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What’s the rule of thumb before cutting coils?

Discussion in 'The Hokey Ass Message Board' started by Garage Concepts, Mar 27, 2009.

  1. Garage Concepts
    Joined: Jan 15, 2007
    Posts: 209

    Garage Concepts

    I searched all over this forum and found some really good advice on cutting coils. Everybody keeps saying to cut a ½” coil at a time. The only thing I need to know is:

    When cutting coil springs, do I measure from the end tip of the spring or measure upwards? Hope this makes sense.

  2. rustnpz
    Joined: Nov 4, 2006
    Posts: 74


    Straight across is a half coil,straight up is full coil,from the end of the pig tail. Bear in mind half coils don't seat like a factory coil ,and I say never take more then two coils .
  3. brigrat
    Joined: Nov 9, 2007
    Posts: 5,355

    from Wa.St.

    If the ends sit in a "pocket" you have to cut a hole coil so it will "seat" properly..................
  4. BLAKE
    Joined: Aug 10, 2002
    Posts: 2,775


    Rule of thumb = cut 1/2 coil (straight across the 'circle'), install, then if more is needed remove and cut 1/8 coil at a time and repeat until it sits right... don't sweat if one side needs more than the other side... that is all.

  5. striper
    Joined: Mar 22, 2005
    Posts: 4,498


    Keep yor thumbs out of the way....there, that should help :D
  6. PeteFromTexas
    Joined: Apr 4, 2007
    Posts: 3,837


    Never cut them with a torch! Always use a cut off wheel.
  7. jeffrob
    Joined: Dec 20, 2005
    Posts: 279


    don't take off too much, that front end drops quick!

    small cuts, check your progress.......... I learned the hard way.
  8. I like Blake's idea. Cut a little, install. I cut only 1/2 coil on my 95 caprice wagon, and it was way too low, on the snubbers. Looked cool, but bounced out all of the fillings in my teeth. In retrospect, should've spent the $ for lowering springs. Ya live, ya learn.
  9. Kickstarter
    Joined: Mar 2, 2006
    Posts: 664

    from NC

    "Perhaps it should be rule of wrist"
  10. Jalopy Joker
    Joined: Sep 3, 2006
    Posts: 26,031

    Jalopy Joker

    What kind of car/truck? Have you removed/installed coil springs before? Are you aware that you will lose any ride quality that you have now? You may need to go to a shorter shock. You will need to have front end aligned. Do you have the exact tire wheel combo that you are going to use? If you lower car will tires clear fenders, even when going up a driveway with wheels turned? As long as you have it apart, check bushings, brakes , etc. Go slowly. You can always cut more, or just get new lowered springs.
  11. I took the advice of someone who'd done it many times, he recommended 1-3/4 coils and it worked out very well. If I can remember correctly I did take it to the alignment shop afterward (something I would do). When it was all said and done the car drove like a dream and had no ill effects from the cut coils what so ever...

    Attached Files:

  12. How about if you cut them with a torch ,in the car?
  13. mojo273
    Joined: Mar 30, 2006
    Posts: 394

    Member Emeritus

    right on! lmao! :p
  14. fat141
    Joined: Jul 30, 2006
    Posts: 1,575


    Dont go near them with a torch, all you finish up with is a coil of mild steel, no spring temper left = stuffed job:eek:
  15. We used to take them to local spring shop and had them heated to drop car Never had any problems with this method.
  16. I was going to cut a whole coil on a Vette,thinking it would lower it about an inch or two.I decided to cut only a 1/2 coil just in case.Glad I did, as it lowered it a good 2 inches with just about a half coil cut.Came out perfect,and still rode good (for a vette).
  17. Zookeeper
    Joined: Aug 30, 2006
    Posts: 1,041


    Cutting coils is a VERY polarizing subject. Lots of guys have had lots of experiences, both good and bad and it seems everyone feels their way is the only way it can be done correctly. If I could give some advice, it would be this: beg, borrow, or buy a good spring compressor, they are cheap compared to what happens when one slips. Next, cut a small amount ( 1/4 coil is what I use) at a time, reinstall move it forward and backwards to take out the bind, then re-measure to see if you got what you wanted. It's easier to remove the springs and cut more than to buy new springs because you cut too much. Before you begin, measure both the fender height of the car, and the space between the bump stop and whatever it hits. If there's only 2 inches between the rubber bumper and the stop, you can cut coils until there's nothing left, and it still won't drop more than 2 inches. Be aware of this, and also be aware that to still have good ride quality, you may very well need to maintain the original space between the stops. I use a sawzall on rubber bumpers and cut at an angle. I've been cutting springs to drop cars for 30+ years, and I've done it the wrong way and done it the right way. This is the way that works best for me.
  18. budssuperpro
    Joined: Jul 30, 2008
    Posts: 391


    CLOSE YOUR EYES and just do it..... thats what I did to my 1956 Chevy in 1959 the only thing I had to do after droping was to have the front end alined other than that everything was fine.your never going to get a soft ride when you reduce the over all coil height its always going to ride harder than stock.
  19. bigBADwolf
    Joined: May 27, 2006
    Posts: 148

    from Batavia,IL

  20. Leaky Pipes
    Joined: Jan 11, 2005
    Posts: 596

    Leaky Pipes

    Check to make sure the coils are exactly same height first and that your car sits level. You'd be surprised, not all are equal. Then measure the amount to be cut accordingly. Cut, and compare the cut off pieces, they should be the same. then compare the height of the cut coils, then measure your car again when they're back in.
  21. budssuperpro
    Joined: Jul 30, 2008
    Posts: 391


    Same here hank..
    Don't try to over think it or you will never do it.
    Last edited: Mar 28, 2009
  22. jusjunk
    Joined: Dec 3, 2004
    Posts: 3,138

    from Michigan

    Had a buddy that did 2 55 chevys that way but he did it himself.. He figures he wanted a 2 inch drop or sumpin like that so he put blocks under the car that were 2 inches lower than the car as it sat.. fired up the torch started on the 2nd coil up and heated both sides till it fell on the blocks.. Let em cool jacked it up and pulled the blocks and done deal :)
  23. budssuperpro
    Joined: Jul 30, 2008
    Posts: 391


    Yup it's no big deal I use to get Tickets in Downey Cal so I would shove in Rubber Shims and get it inspected buy the cops and go home and take then back out till next time.. etc etc etc ...
  24. panic
    Joined: Jan 3, 2004
    Posts: 1,450


    It's not true that using a torch will weaken and soften the entire spring. The annealing temperature of a spring is over 350° F, and it won't be affected by any temperature below this. All you have to do is wrap a wet (junk) towel around the spring right below where you cut it. If it stops steaming and you're still cutting (and this shouldn't happen), wet the towel.
    Remember that cutting a coil increases the spring rate: it now takes more pounds of weight or shock (pothole) to move compress the spring by 1".
    How to guess at the effect?
    1. Count the total number of coils
    2. Subtract 1 for the seat top and bottom
    3. The remaining number is the # of active coils
    4. subtract the number you're cutting (1/2, 1, etc.)
    5. divide the number of active coils (3.) by the result from 4.
    6. this is how much stiffer the ride will be, as a %
    Start with 7 coils
    Subtract 1 = 6 active coils
    Cut 1/2 coil = 5.5 remaining coils
    6 ÷ 5.5 = 109% or +9%

    YRMV depending on how much you curve the cut end back, shocks, etc.
  25. 38FLATTIE
    Joined: Oct 26, 2008
    Posts: 4,350

    from Colorado

    That's what I was looking for.

    Thereore, unless a stiffer ride is wanted, which I don't, seems the heat and drop method will work the best.
    Last edited: Mar 28, 2009
  26. panic
    Joined: Jan 3, 2004
    Posts: 1,450


    Well, there's really no practical way to weaken an existing spring, except:
    1. increase the number of coils (raise the car - not useful here)
    2. reduce the wire diameter (good luck with that!)
    3. change the leverage angle (move the mounts away from each other laterally)
    4. increase the coil diameter (almost impossible)
    5. make part of it stop being a spring - that's what heating it does. Unfortunately, that part still bends, and I don't know how much the heat affects its working life (how many bounces before it cracks).
    For some cars, coils are still available - take a look to see if there's a 6 cylinder spring instead of your V8 to get slightly lower ride height + softer ride.
  27. panic
    Joined: Jan 3, 2004
    Posts: 1,450


    I've also seen pictures of control arms with new cups (cut from junkers) welded below the originals, then the original bottom cut away so the spring just sits down farther. Still need to check ground clearance, shock travel, bump stops etc. Your camber will also go to hell, and may be beyond adjustment.
  28. I always use a torch [with a wet rag close to my cut] to cut the springs. The heat is so localized it won't affect the rest of the spring....guaranteed. I've done it many times. I've found if I heat coils, the spring will continue to weaken and the car will slowly drop over time, putting it on the bump stops after a few weeks/months. Just my experience.
    I sawsall the bump stops to about 1/2 inch height to gain sprung room. When you cut the spring, it stiffens the spring which is good if you want to keep off the bump stops. Every car I cut the coils on had way too soft springs for my taste anyway. I love the firm ride. Pot holes are gonna be something to avoid with cut coils but they should be anyway.

    Attached Files:

  29. panic
    Joined: Jan 3, 2004
    Posts: 1,450


    If the springs have many miles on them, reducing the number of active coils works the remainder harder, and they will take a new "set". I haven't seen any bottom out (some haven't changed in 2 years), but my experience on this is limited to a few.
  30. Zookeeper
    Joined: Aug 30, 2006
    Posts: 1,041


    Very good post. I don't know how many guys here know who Herb Adams is, but he's an ex-GM engineer and Firebird/Camaro handling guru who wrote one of the best chassis books ever many years ago. In that book, he recommended using a torch, and while I prefer an abrasive chop saw, I would not have a problem using a torch if that's all I had. I love hearing all the backyard engineers claim that cutting with a torch ruins the spring. In order for that to happen, the entire spring would have to be heated enough to ruin the temper, and I seriously doubt that could happen on accident. I also feel most older (pre-1980) cars have too soft a spring rate, therefore, chopping a coil or so off will actually improve the ride quality as long as you aren't slamming into or riding on the bump stops. Yet sometimes stories get repeated enough times and get accepted as fact.

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