Cutting Front Coils

[69CamaroChesapeakeVA]

Im looking to lower the front of my 69 a little. What is the correct way of cutting the front coils? Should I cut 1 complete coil off first. I dont know if cutting a half coil off would work. Doesnt the springs sit in some sort of pocket in the lower control arm. I have a cut off wheel and I know how to use it well, I just dont know how much to cut off to start with. Im looking for a 2 inch drop total over what I have now.

[will69camaro]

Dont cut an entire coil off first time!!! remember you can always take it off and cut more, start out small and keep cutting off small amounts to get to where you want to be. You dont want to cut off too much and have it SLAMMED! Not sure how everyone else feels but for a 2 inch drop i'd start with 1/2 coil and see where that leaves you and go from there.

William

[69CamaroChesapeakeVA]

If I cut off a half-coil, will the springs fit in the pockets of the A-arms correctly?

[Marcus SC&C]

Yeah it`ll fit fine if you cut half a coil. Just rotate it in the lower spring pocket until the pigtail is butted up against the end stop. Don`t go more than 1/2 coil at a time and once you cut them and reinstall em take the car for a drive and bounce it around a little before you measure the new ride height. Marcus SC&C

[CAMAROBOY69]

I agree with them. Start with 1/2 coil at a time just to be safe.
Don't be fooled by your first cut though. It will not drop very much but believe me after you get past the first cut or 2 it will start dropping a LOT. I cut my coils to get my stance.

[34X2Camaro]

For those of you that cut your coils, how is the ride quality? Is it rough and bouncy or good?

[CAMAROBOY69]

I have been 100% happy with my ride in the since I cut the coils in the front. :icon996:
I cut 2 and a half coils out. with the coil out of the car it was 16.5 NOW it is 12.5.

[MrQuick]

Hey Adam how far is your car from contacting the bump stops? 2 inches off of the spring is usually a 4 inch drop(small block spring that is). How much did that lower you from stock height?

[CAMAROBOY69]

I am not sure right now (im at work) how far my bump stops are from hitting. My car sat really high for some reason so I had to cut out more than the average person. If I remember correctly I dropped the car over 5" in front and 5.5" in rear. Sorry we hyjacked the thread but hopefully this info helps you. Otherwise you can both of us.

[69CamaroChesapeakeVA]

If you cut 2 inches out of the coil, how does that drop the front end 4 inches??

[CAMAROBOY69]

If you cut 2 inches out of the coil, how does that drop the front end 4 inches??

His theory is very close to correct.
If you look at the pic I posted you will see that at the very end of the spring it is a lot more compressed. WHen that compressed part is cut off it doesnt lower the car much. BUT when you get into the part of the spring that is spaced out further it drops a lot more once the weight of the car is placed on it. Hope that helps.

[Romy]

Per the book by Herb Adams called Chassis Engineering it says to cut off half at a time with an acetalyne torch till you get the ride height that you want.
I know that this Herb Adams guy knows what's going on, but I swear that sounds funky. When you heat steel, it's gonna harden (due to the carbon in the steel) as it cools unless you really cool it slowly. So maybe you should use a cut-off. I guess it's up to you.
However, if it does harden, it'll increase your spring rate, so you'll have a stiffer front suspension, which may not be a bad thing.
He also says that after you cut it to flip it over quickly (before it has much of a chance to cool) and push down on it to bend the coil so it's flat and you don't have issues mouting it back up.

[Norm Peterson]

If you can get your cut started right away and finish your cut promptly acetylene is OK. A little unknown heat-treat at the end of the half coil or so that's always resting on the control arm won't affect either ride height or spring rate, as it's not an active coil. But you need something with more cutting power than a home-hobby sized rig, as they take longer to get a cut started in anything as heavy as spring coil stock (read: more heat is input to the spring).

Ride height drops by more than the amount cut from the spring due to the springs' motion ratio. Since the springs are midway-ish out the control arm, the balljoint moves about double whatever happens at the spring seat.

You can estimate fairly closely how much drop you'll get if you know the loaded coil spacing with the car at rest on the springs in question and the motion ratio for the spring. It's less accurate for cutting more than about one full coil, but at least the answers tend to be conservative (better to not cut quite enough and have to trim a little more than to cut too much the first time).

Norm

[David Pozzi]

Adams says to cut quickly then dunk in water. Norm is correct the end of the spring is not holding the whole car up so it's not a big deal.

The unpredictable part is the first half coil of the spring is tapered so does little when cut off. The seat is tapered too, so it is following the taper angle of the spring end. The second half of coil removed does a lot more, and the first whole coil causes the spring to drop down into the pocket and you instantly lose aprox 3/4" of spring height.

I think something like .6" of coil height loss equals 1" of height change, BUT the coil get's stiffer as you shorten it, so the added stiffness reduces drop. The taper of the seat makes cutting unpredictable.

I like a stock car racing coil with AFCO "hidden" adjuster, you can just turn the adjuster to change height.
David

[harshman]

If you or somebody that you know can use a torch very well, the heat generated is fairly minimal on a cut and it is at the end of the spring – that has very little to do with the height. Also, the amount of drop that is attained per cut would depend on the spring rate wouldn’t it? Cutting a 350 #/in spring would yield a different installed height than a 650 #/in spring.

[68LSS1]

David, I was looking at my "Chassis Engeering" book and in it Herb says to let air cool.

[CAMAROBOY69]

Guys its not rocket science. Just use a cutting disk from a grinder and it will be fine. Only takes about 10 seconds.

[smittys69]

One more question for you guru's. Can you remove and reinstall the springs without busting the balljoint(s) loose? I am installing all new front suspension and I'm not too enthuised on tightening up the balljoints and then busting them loose several times. I could see where you might screw up the rubber cup unless you could do it without a fork.

[Norm Peterson]

One more question for you guru's. Can you remove and reinstall the springs without busting the balljoint(s) loose? I am installing all new front suspension and I'm not too enthuised on tightening up the balljoints and then busting them loose several times. I could see where you might screw up the rubber cup unless you could do it without a fork.

You don't need to use a fork. Use the weight of the car and the spring to do the work. Here's how:

NOTE - this was more-or-less generically written for balljoint replacement - for spring replacement you normally need only break the lower BJ loose.

With the car supported under the frame, remove the front wheels.

Remove the cotter pins from the nuts of all the balljoints being broken loose.

Loosen the nuts, but do not remove them. About 1/8" gap between the faces of the nuts and the knuckle is all you need.

If you're breaking both balljoints on a side loose, do the unloaded one first (typically the upper).

UPPERS: Jack up the upper arm to load up the upper balljoint. Not so much as to raise the car off the frame support, but the closer you get to this point the better this method will work. Typically you'll need something like a length of 4x4 between the jack and the UCA. Place another piece of wood or metal on the top of the 4x4 so the UCA doesn't split the 4x4.

Smack the knuckle where the UBJ stud goes through it, and use a decent size hammer - no 16-oz toys need apply for this job. Using a soft punch will keep you from scarring the knuckle. The vibration plus the spring load (carried through the knuckle) will pop the stud's taper loose. That's why you leave the nut on with only a little free space to "pop" across, so things don't completely fly apart and/or escape. In stubborn cases you may end up capping an oversize nut over the stud (against the BJ's loosened nut) and striking it in a direction that's as close to along the axis of the balljoint stud as is practical. Or striking the knuckle to drive it downward off the BJ stud.

LOWERS: If you've broken the UBJ loose, leave it loose and let the suspension lower. Jack up under the rotor or its hat to load up the lower balljoint.

Same deal with the hammer and soft punch to get the LBJ stud to "pop".

Norm

[David Pozzi]

68LSS1,
It might be in his parts catalog that he has a lot of tips and it shows a photo of Herb Adams dunking a coil in a bucket of water. I don't think it matters how it cools since the end of the spring has some load on it but the load has no twisting effect on the spring end like it does on the rest of the spring.

One caution though, DO NOT allow cutting or weld spatter to hit the main coils! It can cause a stress riser that can eventually cause the spring to snap!
Lay the spring on it's side and cut away from the main coils, don't weld near coil springs unless you shield them from damage.