customblackbird

iTrader: (15)

ive done searches, the moog replacements for the rear cargo springs is 5665.... thats the stiffest spring they offer. now i have sportline springs in my car now but the added weight of a 6pt cage roughly 80lbs will decrease ride height even more to what is already a soft rear sportline spring. i was wondering if cutting a stock moog spring will give me a stiffer spring rate over the sportlines to help combat the 6pt cage weight.

here are the specs...

MOOG 5665
inside DIA: 4.3"
bar DIA: 0.485"
installed height: 10"
load rate: 580lbs
spring rate: 107lb/in
free height: 15.42"

sportlines
bar DIA: 0.5"
spring rate: 107-130lb/in progressive
free height: 14.75"

now if i were to cut the MOOG springs i would increase spring rate. what i was wondering is how much the spring rate would increase with every 1/4 or 1/2 coil i cut off. theres a formula to figure this out in linear springs which i want since progressives have to compress before they get stiffer and linear is the same all right off the bat. what i dont kno is the number of coils in the moog springs inorder to figure out the spring rate as well as the average coil DIA.

does anyone kno how much the spring rate increases when coils are cut. i want the same ride height as my sportines but somewhere around 150/160lb/in spring rate like the prokit. as u can see the free height diff of the moogs and sportlines is roughly 3/4" so i would hack at least 1/2 coil of to achieve same free height.

91_5.7_TPI

iTrader: (2)

Have you considered ordering springs from SSS or ERS (Eibach Race springs) to fit you needs? You could probably find the uncompressed height you need and the spring rate to get the ride height you want by contacting their tech department.

customblackbird

iTrader: (15)

yea i heard about them but unfortunatly to late... i already have a pair of the moog5665's shipped and on the way. i figured i could get at least 130lbin outa the 5665's witht he same ride height as the sportlines which wouldnt be too bad since thats the sportlines max spring rate when its compressed... which is only achieved in high cornering/spirited driving. i just want that lag to the 130lbin rate to be gone.

so does anyone kno how much the spring rate increases when a 1/4, 1/2, 3/4. or 1 coils is hacked off the moog 5665 rear springs????

online170

What are the other rear spring rates?

91, i know youre running 5662's cut, and 5665s. Thats exactly what i want to do, but i wasnt aware the 5665s were the stiffest. How do they "match" for you? I know youve had them on ffrom a while back (dont know if you still have them). But you did a writeup on it right?

91_5.7_TPI

iTrader: (2)

I'm running the Eibach ProKit. I don't have the cut Moogs. The other rear spring rate is just a few pounds softer than the stiffer ones. There is a right up about it online somewhere. I have this that I saved. Didn't save the name of the original poster, though.

online170

I already know those, but i cant seem to find rear rates... In any case, heres the thread i was thinking of. "Cut springs"

SuperKev did the 5662/5665 chopped, and i was curious how theyd match is all.
https://www.thirdgen.org/forums/susp...light=lowering

Dunno why i confused that thread with your write up... Maybe its cuz they follow a very similar format. Anyway..

customblackbird

iTrader: (15)

yea ikno what the fronts are chopped but i as well want to kno about the rear springs being chopped. the 5665's are the linear stock Z28/IROC/WS6 springs that have a 0.485 bar DIA, 10" installed height, 580lb load rate, and a 107lb/in spring rate.and a 15.42" free height. if these are chopped what is the increased spring rate just like how u posted them for the fronts.

the rears are alot softer thant he front so they wont gain 61lb/in with a 1" drop. but i was wondering if they would increase the same percentage.

so the 5660 springs gained 61lb/in with a 1" drop... thats 9.8% increase over original spring rate... if i apply that to the 107lbin rears it would increase 10.4lb/in with a 1" drop... putting it at 117.4lb/in.... this is just an estimation but i would like to kno sum cold hard numbers.

ive also heard 2 different numbers for the sportline springs.... one being 80-130lb/in spring rate, and the other being 107-130lb/in both progressive, now i can compress my sportlines slightly just by leaning on them... i would like to get the 130lb/in linear spring rate so i dont have that lag of compression with the springs with progressive springs which causes a bottoming out.

also ive posted that the stock MOOG 5662 spring rates are not 748 at load height... it seems that moog as over embelished on the spring rate numbers... the moog 5662s are really sumwhere around 650lb/in spring rate. here SPOHN states them at 706lb/in at load height
http://www.spohn.net/shop/1982-1992-...ings-Pair.html

also stated here
http://www.banningcohen.com/buick/ha...ng%20chart.pdf

customblackbird

iTrader: (15)

ok so my moog 5665s arrived today.... they are about an inch taller than the ebach sportlines, and they both have a .5" aka 1/2" wire diameter. the sportlines have been in the car only 6months id say, and about 6000 miles id say give or take a 1000. when i press down on the sportlines with only my weight (if that) the spring compresses considerably. the moogs do NOT compress nearly as much. there is an obvious difference in spring rate between the 2... and moogs seem to be stiffer when compressed with only my body weight. this confuses me, the moogs are only rated at 107lb/in linear. the sportlines are rated at 107-130lb/in progressive, so they should be the same stiffness right off the bat and then the sportlines should get stiffer the more they are compressed. unless the sportlines are 80-130lb progressive which is what i heard also. but the general concessus is that they are 107-103lb/in. soo how is this so???


also to get the same ride height as the sportlines and judging by this picture... how much should i trim off the moogs to get the same ride height? and how much would the spring rate go up given a certain amount trimmed? i want about 130lb/in from the moogs. dont forget ive added 80lb over the rear cargo area with the installation of a 6pt cage.... so how much do i trim? or do i leave it bc the roll cage will lower the car due to more weight?

//<86TA>\\

iTrader: (15)

your probably going to have to go by the tried and true method of trial and error, cut a quarter coil off, and see where it puts you, and continue as needed.

I feel that the sportlines are probably the 80-130 rate, i had them and they were waaaay soft, in a bad way, hated them. I had the moog Iroc springs, and they were nice, but sat the car up like a 4x4.

Time2Fly

Try this: http://www.pontiacracing.net/js_coil_spring_rate.htm

As you cut coils, the spring rate will go up as the load is shared over fewer coils.

91_5.7_TPI

iTrader: (2)

This thread seems like a handy calculator. Using the information given on the Moog (and if I entered it correctly), it calculates the spring rate at 109 intstead of 107, so it's pretty close.

customblackbird

iTrader: (15)

wow that page is amazing! im not sure on the active coils... so i coounted... i said 6. the say on moog that the fee height is 15.42" and that the wire DIA is 0.485... but ive tested it and its more like .5". so i did the .485 wire DIA and i came up with 106.84lb/in.

i then figured a full coil cut, and free height measuring for the widest (bottom) coil cut is 14.75" free height, and i also decreased insalled height to 9.25" since only 3/4" of height is lost with the bottom coil cut and then minus the 1 coil cut i have 5 active coils... that increases spring rate to 128.11lb/in. did i do anything wrong? how much drop is achieved with a 1/4, 1/2, 3/4, 1 coil cut off?

also how will this thing seat itself when i cut the "widest" coil off at the bottom of the spring? it will lose that only tight coil and prob dig into the rubber mount that is put into the rear subframe when mounted.

customblackbird

iTrader: (15)

sooo here are the definitive answers. in the pic if the springs.

5665 moog
active coils= 5
wire DIA= .485 or .500" (they say .485 but i caliper shows .5" around)
free height= new pic shows with wood on top, 15.25"(added .25" bc numbers start .25" from the floor.)
outside spring DIA= 5.5"
installed height= 10"
the moog 5665 compressed 1.75" when my full weight was on it,(190lbs) which means it took 108.5lbs to depress the spring 1" giving it a 108lb/in spring rate.

if you plug this info into that website posted above it comes out to 123lb/in with the .485" DIA wire and with .5" DIA wire we have 140lb/in spring rate. they stated 107lb/in spring rate. someone posted moog was wrong(just like the 5662/5664 mess) and that they were around 180lb/in spring rate.... now i kno this isnt at load height which is 10" but that would mean id have to be like 580lbs. but its a linear spring so it should only take 108lbs to depress it every inch.

first pic is free height, (add .25" due to numbers starting .25" up from the floor)

second pic is me standing on it, depressed height 13.5" (already added .25") at 190lbs and it compressed 1.75" giving it 108lb/in rate.

customblackbird

iTrader: (15)

now i did the sportlines.

sportlines
active coils= 4 (has 4 tightly wound coils that become inactive once any weight is added)
free height= 14.5"(added .25" already)
Wire DIA= same as above .485 or i measured .5"
outside DIA= 5.5"
compressed height 190lbs= 12.5" (already added .25")

now u can see in the pics that the free height is 14.5" (added .25") and compressed more than the MOOG 5665 at 2" vs the moogs 1.75" under the same weight of about 190lbs. which gives the sportlines a 95lb/in spring rate even with the 4 inactive coils. now since the sportlines have 4 less inactive coils since the bottom the the spring is wound so close together they become inactive after any weight is added leaving only 4 active coils to absorb the weight of the car during cornering/bumps. which will increase spring rate drastically. which is where they prob get it to go up to 130lb/in.

customblackbird

iTrader: (15)

not sure why i did this, i just wanted to prove that the sprotlines felt softer to me..

now how much does spring rate increase when coils are cut to the 5665s and how much drop is achieved with a 1/2 or full coil cut???