BC coilover spring rate questions

[1Willy1]

Hey guys , the stock suspension on my 05 is horrible, the stock ride height is way too high also ,a set of coilovers is needed bad and I plan to order tomorow

Anyone here on bc coilovers or other coilovers and if so what spring rates did you use ?

The Bc Comes stock with 10k front and 12k rear as far as I know , I'm wondering if I should go slightly stiffer , maybe 12k and 14k?

I'm not tracking the car just street cruising

Thanks in advance guys

[Steve M]

Whatever you end up doing, the shock valving needs to be able to handle the spring rate chosen. If you go with too heavy of a spring, the shock won't be able to control it, and the ride will suffer accordingly.

Not apples to apples, but a data point: Mark Jorgensen did a 500/800 pound per inch (front/rear) split for the MCS shocks currently on my car.

That comes out to roughly a 9k front, 14k rear if you go by their preferred spring rate units.

For those wondering, 1k = 1 kg/mm of spring rate. To convert to pounds per inch, multiply the "_"k value by 55.88 (25.4 mm per inch, 2.2 pounds per kilogram).

9k = 502.92 lb/in
14k = 782.32 lb/in

I've been very happy with those rates on my Gen 4, but that's mostly because the shocks can easily handle them. I'm not sure about the limits of the BC coilovers.

[SRT_BluByU]

considering the similarities in chassis between gen 3, 4 and 5. do you think it owuld be a good idea to looks at the latest design setups as a starting point? If you dont have significant aero maybe the TA 1.0 setup might be something to consider for spring rates?

[Ramtuff]

The stock BC rates will be just fine and be much improved from the factory setup. Others have found the 14k to be a little stiff for the street.

[Aevus]

Hey guys , the stock suspension on my 05 is horrible, the stock ride height is way too high also ,a set of coilovers is needed bad and I plan to order tomorow

Anyone here on bc coilovers or other coilovers and if so what spring rates did you use ?

The Bc Comes stock with 10k front and 12k rear as far as I know , I'm wondering if I should go slightly stiffer , maybe 12k and 14k?

I'm not tracking the car just street cruising

Thanks in advance guys


I would highly recommend to buy the Swift spring upgrade. Better ride and better handling. I compared both standard BC's and Swift and it's an excellent upgrade option.

[Aevus]

Whatever you end up doing, the shock valving needs to be able to handle the spring rate chosen. If you go with too heavy of a spring, the shock won't be able to control it, and the ride will suffer accordingly.

Not apples to apples, but a data point: Mark Jorgensen did a 500/800 pound per inch (front/rear) split for the MCS shocks currently on my car.

That comes out to roughly a 9k front, 14k rear if you go by their preferred spring rate units.

For those wondering, 1k = 1 kg/mm of spring rate. To convert to pounds per inch, multiply the "_"k value by 55.88 (25.4 mm per inch, 2.2 pounds per kilogram).

9k = 502.92 lb/in
14k = 782.32 lb/in

I've been very happy with those rates on my Gen 4, but that's mostly because the shocks can easily handle them. I'm not sure about the limits of the BC coilovers.



Had BC racing standard 10/12kg spring rates on my '05 and recently upgraded to 12kg front and 14kg rear, the max before the need to revalve dampers. However I think I should get my rear damper revalved anyway, it's clearly a limiting factor now so I wouldnt recommend pushing it too far with the stock valves.

I'd do now a 13/16kg but with proper valves and Swift springs of course. That being said, if you don't track your car stick with 10/12 spring rates or so. Won't feel/handle as good but will be comfier. Also consider what kind of tires you'll use...

[Aevus]

The Bc Comes stock with 10k front and 12k rear as far as I know , I'm wondering if I should go slightly stiffer , maybe 12k and 14k?

I'm not tracking the car just street cruising



If you don't track, just the usual spirited driving, the solution is very simple: BC racing + Swift springs upgrade 10/12kg rates + ACR solid sway bars front & rear + IPSCO billet sway bar bushings.

You will pretty much keep all the ride quality and comfort while having lots of fun on the street.

[1Willy1]

Thanks guys , really glad to hear some good replies

I heard great things about swift springs on other forums but the cost of everything here in Canada is nearly doubled , $1200 usd for coilovers there is about $2000 here once I I clude duties , exchange and shipping fees

If the consensus is that the standard 10 and 12k rates are good enough i may go with that

Again I'm not a 5rack guy and as long as they improve the ride and allow me to lower the car an inch or two I'm happy with that

Just didnt want to end up with a soft bouncy ride or some other issues.

[Aevus]

I'm from Canada too and I ordered directly from bcracing-na.com without problem, and the exchange rate is very good at this moment.

The standard springs that comes with the coilovers kit is the weakest point. It's exactly bouncy. The car itself is somewhat bouncy so anything that improves the suspension is usually very appreciated.

Bytheway, if interested I can sell you my whole kit: 4x standard 10/12 springs + 4x Swift 12/14 springs with dampers since I will order revalved ones with higher spring rates. They're used but excellent condition.

[1Willy1]

Hey Aevus

I sent you a pm about your coilovers ������������������

[1Willy1]

hey guys, i ordered a set of 12k and 14k coilovers from BC

im not a mechanic but got tools and can do basic work, do you think this is a job that is easily DIY'able?

[Steve M]

hey guys, i ordered a set of 12k and 14k coilovers from BC

im not a mechanic but got tools and can do basic work, do you think this is a job that is easily DIY'able?

Easily DIY.

Righty tighty, lefty loosey. Don't be afraid to remove extra stuff to make your life easier (like the fender liners in this case).

[John L.]

How do you like the 12k front and 14k rear on the street? I can’t decide if I should do the same or go with 10k-12k for the street. Thanks!

[Aevus]

it's great but take the SWIFT springs option, not the standard BC racing ones.
Will post for sale my kit soon bytheway, I am installing my Penske double in few weeks

[proedge]

I installed the BC racing BR series coilovers with the 62-160-10 Front Spring Rate and 62-180-12 Rear Spring Rate., I didn't opt for the Swift springs. I found the ride greatly improved over stock. I set the shocks based on others' recommendations

[Aevus]

How do you like the 12k front and 14k rear on the street? I can’t decide if I should do the same or go with 10k-12k for the street. Thanks!

going to 12/14kg from 10/12kg per mm of travel is not that huge of a difference. If you want to feel what the difference might feel like, just change your tire pressure by 4-5 psi up and you'll feel, more or less, what kind of firmer ride you'll experience.

Going with even stiffer springs, though, that's another story. I've decided to go to 13.4kg (750lbs) front and 17kg (950lbs) rear, which is probably the absolute limit for a street driven car with minimum creature comfort, and I wouldnt do that with the somewhat entry-level quality of the BC racing shocks.

But 12/14kg with the Swift brand springs, it's very decent. Better quality Swift springs gives better control so it's firmer but smoother at the same time. And of course, more predictable and better handling in general.