Going CRAZY with Coil Springs

[prayers1 153]

As most of you know, I installed new coil springs last year that I got from Eaton Detroit Springs, unfortunately they sent the wrong set and instead of taking them back out (which I hate to do) I put spacers in to salvage the rest of the Summer.

 

So now I decided to fix the problem and had several conversations with EATON, we settled on getting springs 2" higher than what I have.  In was told that the springs should settle a 1/2".

 

To start, I am 23" form ground to apex of the fender, 2 more inches would get me 25 and a 1/2" to settle should leave me at 24".

 

Well the new springs measure 27 1/2", that's 2 1/2" more then I was suppose to get!

 

To settle 2/1/2" is an awful lot. Installing these springs seems so straight forward, could I be doing something wrong!!!!!

[barnett468 418]

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sorry but i dont know what your question is.

[SA69mach 39]

Your currently installed springs are 300 lb linear rate springs, right?  (From your post last year)

 

What size spacer?

 

With that spring and spacer, you have 23 inches fender height, right?

 

If your new springs are 300lb linear rate then it is a matter of mathematics to get your height with the new springs and no spacer -

 

If they are the same spring rate, then remove a spring from your car and lay it alongside the new one for measuring and trimming.  Take overall height of old spring, plus the spacer, and mark it.  Add two inches and again mark the new spring.  Add 1/2 inch for the settling of your old spring. Mark that height on your spring.

Then double check the measurements and markings.

 

It may add up to 27 1/2 inches.  Don't worry until you have done the measurements of the uncompressed springs, side by side.  Remember your old springs have already settled.

The new springs may be right on the mark. 

 

I hope this makes sense..

[blueblood 26]

The springs will settle up to 1/2 an inch from their initial compressed height when the weight of the car is on them.

[BuckeyeDemon 211]

is there an issue with the communication such that eaton is talking about length at the spring and you are talking about at the edge of the tire (with suspension ratio (probably incorrect terminology)) being the fundamental difference?

[Max Power 74]

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sorry but i dont know what your question is.

Well....don't answer then.....

[SM69Mach 68]

Can you just cut the longer springs some.  I know it changes the spring rate, but you as high as they are, it would seem you have some room to work with them.

 

 

Just a thought.

[prayers1 153]

Eaton asked me to get some measurement, from ground to the apex of the fender lip.  That is how we are figuring the height.

 

Without any spacers and with the 1st set of springs in that measurement is 23".

 

To get the desired height, I jack the front end up until I find the height I want and that was 24 1/2".

 

I gave Eaton this information and they told me that the springs will settle a 1/2", so they suggested 25".

 

I'm not going to cut coils off.  I feel that I should get what I paid for, the right springs.

 

Weird thing is that I still have the springs that came with the car.  The PO said he installed an old set of big block springs for a future 390.

Those springs were too tall with my first motor a 289.  Since I changed motors and while the 351C was being rebuilt I rebuilt the front end and thought why not new springs. 

 

Those BB springs are the same height as the one's I just got from Eaton.

 

I like to do this job once and be finish with it, I'm not a big fan of coil spring R&R.

 

I will get some picture!

 

Buckeye-That is an interesting thought and I will look into that.

[LoneWolf2U 136]

Well you made me open the trailer and look so I measured her front. She sits at 24. inches to the center of the fender. This is with 14in bfg tires.

I have big block springs installed for the 351C engine, It had lighter springs at first but it sat soooo low to the ground I could not even get the lift arms under the front without driving up on a set f 2x6's to raise it enough to position the cups under the frame rails. A floor jack was even impossible to use.

 

My suggestion is throw the big block springs on or the new ones if they are the same length and coil weight.

the problem you were incurring with the bb springs with the 289 is weight difference of the engines.

[1969_Mach1 333]

This probably won't held solve your issues.  But if you are curious, here are a couple of links for spring rate calculators.  The first link has a discussion and the second link goes to an online calculator.

 

http://engineersedge.com/spring_comp_calc_k.htm

 

http://www.engineersedge.com/calculators/comp_spring_k_pop.htm

 

I think you will have a difficult time getting a soft off-the-shelf spring, with soft I am referring to any stock replacement spring, to work without some trimming.  I've been down that road.  Trimming is a pain because you have to take small increments to be safe.  Its easy to go too far then the spring is garbage.  For my taste, I've always ended up with either the aftermarket 550 lb/in or 600 lb/in springs.  Those sound strong.  But I got tired of trying to get big block or GT springs to work.  Plus, the shortest tire I have run is a 60 series so the tire helps soften the ride. 

[prayers1 153]

OK, here's where I'm at.  I thought that MAYBE over nite the car would settle. It didn't. So much for positive thinking.....

 

The LH is 27 7/8" from the ground to the apex of the fender, the RH is 26 7/8".  There is a 1" difference.  It maybe due to the coil bending and the spring perch has tilted back on the RH side. In any case the front is too tall.. As you may recall, The 1st set sat me at 23" and I wanted 24 1/2".

 

The first set of coil springs were 14 1/2" tall the 2nd set is 17" tall.

 

I have the Shelby drop, NO AC or Pwr steering, a 351C with iron heads and an AOD trans.

 

Here's some pictures.

 

Comments welcomed..................

 

[LoneWolf2U 136]

Weight wise we should be about the same, I did try and give her frontend a reduction by changing intake, water pump, ac comp to aluminum but seem to have added pounds with the scatter shield and a few minor parts.

From the pic's posted, Yes its just my thoughts it looks like the old springs would be your best chance to get to the level your after. It looks like they are better made to sit in the pocket and spring perch.

Letting it sit overnight is nice, but it needs to move to allow everything to settle in place. Your 1/2 inch difference could change with a short spin around the block.

 

Ps. After studying the photos more I can see what the problem is......The garage is TOO clean!

[MikeStang 247]

Go Drive it and hit the brakes a few times pretty good and shift the weight, then take it through a few hard parking lot turns and take home and remeasure, then cut the springs to get the desired height.

Done

[barnett468 418]

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Cutting springs will reduce the amount of resistance they have with the suspension fully compressed. For this reason, stock springs should not be cut.

 

good springs like eibach are pre-stressed so they will not settle much, if at all . . detroit eaton claims theirs are good and will not settle.

[1969_Mach1 333]

Go Drive it and hit the brakes a few times pretty good and shift the weight, then take it through a few hard parking lot turns and take home and remeasure, then cut the springs to get the desired height.

Done

I can't believe I'm saying this, but I kind of like MikeStang's approach.  I would start with a spring with the rate you are looking for, then work with it to get the ride height you want.  It may be a pain, but might be the only way.  This is merely my opinion, but the 69 Mustang is fairly heavy even with a small block and a 550 lb/in rate spring is more suitable on a lowered car.

 

I've haven't cut many springs in my time, but never had any luck trying to lower a car using the stock springs.  Even though the spring rate increases as the number of active coils is reduced, they end up too soft for a lowered car and the suspension will bottom out a lot.  I think that is basically what barnett468 is saying.

[SA69mach 39]

You have 300 lb springs, which are mid range for spring rates, and should prove effective with a Cleveland.  I would not hesitate to cut a coil off either the old BB spring, or the newest spring from Eaton.  Cutting one coil will not increase the  spring rate more than about 10 lbs. (Done it, measured the change - 6 lbs  increase for me with one coil off a 420lb spring)

 

The spring rate is fine, so just cut the coil to size.  You simply will not find an exact spring to suit you exact height for your exact car.  Don't sweat the issue of cutting it,

 

Cut until it is about 1/2 inch taller than your desired end-point, and give it a few weeks and 100 miles to let the settling process occur.

 

You are almost there.  Stick with it.  And you have two sets of suitable springs to work with.  Send the shorties back to Eaton if you can.

 

I just do not understand the agonizing folks have over cutting small amounts off springs.  Millions of successful operations every year, so why worry.  You realize the common method for setting height was (and remains for some folks I guess) heating springs with a torch and bouncing the car down until it was "right"  Now that will affect the temper and spring rate.  Cutting is not a big deal.  One coil is negligible for rate change.  Especially if you are not on a spring which is at the very top of useful rates, such as a 600 lb spring.

[SA69mach 39]

Check out the front springs on my 70 coupe when I got it.  I was told it was a Mexican suspension job, whatever that means...

 

 

Cutting a coil looks kinds tame professional and scientific to that mess, now, doesn't it?

[prayers1 153]

Thank you for all of your comments, it does help!!!!!

 

I sent Eaton Detroit Springs pictures and called them today, since it was late they said they would look at it and get back to me.

The Guy on the phone couldn't believe it sat that high.

 

Because the springs were too high I couldn't mount the front shocks, therefore the stabilizer pins were off and I would be able to drive the car, besides I also took apart the strut rods, therefore the front end would need to be aligned before driving any wheres.

 

I went by a buddy's house today and he had a set of 428/390 springs w/ AC they are the same height as my old ones, but his are more thicker by a thousandth.

 

I'm thinking of putting back in the old springs and see how it looks. Here's a picture with the old springs in with the 289 and a set of 235/60/15 front tires.

 

Here's a picture with the 1st short set from EATON, on 215/65/15 tires and a 351 Cleveland.

I did drive the vehicle with this set up but I had (2) 1" spacers on each coil spring.  The spacers were taken out in this photo.

[barnett468 418]

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Below are some of the factory spring specs from original Ford engineering drawings for a 1967 Mustang small block V8 . . These specs can be verified by contacting the link below . . They are one of the biggest automotive spring mfg’s in the world and have the original factory blueprints for springs for many cars.

http://www.eatondetroitspring.com/contact/ . . ask for Mike

 

269 lbs per inch

8 active coils

.610 wire diameter.

16.145†free length [i used 16.5]

3.875 id

 

The following calculations gives a close estimate of the actual resistance in lbs this spring will have when the suspension is fully compressed.

 

Active coils . . . . . . . . . . . . . . . . . . . . . . . . . 8

Spring Free length . . . . . . . . . . . . . . . . . . 16.5 inches

Spring rate . . . . . . . . . . . . . . . . . . . . . . . 269 lbs per inch

Preload when installed . . . . . . . . . . . . . . . 3 inches

spring resistance when installed . . . . . 807 lbs per inch

suspension ratio . . . . . . . . . . . . . . . . . . . . .2 to 1

total suspension travel . . . . . . . . . . . . . . 16 inches

spring resistance with suspension fully compressed is 8 x 269 = 2152 + 807 lbs of preload = 2959

 

Shorten spring 10% [.8 coils] . . . . . . . . . . . .7.2 coils

Spring free length . . . . . . . . . . . . . . . . . . . .16.5†– 10% = 1.65†= 14.85 cut length

Spring rate increases to . . . . . . . . . . . . .  299.75 lbs per inch

Preload when installed . . . . . . . . . . . . . . . . 1.35 inches

spring resistance when installed . . . . . . 404.6625 lbs per inch due to no preload

suspension ratio . . . . . . . . . . . . . . . . . . . . ..2 to 1

total suspension travel . . . . . . . . . . . . . . . 16 inches

spring resistance with suspension fully compressed is 8 x 299.75  2398 + 404.6625 preload = 2802.6625

2959 – 2802 = 157 lbs less resistance with suspension fully compressed.

 

Shorten spring 25% [2 coils] . . . . . . . . . . . ..6 coils

Spring free length . . . . . . . . . . . . . . . . . . 16.5 – 25% = 4.125†-12.375 cut length

Spring rate increases to . . . . . . . . . . . . . 360 lbs per inch

Preload when installed . . . . . . . . . . . . . . . . 1.125 inches negative [free space]

spring resistance when installed . . . . . . . . .0 lbs per inch due to no preload

suspension ratio . . . . . . . . . . . . . . . . . . . . . .2 to 1

total suspension travel . . . . . . . . . . . . . . . 16 inches

spring resistance with suspension fully compressed is 6.875 x 360 =2475 lbs.

2959 – 2475 = 484 lbs less resistance with suspension fully compressed which is a decrease of 16 .35%.

 

 

If the rate of the spring is high enough such as a 350 for comparison in this case, it will still have a higher resistance than the stock one when the suspension is fully compressed.

[prayers1 153]

Thank you barnett468 for taking the time to post the above information! 

 

It was Mike at EATON that ordered the 1st set of springs.  Mike isn't answering phones at this time and I've been speaking with Gary who ordered the 2nd set.

 

SA69mach- When you cut a coil off how many inches did it decrease your car height.   So, can you say the car will drop by so many inches per coil??

 

Like I said before, I'm gonna try to use the old BB set, IMO I think it's  a BB set w/o AC ( coil is not as thick as the ones with AC) which will be good for me.

 

I'd like to get my ride height at 24 1/2 or 25".

[barnett468 418]

Well....don't answer then.....

 

lol, i didn't.

 

i'm bored, want another 400 post timing thread . . wasn't that fun . . and guess what . . he has not made a single post since he fixed his carb leak, set his timing and jetting . . i actually cant believe he stuck it out.

[SA69mach 39]

Good question, and I should have covered it. My experience was with the 429 BB spring (not 428) available through Oreillys, believe it or not. My suspension guy uses them on his mustang builds, so that's what I got.

 

On a 70 coupe with stock engine, no AC, No PS. The installed height was 1.5" inches high for my liking. I cut exactly one coil and this dropped the car 1 inch. I did not cut more, as I wanted the stock look for this car.

 

There may be a science to this, but as you have found, even the so called experts with their years of spring making , and thousands of example cars to reference, they still often make horrible choices for springs for customers. It is almost unbelievable how bad they are. Take Eaton - they have a great rep, and they make lots of springs, but they sent you two completely unsuitable sets. Even after getting all that information from you for the second set.

 

My advice, is select a spring rate that suits your engine (and car) and stick with it for your height selection. Every time a retailer or springmaker starts meddling with different coil numbers, wire thickness and height, it gets messier and more unlikely that you will get a fix. As you have found....

 

It does help to have a baseline spring to work from, rather than a custom spring from one maker. For example, I know I need a BB429 stock spring with 1 coil cut off. I can get one of those springs anywhere. if I want a lower front, I will cut 1.5 coils off. The spring rate does not get noticeably stiffer until 2 or more coils are cut, in most cases. A 420 lb spring is mid-range with plenty of scope for higher rate by cutting a coil, without becoming stupidly stiff.

 

I would try your "old" BB spring as it is and check height, then go ahead and cut as required. Half a coil at a time if you like, until it is perfect. Measure and record every time you cut.

 

You can transfer that final height to your "new" Easton spring and you should be right on. And you will have a spare set of front coil springs too.

[barnett468 418]

There may be a science to this, but as you have found, even the so called experts with their years of spring making , and thousands of example cars to reference, they still often make horrible choices for springs for customers. It is almost unbelievable how bad they are. Take Eaton - they have a great rep, and they make lots of springs, but they sent you two completely unsuitable sets. Even after getting all that information from you for the second set.

 

Yes there definitely is a science to it . . I actually did over three thousand hours of spring, shock and suspension ratio testing . . We had an MTS machine to plot the damping characteristics of shocks and a portable telemetry unit to attach to the vehicles while testing.

 

All the spring mfg’s use the exact same formulae to calculate spring rates and ride height etc . . I have the formulae which is what I used to calculate the info in the previous post I made but its not a secret. There are a few places online that you can get it.

 

As far as Eaton goes, they definitely know what they are doing from an engineering stand point and Mike knows what he is doing, so until the real cause of the mystery springs is solved, it's impossible to pin point the blame other than Eaton as a company gave you high quality parts that were incorrect for your car . . I have never read or heard about this happening with them before.

.

[SA69mach 39]

OK.....so how did Eaton get it so horribly wrong...twice, given they had so much information from the owner about his particular car, and given the Mustang is the most popular and numerous Muscle Cars in America.

 

It is not a 5 minute job to change out springs on a Mustang. I would be pi$$ed if I were doing it three times, and that is assuming the next ones are perfect. I doubt the vendor would be picking up the tab for multiple installations if the poster is paying a shop.

 

I will be very interested to hear what Eaton is going to do for this unhappy customer. Prayers1 please be sure to post it up.

[barnett468 418]

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Why are you asking me how they got it wrong since they are the ones who sold him the springs?

 

someone there is obviously to blame . . should we blame mike or the other guy or perhaps the guy in the parts department mixed up the order or simply accidentally picked out the wrong springs or maybe the sales guy misunderstood what the op said . . i'm certainly not going to jump on a band wagon and blame anyone without sufficient facts . . i've seen that type of blind group mentality before on a few occasions and it is not a good thing.

 

the fact is, if the op supplied the correct info and it was eaton that screwed up then yes, i agree that eaton should pay for all the shipping and labor costs but unfortunately that is usually not how it works with any mfg which i think is simply morally wrong but it is certainly not illegal.

 

if a faulty piston or rod takes out a $10,000.00 engine, the company that made the faulty part should pay for all the damage their part caused which some companies actually do, however, it is very rare that they do pay and it is a lot of trouble to get them to, but the fact remains that there is no law stating they have to, therefore, there is no sufficient incentive for them to do so.

 

i restored and repaired cars for a living full time for around 30 years and part time for around 15 years prior to that . . i was partners in one of the biggest and busiest mustang shops in the western us so i saw a lot of faulty parts and we never got paid a dime for any of our labor to replace them, so i seriously doubt that anyone can tell me anything i dont already know about this subject.