Hope someone can help out... So much good info on the forums here... but search came up nill for me on this topic.

Looking for SPRING RATE numbers for F&R on the stock/OEM front and rear coil springs.

Many of the coilovers are running 7Kg/mm front 5K rear, some run 5k/5k (My current Stance).... 6.12kg/mm/5.1 (Ohlins R&T's), GodSpeed 6K/6K,

For me.... seems it should be a lower spring rate in the rear (like on the Ohlins)

Seems no-one is giving travel, free-length or coil-bind measurements... and I've yet to see a graph of the progressive spring rate curves.

On the uprated/lowered stock replacement springs (non coilover) ... Super strange to me... Swift Spec-R springs for the R53... are 5.0Kg/mm front, 5.5 Rear... I'm SUPER surprised by the rear rate being higher even though It is much lighter in the back.... and you'd have to have no legs or be a child to ride in the back seat... Maybe they are trying to cover bases with the Cabrio cars??

Other uprated/lowered stock replacement springs AST.... 4.6Kg/mm front, 4.1 Rear ... Megan 2.73kg/mm front 3.74 rear (WTH??)

These rates are all over the place... hmmm.

Many don't provide ANY info other than very loose "range" of drop.... without rate etc info... some have same springs for Cabrio and Hardtops.... which I find disappointing.

The amount of 'drop' in the ride height really has little to tell me about the ride 'character' and handling improvements I could expect in buying these products.

Hmm ... Leaves me pondering.






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Funny... Search came up with nothing... but the "Related topics" at the bottom here came up with some info AFTER I posted this thread??



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Seems the rates on the R53 are 165lb/in... OR 2.9 kg/mm.
TSW....
155-165 lb/in => 2.8 kg/mm - 2.95 kg/mm
*200 lb/in => 2.58 kg/mm
And then this good article from TXW.
https://www.motoringalliance.com/art...gs-review.102/
Has them spec'ing out 4 kg/mm front 4.81 rear...but for an R56
MORE on the rear
I wonder if the rear is higher rate to run with stock REAR 17mm swaybar or NO swaybar at all??

 

Is the TSW spring the ONLY linear rate STOCK REPLACEMENT (non coilover) spring kit on the market? (I know it lowers the car a bit)









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you want higher in the rear anyway, that's why everyone puts a big stiff rear bar in.

I run 8kg/mm in front 9kg/mm in rear, swift springs

 

Very interesting your rear is 12.5% higher than front. Your springs are 60% stiffer than my Swift Sport Springs. Mine are 5kg/mm front and 5.5 kg/mm rear. So similarly the rear is 10% stiffer than the front. I chose them at the time thinking I would be using them mostly street driving and occasional track. But I would discover track is so fun.



At their rates the ride is a bit jaunting compared to the stock S but quite fitting for this car. I thought I way outgrown the Koni Yellow and Swift Sport Springs but so far I am still the limiting factor. I know a set of good coilovers would eventually inevitable.

It seems to be the lower spring rate actually helps to alleviate the camber constraint of the front in my case.

 

Old thread I know but just posting as a reference for the rear springs:

R53 S228A SS+ 33536758356 255x10.75x103
Spring Rate (or Spring constant), k : 28.084 N/mm
Loaded Height 176.8526mm

R56S S226A SS 33536772780-1 246x11.25x106
Spring Rate (or Spring constant), k : 31.750 N/mm
Loaded Height 176.8753mm

I've done some rough calculations and from what I can see the R56S uses stiffer rears and softer fronts when compared to the R53. The roll bar on the rear is also increased by +1mm, +1.5mm on GP2/FJCW suspension cars (JCW suspension is now SS+, option S228A). The roll bar up front is thinner but then it's a different shape to the R53 bar so hard to claim wether it is stiffer or softer.

 

The main reason you have to use stiffer rear is because it's a trailing arm The spring is mounted on the arm so there's leverage unlike the front that's mounted directly onto the hub, all cars that are set up with the trailing arm and the spring recessed back into the arm have to run a stiffer spring in the back to keep the same final spring rate front to rear.

The terminology they use is motion ratio The trailing arm has a significantly different motion ratio

 

Interesting thread as I have little knowledge about this subject

 

Hi all, Thinking of putting Swift springs on my Ohlins. Has anyone done that here yet? What spring rates / lengths did you use? Were "helper springs" used??

 

Mr Blah, I know you stated this 2 years ago. I'm looking to replace or upgrade my Swift Spec R Bilstein B4 combo. Do you still use/recommend this setup for the track? 8k front and 9k rear? this is on BC BRs right? Is it critical to get their Swift spring upgrade over their standard BCs?

 

I use KW V3. But I would use the same combo on any coilover that has enough damping, can probably go stiffer yet in the rear, there's a reason everyone throws stiff swaybars on the back.

Swift springs are very good, I run them on my e82 and my r53

 

Thanks Mr Blah. I'll stick to my Swifts for now. I know you use Koni Yellows with the Swifts. Do you recommend them? Or would I be better with Bilstein B6?