Spring Plate Angle Confusion

[voxboxer]

Hello everyone. I've just reassembled my rear suspension on my '68. I've put a 2.7L in a 912 body and have 24mm torsion bars w/ Koni shocks. For my stance, I'm trying to have my rear wheels just creep up into the wheel wells. After using the Elephant Racing Spring Plate Angle Calculator, I've arrived at an angle of about 29°.

Here's my issue... I have to set my spring plate angles at 15° to get that ride height! I've triple checked the size of my torsion bars. This being my first ride adjustment on a SWB Porsche, I imagine there must be something I'm doing wrong. Additionally, everything squeaks when I put weight on the back of the car. Is this a related issue? Any help would be greatly appreciated.

I've attached a few pic (Please disregard my boy's head in the pic of the whole car!)

Thanks!

Jeff

[Mark Salvetti]

That's going to be a fun car! No need to excuse your son, that's a great photo. He's going to have some great memories. And that engine is gorgeous.

Are those the Pelican heater blower delete plates?

So to your spring plates - that looks fine. Quick question - when are you measuring 15 degrees? I ask because that sort of looks like the angle you have in the photo with the suspension compressed. The Elephant calculator is for the spring plate in full droop, before you set the car down.

Mark

[Tyson Schmidt]

The discrepancy lies in what the ride height on their calculator actually is.

For example, actual Euro ride height is much higher than people think it is.
The commonly held idea is that Euro height results in fender lip measurements of 25.5” front and 25” rear with a 25” tall tire. But if you set it to factory Euro specs it’s actually 1” higher than that.

Other factors at play are gas pressure of the shocks that have to be taken into account, and the rubber control arm and spring plate bushings that will settle about 1/2” after driving.