Coil spring rates

[Rich]

I'm currently chucking about ideas for coil springing my Midas, the majority of parts required I can make on the lathe. Where I'm currently stuck is on suitable spring rates to use.

At the front I'm intending to use springs in place of the displacers rather than coil over arrangements. Does anyone know the poundage rating of a displacer? I'm looking to create a more compliant road suspension rather than race track stiffness.

At the back it would seem sensible to use the coil over arrangement already designed, I understand there has been some debate on what is suitable to use spring/damper wise.

Cheers

Rich

[Stuart]

I'm only 99% sure on this, the Watsons spring rate is in the region of 3850 to 3900 lb....

[Rich]

I'm only 99% sure on this, the Watsons spring rate is in the region of 3850 to 3900 lb....

Woo, that's more of a strut than a spring..

I remember Opel tarmac rally springs being rated at 700lbs, they also work on a ratio and made the anti-roll bar superfluous.

[manifold]

sounds about right but I would check.

[Alan D.]

Hi Rich,

I have a little experience of spring rates on the rear. I started off with 140lbs, then reduce them to 120lbs. Still to firm for me. I think I will try 100lbs next, due to my excessive weight. But for normal people I would think 90lbs!

With regards to the front all that I can tell you is that the Mini boys seem to use between 450-650lbs, depending on how much you want to rattle your teeth.

Inclined coilovers need higher rates!



I have my own ideas on front suspension for the Mk3. The simplest one being an inclined coilover, from the shock mount on the top arm to a bracket welded to the hydro-gas tower mounting.

Something like the picture below. When you dispose of the Hydro-gas units there is plenty of space. This is a tried and tested method, so no need to reinvent the wheel!

Just brainstorming!
Hope this helps

Alan

[manifold]

theres more than 1 way to skin a cat!

not too difficult to do either.

[Alan D.]

If somebody can work out the angles and dimensions. Then give me a drawing, I can probable get them cut! I already have top arm mounts.

Alan

[Stuart]

Just to confuse the situation regarding rear spring rates, my mk3 coupe I had 160lb rear springs with a little 4lb run-flat taking up about 3/4" of play, I found both the handling and ride spot on.

I'm sure I've seen the four posters on this thread somewhere else on the forum

[Rich]

Thanks Alan,

Funnily enough that's where my brain was going too as springs up to 700lbs are easy to find, heavier gets harder to find.

What was rattling about in my head was a bolt on bracket that uses the four mounting points on the hydragas tower and then mounts against the panel the damper is currently bolted through. As well as triangulating the mount it would also remove the majority of the stress on the glass fibre. That should allow a vertical coil over arrangement following the lines of the original damper position.

[manifold]

Hi Rich,

Thats also been considered too. I put some pics somewhere on the yahoo forum with some ideas like this. Its probably the best method in all honesty...only issue will be variance in grp would mean shimming etc as the subframe mounts are rubber mounted.

Cheers,

David