Spring rate stagger
11-06-2012, 09:42 AM
#1
Member
Thread Starter
Spring rate stagger
Just wondering if anyone runs a higher spring rate at the rear than the front?
Most seem to run even spring rates or stiffer at the front by 2kg.
A lof of the JDM race S2000s seem to run 2kg stiffer at the rear on staggered tyres.
I have 14kg rear and 12kg front and i'm finding the car very stable (no roll) but feels too stiff overall and very snappy rear on the power. Yet to try really backing off the rear damping but suspect my spring rates aren't ideal.
Most seem to run even spring rates or stiffer at the front by 2kg.
A lof of the JDM race S2000s seem to run 2kg stiffer at the rear on staggered tyres.
I have 14kg rear and 12kg front and i'm finding the car very stable (no roll) but feels too stiff overall and very snappy rear on the power. Yet to try really backing off the rear damping but suspect my spring rates aren't ideal.
11-06-2012, 11:43 AM
#3
Member
Thread Starter
Hi,
My issue is power oversteer on corner exit. I am fairly sure I just need to reduce the rear damping to reduce this but i'm also questioning the spring rated being higher at the rear. I do have a big wing which does appear to work, so the car is 50/50 weight distributed static, and unknown what the load on the rear is due to the wing at speed. So from that point of view, I can see how running a bit more stiffness in the spring at the rear would be good in theory.
My geo off the top of my head (printout at home) is:
F camber -3 degrees
R camber -2 1/2 degrees (2.3)
F toe -0.05 toe out
R toe -0.1 each side (total 0.2)
Caster 6.45
Tyres are 235/45 and 255/40 Yoko A048 MH compound rear (I want M but they don't make them) and M front. Nitron 2 way adjustables. Kaaz LSD. OEM ARBs (I have a Saner front and Whiteline rear available to fit)
Car weight is 1010kg.
My issue is power oversteer on corner exit. I am fairly sure I just need to reduce the rear damping to reduce this but i'm also questioning the spring rated being higher at the rear. I do have a big wing which does appear to work, so the car is 50/50 weight distributed static, and unknown what the load on the rear is due to the wing at speed. So from that point of view, I can see how running a bit more stiffness in the spring at the rear would be good in theory.
My geo off the top of my head (printout at home) is:
F camber -3 degrees
R camber -2 1/2 degrees (2.3)
F toe -0.05 toe out
R toe -0.1 each side (total 0.2)
Caster 6.45
Tyres are 235/45 and 255/40 Yoko A048 MH compound rear (I want M but they don't make them) and M front. Nitron 2 way adjustables. Kaaz LSD. OEM ARBs (I have a Saner front and Whiteline rear available to fit)
Car weight is 1010kg.
11-06-2012, 11:45 AM
#4
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In 2011 I ran 10k up front and 12k in the rear the out of box Bilstein bumpstops, I also had a Saner front swaybar and a stock '03 rear sway, .
I thought the balance was just fine when I was also running a staggered set of tires, I had 235 in the front and 255 in the rear.
This year after I switched to a 255 all around, the car became way to loose and it was very hard to keep the backend behind me.
I have since moved to a 14k front springs with shorter, higher rate, linear bump stops and the car is happy again.
Although, I am thinking about moving to a 16k/14k spring rate, on asphalt 14k/12k is fine, but on high grip concert, it has felt too soft.
Some thing to be aware about when look at other spring rates:
- AP1 and AP2 have different rear geometries and may require different spring rates
- Staggered vs non-stagered tires
- Big bar/soft spring vs soft bar/strong spring setups
- Ride height and/or shock length
- Bumpstop length and rates.
Also it sounds like you may need to drop your rear ride height, there is a good discussion about it in the STR section
https://www.s2ki.com/s2000/topic/904.../page__st__200
I thought the balance was just fine when I was also running a staggered set of tires, I had 235 in the front and 255 in the rear.
This year after I switched to a 255 all around, the car became way to loose and it was very hard to keep the backend behind me.
I have since moved to a 14k front springs with shorter, higher rate, linear bump stops and the car is happy again.
Although, I am thinking about moving to a 16k/14k spring rate, on asphalt 14k/12k is fine, but on high grip concert, it has felt too soft.
Some thing to be aware about when look at other spring rates:
- AP1 and AP2 have different rear geometries and may require different spring rates
- Staggered vs non-stagered tires
- Big bar/soft spring vs soft bar/strong spring setups
- Ride height and/or shock length
- Bumpstop length and rates.
Also it sounds like you may need to drop your rear ride height, there is a good discussion about it in the STR section
https://www.s2ki.com/s2000/topic/904.../page__st__200
11-06-2012, 11:55 AM
#5
Member
Thread Starter
Hi Ryan, good info.
So it sounds like you started out similar to me. You basically had a stiffer rear but compensated for the lower front rate by fitting a stiff front bar (even on the lowest hole the Saner if way stiffer then OEM)
It's actually what i'm thinking of doing too by putting the Saner on, or just reducing the rear damping a lot to help keep the tyres on the tarmac.
RE the stiffness, we have a real mix of circuit surfaces here. When I raced at Silverstone I found I could feel some slight chassis movement, but on a rougher circuit it just felt too stiff.
So it sounds like you started out similar to me. You basically had a stiffer rear but compensated for the lower front rate by fitting a stiff front bar (even on the lowest hole the Saner if way stiffer then OEM)
It's actually what i'm thinking of doing too by putting the Saner on, or just reducing the rear damping a lot to help keep the tyres on the tarmac.
RE the stiffness, we have a real mix of circuit surfaces here. When I raced at Silverstone I found I could feel some slight chassis movement, but on a rougher circuit it just felt too stiff.
11-07-2012, 01:57 AM
#7
Member
Thread Starter
It's more the lower speed stuff.
Example at this hairpin at 7:30 ish. Ok it's a tight one but you can see what I mean.
http://www.youtube.com/watch?v=GMO1JDXP5Y4
And this at 13:55 which I caught but then ended up on the grass, which is like ice...
http://www.youtube.com/watch?v=cW7lKqjIfU4
You can see how snappy it is, and with semi slicks it shouldnt be stepping out imo. As I say, i'm sure I need to reduce the rear damping but the springs rates probably wont help.
Example at this hairpin at 7:30 ish. Ok it's a tight one but you can see what I mean.
http://www.youtube.com/watch?v=GMO1JDXP5Y4
And this at 13:55 which I caught but then ended up on the grass, which is like ice...
http://www.youtube.com/watch?v=cW7lKqjIfU4
You can see how snappy it is, and with semi slicks it shouldnt be stepping out imo. As I say, i'm sure I need to reduce the rear damping but the springs rates probably wont help.
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11-07-2012, 04:55 AM
#8
How much rear toe-in are you running?
Most people in US on this side seem to run even rates with a big front bar or stock bars and a slight front bias (50/100lbs).
But thats usualy with the same size tires front/rear and a functional wing.
Seems like springrates around 600-700lbs are popular I think thats about 12kg, 14kg rear sounds like too much.
I'd say you should go even on the springs at 12kg but it'd be easy to just swap the front and rear.
Most people in US on this side seem to run even rates with a big front bar or stock bars and a slight front bias (50/100lbs).
But thats usualy with the same size tires front/rear and a functional wing.
Seems like springrates around 600-700lbs are popular I think thats about 12kg, 14kg rear sounds like too much.
I'd say you should go even on the springs at 12kg but it'd be easy to just swap the front and rear.
11-07-2012, 05:23 PM
#10
Mark I know our cars are hardly comparable but are spring rates are identical with very similar dampers. I have never had a moment like you had even though I'm running double your power. I've very limited time on my new dampers but found them an improvement on my previous setup with 10/8 springs.