What spring rates???

[aerosam]

Hi guys,

I'm almost ready to go ahead and buy my suspension, I've been putting it off for ages as it costs so much.

I know what length dampers I need, but I haven't a clue when it comes to what poundage springs would be appropriate.

The engine is a little heavier than normal, at 146kgs and at the rear I'm using semi trailing arms with an anti-roll bar, if this make any difference at all.

Oh, and the car is going to be used on track only, so handling takes a major precedence over ride quality, as most tracks will be fairly smooth anyway.

[antonia800]

speak to GAZ based in essex found them verry helpfull in every way one comment on your exhaust manifold, it dosent help the flow of gasses i would check that this will be ok as heat build up in the engine could cause disaster performance = flow in and out great idea using the bmw v8 tho

[tex]

depends on your car weight overall really - car engined car - try 300-350 front 200 - 250 rear. bike engined car 200 front - 150 - 200 rear

[mr henderson]

Remember the poundage is only one of the TWO things you need to know, the other is the unfitted length.

[grumpy locost]

Originally Posted by aerosam

Hi guys,

I'm almost ready to go ahead and buy my suspension, I've been putting it off for ages as it costs so much.

I know what length dampers I need, but I haven't a clue when it comes to what poundage springs would be appropriate.

The engine is a little heavier than normal, at 146kgs and at the rear I'm using semi trailing arms with an anti-roll bar, if this make any difference at all.

Oh, and the car is going to be used on track only, so handling takes a major precedence over ride quality, as most tracks will be fairly smooth anyway.

my locost which is ten years old and weights 540 kgs has front springs of 225 and rears of 160 but remember the rear springs on a locost work vertical and not at a angle like the roadster

[HandyAndy]

My Roadster has 350lb up front & 250lb at the rear , using a 1.8CVH engine.

Spuds is the same spring rates too, & it handles like its on rails , with just the "right" amount of sprung weight when he throws it into the corners on a trackday etc.

cheers
andy

[tkpm]

i'm using the same as the Andy's running a Pinto

Terry

[mr henderson]

Don't forget, he needs the unfitted length as well! Poundage is useful but it's not all the story.

[aerosam]

Originally Posted by mr henderson

Don't forget, he needs the unfitted length as well! Poundage is useful but it's not all the story.

How do I figure that out?

I think I might just take Antonia's advice and call GAZ on Monday.

[mr henderson]

Originally Posted by aerosam

How do I figure that out?

I think I might just take Antonia's advice and call GAZ on Monday.

Good thinking.

But to answer your question, you need to know how heavy that corner is, and what ride height you want. If the corner was for instance 400lbs, and the spring was vertical, and you ignored the wight of the wheel, brake etc, then a 200 lb spring would be compressed 2 inches, whereas a 400 lb spring would only be compressed 1 inch, so knowing the unfitted length is important or you may end up with a spring which requires the platform to be done up a long way to get the ride height, or where the car is too high on the platforms lowest setting.

It gets really complicated when you consider that the springs are at an angle to the vertical, and that the spring lower mount is some distance from the wheel.

I've got a spreadsheet written by Mike Capon, who posts on Locostbuilders.co.uk which I could email to anyone who wants it, or who knows how to put it up here so everybody can use it (It won't help if they don't know their wieghts though).

Might be better if you just take advice from someone who has fitted a set that gives good results, AND who knows how long the springs were before they fitted them.