Making IRS work without going to mendeola truetrack... :)

[Humble]

I guess I'll toss in my $.02 here

I would estimate with my 245/45-17 & 275/40-17 slicks and aero, my race bug generates some of the highest lateral loads of the circuit style bugs out there. I went with 944T aluminum arms mainly for the brake and track width upgrades. I swapped out for later 944T s2 arms for wheel speed censors and to correct a bent arm after body contact. I've been pretty happy with my setup over the last 10 years, but it does need some help.

Right now I've got:
944t S2 alu. arms
qa-1 single adjustable shocks
550# springs
17mm rear sway bar, (topline I think?)
urethane bushings everywhere
mendeola stiffy kafer brace
944/911 camber/toe adjustment bolts, also serve as sway bar pick up point
944 spring plates

What i have now is perfect for the street (except the spring rate, that's a bit much) but still a bit too compliant for track use.

-I want to swap out the 944 spring plates for some 935 style
-slighty heavier 600# springs
-swap shocks for double (or triple $$$) adjustable units

Not too much actually, I've been tuning my setup for a long time and I'm pretty close to having it dialed. Finishing around the top 10-15 in raw times out of 200 runners proves that my bug can hold it's own.

Does that mean you need a mendeola rear suspension? Yes and no. I think the mendeola kafer brace is one of the best out there and it's a must have regardless of what you decide. If you want to buy a kit that looks pretty sick, is truly bolt-on, and can take different brake options then it's hard to go wrong with the truetrack. I don't think the mendeola engineering is off base, and even if they were installed on my race bug, I don't think the rear arms would bend or crack under race loads. I do like their adjustable outer pivot for suspension tweaks, and even in single shear I don't think you need to worry about it, though I would still safety wire the thing. If you decide to go 944 aluminum instead you'll have to factor in the cost for arms, bushings, brakes, wheels, e-brake adapters, kafer brace, sway bar and so on. It might not be as good a deal as you think. Upgrading the stock steel arms with just bolt on items, coil overs/upgraded torsion bars, kafer brace, sway bar, and bushings will go farther than most folks have given credit.

[Wally]

Originally Posted by Humble

550# springs
17mm rear sway bar, (topline I think?)


-I want to swap out the 944 spring plates for some 935 style
-slighty heavier 600# springs

Why not use a (much) thicker sway bar first before upping the springs?
17mm is not that much imo.

[Humble]

There are 2 schools of thought on this:

Heavier springs, with lighter sways to fine tune
or
Lighter springs, with heavier sways but more reliance on shocks to tune

For autox and hill climbs where the corners come at you fast, you want to keep weight transfer minimal so the car can react faster. I've found the best way to do this is with heavier springs, so they do most of the work and then you can fine tune it with a sway bar.

Weaker springs won't be able to deal with high cornering loads slick tires can generate even with a ridiculously large sway bar. You'll end up lifting a wheel and losing 1/4 of your grip.

With both setups you have to tune your shocks accordingly or it's all for nought.