Why is 944S M030 suspension weird?

[mallard ducks]

This has really been puzzling me. Does anyone know why Porsche specified the 944S M030 suspension the way they did:

944S (M030 opt) from Clark's:

3286N front springs
23mm tubular front sway bar

25.5mm torsion bar 175lb, or
25.5mm tubular torsion bar 149lb
20mm rear sway bar (opt)

944S M030 wheels/tires are 16x7, 205/55 front, 16x8 225/50 rear

The front is fairly similar to other models, but the rear seems to have gone down a bit of a different path... my car has the 175lb torsion bar and no rear sway bar.

As far as the standard suspension set-ups go, I can't think of anything particular to the "S" that would make Porsche offer a beefier torsion bar than normal and no sway bar versus the "regular" specification of a lower rate torsion bar + sway bar on other 944s.

Plus, if the original owner had checked the rear sway bar option, it would have been 20mm - the thickest of any 944/951.

I'm just wondering if anyone knows the reasoning for the sort of unique rear suspension specifications on the S?

[petrolhead611]

Maybe, I can't be certain, they specified the softer hollow torsion bar only with the optional sway bar, to keep the weight down, and not make the spring rate tooooo stiff at the back,; all this as they reasoned that 944S drivers didn't want the lightly excessive.understeer (pushing) of the regular 944, so they stiffened up the back end.

[flash968]

the workshop manual specs only the tubular 25.4 x 4mm torsion regardless of M030 or not, and 20mm sway as the M030 option for the 944S

it does, however, list 3 different springs for the front - all the same 396mm length, and the same 21.8N/mm rate, but different spring forces at resting compressed length, ranging from 3034N to 3286N

i have found a number of errors in the clark's stuff - i wouldn't necessarily trust it over the porsche material

[mallard ducks]

All pretty curious to me. My rear-end is toward the too-stiff for street side of things - I lose rear traction over bumps in corners pretty easily at reasonable/not flaunting the law speeds (but the ride quality is very good - nice!) and as far as I knew it is stock spec at the rear.

I should check if that is actually the case.

[flash968]

sounds like shocks

[mallard ducks]

Well, I'm a pretty stupid guy. Just went to the car. I could have sworn they were black (assume Sachs/Boge) but they're (grimy) Koni yellows. Would have found out eventually checking the brakes I guess, but still... pretty silly. The Koni discovery explains a lot of things!

I thought my car had a 175lb torsion bar because there's no sway bar - figured from Clark's that the sway bar came with the 149lb bar but was optional with the (non-existent) 175lb bar.

Anyway, the workshop manual info clears-up what I saw on Clark's - so the 944S factory spec for the rear isn't so different from other 944/951 afterall.

[flash968]

yup - probably dialed too stiff for the springs (torsion bars) - this is very common - many people think that shocks stiffen the suspension - they don't - their job is only to slow down and control the spring - setting them too stiff makes the car jittery and jumpy - too soft makes it undulate - yellow konis only have rebound adjustment, so it is very easy to have them get our of control

this is what is sounds like you have going on

for stock 25.4mm tubular bars, the shocks should be on full soft to one half turn up from full soft - if you had solid 25.5mm (175 lb as found in the 968) instead of tubular, then one half turn up from full soft to one turn up from full soft

to set them, you really need to remove them, pull out the foam bump stop in the top can, compress them, and with your weight on them, rotate the lower portion - clockwise to stiffen - counterclockwise to soften

i know some people who have done it with the top mount still connected, but you it takes a herculean effort, and is much easier with them out of the car