I'm trying to assemble my front suspension and I have a couple of issues. First I'm wondering if I made the best choice of springs. I ordered these before I read some of the comments here about repro springs being too tall in many cases. I got the big block A/C springs from GU (p/n DCS-1160) because I plan eventually on putting in air conditioning (Vintage Air or similar). I'm also doing a retro build, so I'm looking for stock height or very slightly higher. Does anyone have experience with these springs? They measure 17.5" tall if that helps any.

Also I'm having spring compressor problems. I bought the compressor from Year One (p/n M34) and I've tried it two different ways. I used it as designed and barely got started before it popped off, and I tried using one half of it only with a 1/2" threaded rod through the upper shock mount. That seemed a bit better but it still popped off before I could get the spring compressed enough to install it. This is the type with two unequal length hooks that catch the coil, and I do have the short and long ends oriented correctly. I'm not sure what happens when it pops off--does the compressor rotate and pop off? It seems that the hooks are strong enough that they couldn't just slip straight off. I'm wondering if I should put a small U-bolt clamped to each coil on each side of the hook to prevent it from turning on the spring.

And ideas what I'm doing wrong, or if the above idea might help?

Okay, how about this. Does anyone have a specific recommendation on a good spring compressor for stock-height big block springs?

And is there anyone who has used those Ground Up springs that can give me an idea of what ride height I'll get?

Removed and reinstalled the front springs in my 66 last week. I don't know what springs I have, except the previous owner said he installed them new, because he wanted that 60's front end jacked up look.

He got it.

I suspect he has SS396 springs.

I cut them a 1/2 coil a year ago and it still was too high. So I cut them 2/3 of a coil again last week in conjunction with installing the new disc brake spindles.

They came out easily with a slight crowbar assist the first time, and went back in without a spring compressor with 1/2 coil removed.

They went in really easy this time with another 2/3 coil cut off. With the tie rods, sway bar, shock, etc removed, you should be able to set the top in the pocket and pry the bottom into the rear of the socket in the lower arm. You have to have the front of the car high enough to let the lower arm drop a lot. Mine was on jackstands and it worked.

Rears go in and out w/o a compressor also.

I also have a homemade internal compressor, of two 1/2 thick, 2 in wide and 5 in long steel plates. Use at least a 5/8 threaded rod and a sloppy hole, since it will be loaded off center and subject to bending and abuse. I snapped a 1/2 rod one time on Mustang springs. This works best if you compress the springs prior to removal, or close them in a press or under the rear bumper of your truck.

So do you have a good idea of how many turns total you removed from the spring? Sounds like about 2 1/2 turns. I think that's a lot more than I would want to take off mine, but I would consider removing one turn, or just getting shorter springs. That would make it a lot easier.

I'd rather not wind up much lower in the front than stock though. On the other hand, I'm starting to fear that the springs I have will put me quite a bit higher than stock.

Anyway, thanks for all the info, it's much appreciated.

Got a question for you.

I thought I had bought a set of 1160 springs from NAPA last year. (NAPA number may have been 277-1160 or 277-1860)
Going back and looking, turns out I got a set of 277-1837 (grr)
(pretty sure I ORDERED BB springs but got small block)

These springs ar 17-1/2" tall, have 11 coils, and wire size is .661
The 1837 springs apply to a SBC in the 66/7 Chevelle.
Set my Elky way too high.
Put the original springs back in (they had been out about 8mo) car is still too high.
Higher than before. (but car is not completely assembled yet)

So----if ya got a chance-----count coils and measure the wire size.
Might give us a chance to see exactly what the difference is between the springs.

I'll re-check tonight if I remember. I'm pretty sure the wire size is 5/8, or .625 measured on my dime-store dial caliper. I'll re-check and count coils tonight, and double-check the overall height.

If yours were the same height and coil count wiith heavier wire, then mine would presumably ride a bit lower. But since yours were way too high, that gives me limited comfort!

I have not set the 66 back down on the wheels yet. I am still fitting up the disc brake conversion stuff.

Hope to get it down this weekend. If I can find my ride height measurements, I will know how much it got lowered and post here.

CORRECT formula for
STIFFNESS OF COIL SPRING

K = W^4 x G / N x D^3

K is the Spring rate (Ib/in) I calculated 486.7# (moog 5536 table says 487#)

SO THIS FORMULA IS REAL CLOSE

W is Diameter of spring wire (in.) .687 (.687^4 = .2227547)

G is a constant of 1,406,250

.2227547 x 1,406,250 = 313,248.8

N is the Number of "free" coils (before cut was 8) (after 1.5 coil cut, which removed about 1 active coil + dead 1/2 coil) that would have been in contact with the LCA seat, so I'll use 7 active coils

D- Diameter of
spring coil (in.) 4.317 (4.317^3 = 80.453723)
center to center

313 248.8 / (7 x 80.453723) = 556#


I just cut my BB springs. Moog 5536 had a 15" original free length.

I cut off 1.5 coils which gave me a free length of 13.25"

This calculates out to a modified spring rate about 556#

I did my front springs on my 66 a few months ago. I had the same compressor you are talking about, except I got it from Summit. I couldn't compress the spring more than an inch before the hooks would let go. Its scary. I gave it a few tries with the same result. I then rented a compressor (same design) from Autozone, which seemed to work a little better (the curvature in the hooks was a little different). In the end however, I ended up using the threaded rod/plate method instead. Worked much better.

Thanks guys. I have worked out in my head an idea for clamping the hooks to the spring. I might try that soon.

My wire size is .640 and there are 11 coils, counting the end ones which are bent back slightly to partially flatten the end of the spring. Free height is 17.5".

Many thanks Bill for the formula above! I'll work through that this weekend, and Ron I'll be very interested in hearing how yours comes out once it's back down on the wheels.

In the end, I'm pretty sure I'll use some variation on the threaded rod method, either using one end of my compressor clamped to the springs, or maybe I'll just build my own setup like you did Mike.

Thanks again guys.

Actually, it occurs to me that the one piece of information that would help me the most, along with the above formula, is to know the approximate compressed height of a front spring, installed in the car, at normal ride height and at normal, stock weight.

I think I could get a better feel for whether I want to use the springs I have if I could know that. Anyone know that figure? Or could someone measure theirs?

My Stock Moog 6330 front springs 350 w/o ac = 11.25" installed height ,
free height 17.5", 293# rate x 6.25" compression = 1827#

Moog BB 5536 front springs = ID 3.63" , coil .687 ,
11" install height , 1985# load , 487# spring rate x 4.06 = 1977# , free height 15.06"

http://bbb-carb.com/moog_Coil_Springs.htm

http://www.eatonsprings.com/atqCuttingCoilSpringsCalculations.htm

Because of where the spring is on the front suspension, any change you make will be doubled at the wheel. Thus if you remove 1" at the spring it can be like removing 2" of ride height.

On the rear suspension it is more like a 1:1 ratio where whatever you remove/add will directly remove/add ride height.

Thanks!

That is precisely the sort of information that I needed!

In case anyone's interested, the clamps I fabricated to hold the spring compressor hooks worked great, and the springs are now in!

All the data above seems to agree that the ride height should be pretty close to stock. I certainly hope so, I really don't want to do this job again. If I ever do, I'll get stiffer springs that won't have to be compressed as much. But we'll see how this looks and drives. I'm pretty much just looking for stock here, so I think this will probably be about right.