Custom Coil-Over Build

[IdealSociety]

Heres The Plan: Since actual festiva coil-overs are in short supply (extremely short like 3 ofem exist and they cost over $1k lol) im going to build my own.

i was remembering back a few weeks ago on the Fiero forums, a thread about building custom coil-overs the the rear suspension on a fiero. since a festiva front strut and a fiero rear strut share the same likeness in design, im going to adapt the idea to a festiva.

Parts:
aluminum 6" threaded sleeves with adjusters to tighly fit over the strut
modified KYB GR2's (cut off the spring Perch... Carefully!!!)
10 inch long 250lb springs to fit over the sleeves



first we cut off the original spring perch on the festiva (or aspire would work too if your doing this to an aspire) very carefully!!! grinding off the last bits flush with the rest of the strut.





next we measure the diameter of the strut and get the closest sized aluminum sleeve to fit over it. since the bottom mount of the strut to the hub assy is larger and wraps around the strut, it would keep the sleeve from going down any further.



possibly using silicone between the sleeve and strut as a sealant and vibration dampner. next we measure the diameter of our spring. we then make a round metal hoop out of 12 guage steel maybe 2 inches deep to fit around the top of the spring to keep it from bouncing around. we then weld this into the center of the top strut mount. a circular piece of rubber with a smaller curcle cut out of the center acts as our noise /vibration dampner between the spring and mount.

this one is buil for a fiero and uses a fiero top mount, the festiva top mount would be significantly smaller and much easier to build as the fieros rear suspension is kinda complicated lol..



we then lower the adjusters down fully, and reattach everything into the assembly.then raise the adjusters up to halfway and install into car.



if everything works out this would help to give an adjustable ride height and a narrowed spring area for wider rim/wheel clearances.

thats for the fronts i figured since we all drive festivas and most of us scoff at prices of anything over a few hundred dollars for our cheap little cars, this would be a great do-it-yourself mod for people.

for the rears though?.... uhh... im still working on that one... any ideas?

[masta-t]

i wonder how thick the wall of the festy strut is, and if thick enough you could just take that to the machine shop and they could thread the actual strut body.......this is of course the wall thickness is decent.

freakin good idea though man

[IdealSociety]

mod should be cheap...

ive done some cost figuring and depending on where you get the parts this can cost as little as around 300$ with new struts included... you can buy a full set of the adjsuters for a civic on ebay for 50$ springs and all, shipping is more than the cost of the product... today i will try to compile a list of other cars they sell adjusters for that will fit the fesiva application...

i dont know for sure how think the strut walls are, i think today i will go outside and cut up one of my shot stock struts for reference to this, although i dont know if i would want to take any integrity away from the walls, they are usually the thickness they are for a reason...

although that would be a possibility for the rears... i think today i might have thought of another way to work around the rears...

you could simply trim down the strut perch so just a little ring is left going around the strut that would only stick out about an eighth of an inch that would be enough to support the adjusters no problem.

putting the adjuster up so high though would require running a much shorter spring, possibly an eight inch or shorter. i will go take some measurements today and come back with the results.

[SimonTuffGuy]

It may be a good idea, but I think it would need some SERIOUS R&D before I'd ever put it on my car.

$1000 for a set of Teins really isn't that much compared to your life if something goes wrong with that suspension setup...

On a side note... I really like the looks of that and it goes look like a nice setup... I'm getting excited more and more everyday for my Teins to come in...

Simon

[IdealSociety]

measurements

took some measurements now, the front springs can be changed from 10 inch to 12 inch lengths to avoid coil bind as festiva front springs measure 15 inches, 10 inch spings would be for a stock diameter tire combo for more drop, since im running quite a bit larger diameter and dont need so much drop but would like less chance of coil bind i will go with a 12 inch spring. i also think the previous 300lb spring rates will ber more than likely waay too much. im ordering a few different kinds now to test them out, i think for a stiff ride a 250 or 275 might be good but for sa softer ride a a 200 would probably be good, anyone know what the stock spring rates are? or even the fms rates?

R&D? thats why im doing this its not that i couldnt afford teins once i get back to work, i just like to make everything possibly for my car myself lol... if i can get everything to work right on this and make it a safe mod, it could be as popular a mod as the aspire brake setup. the sleeves shouldnt be able to move considering the spring pressure is holding them down and as long as the adjusters arent so low the spring is almost loose, there should be no chance if it bouncing with the weight of the car and the strut to keep it from going anywhere.

the top mount will be the only issue for safety as far as i can see. and actually ive found a part that will help make that not even needed for modification. with some sleeve and spring kits you can order a part called a hat for the top to keep the spring centered on the strut. here is a pic of what i mean:



on a further note to that i think the rears may have to stay non-coilover as the strut body itself seems to be waay too narrow for any sleeves i can find, the body on the rear struts seem to be about an inch and a half thick lol. the smallest adjusters i found have been around 2 inches so far...

but if there can be adjusters found, the stock rear springs are 13 and a half inches long... so running with a 6 inch adjsuter still, the 10 inch spring would be easily done and would give still a 2 inch drop, or like in my case a pretty good lift

by the way i cant find my old stock struts, i think they are buried in the snow in my scrap metal pile somewhere, could someone take a measurement of the diameter of these if they have a pair lying around?

[JerseyJay1.8T]

now i'm just totally brainstorming here, since i don't have a stiva rear strut in front of me, but do you think you could used a sleeve-shaped poly bushing to take up the clearance around the strut body in the rear since you say its too thin? Just noting thats what ground control does on their kits, and it worked fine on my prelude back in the day.

[IdealSociety]

hmmm

i think that might be the ticket... now this also depends on if different struts are different sizes and all... ill get a measure on the stock rears tomorrow and shoot back with the numbers. then ill check out the KYB GR2's i have on my car to see if they vary in size.

still trimming down the spring perch to a size that would match the sleeve, maybe also slowly tacking down a ring of sorts around it just for cheap insurance... mind now this would have to be done a little at a time to keep the strut cool... now id need a bushing of sorts to keep the adjuster centered... ill get diameters tomorrow and try to find my stock front struts then get part numbers for the adjusters and springs.

thanks for the bushing idea jj!

[Kindred]

This sounds like it's a bit beyond my skill level. Tell you what, I'll buy the struts, and I'll pay one of you to do the work for me when you get this figured out.

[IdealSociety]

coil rates?

whats the stock coil spring rates?

i remember hearing on the old forums once but i went to search them and as ususal for me, i didnt get squat...

i think festivas were like 75lbs? and aspires somehow came out to 80lbs? or was it 170 and 180? ahh crap i hope someone knows this...

i think i will order 80lb and maybe 90lb springs at 12 inch (im lifting not lowering my festiva :twisted: )

i ordered a 7 inch sleeve kit from www.colemanracing.com cost came to 29$... im pretty impressed with that. springs may be a little more though...

i will check summits catalogs quick to see if their springs are cheaper than colemans site...

edit: im not sure now if the 29$ is for both sides or jsut one... i guess i will find out in a few days and tell you all!

[88FESTIVAGTR]

Good price on those sleeves, I wish there were pics. Check a coupl post down where it says

"Any coilovers?"

spring rates are there

[Whittey]

FMS springs are progressive, so you can't give a real springrate. I broke out ye olde dial calipers and went to work and here's the info I got from the Aspire springs.

=============================
FMS ASPIRE SPRINGS
=============================

-----------------------------
front spring
-----------------------------
0.39" coil diameter (WITH PAINT)
3.81" spring diameter
11.75" spring height

SPACE
0.64"
1.78"
1.78"
1.78"
1.21"
1.05"
0.33"

-----------------------------
rear spring
-----------------------------
0.37" coil diameter (WITH PAINT)
3.58" spring diameter
12.42" spring height

SPACE
1.00"
1.01"
1.01"
1.01"
1.01"
0.85"
0.53"
0.53"
0.53"
0.32"



So they're both bi-rate springs. Oh, and the overall height measurements was made with a straight edge so it's not all that accurate.


-=Whittey=-

[Whittey]

Spring Rate = Gd^4/8ND^3
G = Torsional modulus of steel (11.25x10^6 (11,250,000))
d = Wire diameter (in)
N = Number of ACTIVE coils
D = Mean (average) coil diameter (in)

So let's do a quick and dirty average of the whole damn thing to get an idea of what's going on.

FRONT
11250000 * 0.39 * 0.39 * 0.39 * 0.39 / 8 / 6 / 3.81 / 3.81 / 3.81 = 98

REAR
11250000 * 0.37 * 0.37 * 0.37 * 0.37 / 8 / 10.25 / 3.58 / 3.58 / 3.58 = 56

NOTE - G. Sheer modulus. Some places list as 11.25x10^6. This includes "Chassis Engineering" by Herb Adams. "Race Car Engineering and Mechanics" by Paul Van Valkenburg lists it as 12x10^6. Some spring and metals places on the net list it as 10.5x10^6. The place I would tend to trust the most is the Bosch Handbook, which lists G as 81,400N/mm^2. Converted over to SI measurements and you've got 11,806,093. So who the hell knows for sure.


In any case, your god is that soft. Sheesh. No wonder they "ride good," they're so soft they can't help it. I think that might be another issue. If the production struts are meant to dampen piddly-ass springs, you'll be woefully under-dampened if going to a significantly higher springrate.

I know some of you out there have raced, anyone want to share weight weights? Overall and front/rear of a REAL car, not a rating? It's cool if you've stripped it or whatever, I just want a better idea of what's going on.

[EDIT]
Aspire struts. The KYB Super's (actually Excel-G). Front body diameter is 1.77" and read body diameter is 1.52".
[/EDIT]

[EDIT2]
How To Make Your Car Handle by Fred Puhn lists the sheer modulus as 12x10^6. Also, the Bosch Blue Book lists a couple of spring steels (elsewhere in the book from where I got the previous number) which shows G to be between 73,500-81,500 N/mm^2. That real low number is for non-rusting spring steel wire (DIN 17224). Discounting that, the range is from 79,000 to 81,500 N/mm^2. 73.5k converts to 10.66x10^6, 79k to 11.46x10^6 and 81.5k to 11.82x10^6.
[/EDIT2]


-=Whittey=-

[IdealSociety]

parts today...

got my adjuster (single) today... i was hoping for 2 for trhe 29$ but it appears i only get one w/ a hat like in the pics above to keep the spring in place. no for springs though im still contemplating on what to get for a stiffeness...

since i do alot of rough road driving i want to stick close to the 98lb spring rate on front so i will go with a 100lb 12 inch spring 2.5 inch ID... i also ordered the other side today and will start test fitment tomorrow for the struts to see if everything fits tight.

got my fms spoiler comin in tomorrow so ill be in the garage workin on the festiva anyways :twisted:

[Cpl West]

Hey man, I like where this is going. The only thing I'd be concerned about is making sure that your shocks and struts were matched with the springs, and then also be adjustable in the bound/rebound dept. Thats just a personal preference.

As for the rears though... I went out and took a look at my rear shocks(which happen to be the Aspire that I brought over from the brake swap) and realized you have 2 options:

1. leave them alone(which defeats the purpose of all you're work since they're not adjustable)...
2. grind off the excess from the old perch to where theres just enough of it left to safely support a coilover sleeve like on 88festivaGTR's front struts.(see pg. 2 of the post "15x7" and check out the pic). I think you'd be golden with number two since you plan on raising it.

In my case, I'd like to be able to lower it a bit for aggresive summer driving while still having the ability to raise it as well for winter driving through all the damn snow we get here. If I left the stock "shaved" perch in it's place using the stock spring length, I'd never be able to lower it, only raise it.... That means I'd have to cut the existing perch off it's attatching point and re-weld it a bit lower, or create a new perch altogether and do the same. Wait a minute... I can't weld, so who knows what I'll do... At this point it's all hypothetical since I don't have any of the coilover stuff to compare with anyway.

BTW- which springs and sleeves are you using and on which shocks/struts? KYB GR2's right? Are they the same diameter as a stock festy shock? I'd like an idea so I can get the right sleeve I.D., and use a pair of old stock components to experiment with. Then use the sleeves and springs on the new shocks/struts when these wear out.

[FB71]

Aspire struts. The KYB Super's (actually Excel-G). Front body diameter is 1.77" and read body diameter is 1.52".
-=Whittey=-[/quote]

found some coil-over sleeves for the rears. Speedway Motors, Carrera coil-over mounting kit for 1.63 in outside dia shock w/ 2.5 in spring dia.

part# is 255-1951

includes sleeve, adj nut, upper seat and snap ring

They also have 2 in sleeves and kits in 5 and 7 in lenghts for Carrera, Monroe, Pro and Bilstein.

Also springs in 8, 10, 12, 14 inch from 85 to 750 lb rates

Guess what Uncle Fester might get with his engine swap.....

https://www.speedwaymotors.com