Now I thought I had things sussed

Can any one tell me a ball park figure of how much the suspension will compress when sat still with me in it.

I know this depends on lots of things such as total weight and the amount the spring pushes back ect. But im just after an idea so I can set brackets and ride heights.

Having followed the GTS planes I’ve found tonight that the top of the rear bulkhead is an inch higher than book. That’s good for harness mounts but bad as I now need extra brackets on the axle.
And other of the shelf bits now won’t fit.

Still never a chore always a challenge.

Thanks for any help/advice Warren.

Assuming you have 150lb springs, and you weigh about 150lb (optimistic?)
Your suspension will move a little less than 1/2" when you sit in the car ('cos there are 2 springs, and you ain't sat on the axle).
Mine dropped 1", 2 up with a rack full of luggage.

Marcus

Not a lot is the answer to this one.

"assuming you weigh about 150lb (optimistic?)"

Your not wrong When I first signed up for this forum I was a very big Lad Hence the name "Big_wasa" and im 6'3" tall but when I couldnt get in an Avon I decided to work on that aswell as the locost

Thanks I was expecting it to sag more than that ? I think I have 160 lb springs.

Don't most cars have 4 springs?
Anyhow, at 160lbs/inch it takes 160lbs on the spring to compress it 1inch. You have 4 springs, and reduced leverage because you aren't directly on the springs. Like the others said, not much.
Generally you support the vehicle with solid tubes bolted to the spring mounts while building. Then once everything else is done you weigh the corners of the car and figure out what load/rate spring you need. Lots of cars get built by trial andf error though . Spring load controls the ride height, and spring rate controls how easily it compresses. Dont know if this helps you, but can't say I didn't try.
Cheers.

Basically it's up to you how much the springs compress under the cars own weight - you control it with preload. I'm setting my ride height so that static with me in the car the dampers will have compressed about a third of their stroke. That gives me 2/3 travel for bump and 1/3 travel for droop, which I've read is about what you want.

Liam

You can work out the position for the trailing arm brackets on the chassis from the tyre outer radius and desired (chassis) ground clearance -- once you have that you know where the brackets on the axle will lie relative to the bottom of the chassis then use Liams sugestion.