Spring plate angle without engine

[skunkwerks]

Hi all,

I'm putting everything back together after a major refresh on my '87 Carrera. The engine is out after a complete rebuild. The rear suspension also was completely refreshed with new bushings, bearings, powdercoat, etc. During the teardown, I didn't record the spring plate angle before removing them from the torsion bars.

I am having it corner balanced and aligned once I get the engine back in, but I need a ballpark angle to re-index the bars to at least get it rolling. Anyone have an idea what I should aim for WITHOUT the engine weight?

[tirwin]

Maybe I haven’t had enough coffee on a Monday, but why does it matter if the engine is in or out at this point? If you have the weight off the wheels, the droop is from the weight of the trailing arm. It’s only going to matter once you have the engine back in the car. It’s going to be like a dog in heat until then anyway.

There are some old posts of Will Ferch’s spring plate angle calculator. I think there is a link to it on the Elephant Racing site too.

[roblav]

Spring plate angle setting has nothing to do with engine in or out.

[Driven97]

Use this but, uh, obviously use the weight of the car once it's all together.

There's no instructions on that page, but it's the spring plate angle relative to the sill, with the a-arm not connected. And if you have softer torsion bars, watch out for that bottom rear bolt on the spring plate cover too, that can interfere with some TB/height settings. Make sure to center the height cams on both spring plates before you slap it together to give yourself wiggle room.

[skunkwerks]

Sorry, guess I wasn't super clear in my original post. Look's like I'll just shoot for something in the mid 30 degree area for the droop. I don't have the plate connected to the trailing arm at the moment, so it's a bit hard to measure. I'll just set it a bit less than the lowest point on the trailing arm, then add some pre-load to align the bolt holes.

[Driven97]

Wait, why mid 30? I see 41° for a stock torsion bar Carrera, at Euro height, using vehicle weight without driver.

That angle is without the plate connected to the trailing arm.

[bkreigsr]

I just checked my numbers.
My 930 was set at 30.4 - 30.6 degrees.
That resulted in a fender lip height of 24 and 24.25 inches.

My 912 E was 31.6 degrees - resulting in fender lip height at 24.25 inches on both sides.

Cars were both set to level on the door threshold.

This should at least give you some starting numbers.

Bill K

[juanbenae]

I with bill. I do not remember such a high degree as anything near 41 and ive done it 4-5 times over the years.

just make sure you put the eccentric ride height adjustment in the middle so you've got the option to adjust either way.

[Driven97]

Wonder if there's an issue with the Elephant calculator?

[bkreigsr]

Originally Posted by Driven97

Wonder if there's an issue with the Elephant calculator?

...worked ok for me when I plugged in the numbers for the 912.
The trick is deciding what height level you want to end up with.
I used race/track.