Suspension gurus. Spring rates for my car, w/ Konis.

[thrdeye]

I had originally planned on coilovers, but I have decided that I don't really give a crap about height adjustability. I am going to try and take the Ron Popeil approach and "set it and forget it".....well, aside from the adjustable konis.

Need some input regarding spring rates for my car. Obviously, stiffer is better, but at what point on a 3100 lb car is stiff too stiff. I have just a basic macpherson system. I've searched on the subaru board, but people there claim anything from 6kg/mm up to 13kg/mm. The coilovers I had my eye on are 7kg front, 5kg rear.

What is the formula to convert to US units?

I know eibach makes good springs, so that's who I'd probably go with. I saw some information on their site about determining the best spring rates for a particular suspension, but besides from being supremely complicated, it really doesn't matter, because people can argue all day long about spring rate and what will feel best.

Right now I have a linear spring that is designed for the stock strut, so it isn't really that stiff, although it is much better than stock.

Also, how much would a custom spring rate/koni setup cost? While looking around on the Koni site, it looks like I would have to have them custom valved. I know springs are really relativley cheap, so, would all of this be doable under $1K?

QUESTIONS

1 Is this setup competitive enough for SM regionally (I know I have no chace against those M3's)?
2 Spring Rate (or just use the current springs)?
3 How much of a pain is it to transfer the strut housings?
4 Are double adjustables worth the extra cost (how much are they)?
5 Any input on ride height?

After this, I'd probably just get some camber plates and call the suspension done, for better or worse.

Thanks for any help with your experiences.

[dfoulk]

1 kilogram = 2.20462 pounds, 1 millimeter = 0.3937 inch. If you want to go the other way, 1 lb = 0.4536 kg, 1 in = 25.40 mm.

[steverife]

Based off of Mustang pricing, I'd expect off the shelf Koni DA's to pretty much eat up your entire $1k budget.

[thrdeye]

Well, I can get the off the shelf yellows for $159 ea. from tirerack.

[MARKP]

Well, I can get the off the shelf yellows for $159 ea. from tirerack.

Those are straight out of the box single adjustables. The best deal I have heard of on custom double adjustables was on Robert's CRX @ $1600 for the set of four. $2000 isn't out of the ballpark.

I would encourage you to go with coilovers and single adjustables. The advantage of the coilover is the cheap springs and the ease of changing them to different rates. Ride height adjustability is just a neat add-on to that, IMHO. Also, you can get your car corner balanced with coil overs. That is tougher to do without them.

With the coilover / Koni single setup, you should be able to stay close to your budget. You can always do the double adjustable conversion later when you have money again.

As far as rates go, I really can't help you and I would be surprised if anyone on this board can since you are the "big dog" when it comes to Subarus around here. You will probably have to talk to some Subaru guys that know what they are doing with the suspension and doesn't want to sell you their spring setup. I can help you with VW rates but that won't do anything for your Subaru.

[scottgib]

That WRX that whooped up on me this weekend seemed to have it right.

Mike Winn drove it and I think now owns it. It was a nat. champ car. Getting anyone to tell you what it has underneath might take some diplomacy. Maybe one of our nat. drivers knows someone.

[thrdeye]

Well, I found a few posts by tom hoppe.

Looks like a good setup for me, being that the car is daily driven is 350 lb springs all around. The normal Koni's can handle this, I have heard. I figure about a 7 inch spring, but I'm looking for some pics to see if that will be too low for my tastes.

[MARKP]

James Swanson (hope he doesn't mind me spilling the beans on his car) is running 500 lb springs all around. He drives his car daily. I drove it on the street and I thought it was fine. This is probably as much spring as you want without revalving the Konis.

Since your car is heavier, the rule of thumb would seem to indicate you would generally want more spring than James's lighter car.

What rate are the springs currently on your car?

[thrdeye]

James Swanson (hope he doesn't mind me spilling the beans on his car) is running 500 lb springs all around. He drives his car daily. I drove it on the street and I thought it was fine. This is probably as much spring as you want without revalving the Konis.

Since your car is heavier, the rule of thumb would seem to indicate you would generally want more spring than James's lighter car.

What rate are the springs currently on your car?

prodrive will not release the rate, and no ones ever bothered to figure it out, I guess. Rumor has it that they are 270/in

[BillyM]

What they said about coilovers, the greatest aspect is that there are unlimited rates you can get, and if the length is off a bit, just twist it to where you want it.

I dont know what your suspension setup looks like, but the Supradupra has a single-control arm mcpherson strut setup up front. Pull the strut tube, hack off the spring perch, and weld on the threaded collar, *POOF* now I have unlimited options for springrates (as compared to the previous 2 options stock and almost-stock).

I dont know if this will help you whatsoever, but I opted for a set of 450lb springs for my front coilovers and short-stroke AGX's borrowed from the front of the all-trac. Total cost for my front setup was $340 ($175 shp'd for the coilovers/w springs, and $165 shp'd for the AGX's)...

--BillyM
(mmm 3-liter stroker crank/rods, definately SM now...)

[thrdeye]

Anyone else with info on how much spring the Koni can handle? If it can handle 500 lbs, I'll do those very soon. Revalving would be another $100/corner.

[TedV]

might try calling Koni, or ground control... "politely gathering info on what route you will take with your suspension upgrade" find out exactly what rates the stock koni will handle.. trust me.. too much spring on too weak valved a shock aint fun... actually dangerous. Ground control might even have a decent priced package deal coil over kit. don't know till ya ask. most off the shelf sport springs are too soft to autocross on effectively even localy. just more fun than stock

wait.. we're in the same class.. umm.. softer is better.. (jk)

[thrdeye]

0 Kg/mm 0 Lb/In
1 Kg/mm 56 Lb/In
2 Kg/mm 111.9 Lb/In
3 Kg/mm 167.9 Lb/In
4 Kg/mm 223.8 Lb/In
5 Kg/mm 279.8 Lb/In
6 Kg/mm 335.7 Lb/In
7 Kg/mm 391.7 Lb/In
8 Kg/mm 447.6 Lb/In
9 Kg/mm 503.6 Lb/In
10 Kg/mm 559.5 Lb/In
11 Kg/mm 615.4 Lb/In
12 Kg/mm 671.4 Lb/In
13 Kg/mm 727.4 Lb/In
14 Kg/mm 783.4 Lb/In
15 Kg/mm 839.2 Lb/In
16 Kg/mm 895.2 Lb/In
17 Kg/mm 951.2 Lb/In
18 Kg/mm 1007.1 Lb/In
19 Kg/mm 1063.2 Lb/In
20 Kg/mm 1119 Lb/In
21 Kg/mm 1175 Lb/In
22 Kg/mm 1230.8 Lb/In

[thrdeye]

With the above in mind, I have just about settled on 400 all the way around. That is the most constant figure I'm hearing for the max application of the insert w/o revalve.

[Steven]

Tony ran 600lb springs w/ his koni yellows on his integra. 400-500 is the max I would go on a daily driver. Tony's 600s were a little harsh on the rd.