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Radar
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Discussion Starter · #1 ·
Rather than tack all this on to the "What we know, and what we don't" thread, and thereby save future readers time and trouble(not to mention tedium), I thought starting a new thread of findings and observations would be in order.

Here they are, as subject categories:

STEEL. To make a long story short SAE 5160 is what you want. Readers can skip ahead to the next section if they so desire. There are so many grades of steel, and so many different designations for them(and their equivalents), that this subject alone can be mind numbing to sort through. There are many grades of leaf spring steel. 5160 by virtue of it's materials content is the highest quality and longest lasting of them. It is also more expensive to produce. The manufacturers know this. If a spring maker does not say up front and in writing that they use only 5160 steel they should be considered as not using it. To put it bluntly, they know full well it's the best stuff and if they used it they should be screaming so from mountaintops. Other common grades of leaf spring steel are 1092, 1095, 4140, and 9260(En45A) to name a few. They are accepted grades, but not as good. "Quality High Carbon Steel" is not a description for 5160. In fact, 5160 is a medium carbon content alloy with a significant chromium content and some silicon too.

STEEL SOURCES. Shoot, you can get it through any number of steel brokerages, and there many of them. India it turns out is home to more than just a few. Is that an elephant that just entered the room? I frankly don't know. If a less than honorable broker were to sell 1095 steel as 5160 instead, and reap huge profits in so doing...Also, China just happens to be the world's largest steel producing country, by far.

You can get 5160 from the U.S. though, Nucor and U.S. Steel are still kicking.

HOW LEAF SPRINGS ARE MADE. It's a process that requires skill and consistency. A good maker will pay attention to the details of quality. Is the steel shot-peened correctly and thoroughly? Heated and cooled to the best standards? What about tapered leaf-ends, non-friction pads being used and fully boxed rebound clips? Cutting corners in these areas is very common. The quality of production(or the lack thereof), is a function of management and design. That holds no matter where they are made. If a maker proclaims they are made to Spring Research Institute Standards, that means little. They could just as easily be made of silly-putty and still meet those size and shape parameters to be stamped. That's a gross exaggeration of course, but a point to be made here. They can and are made to those standards all the time with non-5160 steel.

SELECTION. Start with what you want them for. Driving to the local Sonic or Dairy Queen on Sunday's hardly requires street performance or competition stiff springs, your passengers won't like it, even if you think you do. On the other hand maybe you autocross, drag, or visit a road course from time to time. Select what suits your use. While we are here, let's talk about eyes. Standard, mid, reverse. I found a common misconception as to where you must shop to find other than oem style stock offerings. The fact is that many companies(and Eaton is one of them) can make those too. They can make you whatever your little heart desires. Want standard eye on one end and mid on the other? No problem. However, it is crucial that you speak the truth about what you have when specifying custom springs. Don't say you have a big block if you have a small one. Don't say you have A/C if you don't. Got that?

COST. When it comes to leaf springs, you generally get what you pay for. If you want long lasting quality don't get the el-cheapo's. The original springs on our cars were engineered to last for years, and did. They do eventually wear out of course, or you wouldn't be reading this. Occurrences of having to replace leaf springs every few years is testimony only to one of three things; either inferior grade steel/quality, extreme performance use, or both. Just an aside here, but why do the non-standard eye springs cost more? They are on the same shelf, right? It doesn't cost any more to make them, right? I understand that extra leafs should cost more, more steel, more pads, more tapering etc. I never asked that question of any of the makers I spoke with, but wish I had.

I hope this will be of some benefit to the gang and observers here at VMF. I'm outta here. :burnout::burnout:
 

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Nice write-up, thanks for the explanation.
 
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Excellent! If you can still modify your post, you should explain how spring rate works and why it's important.
 
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Radar
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Discussion Starter · #8 · (Edited)
Excellent! If you can still modify your post, you should explain how spring rate works and why it's important.
I have a strong hunch you already know about this Kelly(and Jane too), but for the benefit of those that don't it's really quite simple. A rate, expressed in pounds, is the amount of weight required to compress a spring one inch. Taking your car as an example(and this was in the previous thread too I think), the base original leaf spring rate was 85lbs. and the GT option was 110lbs. As one can surmise the lower the rate the softer the ride. As spring rate increases so does firmness. That's all fine and dandy as far as it goes, but these days there's more to it than that. What we are getting at here and why it's important is ride quality. The Dairy Queen/Sunday evening crowd neither wants nor needs a stiff ride. The Track folk want nothing to do with soft, they want firm, and the 110 rate springs are way too soft for their use. Some want a happy medium. What to do?

As good luck would have it, there are stiffer rates available for those that have a need/want for them. As bad luck would have it, sometimes people select springs that are less than optimal despite what they think they need or want. It happens.

I'm going to tell a story here, and although it involves a Porsche I think it is pertinent. Husband wants his first sports car, a new Porsche, and wife says great honey, you deserve it. Hubby does homework on all the options available and what he wants. He decides he simply must have the sport tuned suspension option because he read about a test drive review in some enthusiast magazine or other. I tried my level best to talk him out of it to no avail. What he doesn't know, doesn't realize, is that a base Porsche's suspension is already stiff, autobahn ready as it were. Checking the option for the "upgrade" is getting him a full-on track car suspension so stiff a 200lb. person sitting on a fender changes the car's stance barely at all. It's that stiff. Hubby and wife come to take delivery when the car arrives. Test drive just prior to signing on the dotted line, huge deposit non-refundable. Wife gets out of car after drive on normal roads and highway and tells husband that he may have a new Porsche, but she will never ride in it again. I had to wonder if that was his plan all along. There is actually a bit more to that story, but it's not pertinent.

The point is that I believe there is a tendency for the classic car hobby/enthusiast to always want to go up "just one more notch", whatever that notch may be. It is not always the best way. A spring in the 130lb. range is quite stiff. Get up into the 150lb.+ range and the ride on most roads we know will not be comfortable or enjoyable at all. Ka-thump, Ka-thump, Ka-thump. Those expansion cracks and bumps are going to hit those wider and lower profile tires(so many have these days) first, the springs and shocks right after. You will get jounced. The amazing thing to me is that some actually like it that way, or claim they do anyways. If you are on the fence between, say 114lb. springs and 138lb. jobs, my sincere advice to most people would be go with the 114's. Your mileage may vary of course. This is just my opinion having been around the block a few times, and a track or two too. :)
 

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Radar
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Discussion Starter · #9 · (Edited)
I decided to add a bit to this thread, to make a few points clear(er) if possible.

In order to get to the bottom of the whole steel quality issue, I actually found myself joining/becoming a member of a large materials research testing company website. This allowed me to view the raw specifications data, various compositions, and testing results of virtually all the spring steels that are used in the automotive industry, past and present. There were side-by-side and column after column of various testing criteria to sort through. Fascinating stuff. There was no doubt that the best steel for our purposes here at VMF is SAE 5160 grade, and preferably from North American mills.

I said this before, but it should be stressed; If a retailer doesn't say right up front and loudly what steel they are using, you can safely assume it is not 5160. The pricing of springs is a good indicator too. 5160 is more expensive due to its high chromium content.

Some retailers will add a half-leaf, maybe a whole one, maybe mid-eye or reverse, maybe move a leaf to reduce wheel hop, all in order to fill some particular customer needs/wants. Fine, that is cool. That does not mean those springs will last indefinitely though, or have superior "memory", or consistency of tensile strength, or not begin to sag unduly early. Just fyi.

Many of the springs reviewed from different retailers had an uncanny resemblance to each other, despite being stamped as say, "Scott Drake", or "JR Spring", or "Grab-A-Trac", or whoever.

Most of the brand name retailers do not actually manufacture the springs they sell with their name on them. That's a fact, Jack.

If you want high quality Eaton Detroit Springs, they are carried by both NPD and CJ Pony Parts. They go head-to-head on pricing.

If a true custom set of springs is in order for you, Eaton can do that. Be sure to answer all their questions completely and honestly to ensure you get the specification you want correct.

One leaf spring "Brand" that somehow managed to escape my notice until recently was "G-MAX". I started to look into that and only kept coming across different names of middle-men trying to trace them back to an actual manufacturing source. I gave up out of frustration. :wtf:
 

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Naively I went with a budget spring - believing that it wouldnt matter (from CJs & had India stamped on it) - it lasted one summer season of normal driving. Called Eaton Springs and told them what had happened and got a brief education on steel quality and manufacturing standards. Have had their springs on for 4 years now without any issues...very happy with them...thanks for the write up
 

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Your write-up is good but does miss some details.
Leaf spring rate vs ride is elusive because other factors are in play.
In general, anytime you support the spring with rubber bushings
the ride you get is significantly impacted by two factors from the
rubber, resistance to twist and durometer. These types of bushings
are considered a high coefficient of friction part and that, coupled
with what, by design, aren't really very soft eyelet bushings, make
even the 110# GT springs seem stiff.

A low coefficient bushing design, like a spherical/roller bearing or a
del-a-lum bushing used with a 150# spring actually produces a ride
that is on paper stiffer but in reality not that much more so than
the 110# spring hung in rubber. This is in spite of the fact the bearings
or the essentially solid del-a-lum bushings have infinite/solid durometer.

Last but not least, I must say that RIDE is a highly subjective discussion.
Any conversation on VMF concerning KYB, Bilstein, Koni, etc. pretty
much drives that point home.

ex-Global West GM
1991-1995
 
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Another thread I wish I had read before purchasing anything. On a side note, now I'm fanatic about researching on here almost to the point of being afraid to do anything!

I too bought some from CJ's as they were having a big holiday sale so what the heck. Hate them. If I have my boys in the back seat, any type of bump in the road causes my back tires to bottom out. They will be replaced one of these days for sure.

Great info, and thanks for sharing.
 

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Radar
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Discussion Starter · #13 ·
Your write-up is good but does miss some details.
Leaf spring rate vs ride is elusive because other factors are in play.
In general, anytime you support the spring with rubber bushings
the ride you get is significantly impacted by two factors from the
rubber, resistance to twist and durometer. These types of bushings
are considered a high coefficient of friction part and that, coupled
with what, by design, aren't really very soft eyelet bushings, make
even the 110# GT springs seem stiff.

A low coefficient bushing design, like a spherical/roller bearing or a
del-a-lum bushing used with a 150# spring actually produces a ride
that is on paper stiffer but in reality not that much more so than
the 110# spring hung in rubber. This is in spite of the fact the bearings
or the essentially solid del-a-lum bushings have infinite/solid durometer.

Last but not least, I must say that RIDE is a highly subjective discussion.
Any conversation on VMF concerning KYB, Bilstein, Koni, etc. pretty
much drives that point home.

ex-Global West GM
1991-1995
That is correct. I did not get into any of the nuances of different bushings that could be employed, or raising/lowering methods either, for that matter. I also did not bring up the impact that different sizes of wheels and tires have, and though you didn't mention that, I'm sure you would agree that it is substantial.

The focus was just leaf springs and increasing knowledge of them. Ride quality is indeed a very subjective topic. In retrospect I probably should not have interjected my opinion as part of my response to Kelly's good question. My bad.
 

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Radar
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Discussion Starter · #14 ·
Another thread I wish I had read before purchasing anything. On a side note, now I'm fanatic about researching on here almost to the point of being afraid to do anything!

I too bought some from CJ's as they were having a big holiday sale so what the heck. Hate them. If I have my boys in the back seat, any type of bump in the road causes my back tires to bottom out. They will be replaced one of these days for sure.

Great info, and thanks for sharing.
That may be a function of tire and wheel sizing, not incorrect springs necessarily. Is that a possibility? :shrug:
 

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nice write up but for my intents and purposes i just need two words

EATON, OEM......done. case closed :)
 
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Although Eaton is an OEM producer, they didn't build the Mustang springs
used on the assembly line.

ex-Global West GM
1991-1995
 

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Radar
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Discussion Starter · #17 ·
Although Eaton is an OEM producer, they didn't build the Mustang springs
used on the assembly line.

ex-Global West GM
1991-1995
Quite right, and that little factoid was established very early in the research thread. They are however made as closely to OEM specifications as anyone could possibly hope for, like pretty much identical. That goes right down to the details. Like the fully boxed rebound clips (nearly no others have them), the both tapered and angled leaf ends (you can find one or the other on others, rarely both), full use of anti-friction pads where they were originally (some others have few if any), and the use of american sourced 5160 steel (also as it turns out, rare). Yup, they didn't make the originals. They might just as well have though.
 

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No comprehensive leaf spring thread can survive without an old school boomer bringing up the dying art of rearching leaf springs. Years of reading vmf wrt leafs yield countless complaints of predicting a height, choosing between reverse, mid eye and stock only to find you have a silly looking 70's vintage ***-in-the-air result - or Santa Ana style low rider. Don't get me wrong, a slammed '62 or gen I Rivera can be a beautiful thing, perhaps not quite the look you were going for...

The answer if you like the spring rate is to find one of these old school shops (probably next door to the only guy that can fix/clean your copper radiator for $25). These guys can put your fender right where you want it - the alternatives are micky mouse blocks or shackles or returning the springs and take another spin at the roulette wheel for a different set of springs...

M
 

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They are however made as closely to OEM specifications as anyone could possibly hope for, like pretty much identical. That goes right down to the details. Like the fully boxed rebound clips (nearly no others have them), the both tapered and angled leaf ends (you can find one or the other on others, rarely both), .
Since when? I looked them last year and the ends were squared off not rounded like the OEM springs.
 

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Radar
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Discussion Starter · #20 ·
Since when? I looked them last year and the ends were squared off not rounded like the OEM springs.
My GT spec Eaton's (purchased late last year) have only the shortest leaf straight cut and the others are very much rounded. All of them are tapered. Maybe some Eaton springs have differing characteristics depending on the spec?
I just don't know what you were looking at. :shrug:
 
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