There are a few ebay sellers that have smoking hot deals on used afco springs. The only issue is they are much longer than what I need.
Is there any way to make two 7" springs out of a single 14" spring?
I notice that the dead coils at the ends of automotive springs are usually wound tighter and are also tapered (belt grinder?). Not sure how I could reproduce this safely. It seems to me that I would want to, otherwise that end would sit cock-eyed in the spring perch.
Thoughts?
AFCO springs aren't that expensive new...
I don't think AFCO makes springs shorter then say 10 inches. What spring rate are you looking for? I have some 7 X 2.5 X #700 springs I don't need.
still doing my research but somewhere around 300-350 lb/in @ 7" looks to be just about right for the front. I'd likely opt closer to 300.
there are a few used afcos on ebay 150-175 @ 14" and are about $20 a pop. Cut them in half and I get pretty darn close to what I want
still need to work out the numbers to be sure but this is what I"m looking at
$40 for springs front and rear for the e30 would be great, then all i'd need is the adjustable perches.
Brand new QA1 springs are $40 in the size you need. Cutting a spring will change the structure of the metal enough to cause the spring rate to change an unpredictable amount. I say skip a few meals and buy good springs.
jimbbski wrote: I don't think AFCO makes springs shorter then say 10 inches. What spring rate are you looking for? I have some 7 X 2.5 X #700 springs I don't need.
Yeah, they do. A big selection of 8" and a smaller selection of 7". Just FYI. And I've seen sales where they go for under $30 new.
unevolved wrote: Brand new QA1 springs are $40 in the size you need. Cutting a spring will change the structure of the metal enough to cause the spring rate to change an unpredictable amount. I say skip a few meals and buy good springs.
Their six inch rates (for the rear) make a quantum leap from 170 lb/in to 900 lb/in (at least on Summit racing they do).
What changes? I don't have my notebook on me so my spring rate formula is not on hand, but if the number of active coils is halved, in theory the spring rate doubles exactly.
On a side note... why are eibach springs $80 a pop while afco/qa1 is about $40?
paging poopshovel and the Boss Hong!
if i remember correctly Hong Norrth did just that with something like a huge ford van spring for the rear of their $06 challenge car.
Taiden wrote:unevolved wrote: Brand new QA1 springs are $40 in the size you need. Cutting a spring will change the structure of the metal enough to cause the spring rate to change an unpredictable amount. I say skip a few meals and buy good springs.Their six inch rates (for the rear) make a quantum leap from 170 lb/in to 900 lb/in (at least on Summit racing they do). What changes? I don't have my notebook on me so my spring rate formula is not on hand, but if the number of active coils is halved, in theory the spring rate doubles exactly. On a side note... why are eibach springs $80 a pop while afco/qa1 is about $40?
Right, but when the springs are cut, I believe they work harden from the actual cutting, and the heating makes them more brittle as well. I'd go check my Mechanics of Materials textbook, but it's propping up my TV. Something about martensitic formations.
Unless you cut them slowly with torch, you won't have to worry about material changes. I used a HD cutting disc on a dremel tool (really!) to cut my Volvo's springs - it took about 2 min per cut, and the spring was cool to the touch at 1/4 coil turn from the cut.
Yeah, there may be other good reasons not to cut a spring, but I doubt that heat from the cutting process is one of them.
skip summit and go straight to speedwaymotors.com for more brands and choices
Speedway still doesn't go quite short enough. :\
It's pretty trivial to do coilovers on the front. The back on the e30 is a little weird. I don't know if I can just toss threaded sleeves in the back with the proper length spring and have it just work. I'm concerned that at full droop the sleeve and spring will be inspired to take a walk.
I could easily enough convert the shocks to a coil over setup, but people say this is horrible as the shock towers aren't up to the task without reinforcement. I do not know if this is true.
Try southwest speed. there a huge suppler that doesn't do heavy advertising, thus prices are great. product second to none. I've got a mag rack from them wow light and use plenty of other parts from them.
44 no not afilliated with them in any way just happy customer
In reply to 44Dwarf:
WOW . . .this is timely. I was looking at their site for a hydraulic throwout bearings.
Thanks!!
If it's a constant taper, constant diameter spring, cutting it in half will get you two springs with double the spring rate of the original and is perfectly fine as long as you don't put enough heat into the spring to affect the heat treatment.
MadScientistMatt wrote: If it's a constant taper, constant diameter spring, cutting it in half will get you two springs with double the spring rate of the original and is perfectly fine as long as you don't put enough heat into the spring to affect the heat treatment.
Probably not, because you double the number of dead coils/reduce the number of active coils to less than half.
There is also Eibach, Hyperco, etc etc etc that make a quality spring.
OP, both my E30s had 5" spring with an adjuster, no problem falling out or coming unseated.
I see no reason to convert to a "true" coilover on the rear on an E30.
Zomby woof wrote: Probably not, because you double the number of dead coils/reduce the number of active coils to less than half.
I meant to say constant pitch rather than constant taper - I should have said zero taper, so there aren't any dead coils on the ends. However, you are correct that the spring perches will render a portion of the first coil dead, so it's a little stiffer than twice the initial spring constant.
In reply to the coilover q... The ti people say the same thing. Shock tower needs reinforcement.
However, the compact cup across the pond uses true coilovers, no reinforcements. Haven't heard of any failures.
What do the spec E30 guys run?
Most of the ti guys run the short spring and an adjuster, the spring pads do a good job of keeping the springs where they are supposed to be. You can always run a limiting chain/strap to keep the arms from drooping too much.
H&R race and Bilstein Sports.
z31maniac wrote: H&R race and Bilstein Sports.
Too low IMO. I want pretty minimal drop because of the crap roads around here. Main reason for wanting adjustment is because a friend has cornerweight scales.
Edit: just realized you were answering his question
I've bought springs from Suspension Spring Specialist, Inc.
http://www.webpage-design.biz/bluecoil/coil-over4.htm
They stock 7" springs.
Yes, their website is hurting. http://www.bluecoilspring.com/
Whaddya know, I'm looking to do the exact same project! Did you end up trying this out? The math is telling me to go for it, but I'm wondering about leaving an open coil end in contact with one of the spring perches...anyone have experience with this (positive or negative)?
To minimize heating I'm going to either chop these in half on the water jet or submerge most of them in water and use a cutoff wheel, so I think I should keep the spring in good shape.
Scroll halfway down this page for the best idea I've come up with so far: http://www.motoiq.com/magazine_articles/id/1439/frankenmiata--handling-with-a-hacksaw.aspx
They use stock miata bilstein perches (cast aluminum deals) which are designed to take an open coil end. Problem is making some up myself or sourcing four of these...then running two upside-down!
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