[aslet]

I want to upgrade my suspension; making it both stiffer and balancing the front to rear. I want to add a rear coilover, but am not sure what spring will be the most balanced for my intended setup.

17" 993 cup wheels, stock size tires
M030 front and rear sway bars
Koni yellow shocks
350lb front spring
Stock rear torsion bar
Upper strut brace

What would be a good rear spring? The kit RS Barn sells has a 350lb front spring and 150lb rear. I would guess this works well. The Koni coilover kit I want to get from Paragon Products has rear springs starting at 250lbs. Is that too much rear spring? I was thinking about thios kit for the lower price.

Koni kit: http://www.paragon-products.com/Coil_Over_...oni_cup_kit.htm

Thanks,
Randy

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[flash]

that kit will not work without adding a tender spring and coupler in the rear, unless you are willing to raise the rear of the car

the problem is that the torsion bars establish the ride height - adding a spring either further raises it, or falls loose during wheel drop, unless you have a tender spring so you can set it at zero preload and not have it fall loose

as for spring rates, it really depends on how you plan to drive the car - stock springs are 160 front and 175 rear - 350 front is pretty stiff for the street, and at the very limits of the koni yellow - you may find that to be a bit skittish on bumps - pretty decent for track though - i had koni yellows up front, and found that anything over 300 was not a good setup for street, as it was too jumpy - i changed to hydraulic double adjustable konis, and am much happier at how calm they are

the first thing to do is figure out what the 80% use is, and then determine what compromises you are and are not willing to make - then you can figure out what to do in setup

typically for a street car on koni yellows, i recommend not going over 250# on front spring, and that requires a 90# helper in the rear - if you don't want to mess with the rear spring rates, then 200 would be the max if you want to maintain balance - you can run a stiffer spring, and it won't be horrible, but it won't be balanced

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[Eric_Oz_S2]

I run 350 front and 225 rear with M030 front and rear sways. 250 would also be OK, but 225 is better (I have run both). This feels pretty balanced to me. I have the koni yellows in front and the GC coilovers on the rear (Koni series 30). I agree that 350 F is not that great for a daily driver, but on most roads it is fine, only on uneven/broken roads does it get quite rough. Perfect for the track though. You will need to reindex the tbars by 1 spline on the inside to get the tbars and springs to work together correctly and also get the right ride height - I run stock less about 1-1.5". I run 8" long rear springs, no tenders springs.

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[rl968]

I run the Koni struts up front and the koni 30 series shocks in the rear. I have 400lb springs in front and 250 lb in the rear. I run the car on the track and it handles extremely well with this setup. It also feels fine on the street in terms of harshness (Koni struts can be adjusted to make the ride softer) As Flash notes, you WILL need the coupler and tender spring in the rear or the coils will come loose.

Your car will be raised up in the rear after you do this set up so you will have to use the eccentric bolt to lower the car. I started off with stock 26.5" height in the rear and it moved to 27.5 with the new setup, turning the eccentric bolt brought me back down close to stock height. If you want to lower more, torsion bars will need to be re-indexed or removed completely.

In the front, the 10" springs paragon gives you will raise your car too much and you won't have enough room for adjustment so tell them you want the 8" springs instead. With the 10", my car went up to almost 28" from 26.5", but with the 8", I'm now below 26".

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[aslet]

I can get helper springs, thats not a big deal. I will also be re-indexing the rear torsion bar. I want the car about 1 to 1.5" lower than stock.

rl968: What is the length of the stock front spring, 10"? Why would I need to get an 8" front spring to lower thecar enough?




I also have a 2500lb 944 with 300lb front springs and a 27mm rear torsion bar (and Koni yellows). I like the feel and am not too concerned about 350lb fronts and 200/225lb rears.

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[flash]

the oem front spring is about 13.75"

that's why you really need an 8" spring if you want to lower the car - depending on where you are now, 1.5" may be too low though, and can push your roll center below ground, which will actually cost you in corners, as well as create all sorts of interference issues on the street

what spring rate you run depends on what shocks and struts you run too - koni yellows max out much earlier than others - the problem is that they have fixed compression, and only adjustable rebound - this makes them a bit bouncy if you get over 300# on them - shop around - i think pete has bilsteins he likes - i haven't played with the new ones enough to have an opinion on those - i do like the koni hydraulic ones i have though, and the separate adjustability of compression and rebound has really made it quite civilized

if you are going to reindex, why not just delete? then you can run coilovers in the rear and be able to set your ride height at will, as well as change out springs until you find what you like in ride

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[aslet]

I realize that the valving in the Konis max at around 300-350lb srpings. I may end up using a lighter spring. I also didn't want to get into a torsion bar delete. I do think the coil-overs are cool, but using a rear torsion bar may be the way to go if the coil-overs can't get me what I want.

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[flash]

boy do i know that one - i have a torsion delete, and while the springs are easy, and the adjustability is cool, the rest of it has been a noisy issue - i almost wish i had just stuck 31mm bars in there and been done with it - i do like the valving on the hydraulic shocks though - much nicer than gas

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[rl968]

With the 10"spring and the Koni conversion, I had no room to adjust the coupler nut, it was at the bottom. with the 8" spring, it gives an extra 2" of space. You'll need to have the car balanced when you are done with all four sides (and aligned)

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[PhilG968]

I don't know this is helpful, in my very not informed opinion.
What are you lowering for?
I had Pete RSBarn send me the front Bilstein set up with 400 main and 200 lbs helpers.
In the back I have heavy duty bilstein shocks.
The ride is amazing but firm, and in the corners (gravity defying), flat.
Nice set up.

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[Eric_Oz_S2]

You can get a away with 10" springs in the front, but you will be at the very bottom of the adjustment range for 1-1.5" drop. As said previously, best get 8" springs. If you run bottom mount camber plates you will definitely need 8" front springs. You don't actually need the tender springs in the back if you reindex the tbars, as the springs will stay in compression when you lift the car. It is best to reindex, as otherwise the handling can get a little weird due to the way the springs work together. I have noticed a definite improvement after reindexing (I originally ran just using the spring plates, but the ride and handling weren't quite right). 350 lb springs work fine with koni yellows. I run fronts at about 1/2 to 1 turn from full soft on the road and track and they seem to work better than when near the full stiff range on the road and on the track.

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[firefish]

I have 800 up front and 1100 in the rear and it can be teeth jarring at times although it is amazing to drive (not to ride but to drive). For this you need custom gas shocks as regular gas, and certainly regular hydraulics, will not be able to cope. Also, my springs are not for "normal" street tires, but rather for stickier r-compuonds or slicks.

IMO, choose the meanest springs that your tires can handle. The most common mistake is to pick a spring that's too weak and the maxing out the shock to compensate. Also, these cars are picky when it comes to rear shocks, especially if you are running stiff springs. This is due to the design of the rear suspension where there is very little travel in the shock compared to the wheel (there's probably a fancy word for this). I believe the MR for the rear is something like 0,6 compared to the front which is virtually 1,0 (like .97 or so). This is really hard on the shocks.

I have t-bar delete and wouldn't refit the bars unless at gun point and re-indexing is about as much trouble as removing. Put them away together with all those other nicetohavebutwillneveruse items and enjoy how fast you can play with both ride heights and spring rates.

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[flash]

i think everyone is missing the first step in making such a decision

what is the car to be used for 80% of the time?

i have 2 968s, and they have entirely different setups, because they have entirely different primary uses, i am about to get a 3rd - it will be very different than the other 2, as it will have yet another different use

you wouldn't set up a car for daily driving like you would for high speed highway, nor like you would for canyon carving, nor like you would for autocross, nor like you would for DE, nor like you would for racing

also, set the chassis up first, before springing the car or getting aggressive - taking the flex out of the suspension mounting points is key to achieving any decent setup

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[aslet]

Agreed Flash. This is my DD, that I want to handle real well on the streets and to be good for a few autocrosses. I have a track car, so I don't need this for track. Part of the decision will be if Paragon can replace the springs in the kit with the height and weight I want.

So far 350 or 325ln front and 225 or 200 rear sounds like what I want.

This with M030 sways and at least an upper strut brace, if not also the lower one...

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[rl968]

Paragon will allow you to swap springs and rates at no charge, speak with Jason. the couplers and helper springs are extra and aren't cheap, about $100 for all four corners.

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[flash]

i doubt it - that is pretty stiff - keep in mind that i come from a car that weighed 1800lbs and had REALLY stiff springs, so i'm no stranger to firm rides

on the 968, i had 300# springs up front on the konis, and it was too much for the street - it was fun at first, but every bump and wiggle in the road eventually made me nuts - the valving just wasn't right - having driven "right" i could tell immediately - it didn't suck, but it was enough that i kept searching for smooth spots in the road and clenched up when i hit bumps

i wish you were out here - i would have you drive ds968's car - he has 250# springs up front on koni yellow struts with 90# in the rear on carrera hydraulic shocks - VERY nice ride - smooth yet firm when he wants it to be - by far the best +2 street package i've ridden in yet

for a daily driver, i would leave the rear alone and add 200# springs up front, and add the braces and konis up front, lowering it as far as it would go with the eccentrics and matching at the front

maybe i maybe would add koni yellow shocks on the softest or next to softest setting, or perhaps the koni shocks they show, but with no springs

this would also be a really good first step, even if you decided to go farther, as the only thing lost might be springs (though those would be very easy to sell) - the rest would stay, even if you decided to go stiffer, but at least this way you could find out how it is and you would not have had to mess with the torsion bars - if you do it right, you wouldn't even need to change your alignment if you changed springs again

i'd do it in steps - you just might be surprised at the result

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[aslet]

I agree that what I want to do is agressive and stiff, but I want that. Like I said, I drove my 944 as a DD for a year with 300lb front springs, 27mm torsion bar, and Koni yellow. Since the 968 is a few hundred pounds heavier, having slightly stiffer springs will net around the same feel.

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[flash]

that is a much softer chassis though - good luck

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[Eric_Oz_S2]

Another option is to go for the KWV3 setup front and rear - around $2,000 all up IIRC. Springs are 340F, 280R - but much better valving for the street than Koni. I think I will eventually upgrade my Konis to KW Clubsports.

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[flash]

the kws seem to get much better reviews abroad than they do here - those who have tried them here think they are too jouncy - one guy yanked them out shortly after installing them due to that

perhaps it's an age thing - i know that i liked stiffer cars when i was younger, but then i though that stiff automatically meant better handling - over the years i have come to understand how suspensions actually work, and learned that this is not the case

in the case of this car, it is not true - the car actually works better when it is a bit softer than what you might normally set it up, especially in the rear - it's really very deceiving, and goes against intuitive thinking, but i've checked entry and exit speeds, and it's true - when i had the koni yellows up front, i was faster with 300 than 400 - the car still felt better and more planted on the eibach/techart/porsche motorsport springs i used to have that were 150-250, but it wasn't horrible - anything more than 300 and the front end was too skittish and i actually lost speed

when you get the chassis braced, you will find that it does not require nearly as stiff of a spring to achieve the same cornering speeds, as the suspension is then staying where it should, and not flexing around, effectively using up the first 100# of spring, due to weight transfer that will no longer happen

noises are another thing to be considered in a daily driver - squeaks and rattles start to come into play with the valves have to react to high spring rates - that is actually why i don't have the 400# springs in my car now - the dash made too much noise

i'm on my 7th set of springs, and 3rd set of struts and shocks, and set up quite a few cars now, so i've been around the block on this one, figuring out what suspension setup works best for what kind of driving - but in the end, it really comes down to what you like, even if it means being slower or less comfortable

lots to think about

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