Spring Rates for a track NB

[forcedfive]

I am currently running standard Bilstein PSS9's in my mainly tracked NB turbo. I have been told the standard springs are 340lbs all round. The car runs 225 50 AO50 Advans, a racing beat heavy duty hollow front sway bar and the standard rear bar. The car is registered but rarely road dríven.

I beleive the spring rates feel a bit softer than would be ideal on the track and was wandering what sort of spring rates others are running for track duty cars?

Cheers

[kazama]

seems like 700/400 is a popular setup north side

[david_syd_au]

My track NB has 12 kg/mm front and 10 kg/mm rear springs on YS coilovers.
I think that translates to roughly 670 lb/in front and 560 lb/in rear springs.
That is ok for a track-only car, but it would be a nightmare on public roads.

[Trackphotos]

I run 11/9KG sprints on my MCA blues. Perfectly comfortable on the road, if anything it's a tiny little bit soft for track work. If you think 12/10 would be a nightmare on the road, either you have particularly shitty local roads, you're particularly fragile, or the problem is with the shock absorbers, not the springs.

Incidentally forcedfive, when I swapped from stock suspension to 11/7 Blues, I cut more than a second off my PB without any other changes. Corner speeds rose a reasonable amount, and whether it's mostly that or mostly just the confidence it gives you by feeling grippier, it's totally worth it.

[RS2000]

Just wondering....
with higher front spring rates (ie 10+ kg/mm), do you run factory sway bar or larger aftermarket ?

Cheers

[david_syd_au]

If you think 12/10 would be a nightmare on the road, either you have particularly shitty local roads, you're particularly fragile, or the problem is with the shock absorbers, not the springs.

Probably all 3

Just wondering....
with higher front spring rates (ie 10+ kg/mm), do you run factory sway bar or larger aftermarket ?

I have whiteline adjustables front and rear. My experience was that changing the swaybars resulted in a bigger improvement in laptimes than going from std shocks to coilovers.

[manga_blue]

You can run anything from 7/5 up to 14/10 Kg/mm. Go closer to 7/5 if it's also a daily driver and head towards 14/10 if it's almost dedicated track.

Choice of sway bars almost comes down to personal preference, as long as the spring rate combination is right. I run 10/7 with either no sways or OEM sways. No sways gives me better grip and faster lap times but at the expense of a little bit of ducking and weaving under brakes. OEM sways on those springs is a good compromise. When I've used stiffer sways the car felt like it was runningon rails but the lap times just didn't reflect that.

[rascal]

I run 11/9KG sprints on my MCA blues. ......

Incidentally forcedfive, when I swapped from stock suspension to 11/7 Blues, ......

Was the different rear rates a typo, or did you actually then upgrade again to 9kg rears.
If so then what was the reason for the upgrade, did you find the rears still too soft?

[Trackphotos]

11/7, not sure why I wrote 11/9 in the first post.

[Luke]

I use my car much the same as you, road registered to get to the track. This is what I have and is not what you want.
Tein Street Flex, 7kg front, 6kg rear(Aussie spec) with standard SE front sway and no rear(was un-driveable with SE rear).
Pretty close to your current setup except your front and rears are both 6.1kg/mm.
Like you I do not have the "optimum" 3:2 front to rear spring ratio, which was balanced out with the sway bars to compensate.
Incidentally these Tein's are not comfortable on the road and feel a tad too soft on the track. Plus my rears are pretty much set at max height, which you have seen yourself is quite low. I would say that they are not long enough for a NB considering I can drop the car to the point that the braces are on the ground.


You could make yourself the test dummy and test these.
Tein Mono Sport. http://performance.fulcrumsuspensions.com.au/tein-suspension-for/1998.01-2005.08-mazda-mx-5-nb8c-s,-rs,-vs/GSM40-71SS1
10KG Front and 8KG rear. Tein never give you a 3:2 ratio standard.
They have not been out for long, maybe since the beginning of the year. I wish they came out when I ordered my street flex last year, I would have gladly been the test dummy.
I haven't heard of anyone in Australia using these and haven't seen any reviews online.
Doing a Search on the forum reveals "The Green Goblin" has bought a set but has not installed them as of yet.

[Lokiel]

I use my car much the same as you, road registered to get to the track. This is what I have and is not what you want.
Tein Street Flex, 7kg front, 6kg rear(Aussie spec) with standard SE front sway and no rear(was un-driveable with SE rear).
:

The name of those "Street Flex" coilovers should give you a big hint about their intended use - they're intended for a smoother ride on the street, hence the close front:rear spring rate ratio.

Interesting that you don't find them comfortable on the road.
Are they really just a "gimmick"?
ie. Are Tein just relying on the fact that "Street" buyers are uneducated and will buy their "Street" coilovers based on the Tein brand name - they just make their "Streets" harsh to make them feel "sporty" and different to OEM shocks?

[NitroDann]

"The name of those "Street Flex" coilovers should give you a big hint about their intended use"

You're alluding to your old ways of "if the manufacturer put it on it must work!".

ie. Are Tein just relying on the fact that "Street" buyers are uneducated and will buy their "Street" coilovers based on the Tein brand name - they just make their "Streets" harsh to make them feel "sporty" and different to OEM shocks?

.....yes.

[forcedfive]

Thanks for all the feedback guys. Really helpfull.

Luke I know with some old HKS coilovers I have the NB rears were quite a bit longer than the NA so I assume the Tiens do a one size one fits all and probably short so they work with the NA. Your car is low given you are nearly out of hight adjustment. I think i will just see what springs rates are around for the Bilsteins that might work and i am not really worried about on road comfort (I may regreat that one day)

David, so with your rates you have are you happy? If you were buying new springs today do you think you would go with the same rate combination or maybe vary it?

Cheers

[rascal]

I'd agree with the one size fits all theory.

I have Super streets on my NB8A, and they came std with 150mm springs, which needs the collars to be wound up almost to the top just to get a reasonable ride height.

I am thinking of going to heavier springs, and will go for 200mm springs so can put the collars back down to the middle where they should be

[plohl]

Dude, remember you only need to match the internal diameter and free length of the spring, the rate will change depending on material thickness and number of coils. - you don't need bilstein specific springs. This means you could fit a number of different brands: king race series, eibach, mca have their own for the red and blue series shocks, otomoto sell hsd springs iirc too.
So when you order a sping, you need the internal diameter, 63.5mm or 2.5" is common for mx5 coilovers, the free length, ~200mm and rate in ft lb or Nm or kg/mm.

You should be able to find this information on you current springs. Written generally allong one of the coils.

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