I Wanna Change Coilover Springs - What Spring Rate Is Good For Street?

[ausdrift]

Heres the short version. I used to run KTS coilovers, then I changed to stock suspension for 6 months, but the stock units are shite and I want some proper handling back. Although I used the coilovers before previously for drift, I now use my car as a daily driver and have no time for the harshness, especially on Melbourne roads with all those damn tramlines. So my question is,

What spring rates would give me still some firmness (it is a sportscar afterall) and yet still be soft enough that I would have a reasonable level of comfort on the roads. I might take it to the track, say a couple of times a year, but for the other 98% of the time, I want something that wont rattle my fillings out. The current spring rates are F 8kg/mm and R 7kg/mm.

What have you run?

What feels good for the road?

thanks

[GTSBoy]

Anything softer from there will feel better on the road. 6/4 would be OK, if perhaps a tiny bit soft. The problem would be that unless the dampers have good adjustability, you may find tha they are just too overdamped for softer springs, which would suck balls.

[Shazbanger]

I run 8kg/6kg with Blitz ZZRs and IMO, its perfect for dailying. Perhaps slightly on the stiff side, but very manageable.

[ARTZ]

i mine are at least 8/6 probably stiffer, you down push on the front and it doesnt budge...with bilsteins shocks it rides beautifully...

Only issue I find is due to the stiffness unexpected dips in the road can sometimes try throw the car of line....that just keeps you awake though and theres no teeth shattering ...if you want smooth its all in the shocks man..

[ausdrift]

Thanks. I owned my car in japan and drove it only weekends. The harshness didnt bother me because of that, as it was only short trips or on the track. i always had the shocks on full soft on the street as it would be pointless not too.

What about just say, changing the rear to a bit softer, or visa-versa instead of softnening both F and R? Anyone had experience with that?

And what else are you guys running for spring rates?

[simpletool]

I currently run 5/4.5 and I find it a great compromise. (I have front and rear whiteline adjustable sway bars with both set to hard). I'd be reluctant to change my setup but if I had a choice of any spring rate for a street R33 and custom shocks to match I would go 6/5 (max).

I can't see how you could need any more than 6/5 for street duty. I actually doubt I use use more than 5/4.5 and that's with Federal RSR tyres around Mt Nebo.

You only need enough spring to control pitch, any excessive body roll should be cured with sway bar rates. A car with 6kg rear springs wouldn't have much rear grip on street tyres.

Edited January 7, 2013 by simpletool

[R TUNE]

From my exsperance,

My R31 had king sprins, 3.5kg/mm front and 2.9k/mm rear with kyb shocks. I also had strut braces, sway bars, and nolerthane bushes.

The car handled great for daily driving and was very comfterble, but also courned very well. May be look at the king spring rates for your car and combine those with either kyb or bilstin shocks.

As a compaison i have Cusco zero 2 coilovers 10/8 i believe and they are very hard for street use.

[Frosty]

Heres the short version. I used to run KTS coilovers, then I changed to stock suspension for 6 months, but the stock units are shite and I want some proper handling back. Although I used the coilovers before previously for drift, I now use my car as a daily driver and have no time for the harshness, especially on Melbourne roads with all those damn tramlines. So my question is,

What spring rates would give me still some firmness (it is a sportscar afterall) and yet still be soft enough that I would have a reasonable level of comfort on the roads. I might take it to the track, say a couple of times a year, but for the other 98% of the time, I want something that wont rattle my fillings out. The current spring rates are F 8kg/mm and R 7kg/mm.

What have you run?

What feels good for the road?

thanks

springs are great but the damper comes into play here....but saying that what feels great for us might not be so good for you.

id be going for about what you already have and softening the damper a bit

Edited January 8, 2013 by Frosty

[Dose Pipe Sutututu]

The recommendation of 6/4kg/mm would be spot on, just run the thickest matched anti roll bars aka sway bars and you'll be sweet.

It's the in thing these days, stiff doesn't always mean good handling.

[ausdrift]

Cool. Does anyone know the spring rate for standard R33 shocks? I just realised tbhis would be good to compare

[GTSBoy]

You will find some guidance in the first several posts of this thread. http://www.skylinesaustralia.com/forums/topic/79157-how-do-i-tell-what-my-spring-rates-are/

FWIW, stock R32 rears are less than 2.5 kg/mm from what I can tell. Stock R33 won't be much more despite the extra fat on the chassis. The fronts would probably be in the region of 4 kg/mm.

6/4 is pretty close to the optimum that Sydneykid recommended in the way backs.

[simpletool]

Stock are around 2.7 - 2.9kg/mm., according to Tein.

I don't remember SK recommended 6/4 for the street, I'm sure he would say that is well on the firm side.

Edited January 11, 2013 by simpletool

[GTSBoy]

It was my (vague) memory that he recommended ~200lb/in for the rears. That works out to about 3.6 kg/mm, and 4 is not that much stiffer. OK, 10% stiffer.

If he was instead recommending 200 lb/in for the fronts, then that's a different story. But that seems rather soft, even to me, and I'm not one of the hard spring junkies around here.

[ausdrift]

great, thanks. Now to make some decisions...

[R31Nismoid]

I was using 6/4 in a full weight GTR with custom valved Tien's... Problem is that it isn't just spring rates which dictate the ride.

As mentioned the damper, rebound and other factors come into play. Generally shit hard shocks will not benefit from going soft on the springs without being adjusted elsewhere to suit.

[ausdrift]

With that in mind, what more can be done with my coilovers to adjust damping, over just turning the knob to full soft? Apart from buying new dampers

[GTSBoy]

If they are rebuildable, then they could be dismantled and the valve stacks altered. There's cubic $$ hiding in that sort of work through.

[simpletool]

The best way is almost certain to be to sell the coilovers as they are, and buy something with a lower spring rate (BC racing get a good mention for the low $$$). But they don't make anything all that soft, and the valving is only OK.

Edited January 15, 2013 by simpletool

[craigy32]

yep spring rate is only part of it.. shock valving is also a major part of how the car rides... I have had D2 coilovers with 12/10 ride softer than cusco coilvovers with 8/6 int he same car.. I'm no expert but that's my experience

[ausdrift]

hmm this is a pickle. makes me wonder why they sell springs separatly for coilovers when it appears like it wouldnt be a great fix by just doing this. ahhhh what to do.....