NEW REPLACEMENT Issue 20/2018
COIL SPRINGS SHOCK ABSORBER, SUSPENSION, BRAKES, TOWBARS AND WHEEL ALIGNMENT SPECIALISTS
New Replacement Coil Springs
Mean diameter of spring
One of the most frequently asked question is “How do new replacement coil springs restore a vehicle’s standard ride height when they are lower in free height than Original Equipment units?”
When the mean diameter increases, the spring rate decreases. Active coils
Determining the number of active (working) coils varies The free height of a coil is important, however the way a according to spring design. Coils stop working when coil reacts at its “loaded ride height” is more significant. they are in contact with the spring mount or the coil All Pedders coil springs are designed with a heavier rate below them. As the number of active coils increases, the than Original Equipment. The rate for every coil for each spring rate decreases. uestions (F.A.Q.) asked is “Why are the new springs car is designed very carefully andreplacement is calculatedcoil using a hey are supposed to raise the car formula. to a restored ridecompress height. “load vs deflection” The standard coil will not Coil Spring Design as much at its loaded ride height therefore the starting There are two basic coil spring designs and they are: d rate coil height is somewhat but will not be as important of the important, “free length” shorter. as the “loaded gs are designed with a heavier rate. The rate for every coil for every car is• Linear rate Factors that determine springInrate ulated using a “load verses deflection” formula. doing so, as the rate is • Progressive or Variable rate much, so the starting height of the “free Length” will be shorter. There are three main elements to be taken into account Linear rate springs when designing a coil spring: g rate Linear rate springs maintain one spring rate throughout • Material size (wire diameter) most of their range of travel. For instance, if we have e taken into• account when designing a coil The mean diameter of the coilspring: a 350lb/inch linear rate spring that is 16 inches long, it will take approximately 350lb to deflect it 1 inch. It will • The amount of active (working) coils er) take another 350lb of load to compress it another inch, etc. until all coils bind, and the spring goes solid. This ls would represent 1050lb of load on a 16-inch spring that has now been compressed to 13-inch of loaded spring height. oil
placement Coil Springs
d they are:
spring rate per inch of deflection throughout most Figure 1. Springrate Rate spring that is 16 e have a 350lb/inch linear Spring rate refers to the amount of weight needed to weight to compress spring a given distance (Example:500lb 0lb toneeded deflect 1a inch. The next inch per of per compress a it spring a given distance (example:500lb inch). a spring for rate you need to know the factors that determine the rate ofan and the next inch of deflection will take To understand properly spring rate nly three things that affect and spring rate, socheck there'sanot that for much toyou need to know the factors that determine the rate of the e spring goes solid). At this point there will be spring. Fortunately, there are only three things that affect spring rate,than so there’s not thatwire. muchSo, to when remember. meter wire is stronger lesser diameter wire diameter is at has now been compressed to 13” of loaded Wire diameter
greater of wire the more strength in the de diameterThe of the springdiameter less one wire diameter. When the mean diameter finished coil and the spring rate increases. .
tive coils varies according to spring design. Count the total coils minus “locating” coils not “working coils. As the number of active coils .
Figure 2. Linear Rate Spring
s called “Variable Rate” springs. The purpose Straight advice, specialists you understand and... mpliance in the suspension over rough
of deflection load on a 16 inch long spring that has now been tion will take another 350lb of load and the next1050lb inch of take an 1050lb of load a will 16 inch long of their range of travel. For instance, if we have a 350lb/inch linearonrate spring that spring is 16 that has now be spring height. onal 350lb of itload on until the350lb springtogoes solid). At this thereofwill be spring inches long, will(and take so approximately deflect it 1height. inch. Thepoint next inch b of load onwill a 16take inch long spring that has now compressed to 13” loaded deflection another 350lb of load and the been next inch of deflection willoftake an height. additional 350lb of load (and so on until the spring goes solid). At this point there will be
“Progressive rate springs” are sometimes called “Variab
rate springs” sometimes called “Var 1050lb of load on a 16 inch long spring that has now“Progressive been compressed to 13” ofare loaded NEW REPLACEMENT of of non-linear springs is to provide more compliance in in thet non-linear springs is to provide more compliance spring height.
COIL ressive rate springs” are sometimes called “Variable SPRINGS Rate” springs. The purpose
surfaces. These springs areare designed with low initial sprin surfaces. These springs designed with low initial spr thethe spring is compressed. The theory is that thisthis allows the spring is compressed. The theory is that allows Issue 20/2018 andand road imperfections still be be tight enough to -linear springs is to provide more compliance inbumps the suspension over roughbutbut bumps road imperfections still tight enough rateare springs” arewith sometimes called “Variable Rate” springs. The purpose prevent thethe chassis from bottoming out. of of this, ABSORBER, SUSPENSION, BRAKES, TOWBARS prevent chassis from bottoming Because thist es.“Progressive These springs designed lowSHOCK initial spring rates but rapidly increase asout.Because AND WHEEL ALIGNMENT SPECIALISTS springs intended useuse onon public ro of non-linear springs is to provide more compliance in the suspension over rough aftermarket lowering springs intended public ring is compressed. The theory is that this allowsaftermarket the car tolowering travel smoothly over forfor springs areare easy to to spot because the springs are not symm surfaces. These springs are designed with low initial spring rates but rapidly increase as Progressive rate springs Pedders Coil Springs springs easy spot because s and road imperfections but still be tight enough to provide good handling andthe springs are not sym thethe spring is wound tighter than the other endend with thethe mom Progressive rate springs are sometimes Pedders coil manufacturing plant in Victoria holds the spring is compressed. The theory called is that“Variable this allows the car towound travel smoothly over spring isspring tighter than the other with nt the chassis fromThe bottoming out. Because these springs are popular in Rate” springs. purpose of non-linear springs is of this, the internationally recognised manufacturing quality softer part of of thethe spring. AsAs thethe spring is compressed, theth softer part spring. spring is compressed, bumpstoand road imperfections but still be tight enough to provide good handling and provide a softer ride in the suspension over rough standard of QS 9001. Pedders is one of the very few Progressive/ Variable rate market lowering springs intended forout. use on public roads. side will collapse, coming into contact each other. W surfaces. These springs designed with low initial aftermarket supplier ofcoming coil in Australia to hold will collapse, into contact with each other. prevent the chassis from are bottoming Because of side this, these springs aresprings popular in with spring rapidly increase as the spring this quality certification. Thisone means that Pedders coilslarger pitch thethe spring starts to to compress the coils with the s aftermarket are easy torates spotbutbecause theintended springs areisuse notonsymmetrical. Typically, end of spring starts compress the coils with the larger pit lowering springs for public roads. Progressive/ Variable rate compressed. Because of this, these springs are popular
are equivalent to, if not exceeding, the quality required
ring is wound tighter than the intended other end with tightly wound being the in are aftermarket springs for use on for suppliers of coil springsend to Original Equipment springs easy tolowering spot because the springs arethe not more symmetrical. Typically, one end of public roads. Progressive/Variable rate springs are manufacturers. part the to spring. Astighter the isnot compressed, on wound the tightly wound the of spring isspot wound than are the other end withthe thesoft morecoils tightly end being the easy because the spring springs symmetrical. Pedders undertakes the following key steps in relation to Springs that are designed to include coils of of different diam Typically, one end of the spring is wound tighter than Springs that are on designed torest include different di willsofter collapse, intoAs contact withiseach other. When this happens, of coils part ofcoming the spring. the spring compressed, coils the the tightly wound itsthe Coilsoft Spring Manufacturing Process. the other. The more tightly wound end being the softer tapered wire will also produce a progressive rate. roughout mostto compress tapered wirehas will alsohigher produce a progressive rate. sidestarts will coming into withlarger each When happens, the rate. rest of • Hot coilingthis ring thespring coilsiscontact with the pitch, which the partcollapse, of the spring. As the compressed, the soft other. The smaller mean diameter the higher the coils rate and th
g that is 16 coils compress and bind. This activates the coils with the The smaller mean diameter the higher the coils rate and • pitch, Oilthe Quenching the spring starts to compress the coils with the largerlower which has the higher rate. spring rate. larger pitch, which has the higher rate. Tapered design lower the spring rate. ch of • Furnace Tempering take an springs that are designed to include coils of different diameters or are wound using a tapered wire will also • Shot Peening there willproduce be a progressive rate. gs that are designed to include coils of different Pedders diameter or are wound using amanufacturing Suspension coil spring manufacturing plant holds • Scragging Pedders Suspension coil spring plant hol ofSprings loadedThethat smaller mean diameter, the higher theof springs arethe designed to include coils different diameter or are wound using a
d wire will also produce a progressive rate. manufacturing quality standard of ofISO 9001. manufacturing quality standard ISO 9001. • Loaded Height and Rate Testing rate and the larger the mean diameter, the lower the tapered wire will also produce a progressive rate. What this means to the Pedders Suspension customers, is maller mean diameter the higher the coils rate and the larger the mean diameter the What this means to the Pedders Suspension customers, spring rate. • Powder Coating and Packaging The smaller mean diameter the higher the coils rate and the larger the mean diameter the areare being supplied a product of of significantly high quality. being supplied a product significantly high qualit the spring rate. lower the spring rate.
he purpose ugh rsPedders Suspension coil spring manufacturing plantplant holds the the internationally recognised ncrease as Suspension coil spring manufacturing holds internationally recognised acturing quality standard of ISO 9001. hly over manufacturing quality standard of ISO 9001. ing and this means the Pedders Suspension customers, is that they cancan bebe assured What this to means to the Pedders Suspension customers, is that they assuredthey they pular in Figure 5. Hot Rolled Figure 6. Slowly Tempered HotHot Rolled Slowly Tempered ing a product of significantly highhigh quality. aresupplied being supplied a product of significantly quality. Rolled Slowly Tempered riable rate ne end of d being the htly wound he rest of her rate. Figure 3. Progressive Figure 4. Tapered Rate Spring
Hot Rolled
Hot Rolled
Design Spring
Slowly Tempered
Slowly Tempered
Shot Peened Figure 7. Shot Peened
Shot Peened
Scragged Figure 8. Scragged
Scragged
using a
iameter the
recognised
ured they
Straight advice, specialists you understand and...