Q: Is it possible to DIY-cut stiffened SPAX already lowered springs, by hand and without removing the shock from the car and without messing it all up?
A: Yes!
I've wanted to slam the front down so it matches or is lower than the rear since day one and with my recent splurge on the rear axle I thought it was about time. I had my heart set on a set of shortened SPAX strut-inserts, £200, assuming they were what was keeping the front end up, but it turns out I may have -40mm springs, not -60 as I thought, so the best bet is shorter coils. I would never in my wildest dreams have considered cutting the springs shorter and getting away with it, but it turns out the front springs on E21s are the 'pigtail' kind so can be cut and there are a lot of E21 guys doing this successfully on the forums, so considering a set of -60mm SPAX are £123, I thought I'd give it my best shot.
This page on E21Build.com on chopping stock springs was the most helpful with the process -
http://www.e21build.com/2012/12/cut-springs-and-other-things.html - but I thought I'd try and do a slightly more in depth guide, below.
First remove the top-nut using a 19mm deep-socket and yank the strut down a bit in the wheel-arch. This is so there is no tension left on the spring. Although the car's weight is taken off the spring by the jack it is still under a bit of tension, enough to cause harm, until the top-nut is undone.
Mark a line on whichever coil you are cutting directly above the natural bottom-end of the spring [where it fits to the notch in the baseplate]. This is the ONLY position at which the spring coils can be cut as the top-end of the spring fits into another notch in the top-mount and it won't line up if the spring is rotated.
I went with cutting one coil off for now to see how things go. *NB: The cable-ties I've used in the pic are NOT for compressing the spring. The spring was already under no tension, I was holding it up to cut.
Once the spring is cut the gap is too small to remove it from around the strut-body, so the only way to do so is to chop the off-cut in a second place and remove it in two pieces. Lowered-springs are made of some seriously tough sprung-steel and making one cut, let alone two, is hard work, particularly if you're only using hand tools as I was. Due to limited space I'd recommend the smallest profile whizzer-disc you can find, otherwise you'll wind up using a hacksaw blade by itself, as I did.
Seat the new bottom-end of the spring into the baseplate notch, make sure the top-end is still in the right place in it's notch and gently jack the strut back up through the hole in the top-mount. The tricky part is getting the strut-insert in the right position to get through the top-plate/mount enough to get the top-nut in place, without shifting the spring from either notch. I found the best way was to press the top-plate and washer down over the insert first, then guide it up through the top-mount and slide my hands out as the strut was jacked up by a pal. Once the threaded part of the insert can be reached by the nut from above the top-mount, even just a couple of turns, tightening the nut should be enough to raise the strut into the mount. Again, make sure the spring is seated correctly, as are the rubber boots - these can be seriously annoying to hold in place!
The spring position might look a bit jenky while the car is still raised, but fear not, as long as the spring is seated flush, with the first coil up from the cut end sitting snugly inside the rim of the baseplate, not proud of the edge, then all should be well and they'll settle nicely with the weight of the car on them.
How much lower?
I am led to believe by the previous owner that my front SPAX SSX springs are -40mm [
though they may be -60mm after all]. After cutting just the bottom coil out the car has dropped another 3/8 of an inch [~15mm]. If i'm right and they are the 40mm springs, I'm currently at about -55mm. If, fingers crossed, cutting a second coil will give me another 15-20mm, I'll be running at a 70-75mm drop, which is exactly what I want, given that the £700 GAZ coil-over setup, boasting the biggest off-the-shelf drop of all, only goes down to -65mm. On the other hand if I do end up having started with the 60mm springs, then I'm already at -75mm still with nearly two fingers of tyre to arch clearance and going any lower will probably wreck the springs - oh well, at least the full set of 4 SPAX SSX is only £123, [
http://www.larkspeed.com/index.pl?p=60S003043&a=i].
An added worry is the strut-inserts bottoming out from the spring only having 4.5 coils of resistance rather than 6.5, but that's still a little over two-thirds of stock and my inserts are stiffened SPAX PSX anyway, so I don't see why they won't hold up in theory with the damper set quite stiff. There doesn't seem to be any bottoming out with one coil cut, but if they start doing it with two I guess I'll have to fork out for the shortened strut-inserts after all [
http://www.larkspeed.com/index.pl?a=i&p=SPX112TAS155I&part=BMW-E21-3-Series-incl-M-Technik-45mm-strut-insert-Spax-Adjustable-Shock-Absorber-Insert-Shortened]. As for ground clearance, the metal bar that runs under the sump is currently just under 4 inches from the floor. It wasn't much more than that before, granted, but could cutting out one more coil be the tipping-point in losing all everyday drivability? We will find out tomorrow!
