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Old 01-28-2009, 05:08 PM   #1
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cut bottom or top of coil spring? MOOG 5664s

when u cut coil springs on a 3rd gen do u cut the top or bottom of the spring.

top= where it tucks into the spring pocket on the Kmemeber
bottom= where is fits in the Aarm.

just got my Aarms connected and gona install my new moog 5664s but i want to hack 3/4 coil off. what side to i chop? the TOP (spray painted white mark) or BOTTOM where it fits in the Aarm???? i thought it was the bottom.
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Old 01-30-2009, 10:46 AM   #2
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Re: cut bottom or top of coil spring? MOOG 5664s

I'm pretty sure you cut on it the end that goes into the a-arm. The one where the coil is just cut and not flattened. Just a word of advice, don't cut it all off at once. Do a 1/4 at a time. You can take more off, but not put it back on. Good luck.
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Old 01-31-2009, 03:47 PM   #3
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Re: cut bottom or top of coil spring? MOOG 5664s

yea thats what i figured. i went all out and cut 3/4 coil off. i measured them from the link on lowering101. he stated he cut 14" off the front coil and 7" off the rear (length of string on outside of coils. the 14" off the front is exactly 3/4 of a coil. i also marked the same free height when held up against the sportlines free height. is also 3/4 of a coil cut to get the same free hieght as the sportlines. so i went for it. i barely could get them in the Aarm pockets. didnt even need a spring compressor... just like the sportlines. figured it wouldnt lower it the 1.7" like the sportlines since the cut moogs 5664s would put me at about 875lb rate. and im taking about 80lbs off the front end. (aluminum heads, HSR, AC delete, etc)
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Old 02-05-2009, 01:30 PM   #4
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Re: cut bottom or top of coil spring? MOOG 5664s

Not to Hijack your thread but I also have a question on 5664's. Are these the 748# springs? Seems to be a lot of conflicting info on the 5662's and 5664's.

From the info I found. Cutting off one coil would bring the spring rate to 919# and lower the car approximatly 2 inches. If I have figured right, cutting 1 1/2 coils will bring the spring in right at 1000# and lower the car 3 inches.

The reason I am asking is because I have 1200# spring in my autocross car now and it is a bit too much. I feel 1000# would be about right but instead of paying $60.00 per spring for racing springs I would rather pay $60.00 per pair of 5664's and cut them to get my desired rate. I realize that I will probably need to use a small spring spacer to get the correct ride height but I am allready doing that with 1200# springs so thats not a problem. I am thinking that it won't hurt to try.
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Old 02-05-2009, 02:52 PM   #5
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Re: cut bottom or top of coil spring? MOOG 5664s

the moog 5664s are the correct 748lb/in spring rate... not the 5662s.... they swapped it. the 5664s have a thicker wire DIA of .762" vs the 5662s .75".

you are correct on the cutting 1 coil off and having 919lb/in rate, also lowers car approximatly 2". 1/2 coil is worth about 1". but the 1 1/2 coils wont lower u 3" it will be alil less due to the increase in spring rate. might only lower it 2.8" or so. thats why i hacked off 3/4 coil for a total drop of about 1.5" and if needed i will rip them out and hack another 1/4 coil for 2" drop and more spring rate. i wanted high 800's in spring rate to match the cut moog 5665 rears.

it would be cheaper but is the extra 60$ to get a better spring specifically made for your application really all that much? vs trying to guess with the spring rates of the cut moog 5664s? the 1200lb springs are pretty high... what are u running in the rear?

posted is a pic of the 3/4 coil cut off. took about 6min with 30 sec on and 30s off with a air cutter so i didnt heat it to much. dont have any with ride height since i dont have an engine/trans in the car or my rear.

due to the weight reduction of the heater core/AC delete/aluminum heads/HSR etc i would think that i wouldnt get the 1.5" drop with a 875lb spring rate so i will prob have to hack another 1/4 coil off. still with 3/4 coil hacked i didnt need a spring compressor since it was the same free height as the sportlines... i just didnt want to take too much off at once.
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Old 02-05-2009, 04:07 PM   #6
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Re: cut bottom or top of coil spring? MOOG 5664s

Quote:
Originally Posted by rayar View Post
Not to Hijack your thread but I also have a question on 5664's. Are these the 748# springs? Seems to be a lot of conflicting info on the 5662's and 5664's.

From the info I found. Cutting off one coil would bring the spring rate to 919# and lower the car approximatly 2 inches. If I have figured right, cutting 1 1/2 coils will bring the spring in right at 1000# and lower the car 3 inches.

The reason I am asking is because I have 1200# spring in my autocross car now and it is a bit too much. I feel 1000# would be about right but instead of paying $60.00 per spring for racing springs I would rather pay $60.00 per pair of 5664's and cut them to get my desired rate. I realize that I will probably need to use a small spring spacer to get the correct ride height but I am allready doing that with 1200# springs so thats not a problem. I am thinking that it won't hurt to try.
are you using standard 5" or 5.5" racing springs?
what height and where did you get them?
did you have to change/modify anything?
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Old 02-05-2009, 06:35 PM   #7
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Re: cut bottom or top of coil spring? MOOG 5664s

The springs are 5.5 X 9.5 That I actually bought on EBAY. I have just found them new from speedway motors for only $41.99 each so I guess that isn't very expensive but anytime I can save a little money it is good. A 1000lb spring is a 1000lb spring anyway you look at it so why would I spend another $25.00 or more for the same thing? Even the racing springs won't check at the same rate that they are supposed to be so being off a few lbs or so either way won't make a big difference in my application. I just had to buy some spacers to run the shorter racing springs but you could also do weight jacks and that is one of my winter projects.

The rear spring rate is 425lbs and no the car is not tail happy with that stiff of a spring in the rear. I do have a set of 375 lb springs if it get tail happy after I put in the softer fronts.

I just needed someone to confirm that the 5664 are the higher rate springs and cutting 1 1/2 coils off would get me close to a 1000lb spring rate.
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Old 02-06-2009, 12:10 AM   #8
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Re: cut bottom or top of coil spring? MOOG 5664s

again sorry to hijack but as long as you dont have to do any mods, then what do you think about these springs and weight jacks?
circle track vendors seem to have the best prices on this stuff

weight jack
http://www.daymotorsports.com/produc...-JACK-ASSEMBLY

springs
http://www.daymotorsports.com/produc...T-COIL-SPRINGS

i was going to use 900 lb 9.5" springs.

how stiff is your ride on 1200lb springs...
i would imagine that it would be pretty crazy stiff.
do you drive it on the street at all?
does it beat you up or is it livable
also, what shocks do you run
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Old 02-06-2009, 01:14 AM   #9
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Re: cut bottom or top of coil spring? MOOG 5664s

That type of circle track weight jack (Day Racing) is meant to have the top plate welded to the top of the frame rail. It is made to be easily adjustable from under the hood, but the bolt goes down through the frame and into the cup in the spring right in the middle of the spring diameter, there is no place for a shock or strut in this type of weight jack, so it won't work with a stock strut setup. You have to have your shocks outside the spring for these to work.

There are different style "cheater" weight jacks for entry level street stock circle track cars where they aren't supposed to be able to adjust the ride height. These are like a large, hollow, round nut and bolt that can add space between the top of the spring and the inside of the upper frame rail or wherever the top of your spring rests, where they can't be easily seen.

If they can be adapted to your car, circle track parts are waaayyyy less expensive than hot rod parts. But they may not work since they are mostly meant for second gen sub frames or Chevelle or Monte Carlo/Metric full frame cars.
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Old 02-06-2009, 03:38 AM   #10
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Re: cut bottom or top of coil spring? MOOG 5664s

Quote:
Originally Posted by RED_DRAGON_85 View Post
again sorry to hijack but as long as you dont have to do any mods, then what do you think about these springs and weight jacks?
circle track vendors seem to have the best prices on this stuff

weight jack
http://www.daymotorsports.com/produc...-JACK-ASSEMBLY

springs
http://www.daymotorsports.com/produc...T-COIL-SPRINGS

i was going to use 900 lb 9.5" springs.

how stiff is your ride on 1200lb springs...
i would imagine that it would be pretty crazy stiff.
do you drive it on the street at all?
does it beat you up or is it livable
also, what shocks do you run
Those weight jacks will work because we don't have shocks going through the spring. It will require some cutting of sheetmetal above the spring pocket and I am not sure how that will affect how strong that area will be. You would probably need to reinforce it. That is the same type of weight jack I am planning on putting in my car. Maybe if you drill up from under the car and also weld the plate up in the spring pocket instead of on top of the frame you might get away without removing much material, Thats probably how I will do it.

The car is a race car, I don't drive it on the street at all but it really dosen't feel all that stiff and I still get more body roll then I want, Probably because of the struts. The front struts are just some new OEM replacements until I can get the money for some Koni DA's from GC. The rear shocks are some medium valved Bilstein Circle track shocks. I might also try some Bilstein front struts because I have heard that all Bilstein shocks from stock replacement up to race shocks are rebuildable and easily modified for valving. Not sure if the same is true about struts but I will do a little research. Might be a less expensive way to get what I need.
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Old 02-06-2009, 08:10 AM   #11
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Re: cut bottom or top of coil spring? MOOG 5664s

let me know if you do that weight jack system.
i was thinking that the weight jack would go between the spring and the a-arm and the adjustment was through the a-arm.
why not do it this way?
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Old 02-06-2009, 01:09 PM   #12
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Re: cut bottom or top of coil spring? MOOG 5664s

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let me know if you do that weight jack system.
i was thinking that the weight jack would go between the spring and the a-arm and the adjustment was through the a-arm.
why not do it this way?
The adjusting bolt would probably hit the ground or get bent the first time it hits something.
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Old 02-09-2009, 10:11 PM   #13
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Re: cut bottom or top of coil spring? MOOG 5664s

Well I ended up getting some 1000lb(Checked in a spring rater) 5.5"X8.5" tall springs from EBAY, about $22.00 each including frt. I will either need to modify my spring spacers(again) or install weight jacks. Leaning towards weight jacks.
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Old 02-09-2009, 11:48 PM   #14
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Re: cut bottom or top of coil spring? MOOG 5664s

about the adjuster getting bent, wouldnt it make sense to just cut the adjusting bolt to the length you needed?
i cant see anyone needing more than 2" of adustability or so once they have their ride height dialed in.

if it were me, id put the adjuster against the a arm, set the height how i want it, then trim the bolt so it doesnt hit anything

i think its time for Crazy Hawaiian to shed some light on the situation
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Old 02-10-2009, 12:33 AM   #15
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Re: cut bottom or top of coil spring? MOOG 5664s

Another problem with putting the weight jack on the bottom is only one end on front springs is flat. The other end fits nicely into the A-arm. I suppose that you could flatten that end and it would work fine but I would rather have the weight jack in the engine compartment out of harms way.
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Old 02-11-2009, 03:48 AM   #16
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Re: cut bottom or top of coil spring? MOOG 5664s

you can see in the front subframes right where the Kmember bolts to, the bolts for that adjuster are right throught the subframes. thats how he did it and it looks good. i remember the rear he did the same thing and it just stuck out above the spring and up through the carpet in the inside.

as far as getting the rate u asked for when u order a spring... i hope you kno that the spring manufactures usually state the spring is within about 5% of its advertised rate. so your springs rates could be off by as much a 50lb/in. just food for thought.
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Old 02-11-2009, 06:31 PM   #17
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Re: cut bottom or top of coil spring? MOOG 5664s

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Originally Posted by customblackbird View Post
you can see in the front subframes right where the Kmember bolts to, the bolts for that adjuster are right throught the subframes. thats how he did it and it looks good. i remember the rear he did the same thing and it just stuck out above the spring and up through the carpet in the inside.

as far as getting the rate u asked for when u order a spring... i hope you kno that the spring manufactures usually state the spring is within about 5% of its advertised rate. so your springs rates could be off by as much a 50lb/in. just food for thought.
That is how I am planning on doing my weight jacks. Use a long drill bit so I can drill all the way through the K-member and subframe and then weld the adjusting nut on from the underside of the k-Member because if the K-member is still bolted in you cant get to the top side. Should work out just fine but the overhead welding is going to suck.

I did mention about spring rates not being completly accurate earlier in this thread.
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Old 02-12-2009, 09:50 AM   #18
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Re: cut bottom or top of coil spring? MOOG 5664s

Quote:
Originally Posted by rayar View Post
The car is a race car, I don't drive it on the street at all but it really dosen't feel all that stiff and I still get more body roll then I want, Probably because of the struts. The front struts are just some new OEM replacements until I can get the money for some Koni DA's from GC. The rear shocks are some medium valved Bilstein Circle track shocks. I might also try some Bilstein front struts because I have heard that all Bilstein shocks from stock replacement up to race shocks are rebuildable and easily modified for valving. Not sure if the same is true about struts but I will do a little research. Might be a less expensive way to get what I need.
The amount of roll that you get depends on the springs, sta-bars, and roll center heights, not the shocks and struts. The amount of damping mostly affects how fast the car gets to its fully rolled over position. I suppose that it would be possible to set up a sufficiently tight slalom such that the car never quite reaches its full roll angle for however many peak lateral g's, but that sounds doubtful with ≥1000 lb/in front and >400 lb/in rear springs and using normal standards for slalom layout (the frequency in roll will simply be too high for the car to not get the full amount of roll in the time it takes to get from gate to gate).


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Old 02-12-2009, 06:13 PM   #19
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Re: cut bottom or top of coil spring? MOOG 5664s

yea i didnt kno if u knew that the aftermarket is also 5%. some ppl have tested that the moogs are rated a good bit lower in spring rate compared to what they actually are. just like GM underates the 4th gen firebird ram air LS1 at 300hp lol when really its like 340 or higher.

norm peterson... how does one lower or raise the front roll center? i was talking to 91 5.7 TPI and we figured how to lower roll center on the rear but not the front. if u lowered roll center in the front would u have to lower or increase spring rate to compensate?
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Old 02-12-2009, 08:48 PM   #20
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Re: cut bottom or top of coil spring? MOOG 5664s

i know it has to do with the height of the ball joints but thats about it.
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Old 02-12-2009, 09:27 PM   #21
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Re: cut bottom or top of coil spring? MOOG 5664s

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i know it has to do with the height of the ball joints but thats about it.
That is true with a double A-arm suspension but I don't believe it will have much of an effect on a strut suspension with regards to roll center.

I found this for a Mustang but our front suspension will be caculated the same way. http://www.miracerros.com/mustang/t_rollcenter.htm

You can see how lowering a car will lower the RC and that is not good. I am planning on raising mine a little.
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Old 02-12-2009, 09:31 PM   #22
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Re: cut bottom or top of coil spring? MOOG 5664s

isnt it bad to have a roll center below the ground?
i mean, its all theoretical, but it seems to me that it would cause lots of un-necessary under steer
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Old 02-13-2009, 06:05 AM   #23
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Re: cut bottom or top of coil spring? MOOG 5664s

Quote:
Originally Posted by customblackbird View Post
norm peterson... how does one lower or raise the front roll center? i was talking to 91 5.7 TPI and we figured how to lower roll center on the rear but not the front. if u lowered roll center in the front would u have to lower or increase spring rate to compensate?
The usual method of moving the front roll center vertically is by lowering or raising the front ride height with different springs. Front RC height is fairly sensitive to ride height in a strut suspension - I think a 1" "drop" lowers the RC by about 1.8" in these cars, and more than 2" in others.


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Old 02-13-2009, 06:43 AM   #24
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Re: cut bottom or top of coil spring? MOOG 5664s

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isnt it bad to have a roll center below the ground?
i mean, its all theoretical, but it seems to me that it would cause lots of un-necessary under steer
Yes and no.

What's bad is to have one geo RC below ground and the other way up above the ground. You can still balance the steady-state handling for a given turn, but the transitions from straight ahead to full-on cornering or slalom maneuvers will suffer and I don't think the handling balance "sweet spot" would be as wide as what you'd have with RC's at more nearly equal heights and the springs/bars balanced accordingly.

What else is bad is if you do not stiffen the suspension in order to counteract the additiona roll that results from a lowered RC. Yes, the car's sprung mass CG drops, but a strut RC drops faster (see above post). Let's say you lower the front 1.8", which drops the sprung mass CG 1". The front RC has dropped about 3.25", and if you're thinking in terms of "roll axis", it has dropped 1.8" where it passes under the CG. The 0.8" difference represents about 10%, so you'd need 10% stiffer springs and bars just to keep the roll rate (/lateral g) where it was originally. In this case, you don't start "gaining ground" as far as roll is concerned until the car's roll stiffness exceeds 10% above its original value. Think "anything less than 10% stiffer springs and about a 2mm thicker front bar and you're losing ground" here.

Actually, a low front geo RC combined with a high rear RC is by itself an oversteer effect and governs the lateral load transfer effect during the early stages of corner entry. Lateral load transfer through the roll centers happens much more quickly than lateral load that comes through the springs and sta-bars as that has to wait until the car has rolled a finite amount.

Below-grade front RC's are specifically bad with SLA front suspensions, as that also means that the camber gain is in the wrong direction. Instead of gaining negative camber on the outside wheel to help counteract roll (which makes the outside tire go in the positive camber direction relative to the road) it adds to the effect of roll. Strut suspensions are not quite so bad in this particular respect.


Norm

Last edited by Norm Peterson; 02-13-2009 at 06:51 AM.
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Old 02-13-2009, 03:45 PM   #25
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Re: cut bottom or top of coil spring? MOOG 5664s

lots of info there lol.
i think i get what you are saying though.
all i know is what i have heard from other people on forums and stuff.

how do you go about lowering the rear RC? seems like it would be difficult to do on a non 4 link suspension.
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Old 02-13-2009, 07:25 PM   #26
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Re: cut bottom or top of coil spring? MOOG 5664s

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Originally Posted by RED_DRAGON_85 View Post
lots of info there lol.
i think i get what you are saying though.
all i know is what i have heard from other people on forums and stuff.

how do you go about lowering the rear RC? seems like it would be difficult to do on a non 4 link suspension.
The rear RC is relativly easy to lower on these cars. Just lower the PHB.
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Old 02-13-2009, 07:32 PM   #27
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Re: cut bottom or top of coil spring? MOOG 5664s

Not that hard really. Just relocate the PHB (or Watts link center pivot) down to suit.

I think that Unbalanced Engineering makes a PHB lowering kit at least for 4th gen F-bodies. www.UnbalancedEngineering.com


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Last edited by Norm Peterson; 02-13-2009 at 07:35 PM.
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Old 02-13-2009, 07:32 PM
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