quite a few people have been asking about this recently, and as I was doing so I thought id show what I did.
firstly, ile say its pretty much impossible to say how much you need to chop out to get a specific drop on a specific car. the only person who knows what drop a specific chop will be is someone whos done the same thing on the same car.
before you even think about chopping anything, you need to do some thinking and measuring.
be realistic about how much drop you want. pretty much all mine are slammed on their
, but some people cant hack that 
you also have to take into account things such as sump clearance, shock length, axle clearance, tyre scrubbage, etc. etc. if your car will be sat arch on tyre with 3" or drop, don't go and lower it 4" !!! wheel and tyre choice have a massive effect on how low you can go.
look at where the spring is in relation to the wishbone or A-arm pivot point. the closer it is to the pivot point, the less you need to chop out to get your drop. as an approximation, if the spring is 50% of the way along the wishbone, you only need to take half the height out of the spring. e.g. remove 2" for a 4" drop. if its further out, remove more. further in, remove less.
right, lets talk about the springs themselves.
evey coil spring ive ever cut looked pretty similar, regardless of car. theyve all been about 10-12" long, and 9-10 turns. some taper out at the end, some (mercs being the most notable) don't.
on those that don't taper out, the spring cup will be shaped to match the spring. they are typically only like this at one end, the other end tapering out. in this case, you cut from the non-tapering end.
on a spring that tapers at both ends, cut from the top, so the cut end is hidden up inside the turret.
as 'most' springs ive encountered are the same, cutting them has always given about the same drop, one turn of spring equalling about 2-2.5" on springs that taper out, the first turn will only give you about 1-1.5", but then the following turns will give you 2-2.5"
so, down to actual method. getting the springs out can be tricky on some cars, but the only thing ive had to use compressors (nasty dangerous things!) on is the back of a merc. most cars have a bolt on plate holding the spring on, or you pop the bottom ball joint using the force of the spring, and a trolley jack to control it. remember, they always go back in easier, cos they're shorter!!
heres the springs I chopped today off the front of a commer.
a fairly typical looking coil spring, average diameter, thickness, length and no. of turns.
using my past experience, I dived straight in and cut 2 coils off. plus I knew I had a spare pair of coils if it went tits up
my tapered coil and one full coil gave me about 3.5" maybe 4".
marked up. notice the horizontal line as well- ile explain that in a mo.
I cut straight down through both turns, as I don't need the scrap bit, and it helps keep your cut straight, but more importantly, stops you catching the turn below with the cutting disc and creating a potential fracture point.
DO NOT cut coils with an oxy torch, its a very stupid idea, keep all heat away from them. if they get hot, you end up with mild steel, not spring steel, and the first time you load the spring up it will permanently deflect, which makes it pretty useless as a spring.
I use 1mm superslim cutting discs in a 5" grinder, as they generate less heat than the thicker ones. take your time with the cut, if the metal is blueing as you cut, its getting too hot.
once id cut down through the coils, I then cut sideways along the other line id marked. why? well, the idea is to create a bit of a flat seat again on the top of the spring, it spreads the load across the turret top better to prevent damage, and stops the spring cracking too as it doesnt put all the load right onto the end of it.
then, grind up all the sharp edge and radius them all in.
you should be left with something like this-
refit, the drop the car down. remember to put something under the tyres, bricks/blocks, or jack up in a different place to what you did when you put it on the axle stands, or itll end up sat on the trolley jack and you want be able to get it off!!
if you cut more than one coil, youll have to give your bumpstops and shocks some attention. cut the bumpstops down and fit shorter shocks. these can be off pretty much anything, they don't have to be uprated, jsut as long as they don't bottom out.
hopefully his lot will be informative and help some of you lower yours coil sprung rides!
I will also do a how-to on doing a stacklight merc soon, cos they are THE easiet car to do this way, and require no extra parts, no new shocks, etc.
firstly, ile say its pretty much impossible to say how much you need to chop out to get a specific drop on a specific car. the only person who knows what drop a specific chop will be is someone whos done the same thing on the same car.
before you even think about chopping anything, you need to do some thinking and measuring.
be realistic about how much drop you want. pretty much all mine are slammed on their
, but some people cant hack that 
you also have to take into account things such as sump clearance, shock length, axle clearance, tyre scrubbage, etc. etc. if your car will be sat arch on tyre with 3" or drop, don't go and lower it 4" !!! wheel and tyre choice have a massive effect on how low you can go.look at where the spring is in relation to the wishbone or A-arm pivot point. the closer it is to the pivot point, the less you need to chop out to get your drop. as an approximation, if the spring is 50% of the way along the wishbone, you only need to take half the height out of the spring. e.g. remove 2" for a 4" drop. if its further out, remove more. further in, remove less.
right, lets talk about the springs themselves.
evey coil spring ive ever cut looked pretty similar, regardless of car. theyve all been about 10-12" long, and 9-10 turns. some taper out at the end, some (mercs being the most notable) don't.
on those that don't taper out, the spring cup will be shaped to match the spring. they are typically only like this at one end, the other end tapering out. in this case, you cut from the non-tapering end.
on a spring that tapers at both ends, cut from the top, so the cut end is hidden up inside the turret.
as 'most' springs ive encountered are the same, cutting them has always given about the same drop, one turn of spring equalling about 2-2.5" on springs that taper out, the first turn will only give you about 1-1.5", but then the following turns will give you 2-2.5"
so, down to actual method. getting the springs out can be tricky on some cars, but the only thing ive had to use compressors (nasty dangerous things!) on is the back of a merc. most cars have a bolt on plate holding the spring on, or you pop the bottom ball joint using the force of the spring, and a trolley jack to control it. remember, they always go back in easier, cos they're shorter!!
heres the springs I chopped today off the front of a commer.
a fairly typical looking coil spring, average diameter, thickness, length and no. of turns.
using my past experience, I dived straight in and cut 2 coils off. plus I knew I had a spare pair of coils if it went tits up
my tapered coil and one full coil gave me about 3.5" maybe 4".
marked up. notice the horizontal line as well- ile explain that in a mo.
I cut straight down through both turns, as I don't need the scrap bit, and it helps keep your cut straight, but more importantly, stops you catching the turn below with the cutting disc and creating a potential fracture point.
DO NOT cut coils with an oxy torch, its a very stupid idea, keep all heat away from them. if they get hot, you end up with mild steel, not spring steel, and the first time you load the spring up it will permanently deflect, which makes it pretty useless as a spring.
I use 1mm superslim cutting discs in a 5" grinder, as they generate less heat than the thicker ones. take your time with the cut, if the metal is blueing as you cut, its getting too hot.
once id cut down through the coils, I then cut sideways along the other line id marked. why? well, the idea is to create a bit of a flat seat again on the top of the spring, it spreads the load across the turret top better to prevent damage, and stops the spring cracking too as it doesnt put all the load right onto the end of it.
then, grind up all the sharp edge and radius them all in.
you should be left with something like this-
refit, the drop the car down. remember to put something under the tyres, bricks/blocks, or jack up in a different place to what you did when you put it on the axle stands, or itll end up sat on the trolley jack and you want be able to get it off!!
if you cut more than one coil, youll have to give your bumpstops and shocks some attention. cut the bumpstops down and fit shorter shocks. these can be off pretty much anything, they don't have to be uprated, jsut as long as they don't bottom out.
hopefully his lot will be informative and help some of you lower yours coil sprung rides!
I will also do a how-to on doing a stacklight merc soon, cos they are THE easiet car to do this way, and require no extra parts, no new shocks, etc.
(never flattened the end
