I was thinking of getting me a set of theese http://www.ksport.co.uk/products.asp?f=coilovers

I can get pretty good price on them here in Sweden. For the coupe the stiffnes of the springs are 7kg/mm (392 lbs/inch) in the front and 9kg/mm (505 lbs/inch) in the back. This can however be changed to whichever spring rate I want without extra cost.

Has anyone here tried theese? I know some people here have some knowledge about this, would you recomend me to change the spring rate to something else?

Those springs sound back to front but they look like nice dampers Oh does this mean I have to buy some to test them ?

I believe so. It's part of your contractual obligation to the forum

I find it strange to so I double checked with the suplyer and he claims it should be like that. I understand you have some custom made suspension. Do you think you could tell me your spring rate?

No idea what he's running on the back.

Have you got my bra size too

Im running coupe Eibachs on the rear, Eibach wont tell me the spring rate of the rears though.

I was talking to a guy on a company here in sweden (Lesjöfors) wich are making sport springs for the coupe. The have progressive springs on front and rear. 11,3-20 N/mm in the front and 24,4-35 N/mm in the rear. K-Sport have 69N/mm in the front and 88N/mm in the rear so they should be very firm

Allso I made a calculation of the eibach springs using the figures from the TÜV document. Asuming they are using regular spring steel and not taking into the calculation that they are progressive I came up with theese figures.

Front: 13,5 N/mm 77 lbs/inch

Rear: 27 N/mm 154 lbs/inch

Since they are progressive it is probablu a bit higher maybe even 100% higher. However it gives a hint about the proportion between front and rear springs.

I just cant see how they can run with such a low rate spring, how can a 13Nmm spring work, it wouldn't even support the weight of the engine, the spring would be coilbound all the time.

Im on 500Lbs on the front and thats not very hard so a 77Lbs spring just wont work will it ?

As I said the eibach springs is just an estiamtion. But if the spring is on 20 N/mm as the lesjöfors one it means that it takes one 20 N to compress the spring 1 mm.

If the front of the car has 65% of the total weight then the front wheels take a load of aprox 420kg each. 420 kg is 4150 N. So both front springs would compress 207 mm. One front eibach spring has a length og 360 mm unloaded. So when the car is standing still the spring would be about 153 mm. I meassured the spring on mine with cobra lowering springs and it was abou 160 mm on the car.

There are a lot of aproximations (is that the right word?) here but I still think 20 N/mm for the front springs is in the right ball park for most sport springs for the coupe. I allso think this mostly is for sunday driving and not for track driving.

Why is it higher spring load at the rear? 9kg/mm vs. 7kg/mm

Jimbo, i don't know if it well help, but i saw on the integrale forum yesterday, someone asking for the spring load on the eibach springs, and it was 25/Nmm for the front and 26 N/mm for the rear. So not sure if the calculations you are doing are getting mixed up or not?

Think I must be getting confused

Im just going off the calculations we made for the coupe to get a good spring rate, my fronts are 550Lbs/in and that equates to 96N/mm.

The progressive tenders I use are 250Lbs/in (44N/mm) to 550Lbs/in (96N/mm) and they just about sit fully coilbound under normal use, they only work when the wheel drops into a pot hole or going over speed bumps etc to give a slightly softer initial movement.

What I'm thinking is a 2.5" coilover spring has to have a higher rate than the full sized spring like the Eibachs so thats why there is such a huge difference between these figures ?

Once again the eibach calculation is mostly an aproximation. It was the difference between front and rear that I was going for. The lesjöfors number on the other hand are correct and probably pretty near all the other manufacturers numbers.

There is no point in comparing with a 4wd grale.

If one would like to find out why the rear spring is harder one would have to do some serious calculations of the geometry of the suspension system. Location of the springs makes a huge difference.

According to numbers in the workshop manual the front spring rate should be somwhere around 16 N/mm.

Coilovers are normally designed for track use and more important with a hard shock absorbers. Lowering spring kits are designed for original shocks.

Are you sure you don't have a helper spring? And it in fact is your main spring that is progressive with that high rate. If you mean it is fully compressed? Or maybe it is very short...
http://e30m3performance.com/tech_articles/susp-tech/springs/index.htm

No not helpers, they only have a rate of 1Nmm and are there to stop the spring dislodging on full droop, I'm using the Eibach ERS range of coilover springs.
ERS uses a main spring and a progressive tender spring to give the progressive rate manufactures usually build into road springs.
I didn't want a race car but I wanted a car that would handle well on the road, we went through 3 different sets of springs before we came to the set I have fitted now.

http://i2.photobucket.com/albums/y5/James_Hardwick/DSC00230.jpg

Picture of my dampers shows the green tender and its progressive rate.

I'll try and find out what my spring rates are. I'm sure they're written on the springs somewhere.

If it is eibach there is supposed to be a stamping on it where the numbers have different meanings like length spring ratio etc. at least that is what I read somwhere on the net...

All I can say is those look very nice. I suppose the price is a bit out of my league so I will try one of those K-Sport and see what they are like. Springs for coilovers are not that expensive so I could allways change if I don't like them.

Exactly, thats the beauty of them, you can swap springs around until you find one you like. They work out at about £50 a pair so not too expensive.

Did K-Sport get back to you, I sent them an email asking about their kit but no reply as yet ?

I have been in touch with their swedish agent. Allso I got to know something from I guy who seems to know what he is talking about. He says if you change the springs from 20 N/mm to 80 N/mm the car will be 2 times harder not 4. Because the spring rate is and the way the car feels is not a linear ratio. It is infact the root of 80/20.