Racing Coilover Spring Rate?

[Modform]

Looking for anyone who is actually time attack/road racing their R for spring rate advice?
Was thinking 10 KG Front and 9 Rear (to dial out some of the understeer).
Any thoughts?
I have only been able to find some general suggestions but would like to hear some more feedback.
Cheers

 

[tenfoloten]

I want buy xyz coil over with 10front and 8rear

 

[gtiroz]

something that hard would be better suited to dedicated circuits (ie. smooth, high quality surfaces)

for road events (with potential potholes, surface changes, roughness, dips, etc) even 7.5kg (420lb) would be high

front/rear variation is personal preference and depends on driving style (and car setup),
but for the 'R in general a good balance seems to be acheived with a 15-20% max difference

only way you are really going to know is to personally test a few different setups

note there were 4 nismo spring options, the hardest of which (the "group n" spec) was 6 front, 5 rear (335/280)

 

[Modform]

something that hard would be better suited to dedicated circuits (ie. smooth, high quality surfaces)

for road events (with potential potholes, surface changes, roughness, dips, etc) even 7.5kg (420lb) would be high

front/rear variation is personal preference and depends on driving style (and car setup),
but for the 'R in general a good balance seems to be acheived with a 15-20% max difference

only way you are really going to know is to personally test a few different setups

note there were 4 nismo spring options, the hardest of which (the "group n" spec) was 6 front, 5 rear (335/280)

Great thanks for the feedback. Interesting info on the Nismo options...those were for Rally (uneven conditions) though correct?
Think I will start with an 8 front and 7 rear and see what happens...I can type without teeth so I will report back.

 

[fubar andy]

Think I will start with an 8 front and 7 rear and see what happens...I can type without teeth so I will report back.

That’s similar to my own set-up and that works well in the dry. In the wet softer springs would be much better such as 4 front 3 rear, but I need to test them out to verify.

 

[Modform]

That’s similar to my own set-up and that works well in the dry. In the wet softer springs would be much better such as 4 front 3 rear, but I need to test them out to verify.

Great to hear. Would you recommend an even higher rate?

Might get an extra set for wet/really bumpy courses...smooth pavement does not last long in Canada!

 

[fubar andy]

Would you recommend an even higher rate?

Not sure to be honest, I know the Mines R34 uses 10kg/mm springs all round.
Whether that would work on the GTiR is another question.

I'm very happy with the spring rates on mine when hitting the track, the car is very solid and stiffness can be extreme on public roads.

I'd personally not go any more than 10kg/mm springs for track, but that is my preference :thumb:

 

[campbellju]

Interesting info from gtiroz on the Nismo rates.

When looking at Spring rates of other cars, assuming they have Macpherson struts then you need to factor in the weight of the car. As modern Evo's, Scoobys and GTR are 20 to 30% heavier then they also need stiffer springs to achieve the same effect

Here is some random waffle I wrote ages ago on spring rates.

http://www.gtiroc.com/forums/showthread.php?t=45662

 

[Modform]

Interesting info from gtiroz on the Nismo rates.

When looking at Spring rates of other cars, assuming they have Macpherson struts then you need to factor in the weight of the car. As modern Evo's, Scoobys and GTR are 20 to 30% heavier then they also need stiffer springs to achieve the same effect

Here is some random waffle I wrote ages ago on spring rates.

http://www.gtiroc.com/forums/showthread.php?t=45662

Thanks for the reply and the link to your write up...really informative.

I am still a little confused though on the R's spring rates.

Because the GTIR is essentially the same weight as the S13/S14 (although the S13/14 runs a 5 link suspension rear)
Can't we gauge some info on racing spring rates by what they are running?
Here is a good link to S13/14 Coilover rates: http://www.badlose.com/tech/springrates.html

I have also looked around at racing sites:http://nissanroadracing.com/vbulleti...searchid=45696
As well as spoken to some Sentra (including b13) racers, such as this company: http://www.madmacsracing.com/gallery.htm
and they are running really high rates.
Mad Macs is running 13KG in the Front and I guess his car is 2500lb's with him in it...:shock:

Seems strange that these cars would run such high rates and the R would be different...hmmm...just don't know???

 

[campbellju]

I'm not going to tell you what springs to use as everyone has their own opinion. I've given mine. On a smooth and fast track I could be convinced to go to an 8/6 but I would start looking for stiffers ARB's first/as well.

On Macphesron strut cars, the camber compensation is rubbish so you have to add more -ve camber to begin with. Some racers fit really stiff springs to stop the roll and so stop the camber loss. Car's are also lowered to control weight transfer but to stop the wheels rubbing under braking or turning people fit really stiff springs.

So ask yourself first why has race/drift/road car X fitted the springs they have, understand all the details and don't just copy one part. You might be copying the wrong part.

For example, if you don't have enough camber in tight corners, don't keep adding camber, look at how much caster you run. Or if you get too much roll, don't fit a whiteline Front ARB that is smaller so will increase the amount of roll and then fit stiffer springs to compensate

I can't see the nissan road racing link, it sounds interesting, please post up what you see.

 

[Modform]

Sorry I haven't had a chance to follow up on this thread lately...stressfully busy but I wanted to take a minute and say what I bought.

Wound up with the Generation 2 KSport Version RR with 9KG Front and 8KG rear. The dampers were matched to suit the spring rate and apparently are the beefiest (how would you spell that word?) that KSport makes.

The quality actually looks really good but we will see. Huge pain getting it set-up...Jim I have been following your info on ride height and wound up going with a 330 front and 340 rear.

I am thinking of running -2.5 front camber and 1.5 rear...any thoughts?

Is there any suggestions on Toe? Been looking around and seems everyone has a different opinion...this will be a track only Short course time attack and autocross car so what ever might work best...might just go with 0 if there are no thoughts.

Will post some pictures as well as give some feedback on the performance on the track.

P.S. Jim I think I was only looking at the spring rate KG to Pounds chart on the nissan road racing site but there is a lot of good info on there.
Cheers

 

[gtiroz]

yeah pics would be great!
what size are the pistons?
and what was the price?

I am thinking of running -2.5 front camber and 1.5 rear...any thoughts?

that is exactly what mine was set to when i got an alignment prior to a track day by a mechanic with a lot of motorsport experience,
and i found significantly more cornering speed than my daily setup of -1.5 and -1...
(unfortunately did not get the toe setting)