/in
Rear: 630 lb/in

M3 KW Clubsport
Front: 508 lb/in
Rear: 800 lb/in

Bilstein PSS10
Front: 385 lb/in
Rear: 615 lb/in

Eibach Pro-kit
Front: 148 lb/in
Rear: 456 lb/in

Eibach Multi-Pro-R1
Front: 200 lb/in
Rear: 500 lb/in

Eibach Pro Street S
Front: 134 - 271 lb/in (Progressive)
Rear: 456 lb/in (Linear)

HKS Hypermax
Front: 448 lb/in
Rear: 504 lb/in

Tein Stech
Front: 191 lb/in
Rear: 593 lb/in

Tein Euro Damper System
Front: 280 lb/in
Rear: 392 lb/in

Tein ss-p
Front: 392 lb/in
Rear: 671 lb/in

JIC-Magic Cross
Front: 450 lb/in
Rear: 674 lb/in

TC Kline Coils
Front: 350 lb/in
Rear: 700 lb/in

HP Autowerks Coilover System
Front: Custom Tailored 300-500 lb/in (Contact HP Autowerks)
Rear: Custom Tailored 500-1000 lb/in (Contact HP Autowerks)

What gives?

Thanks!

[Oh Damn, it's Sam]

k is shorthand for kg/mm, just the metric equivalent of lb/in. Just convert those numbers from lb/in to kg/mm and you're set.

[Al Grain]

Lets see if I remember how maths.

14 Kilograms = 30.8 Lb

25.4 mm in an inch

So 30.8 * 25.4 = 790ish

782 lb/in rear ?

8 Kilograms = 17.637 Lb

17.6 * 25 = 435ish

440 lb/in front

Am I in the right neighborhood? Sounds high.

[Oh Damn, it's Sam]

Looks correct to me.

I wonder why their setup is so stiff in the rear compared to the front? Seems excessive, but I don't know much about the E91.

FWIW, kg/mm * 56 ≈ lb/in, if that makes the maths easier.

[Tuck&Poke]

The E9X chassis needs very stiff rear springs because of the suspension geometry.

[Oh Damn, it's Sam]

The E9X chassis needs very stiff rear springs because of the suspension geometry.

I knew we'd have an answer in here in a minute

[Jesus Christ]

The E9X chassis needs very stiff rear springs because of the suspension geometry.

Correct. The car was made to squat from the factory for grip, which is great for racing but terrible for stance. This was accomplished by moving the components closer to the diff (as opposed to closer to the hubs on previous 3 series models) which makes even the stiffest springs feel soft in comparison to another chassis. The F chassis cars are the same.

I'm not sure what your needs are OP, but I really enjoy 14-16k front and 20k rears on the e9x and e8x chassis.

[kathi]

nice car i like it ,,,