Choosing springs?

Well I got around to changing the rear springs and rubber mounts on my car and the springs I got are 1 1/2" higher than the old ones. This causes the rear end of my car to be pretty high in the air. The original springs were short and had closer distance between the coils. The new springs are just too tall for street driving and have changed the driveshaft angle so I now have a nasty vibration above 40mph. If I blow the driveshaft I'm screwed so no freeway driving now, just limping around town.

My question is how do you buy springs if there aren't any off the shelf options? There is one company that sells a set of short springs, only 800$, which is too much monies. I think H&R makes a set of springs but they would have to be ordered from europe which is very expensive.

So I'm thinking about getting out the tape measure and getting an idea of the spring diameter and height then finding a car of similar weight and using shims to get a nice firm ride that's not too low or high. Does anyone know if there is a catalog of spring sizes and rates I could refer to? I just want some good ideas, thanks folks.

Cut a coil off the spring. Lower the car and stiffens the spring.

Do you know the stock spring rate?

In reply to benzbaron:

http://performance-suspension.eibach.com/

Mercedes gives the stock spring rate as spring travel per 1000N force. The spring rate is 15.9cm/1000N. I don't know what that is in ft/lbs.

I see there are a couple companies that sell lowering springs so I might see about getting a set, but I don't really want my car sitting any lower than it does already.

I thought about cutting the springs down, they are pretty stiff so I don't think a 1inch shortening would hurt. I also thought what if I go to the junkyard and get the front springs off a 450sl/c and save the rears then if I'm going off road I could be sitting tall.

Thanks for the replies! I'll post back when I figure out what I'm going to do.

springs are usually rated in lbs/in rather than lbs/ft. google knows the conversion factors between lbs and N, and between in and cm.

Go to onlineconversion.com to convert. If you know the ID, spring rate and length needed, you can probably find them on Summit Racing.

Cool thank you guys for the information. I have the numbers in the mercedes manual so I should be able to figure out the spring rate. I'll have to check out the summit catalog, that is a good idea. There are only two affordable short springs for the mercedes 280sl/c and they both come from england which make them expensive.

Thanks again!

Lets see how my math is.

For 1000N force the spring deflects 15.9cm.

1N=.224lbs so 1000N = 224lbs 15.9cm = .626in

224lbs/.626in = 358lbs/in

Does this sound like a reasonable number?

Hopefully I'll be able to find a decent set of springs. Thanks folks!