Hi all

I'm getting some PSS9's and want to replace the front progressive rate springs with linear rate ones - this is a trackday car only.

The preferred linear rate for these seem to be 350lbs/in. Any recommendations on what (H&R?) to get and where?

Thanks

 

Shop around, but you want 6" long, 2.5" diameter, 350 lbs/in springs. 7" will be too long, even with the spring perch dropped all the way down (as in higher than stock ride height). I tried the 7" Hyperco's first and changed to the 6" H&R for that reason.

Scott
90SM

 

Thanks
H&R seems to be out of stock on that one.

Do you think 5.5", 345 lb/in will work?
(really a 60mm ID, 60N/mm, 140mm)
Or would that be too short?

It's either that ...or 2.5" ID, 325lb/in, 6"...

I'm leaning towards the slightly softer/longer setup - don't want to run out of spring travel...and my car has been on a bit of a diet...

 

If it were me, I'd probably go with the 325lbs/in, 6" long springs for the reason you noted, though I suspect either would work.

Scott
90SM

 

If it's a track day car only then why such a soft spring?
Been quite a while since my PSS9 days. Is the 350 number what they are valved for? If not, what are they valved for?
On a track day only Mini I would be in the 500 and up range.

 

Fronts are 345 progressive rate. Rears are about 350 linear.
I don't want to make fronts much stiffer than rears, and don't want to go outside the range either is valved for.

90stx you mentioned that your ride height was about .5" higher with the 6" than with stock pss9 springs. Makes me wonder if a .5" shorter spring isn't perhaps the way to go?

 

OK, then do yourself a favor and go 400 front and 500 rear. Really, if it's a track day only car then your shocks will handle this. The PSS9s already overpower the springs they come with on the firmer settings.
The best way to go would be to take the perches off and take them to a machine shop and have them put on a lathe and trim them down so they can take a 2.25 ID spring. Then pick up some Hypercoils. First make sure the PSS9 body is under 2.25", as I believe it is.
6" for the front and rear with a rear helper is what you need. You need the rear helper as it keeps the spring in contact with the perch during droop as the rear has a lot of droop.

It may sound like a lot of work, but it's not. I do it for track day cars all the time.

 

Thanks
Will follow your advice.
What's the advantage of going to 2.25"?
And do I just pick any helper spring? can I reuse the ones that come with pss9?

 

Advantage of the 2.25" is the lower spring rates in the shorter springs. Whith Hypercoil the softest 6" spring in a 2.5 is 600. In a 2.25 the lowest is a 200. 2.25 gives you BEST choices in rates.
I always push Hypercoil as they are hands down the best out there.
Hypercoil makes helper springs which I also recomend as they have as close to a 0 rate as I have seen. As I remember the PSS9's helper spring has a substancial rate to it as far as helpers go.

 

Are hypercoil better than Swift?

 

I read and hear a lot of hype here on NAM about Swift, but have yet to ever find a set being used on the track. Any and about every serious race car uses Hypercoils.
I don't want to say better, ...because I have never touched a Swift spring. Does Swift dyno every single spring and engrave the results on the spring itself? And then sell them as a close to perfect matched pair?

 

Wow. I didn't know they did that. I used swifts on the track with my R53. How much does a set of custom rated hypercoils go for?

 

They are not "custom rated". They make the spring according to factory specs in increments of say 50 lb/in. But they just don't rely on it always being right or "close enough" . They take every spring and dyno it. Say it's a batch of 350s. They may come out 352, 347. They then engrave that number in the spring next to the factory spec. So it would maybe say 350 348. They then pair them up so you get say a 348 and a 349, rather then a 344 and a 355.

Figure a set of four is about $325.

And not to misinform. When I said I have never seen them on the track, I mean in racing, like SCCA. I'm sure they are out there on track day cars.

 

Oh I see. When I meant custom rated, I also meant custom length and diameter, cos I have PSS10s

 

Never really looked into it, but curious what the difference between PSS9 and PSS10 is.

 

I currently use hypercos and would recommend them. I run 450 in/lbs front and rear. That is a little stiff for street but generally good for the track. I am thinking of changing the fronts down to 400 in/lb while keeping the rear the same since the car doubles as a dd. This does introduce a little more oversteer.

I think they cost around $200 per pair which is pretty close to Onasled's number.

 

I wouldn't mind running 8kg/mm front, and 6-7kg/mm in the rear

 

The PSS10 are 1 better! Really though, I don't know the details but other than 1 extra click, the adjuster is supposed to be a bit more consistent.

Hyperco and Swift are the top 2 in my opinion. The Swift fans get on my nerves but they are good springs.

What size and what type of tires are you using Bruce?

- andrew

 

I am guessing this is similar the adjuster used in the PSS10.

http://www.stangtv.com/news/pri-2010...e-shock-shaft/

Looks like good stuff!

 

Just called Blistein and they said the standard springs on the PSS10's for the R56 Cooper S are 325 front and 235 rear.

He would not confirm that front were progressive either, however he seemed to just be reading from the computer screen. Those of you who have them would know better by visual inspection of course.

I've got a set of PSS10 coming in the mail soon, so they should be fun to tinker with. Probably going to shoot for 450 up front and not sure about the rear yet.

Food for thought, TC Kline seem to like the Mini set up at 400 front and 170 rear if I remember correctly, along with camber plates and rear sway. (?)

 

400/170 sounds terrible.

What kind of tires do you run and what size? That will help dictate spring rate choice.

- drew

 

I know, TC Kline set ups tend to be a softer spring, high rebound / compression for the track, then dialed down rebound / compression once you hit the street.