Quote:
Originally Posted by HP Autowerks
Someone mentioned the use of a cone shaped spring on the ST and KW V series, that really has nothing to do with tire/wheel clearance unless it wasn't designed properly and the lower perch is allow to invade the space not previously occupied.
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I will clarify Joe's statement above. The spring length of all the KW cone shaped springs is long so they push the lower spring perch down and result in the need for 10-15mm spacer in many applications we've seen to clear what previously worked. This is because you're no longer clearing the strut tube anymore, you're clearing the spring since it is beside the tire instead of above it.
Harold is correct, the cone shape is not what causes the interference on it's own. To be clear it is the length that causes this problem. Linear cylindrical race springs that are too long would cause just as much interference. But to be clear, there are no cone shaped springs out there for BMW applications that are short. They are all long, and so it is a safe generalization to say that the KW cone shaped springs (springs that go from 61mm diameter at the bottom to OEM spring diameter at the top) will be long and will cause suspension side interfeerance on wide/tight fitments vs. a setup that keeps the lower spring perch above the tire.
Joe stated that one could adjust the lower perch above the tire on those kits, but in reality this is not possible. This would effectively set the ride height above stock height most likely, as the lower perch is usually 1-2" too low to clear the tire.
The 18x8.5" et45 wheel was designed to clear the factory suspension up front spacer free depending on the tire used. If an aftermarket suspension is used that has a wider strut body, then a thin 3-5mm spacer will be needed because of that variable change. If a wide tire is used, the same would be true. Example, a 245/35/18 Hoosier R6 needs a 3mm spacer to clear a koni based coilover like a TCK kit.
The coilovers to really avoid on the 1 series are the ones that use a threaded sleeve on the entire strut body to adjust the ride height instead of the spring perch. The body will be significantly wider, and they tend to use an inverted strut which usually requires the use of a long spring. Those will not play well with wide wheels unless thick spacers are used, and we all know how little room the 1 series has to push wheels out towards the fender.