Cutting front coils??

[leeklm]

I have a new set of Moog coils in my 73 GTO, which are keeping the car about 3/4 to 1" too high. The next step down in their spring offering "might" work, but maybe to save another $100, I was thinking of cutting just a little off the current coils.

To only lower this minimal amount, how much should be cut off the open end of the coil?

[Keith Seymore]

Due to the front suspension geometry it is a 2:1 ratio.

Cutting 1" results in roughly a 2" drop.

K

[leeklm]

"Cutting 1" results in roughly a 2" drop."

I assume by cutting 1 inch, you are referencing 1" off the free standing height of the coil, and not 1" lopped off the coil end? (i.e. going from a 10.5" spring height down to a 10" spring height?)

[78w72]

yes free standing height. if you are only 3/4-1" high i would give it some time to see if they settle a little bit. also be sure you tighten the control arm bolts when the car is on teh ground. many people tighten everything up when its jacked up causing binding & sitting higher.

[leeklm]

Thanks for the note. Yeah, I have seen that in the past with rubber bushings. I have all poly now, so things move pretty freely. The car has about 500 road miles and a dozen drag runs since installing the springs. They are probably as settled as they are going to get for the near term.

Think I will try trimming a 1/2" off the spring height and see what happens.

[rexs73gto]

Its a little bit of a pain but I'd say cut about 1/2 inch at a time until you get the height you want. It takes time to do it that way but its better to cut a little at a time rather then having to buy a new set of springs because you cut to much.

[Chris65LeMans]

Originally Posted by rexs73gto

Its a little bit of a pain but I'd say cut about 1/2 inch at a time until you get the height you want. It takes time to do it that way but its better to cut a little at a time rather then having to buy a new set of springs because you cut to much.

Remember to drive it around a bit after install to get it settled before removing and cutting again.

[leeklm]

Originally Posted by Chris65LeMans

Remember to drive it around a bit after install to get it settled before removing and cutting again.

As much of a pain as springs are, you can bet I will be driving it for a while after making any change

[HWYSTR455]

Originally Posted by Keith Seymore

Due to the front suspension geometry it is a 2:1 ratio.

Cutting 1" results in roughly a 2" drop.

K

Wait, are you saying that cutting 1" off the end of the open coil side it drops 2"? Nah, that ain't right. Maybe if you cut a full coil off it will drop 2", but not 1" of the coil end.

I usually start by cutting a 1/4 of a coil off, note the drop, and go from there. And for obvious reasons, you want to only go a 1/4 of a coil at a time, because you can't put it back on!

.

[abefromen]

Originally Posted by HWYSTR455

Wait, are you saying that cutting 1" off the end of the open coil side it drops 2"? Nah, that ain't right. Maybe if you cut a full coil off it will drop 2", but not 1" of the coil end.

I usually start by cutting a 1/4 of a coil off, note the drop, and go from there. And for obvious reasons, you want to only go a 1/4 of a coil at a time, because you can't put it back on!

.

This is what I do also although I go 1/2 coil first then 1/4 coil afterward if I want more drop. You can trash a set of springs real quick by cutting too much off. Cutting coils will change the spring rate and the car may sit where you want but the spring rate will have been altered too much and the ride quality will suffer if too much is hacked off.

[HWYSTR455]

You can start with a 1/2 a coil, but it's safer to go a 1/4 at a time. Will take more attempts, but you can't go back.

Always cut with a cut off wheel too. If the control arm has a pocket for the spring end, there's no need to 'level' the end that you cut.

I wish I had $10 for ever pair of springs I've cut, and I finally gave up. Buying springs in a set from a knowledgeable and reputable company is the way to go, and they aren't too expensive. My personal experience is that Global West nails the stance you want, AND the rate you want, every time. I once even exchanged a set that I didn't like.

All those ones I've cut? Those were supposedly 'factory blueprint' type springs from places like Moog, Detriot, etc, and NONE were even close. Most were different rates and heights even in the same set. Amazing how many cars I see lean and are uneven.

I'm fairly certain GW gets springs from Afco, and there are like 3 others that make good springs (HyperCo, Landrum, and forget the other) high quality and consistent rates. BUT, you have to do the homework and know what to buy. And THAT info is worth paying the extra $40 or so a set.

.

[Keith Seymore]

I've never had any issues cutting coils as you have described (with a cutoff wheel).

I lowered probably a dozen or so pickups that way back in the day, plus my Chevelle.

My current daily driver was done 29 years ago and has 215k miles with no issues.

K

[78w72]

Originally Posted by HWYSTR455

Wait, are you saying that cutting 1" off the end of the open coil side it drops 2"? Nah, that ain't right. Maybe if you cut a full coil off it will drop 2", but not 1" of the coil end.

cutting 1" off & dropping 2" pertains to the total height of the spring. its usually a ~2:1 ratio. & on many popular gm springs that is about 1 coil. agree you should stay on the safe side unless youve done it before with that vehicle & type of spring. i've lowered all my 2nd gen cars & it is indeed about 1" cut equals 2" drop.

[Keith Seymore]

Originally Posted by Keith Seymore

I've never had any issues cutting coils as you have described (with a cutoff wheel).

I lowered probably a dozen or so pickups that way back in the day, plus my Chevelle.

My current daily driver was done 29 years ago and has 215k miles with no issues.

K

Sorry - lost my internet while I was trying to post pics -

K

[grandville455]

You can take a torch too, and just heat them up and theyll sag some too i have heard.

[78w72]

have heard torching them is a bad idea, yes guys have done it but dave at PTFB & many other suspension guys say heat will ruin the spring ratings. soo much easier to cut them with a cut off wheel or anfle grinder etc.

[Alvin]

You may be interested in this thread post #877 from this parent thread http://forums.maxperformanceinc.com/...755425&page=44
Copied and pasted below as an FYI:

Originally Posted by Bentwheelbob

Alvin - they are OEM size tires in a Polysteel repop. I too would like to see the Herb Adams specs. Below is a photo of the Gold Car alignment sheet. Amazingly, after completely disassembling the entire front end and replacing every bushing and balljoint, all that needed adjusted was the Toe. We took careful measurements before disassembly and that certainly helped.

Originally Posted by 68ragtop

Funny, I was going to post that after looking at the sheet. Adjusting the toe will effect the caster swing measurements a little, & you can see that on your sheet. They could have got it a little closer, but for sure in spec & not worth taking things apart that you put together so carefully.
I have a tendency to fool around for a couple hours getting them as close as I can, because I can Not that it would make much a difference tho.
I'll bet Herb adams bumps the positive caster some & for sure a little negative camber. That would improve handling, but at the cost of some uneven tire wear.

How many shims do your upper arms have in place? I'm sure you already have pictures of that somewhere in your thread?

From reprint in "Pontiac Power"

"Our '77 T/A goes from bumbling to bravo with some help from Nerb Adams VSE." by Tomas A. Demaro reprint of HPP original article.
Herb Adams has a five-part system so you can build up slowly to Fire Am handling. This is the way it lays out:

1. Begin inexpensively by tuning the components you already have. Set tire pressures properly, cut a half-coil off front springs to lower the front end, lighten the front bumper, set the steering lash correctly and, finally, have the Firebird's front end aligned to VSE specs below.

Castor = 1 to 2 degrees positive
Camber = 1/2 to 1 degree negative
Toe-in = 1/16 inch

Low-cost improvements include relocation of the forward leaf spring eyes, banishing the battery to the trunk, and the installation of the front end lowering kit and front structure kit."

This should get you started. I do have the specific '78 specific WS6 Adams specs archived somewhere in my files...IIRC the above alignment specs are the same as recommended by Herb Adams...and should be enough alignment wise to get you in the ball park. IIRC these are the specs used on my former '78 WS6 w 255/60/15 that handled like it was on rails.

Note the "steering lash adjustment" recommendation. Hope this helps.

Edit: Image below of source publication cover of quoted specs from article above. Provided for those who may desire to obtain their own copy.

[leeklm]

Front end height was bugging me so yanked the coils out. Found yet another reason why headers are a pain, as they interfere with the lower A arms when they swing down.

Cut just over 1/4 coil off, which lowered the car about 1/2". Would have liked just a little more, but not going to pull the springs out again unless they need to come out for another reason.

Here is a snapshot of the car. Pointed uphill a little, looks more level on a level surface. Good enough...

[Alvin]

Looks good to me. Great looking car BTW

[78w72]

Originally Posted by leeklm

Pointed uphill a little, looks more level on a level surface. Good enough...

nope -- needs another 1" drop!