Matching Spring Rate to Sway Bar
 

So Im ordering the front coilover kit from paragon for my 1990 944s2 cab along with the 19mm adjustable rear sway bar but I have no idea how heavy I can order the springs. Car has koni sport struts, front strut brace and lower front brace. Currently the car is well balanced with slight oversteer which is how I like it but need to know how heavy I can go on the spring rate for the front coilover kit to match the rear sway on stiff setting while keeping the slight oversteer dynamic. Car is a weekend cruiser and autocross vehicle.

HOW HEAVY can I go on ordering the springs to match? 300? 450? more?
Please guide me to keep this baby bringing smiles to my face. :confused:

I think you are getting the “sleeve over” conversation, not a true coilover but allows you to change springs and adjust ride height so a pretty good alternative.

Check the “ High Performance Street/Track Suspension” section on this website, that’s exactly we’re you need to be.

thanks, ive been there, but it doesnt show the math i need, like if car is at perfect balance to keep perfect balance=
pair 350 lb front spring with 19mm rear sway bar on stiff setting....
thats an example

If you're pairing stiff front springs with stock torsion bars, then trying to make up for the imbalance with the rear ARB, that is a bad approach.

I am well aware of this. Ideally I would get the rear coilover kit to match the front but in this case I cannot do that because of both trying to minimize costs to cover other items and the rear has very little room to drop already.

Paragon states "We normally recommend 350# front springs and 30mm rear torsion bars but the choice is yours."
So should I just swap the RSB upgrade for the 30mm rear torsion bars? But then what happens when I want the stiffer RSB? should I order the RSB with both of them and up the front spring rate to 400? 450?

That is extremely stiff. My race car has #450 and 30mm. My 924 Turbo was #350 and 27 and was a little on the stiff side.

If budget is an issue, why not start with the biggest ARBs you can find and Koni Sports? This will transform the cornering without making the ride excessively harsh.

Also, VW torsion bars will work and can be had cheaply on a website called "jbugs."

I wouldn’t go over 200# front spring with the stock rear torsion bars, the stock rear bars should be around 137#. Pair the 19mm rear sway bar get the adjustable drop links for the rear bar and pair it with the m030 front sway bar and that should keep the handling close to what you are used to. Start with the rear sway bar in the middle setting, and have the car corner balanced and a proper four wheel alignment after you install the coil over front conversion. Tire choice and tire pressures are also going to be a factor in handling. Remember that the rear bar adjustment is just that, an adjustment to alter the under/over steer characteristic, you can also accomplish that with tire pressure adjustment (which is more practical when auto crossing).

Thanks for the reference I have koni sports and front braces. Very tempted to match your race car setting as I am still on 16''s and I do not care about harshness

jbugs shows Chromoly Torsion Bars, 26 9/16" Long, 30mm, Pair for half the price of paragon. You know that these will fit a 944s2? Great find

Also should i get the delrin or aluminum bushings to go with them from paragon? I imagine my bushings are original and rotted out

The 19mm rear sway bar has no effect whatsoever on the static balance of the car. If you want to fit 350 lb front springs you will need to either fit larger torsion bars or rear coilovers with springs iro 550 lbs to maintain the balance.

I used poly bronze spring plate bushings on the race car. Quality pieces and greaseable. Elephant.

So ironically I ordered the front coilover sleeves kit with #350 springs and the 30mm torsion bars from Jbugs (thanks Rasta) only to learn that the bars are backordered for "3+ weeks" so I am back to my original thought of getting the rear sway bar and setting it to stiff while waiting for the torsion bars because I want to get the coilovers installed ASAP and I will be in regret if 3+ weeks turns into 3+ months.
What could I expect the car to feel like with this setup until the torsion bars arrive?
350# front springs, 19mm rear sway on stiff, stock torsion bars
I know many of you will say be patient and wait but I have the coilovers and this is a much needed upgrade I meant to do years ago so I just cannot wait.....

30mm does not match #350 in the front. I ran 27mm with those springs and the car was perfectly balanced on the track...

It won't be the end of the world if you do the fronts while you wait, but if you drive the car hard it will push, so be careful.

Rasta, Paragon would argue that, see my earlier post, as would
Some guys on another Porsche forum. Either way thanks

it will understeer like an ocean liner.
i had 200lb springs with stock t-bars years ago and it was bad...
26mm bars in the back helped even it out.

FYI with the spring rates you're looking at, if this is a street car, it will ride like an empty dump truck.

Thanks for the insight rocket. I ordered the RSB and drop links. Setting it at max stiffness should mitigate some of the understeer until my torsion bars come in.

Paragon are not correct. It may not seem like that much, but increasing from 27 to 30 is a 50% increase in spring rate.

According to the Clark's garage page linked here, 27mm equates to 220lbs while 30mm to 335lbs. So I still doubt your words. I'm another forum, one guys has 350# with 30mm bars and another has 400# with the 30mm and both are happy,and both probably have other modifiers but at the end of the day I'll be doing 350# with 30mm and my 19mm 3way rear sway will hopefully give me a chance to tweak it for slight oversteer.