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Coil Springs


Guest Mr. Solutions
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Guest Mr. Solutions

I would like to replace my REAR coil springs.<P>However, my local antique autoparts store advised that I should get them re-stretched and then re-tempered.<P>I contacted a company that does this, and they advised that if I would like a, lets say 3" rise, they would stretch it only .75". The argument is that the longer you stretch 'em, the stiffer they get.<P>My questions are:<BR> - How effective is re-stretching coil springs? <BR> - How long would they last, assuming occasional use? <BR> - Has anybody done anything like this?<BR> - What about "coil lifters"?<P>There is also another unknown, and that is the *exact* effect on the car, as stretching has different effects on different cars / models...<P>One other thing to consider, cost is a factor for me. I have been quoted Can$75 / pr to re-stretch, and about US$187 / pr for new.<P>Gentlemen, your insight is required!

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From what I have heard, restretching, if cheaper, is a great way to go. The rears dont need it as much as the front because of the lower weight. The restretched ones will last a long time. $75 is cheap to fix such a problem.

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Hi Johan,<BR> There is nothing wrong with this process.<BR>the reason you only have to strecth them a little is because of Hookes Law which states that F=kx where F is the force(weight of your car) x is the distance (how much they compress) and k is a constant(called spring constant) it varies from spring to spring units are lbs/in so if k=1000lb/in and you put 1000 lbs on it,it compresses 1".<BR> by streching the spring you plastically deform the metal changing the shape of the metal crystals, this is called cold working which results in harder and more brittle material, thus the tempering is necessary to restore the original crystal structure, thus restoring properties.<BR> the spring may also be strechted while hot and if temp is high enough it tends to soften metal by grain size growth, then it is rehardened by quenching and the tempered.<BR> BOTTOM LINE, if done properly the springs are as good as ever. and will last longer than you.<p>[ 05-09-2002: Message edited by: Scott W. Taylor ]

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Guest Mr. Solutions

Scott<P>As usual, your input is valuable, accurate, informative and backed by facts; very much appreciated.<P>Thanks to you and everybody else that replied.<P>Stretching it will be then!

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Guest 1965cat

Johan,<P>Who offers this type of service? Is it listed in Hemmings? I woud like to have this done on my 65 Wildcat.<P>Thanks,<P>Mark<BR>BCA 372362

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Guest Mr. Solutions

Mark<P>Goodness no! No listing in Hemmings; that would make it way too easy... <g><P>This was just on the advise of my local auto antiques place that recommended this, as this appears to have been a standard practice when he was young.<P>The company is a local one here in Edmonton, Alberta, Canada. Called "City Spring Ltd.". They can be reached at 780-463-4291 or Fax @ 780-461-3460. No WWW site though.<P>I'm very sure that any company specialising in their line of work will be able to do so, so check locally first. Use City Spring as starting point.<P>Hope this helps.

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Whoa, stop the presses. I am replacing my rear springs on my '53 and found an outfitin Ca., VSW Inc. 800-287-2645. Ordered my new rear, lowered 2" for the small sum of $148/pr, UPS extra. Get on the phone and check it out. Don't waste time and money trying to fix a mistake, get another set and get on enjoying your car! Enjoy. tongue.gif" border="0

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Stretching and retempering coil springs is similar to rearching leaf springs. Remember that all you are trying to do is put things back like they were originally. Just as with leaf springs, the spring shop should know how much to stretch to get the desired "free" length when done. Retempering would be the key operation here, it would seem.<P>The reason the spring compressed was due to use. When the correct free length is achieved and the spring is retempered, it should be the same as when new--if done correctly. Same ride stiffness and all. Generally, the farther apart the coils are, the higher the spring rate, but as you are only trying to reestablish the original condition, those comments about "stiffness" would not really apply, unless the retempering process made the spring metal harder or something.<P>The other key item in that process will be the person doing it. If, in the stretching process, they break the spring, you'll basically end up buying new springs anyway. Unlike with leaf springs where there is a basic curve they work to achieve, the coil spring deal would be totally trial and error to get the right free length. I suspect that some spring shops (that normally deal with leaf springs in the reconditioning operations) might not have the proper equipment to do coil springs, or have the liability insurance to cover that. In any event, the end product will only be a good as the person doing it, I suspect.<P>I concur that there will be more truck spring operations than what you will find for cars. Same principles, just different items. We used to use a HD truck spring shop for our dealership light truck spring repairs. In the earlier times, they heated the leaves before they rearched them. In later years, they did it by using a cold press operation. Personally, the kiln operation seems like it would be the best way.<P>In one respect, reconditioning the spring is what I'd consider a last resort "fix". If a new spring of the correct application can be found, then that would be the best way to go.<P>Just some thoughts . . .<P>NTX5467

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