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Lowering Springs Aluminum Heads
#1
Ok big picture is years ago before I replaced the front springs on my Mach 1 it sagged alot. 30 YO springs and stuff front and rear. So around 2004 or so I replaced front and rear springs and wasn't impressed with how the car set initially. I figured give them some time they would settle in and look good.


Unfortunately no, 9 years later I still don't like how high the front end sets and missed the height on saggy springs. I don't miss the old springs. The car drives and rides alot better with the new stuff.


Brings me here where I am looking at some lowering springs. My issue is I plan to install aluminum heads and intake here shortly. I know that will be a reasonable amount of weight loss and it will affect new springs being installed. I was looking at the opentracker 1" 560 springs. but wonder if they will be to much after weight loss up front. Suggestions or someone who has been this route.

Car is a:

1971 Mach 1
302 Engine
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#2
I would recommend cutting the springs you have once the parts are changed. It will be more predictable than replacing with different springs (1" lower than what?) In a nutshell figure out how much you want the car to drop. Measure the distance between the top of one coil to the top of the next coil with the weight on the suspension, this gives you about 1/2 of the amount the car will drop when you cut one coil off the spring. For the exact amount the car will drop calculate the distance from the inner pivot to the upper ball joint and the distance from the inner pivot to the spring mount and determine the ratio. If you have 1" coil spacing 1 coil off will drop the car about 2". The spring will also get proportionally stiffer when cutting coils. Cutting 1 coil from a 10 coil spring will get 10% stiffer.

Jeff T.

Low buck, touring style, '73 Convertible "rolling restoration", 351c, 2v heads with a shave and a haircut, Performer intake, Holley 650(ish), roller rockers, screw in studs, guideplates, stainless valves, Duraspark / Motorsports MSD, T-5 conversion. 1-1/8" front, 3/4" rear swaybars KYB shocks and some home brewed subframe connectors. Future plans; JGC steering box, Cobra brakes and... paint, interior, etc.

When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passenger.

[Image: 1_12_09_14_10_15_11.png]
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#3
Hello mdan575,

Check out Eaton Detroit Springs. The original factory coil springs are designed with the engine and with or without A/C on board. Also, transmission has a key role in the coil spring configuration. They have available stock, +1, +2, -1, and -2 lower height. At least look at the tech guides on their site.

website: http://www.eatonsprings.com/index.html

Front Coils: http://www.eatonsprings.com/64-73mustangfront.html

mustang7173
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#4
Thanks mustang7173 that is exactly what kind of info I was looking for. Everything I was finding was a limited -1 spring or set rate springs. I think a -2 spring should balance out when adding aluminum heads and intake. Not knowing the exact weight loss on the heads and intake I am figuring 100lbs of weight loss or so. In no way new to suspension design, just don't know some of the better information resources and the search button and google aren't always as useful as we would like them to be. Especially considering our model of mustang doesn't generally get alot of love from the mustang community.


No disrepect droptop73 but IMO cutting is one of the worst possible ways to attain a lowering result. For some of the very reasons you stated. Cutting springs should provide a predictable result but in my experience can provide unpredictable results all to often. In a perfect world a linear spring would be perfect and provide the same spring rate throught out its travel. Unfortunately all to often that is not the case especially with todays aftermarket(China made crap).

In a worst case scenerio I will just order a set of custom rate springs to fit if I have to.
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#5
Yer small block is lighter than my cleveland, and i have alum heads, intake, and water pump with a plain hood. With those 560 springs installed i would like another inch lower at least. Im guessing i have 4" clearnce above the front tires, which have a 26.5" rolling diameter. I have not cut the springs thought Opentracker suggested a 1/2 coil cut would not affet ride much and would lower ride height by at least another inch. My front shocks are a bit stiffer since i took weight off the front end and the springs will only get stiffer if i cut them for the reasons mentioned above. I guess my first choice is to throw in some inexpensive Monroe's to soften up the front before i cut the springs. If they soften up the ride i will assume that i can cut the springs and add fully adjustable shocks to control the front with the lower ride height. Btw, shocks can break the bank. The single racing shock on the back of my bike cost $1700 and a couple more to set it up.
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#6
I have had pretty good luck with the adjustable shocks in the past. For reference I DD a 2003 Harley Davidson F150 that I converted to a coilover 4-Link suspension. So no stranger to custom suspension work. I am a big fan of adjustable shocks with proper rate springs. Had good luck with Strange and Ridetech adjustable shocks, not so much with QA1.

If you are willing to get down and dirty I am a big fan of ordering shocks by size(collapsed/extended length). A little time and some measuring can get a set of shocks perfect length for the application. Then you can dial in the ride comfort you like with the added bonus of being able to dial the firmness for fun time. Strange single adjustable shocks don't break the bank and I have had good luck with them in the past.

Once I get around to it I will post up what I come up with
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#7
Well then whats the problem? Cut yer friggin springs and see how it rides. If you dont like it buy the 560's and start over.
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#8
(05-02-2013, 06:46 PM)wwhite72 Wrote: Well then whats the problem? Cut yer friggin springs and see how it rides. If you dont like it buy the 560's and start over.

Multiple projects going on including said truck and I pick up an engine for the car in a few weeks. Not willing to modify the original stock 302 in the car. Bag it store it for a later time. Once I sort through that suspension is next. Parts are slowly starting to collect. Roller perches are next along with arms. Springs are just one part.
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#9
mdan575;121224 Wrote:No disrepect droptop73 but IMO cutting is one of the worst possible ways to attain a lowering result. For some of the very reasons you stated. Cutting springs should provide a predictable result but in my experience can provide unpredictable results all to often. In a perfect world a linear spring would be perfect and provide the same spring rate throught out its travel. Unfortunately all to often that is not the case especially with todays aftermarket(China made crap).

In a worst case scenerio I will just order a set of custom rate springs to fit if I have to.

Hey mdan575 I don't take disagreement as disrespect. I've had much success with cutting springs (OEM or good quality replacements). Part of the predictability is understanding the motion ratio of the springs mounting point. Many suspension engineers who are way smarter than I am recommend cutting the original rate springs and tune the suspension with sway bars and shocks. There is way more than one way to acheive a goal.

Jeff T.

Low buck, touring style, '73 Convertible "rolling restoration", 351c, 2v heads with a shave and a haircut, Performer intake, Holley 650(ish), roller rockers, screw in studs, guideplates, stainless valves, Duraspark / Motorsports MSD, T-5 conversion. 1-1/8" front, 3/4" rear swaybars KYB shocks and some home brewed subframe connectors. Future plans; JGC steering box, Cobra brakes and... paint, interior, etc.

When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passenger.

[Image: 1_12_09_14_10_15_11.png]
  Reply
#10
Do yourself a favor and install subframe connectors if you haven't yet. You will discover much of the spring softness actually is more likely due to chassis flex. Cutting springs raises the spring rate so be careful. You can run into spring bind or bottoming or just plain harsh ride. These cars all need it.
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