ALFAGTV6.COM

[grant]

I'm looking to go for a more track oriented set up on my 75 3.0 (ABS, Sunroof, interior, quite heavy!)

I'm wondering what spring rates you guys are using? I know different tracks require different rates, but a ball park would be nice.

My setup as of now:
Dropped spindles (1 and 1/8th inch I believe)
RSR front coilovers with spacer on each end and 115nm springs
28mm front sway and 26mm rear sway bar (RSR)
AE86 5.1 KG springs that are way too short
Bilsteins in the rear (CAN BILSTEINS HANDLE SPRINGS FROM 5-7KG??)
225/45/16 ES100s

My old springs rates were around 200lbs/inch and 150lbs/inch front and rear respectively. New spring rates (dunno about wheel rates) are around 700lbs/inch front, 280 lbs/inch rear if I did my math correctly.

I would just imitate Rons suggestions on spring rates for good handling (125/70, 115/60) but my understanding is the dropped spindles will effectively make my front spring rates stiffer than they are due to a higher RC?

I've noticed with my car with the rear sway bar on second to softest, and the 5.1 KG rear springs, my car understeers pretty hard. The question is, what spring rates would you recommend I start off with? I was thinking something in the US that is equivilant to a 6.5kg spring, but will this be enough?

Also, my car is much lower now b/c of the coilovers being a bit too short and the ae86 springs being to small, I think I'm noticing excessive throttle induced oversteer. Could this be because the watts link pivot is not much higher up in respect to the chassis' CG, or is that just a side effect of having stiffer rear springs? Should I be looking into relocating the pivot lower?

I'm new in this area and I'd appreciate any theory or suggestions. What can you guys teach me?

[Mats]

Wow, you're mixing units pretty wildly there..

kg? Can we all agree to use lbs/inch or N/mm?

[grant]

n/mm is pretty close to KG, yeah? Ron's 115nm is pretty close to 11kg.

Aside from that, what would you suggest I try in the rear first?

Also, if I want slow speed damping, but relatively soft high frequency damping (I think that should result in ideal street/track), that's called digressive damping right?

[kevin]

Hi Grant , lot of stuff to digest there but what works for me when using SEMI SLICKS, is 115 front and 50 rear. Strangely I thought that was in Kg's. 30mm front anti roll with standard on back. Only after twelve races last season I only now have started changing setup as there was nothing realy glaring bad with that origional setup. I had to work on my driving skills first as I believed that origional set up was not to far off from what i wanted from the car. Only understeer I had was midway through fast sweeps.Its also not a pure track set up as I still drive it there.

[grant]

Yeah, there is quite a lot of info there, sorry.

Thanks for the info on your setup. I think John had said that Ron feels lower rear spring rates for the GTV6's are the way to go. I'm pretty sure he lists in N/mm though...

Are you going to stiffen the rear springs then?

Anyone else have any suggestions on what spring rates to start off with? I'm going to order them in the next week or so.

[grant]

Ok, I'm going to be ordering rear springs pretty soon. I'm thinking of starting with a 350lb/inch rear spring (or lower, if I have to cut the spring down.) as I might not be able to find a short enough height with the available springs in the US (5 inch ID, 9-11inch height).

350lb/inch converts to about 6.25kg/mm or 63.7 nm/cm (I used kg/mm and nm/cm almost interchangeably above.)

So, does that sound good? Ron's setup is 125/70 or 115/60. I have 115nm fronts, with dropped spindles (which should make the wheel rate effectively higher?) so I'm going with 350lb/inch for starters.

Am I on a path for disaster or what?

[Maurizio]

Spring rates are normally done in lbs/inch, Kg/cm or N/mm.
Rons site states Kg so I guess he means Kg/cm

If you cut a spring the spring rate becomes more not less!

On my 4 cil I use 400 lbs/inch (~70 Kg/cm) springs and standard AR bar in the back. Is hars and too tricky (with the ar bar still connected) for me in the wet

I think that you need a less stiff spring because a gtv has a shorter wheel base. Edit: Stupid remark, you have a 75 V6

[grant]

Sorry if I got the kg/cm thing screwed up.

About cutting the springs, I was saying that I would get a lower spring rate, and calculate what it should be after cutting the coil.

Please! More info like this! What spring rates were you running in the front? I don't want to buy 4 sets of springs just to get something close (can't afford it at the moment either).

Was 400lbs/inch too much at the ring? (if you took it there). My understanding is that it is quite bumpy.

PS, I have rons 26mm rear bar, which I'm afraid is too much. I think I should go lower on the rear springs than what he would recommend for those in the US with his 30mm front AR bar and stock AR rear bar.

[Maurizio]

This is still the setup. Just haven't had the time to visit the ring over the last year.

Front 600 lbs/in + stock torsion bars + my own 32mm hollow ar bar. (my 32mm ~ 1.08 * 30 mm rs bar). Backside 400 lbs/in + standard ar bar.

Ring is bumpy but the car is fine for me in the dry, accept in the rain the ring is tricky, no run out, slippery spot due to leaves/shadow spots. I just don't have a big enough heart and do just some cruising in the wet

[grant]

What shocks are you using?

Since I have a large rear AR bar, should I get an even lower rate spring, like 300lb/inch?

[Maurizio]

What shocks are you using?
Since I have a large rear AR bar, should I get an even lower rate spring, like 300lb/inch?

I'm using revalved bilstein's (from bilstein motorsport), gave them spring rates and the N'burg ring as input.

Stiffness for your application is a difficult one ...
I would say go for 350, since your front is stiffer due to the drop spindles (gut feeling, no science or guaranties here).

[grant]

How are the bilsteins at the ring? How are they on the street. Are they digressive? I like the bilsteins but they are too harsh on little bumps.
MAybe I could have Bilstein europe send the specs to bilstein NA to have them vavled?

[Maurizio]

Yes they are harsh, the setup is too harsh for the street and daily commuting, but I have this car for track days (ring) mainly. For the rest I can't compare as I have never have driven anything comparable back to back on the ring.

As for re-valving, I guess they could do that.

But first I would try just with the stiffer spring.

As far as my knowledge reaches wrt dampers (read: only common sense). When you add a to stiff spring, a damper will act, over damped.
So in rebound it will be not fast enough (like a koni yellow damper). The damper will not get time move to out and you loose traction.
But it will work sort off, so you could try stiffer springs and alter the damper afterwards if not satisfied. But as said before I'm no expert.