Fiberglass Springs any good?

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stiffer? a quick google search shows fiberglass' elastic modulus is 17.2 GPA, steel is 200GPA, so steel is 11.6x stiffer. to get the same effective stiffness, for a same length & width beam segment, the fiberglass spring will need to be approx 2.25x thicker (taller) to have the same spring rate as a comparable steel spring the way the equations work out.

I can't dispute your numbers, they sound correct, but two points, he might have meant comparable weights regrading stiffness, and a "leaf" is not a solid member, but sliding members, where a composite spring is obviously solid.

true, guess I'm a stickler for details I guess....there are 2 components to a part's "stiffness"--material properties and geometry. fact is, from a material property stand point, steel is MUCH stiffer. but a part can be stiffer with changes to the geometry to give more cross section.

but even looking at just a steel main leaf, which is what, 5/16" thick? the thinnest part of a fiberglass leaf would need to be approx 11/16" thick to get a comparable stiffness....

didn't bother looking at densities, steel is 7.85g/cm^3...a quick google search shows fiberglass as 2.5g/cm^3 or less (depending on glass to resin ratios), so you could have 3-4 times the volume of fiberglass in your part before it weighed more than the steel part.

so yes, stiffness per weight can be much better for fiberglass, if the space allows for the geometry differences.

This all kind of goes where I was intending. If you have looked at these aftermarket fiberglass springs, you'll notice that are easily 2.5x as thick as a single steel spring. So by comparison, they are a mono leaf that is provided the additional stiffness and rate that a single steel mono leaf could not provide without a huge weight penalty. Additionally, the added arch of the fiberglass springs allow it to be in a geometric position when loaded that provides the additional short segment stiffness the mopar design is know for. Now, how well would that stand up to the high shock loads of a drag race launch with slicks on a prepared surface, I don't know. In that case I might opt for a Cal-trac or Slide-link traction device. From handling perspective, there are few disadvantages to using a fiberglass leaf.

Yes, Corvettes have been using them for decades. So there are plenty of on road miles that can be attributed to the material.

The best way to chose them would be to speak with the manufacturer or a knowledgeable retailer. They will ask you the specifics of weight, usage, etc. to help dial you in with what you want.

Posted By: jcc

Re: Fiberglass Springs any good? - 02/03/12 12:57 PM

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T-Bars are unsprung weight right?

Actually I believe the correct rule of thumb regarding determination of unsprung weight is only 50% of the tb is considered "unsprung". Think about it, half the bar is attached to the sprung chassis, and the other half to tb connector. Since the tb is uniform shaped, thats likely pretty accurate. In leaf springs and say shocks, the same rule of thumb is used, but likely is not as accurate since their masses are not uniformly spread out along their connecting axis.

Posted By: Mattax

Re: Fiberglass Springs any good? - 02/06/12 03:49 AM

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I have a set of #225 flex a forms, how will they compare in ride and handling to say a set of factory 340 leafs?

How do they work and hold up in drag racing applications?

An A-body with 340 came with leafs with a spring rate of approximately 120 lbs/in.
DC books/bulletins state the super stock springs are 160 lbs/in.

So if nothing else has been changed in terms of front spring rates or front/rear vehicle weight, switching to 225 #/in leafs will cause the vehicle to get loose in the rear (aka oversteer) when in sweeper. Many good autocrossers like the rear a little loose for competition. This is not a winning setup for highway speeds and faster.

A downhill curve on a rainy day can be equally exciting.

If you are drag racing on slicks, I can't really picture launching on a single leaf without other changes. I guess it probably depends on how hard the car launches, but ideally the chassis will lift and maximize the rear wheel's downward force.

Posted By: jcc

Re: Fiberglass Springs any good? - 02/12/12 02:12 PM

I just remebered I ran into an annoying problem with Flex a Forms a few years back. They said its not a problem. I disagree. I suspect the fiberglass springs are made up as one long arc, and with designated design rating. After curing, the arc is sliced like a loaf of bread into spring widths as needed. Additionally, the "arc" is thicker towards the center, and thins towards the edges, depending on how the sliced arc is shortened to needed spring length, this thicken section can be placed in needed location where the axle housing is bolted, ie the difference between SS springs (20"?) front segment and reg (22"?) front segment.

Anyhowe, I will post later a pic of the set I am unhappy with, and you decide. They would not replace them, and I installed them on a beater Charger 318 B body.

Posted By: jcc

Re: Fiberglass Springs any good? - 02/12/12 09:43 PM

I hope its noticeable the thicker cross section behind the axle mounting point.

Attached picture 7068037-IMG_5441BadFiberglassspring.jpg

Posted By: Ovalracer68

Re: Fiberglass Springs any good? - 02/13/12 05:13 AM

i have the hypercos on the stock car--absolutely superior to steel.

Posted By: Mopar Mitch

Re: Fiberglass Springs any good? - 02/13/12 05:52 PM

I've been very pleased with the FlxaForm leafs (225 lbs with 5" arch)for Solo II style autocross events; played with the bushings (poly vs rubber... setteld at rubber endlinks; frame mounts are poly) on the endlinks of the 1"rear bar, as well as the Koni (reds) adjustment at ~3/4 stiff (full stiff lifts the rear tires off the ground at max cornering. Now, for recent road course lapping/track events, all is still the same but it does tend to slightly want to oversteer in hard sweepers, but I'm not driving to the max limits yet at the road course events (need new tires as I'm driving to/from on old BFG T/As instead of trailering with preferred sticky Hoosiers). I may eventually re-install my factory 3/4" rear bar for road course events and then play again with the endlinks to fine tune it, as well as the stiffness of the Konis... perhaps this year with the rear bar, but first I need new tires (Hoosier A6 or else may change to Kumohs XS)...as you know, I have 16x10 race rims ft/rr with very old A6 on them now... driving on street/track with the old BFG T/As on 15x8 minilites.

Posted By: HotRodDave

Re: Fiberglass Springs any good? - 02/14/12 05:20 AM

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I hope its noticeable the thicker cross section behind the axle mounting point.

Thats because like many other speed parts they are desighned for a chevy and modded for a use on a mopar. A mopar does not mount the axle in the middle of a spring like a chevy or ford but those springs are engineered for generic cars and they just move the axle mounting point and sell it for mopars. Mine are not for a mopar at all, the axle perch is centered for a chevy of ford, someone pulled a fast one on me

Posted By: patrick

Re: Fiberglass Springs any good? - 02/14/12 04:41 PM

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I hope its noticeable the thicker cross section behind the axle mounting point.

Thats because like many other speed parts they are desighned for a chevy and modded for a use on a mopar. A mopar does not mount the axle in the middle of a spring like a chevy or ford but those springs are engineered for generic cars and they just move the axle mounting point and sell it for mopars. Mine are not for a mopar at all, the axle perch is centered for a chevy of ford, someone pulled a fast one on me

looks like to work properly you'd need to add some caltracs, to stiffen up the front segment....

Posted By: TC@HP2

Re: Fiberglass Springs any good? - 02/14/12 07:22 PM

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Thats because like many other speed parts they are desighned for a chevy and modded for a use on a mopar. A mopar does not mount the axle in the middle of a spring like a chevy or ford but those springs are engineered for generic cars and they just move the axle mounting point and sell it for mopars.

I have not used nor looked closely at a fiberglass spring to verify this. If that is how they are made, then the thickness of the spring and its location could be a factor in the need for any traction enhancing device. However, if the frotn segment is trimmed shorter to fit a mopar appplication, that should still provide a thicker cross section than a competitors design which is a strength of the mopar design.

A fiberglass spring by nature is more rigid than a steel spring and in a road or autocross setting should not require additional traction devices, IMO, but no first hand experience here. On the other hand, a drag launch may need a device because of the signficant shock loading of the springs and the brittle nature of fiberglass.

Posted By: patrick

Re: Fiberglass Springs any good? - 02/14/12 09:17 PM

stiffer? a quick google search shows fiberglass' elastic modulus is 17.2 GPA, steel is 200GPA, so steel is 11.6x stiffer. to get the same effective stiffness, for a same length & width beam segment, the fiberglass spring will need to be approx 2.25x thicker (taller) to have the same spring rate as a comparable steel spring the way the equations work out.

Posted By: jcc

Re: Fiberglass Springs any good? - 02/15/12 12:02 AM

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stiffer? a quick google search shows fiberglass' elastic modulus is 17.2 GPA, steel is 200GPA, so steel is 11.6x stiffer. to get the same effective stiffness, for a same length & width beam segment, the fiberglass spring will need to be approx 2.25x thicker (taller) to have the same spring rate as a comparable steel spring the way the equations work out.

I can't dispute your numbers, they sound correct, but two points, he might have meant comparable weights regrading stiffness, and a "leaf" is not a solid member, but sliding members, where a composite spring is obviously solid.

Posted By: Pale_Roader

Re: Fiberglass Springs any good? - 02/15/12 12:52 PM

Okay, i gotta ask...

I've always seen the tremendous weight-reduction factor for FG leafs, that one is obvious, but FG just seems like an unlikely material for a spring. Do these things not break? Thats a LOT ov stress, and even more on a race car in corners. Are these safe? Sure, some here have track cars that never see real streets, but how about for a street car? or do you people drive these things (and abuse these things) on the street as well...???

I would love to save a massive chunk o' weight, but i'm leery. I'd also be leery about ordering them, as if they're not quite the rate, or height, load, whatever you wanted, there is no adjustment. How do you make SURE you order the right one...???

Posted By: patrick

Re: Fiberglass Springs any good? - 02/15/12 01:24 PM

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stiffer? a quick google search shows fiberglass' elastic modulus is 17.2 GPA, steel is 200GPA, so steel is 11.6x stiffer. to get the same effective stiffness, for a same length & width beam segment, the fiberglass spring will need to be approx 2.25x thicker (taller) to have the same spring rate as a comparable steel spring the way the equations work out.

I can't dispute your numbers, they sound correct, but two points, he might have meant comparable weights regrading stiffness, and a "leaf" is not a solid member, but sliding members, where a composite spring is obviously solid.

true, guess I'm a stickler for details I guess....there are 2 components to a part's "stiffness"--material properties and geometry. fact is, from a material property stand point, steel is MUCH stiffer. but a part can be stiffer with changes to the geometry to give more cross section.

but even looking at just a steel main leaf, which is what, 5/16" thick? the thinnest part of a fiberglass leaf would need to be approx 11/16" thick to get a comparable stiffness....

didn't bother looking at densities, steel is 7.85g/cm^3...a quick google search shows fiberglass as 2.5g/cm^3 or less (depending on glass to resin ratios), so you could have 3-4 times the volume of fiberglass in your part before it weighed more than the steel part.

so yes, stiffness per weight can be much better for fiberglass, if the space allows for the geometry differences.

Posted By: patrick

Re: Fiberglass Springs any good? - 02/15/12 01:25 PM

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Okay, i gotta ask...

I've always seen the tremendous weight-reduction factor for FG leafs, that one is obvious, but FG just seems like an unlikely material for a spring. Do these things not break? Thats a LOT ov stress, and even more on a race car in corners. Are these safe? Sure, some here have track cars that never see real streets, but how about for a street car? or do you people drive these things (and abuse these things) on the street as well...???

I would love to save a massive chunk o' weight, but i'm leery. I'd also be leery about ordering them, as if they're not quite the rate, or height, load, whatever you wanted, there is no adjustment. How do you make SURE you order the right one...???

then don't buy any corvettes made in the last, oh 30 years or so, as IIRC they all used transverse fiberglass leaf springs in their IRS

Posted By: Bad340fish

Re: Fiberglass Springs any good? - 02/15/12 01:27 PM

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Okay, i gotta ask...

I've always seen the tremendous weight-reduction factor for FG leafs, that one is obvious, but FG just seems like an unlikely material for a spring. Do these things not break? Thats a LOT ov stress, and even more on a race car in corners. Are these safe? Sure, some here have track cars that never see real streets, but how about for a street car? or do you people drive these things (and abuse these things) on the street as well...???

I would love to save a massive chunk o' weight, but i'm leery. I'd also be leery about ordering them, as if they're not quite the rate, or height, load, whatever you wanted, there is no adjustment. How do you make SURE you order the right one...???

then don't buy any corvettes made in the last, oh 30 years or so, as IIRC they all used transverse fiberglass leaf springs in their IRS

I believe the Chevy astro vans used a composite leaf as well.

Posted By: jcc

Re: Fiberglass Springs any good? - 02/15/12 04:35 PM

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Okay, i gotta ask...

I've always seen the tremendous weight-reduction factor for FG leafs, that one is obvious, but FG just seems like an unlikely material for a spring. Do these things not break? Thats a LOT ov stress, and even more on a race car in corners. Are these safe? Sure, some here have track cars that never see real streets, but how about for a street car? or do you people drive these things (and abuse these things) on the street as well...???

I would love to save a massive chunk o' weight, but i'm leery. I'd also be leery about ordering them, as if they're not quite the rate, or height, load, whatever you wanted, there is no adjustment. How do you make SURE you order the right one...???

FWIW, somewhere I have a flyer around promotingFG springs for class 8 semi's (80K stuff), and that would be huge weight savings, but I don't know if they are still marketed for that application. I have high confidence, except for situations that have extreme spring wrap up, and that means 1/4 mile, heavy car , slicks, 4 speed, etc, and that opinion is only based on gut feeling, not real world experience.

Posted By: dangina

Re: Fiberglass Springs any good? - 02/16/12 12:35 AM

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Okay, i gotta ask...

I've always seen the tremendous weight-reduction factor for FG leafs, that one is obvious, but FG just seems like an unlikely material for a spring. Do these things not break? Thats a LOT ov stress, and even more on a race car in corners. Are these safe? Sure, some here have track cars that never see real streets, but how about for a street car? or do you people drive these things (and abuse these things) on the street as well...???

i bought the hypercoils leafs but not until i did some research on them and asked around on forums before buying them - their are guys using these springs on street. dirt. roadcoarse. and scca racing with great success - punishing them in the corners and never having one crack or break. They are pricey but i do like the fact i can pick my own spring rates...
I would love to save a massive chunk o' weight, but i'm leery. I'd also be leery about ordering them, as if they're not quite the rate, or height, load, whatever you wanted, there is no adjustment. How do you make SURE you order the right one...???

Posted By: Pale_Roader

Re: Fiberglass Springs any good? - 02/16/12 01:00 PM

Hmmm... more good answers. I'm sold.

Now, if i go better than give the manufacturer the rates/specs i want, and just give them a steel spring i would like duplicated in FG, that would be easier for them, yes?

And the last question... how much (ballpark) do a set o' Mopar style FG leafs run?

Posted By: TC@HP2

Re: Fiberglass Springs any good? - 02/16/12 03:45 PM

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I would love to save a massive chunk o' weight, but i'm leery. I'd also be leery about ordering them, as if they're not quite the rate, or height, load, whatever you wanted, there is no adjustment. How do you make SURE you order the right one...???

Unless you're real sure of what you want, I'd avoid swap meets and online auction buying of the springs. Talk to a reputable supplier to verify what you want is what you get. They have been doing this a long time and can probably get you what you want. Sure you can't change the rate of a fiberglass leaf, but changes in mounting position are the same as a steel leaf.

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Hmmm... more good answers. I'm sold.

Now, if i go better than give the manufacturer the rates/specs i want, and just give them a steel spring i would like duplicated in FG, that would be easier for them, yes?

And the last question... how much (ballpark) do a set o' Mopar style FG leafs run?

Depends on the manufacturer. Most can get you within the ballpark of what you want with their off the shelf product of few different rates and a few different arches. Creating an exact duplicate of a steel spring isn't necesssarily the best way to go because of the different properties of the materials, but they can give you better info than I could on the details.

Ball park price for fiberglass springs is around $300-400 each. If you want to get into any custom work the price would go up from there. FWIW, a truly custom spec, steel race leaf spring would be comparable in price. I'm not talking about the Espo style, bend em up +1 over stock leafs, but true custom built racing springs with teflon interliners, diamond point tips, hardened, and with consistent taper through each leaf.

Posted By: robsimmons

Re: Fiberglass Springs any good? - 02/16/12 10:48 PM

Great discussion here. I see some "Mopaxers" as well. I didn't even realize there was a "handling" section added to Moparts. I need to surf here more often!

Posted By: dangina

Re: Fiberglass Springs any good? - 02/17/12 01:18 AM

i bought my hypercoils a couple months back - they were 618 shipped. ; bought them through amazon s they have a bit of a discount:

http://www.amazon.com/HYP10231-Hyperco-Hypercoils-COMPOSITE-LEAF/dp/B003PNW8CW

refer to their website for the part numbers with the spring rates you want on page17-18 in the catalog:

http://www.hypercoils.com/leaf-springs.html

they offer spring rates up to 225 lbs

I'll post some pics of them if I get a chance tonight...

Posted By: Pale_Roader

Re: Fiberglass Springs any good? - 02/17/12 01:52 AM

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Quote:

I would love to save a massive chunk o' weight, but i'm leery. I'd also be leery about ordering them, as if they're not quite the rate, or height, load, whatever you wanted, there is no adjustment. How do you make SURE you order the right one...???

Unless you're real sure of what you want, I'd avoid swap meets and online auction buying of the springs. Talk to a reputable supplier to verify what you want is what you get. They have been doing this a long time and can probably get you what you want. Sure you can't change the rate of a fiberglass leaf, but changes in mounting position are the same as a steel leaf.

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Hmmm... more good answers. I'm sold.

Now, if i go better than give the manufacturer the rates/specs i want, and just give them a steel spring i would like duplicated in FG, that would be easier for them, yes?

And the last question... how much (ballpark) do a set o' Mopar style FG leafs run?

Depends on the manufacturer. Most can get you within the ballpark of what you want with their off the shelf product of few different rates and a few different arches. Creating an exact duplicate of a steel spring isn't necesssarily the best way to go because of the different properties of the materials, but they can give you better info than I could on the details.

Ball park price for fiberglass springs is around $300-400 each. If you want to get into any custom work the price would go up from there. FWIW, a truly custom spec, steel race leaf spring would be comparable in price. I'm not talking about the Espo style, bend em up +1 over stock leafs, but true custom built racing springs with teflon interliners, diamond point tips, hardened, and with consistent taper through each leaf.

Basically i was thinking about getting a FG version ov the leafs in the Hotchkis kit. There you have a spring made for a fully dialed in kit, so the specs would be there to try and emulate it (or at least emulate the end-result).

Leafs are bloody heavy... so this is exciting for a weight-loss fanatic...

Posted By: dangina

Re: Fiberglass Springs any good? - 02/20/12 08:17 AM

sorry it took so long:

Posted By: brads70

Re: Fiberglass Springs any good? - 02/20/12 04:49 PM

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i bought my hypercoils a couple months back - they were 618 shipped. ; bought them through amazon s they have a bit of a discount:

http://www.amazon.com/HYP10231-Hyperco-Hypercoils-COMPOSITE-LEAF/dp/B003PNW8CW

refer to their website for the part numbers with the spring rates you want on page17-18 in the catalog:

http://www.hypercoils.com/leaf-springs.html

they offer spring rates up to 225 lbs

I'll post some pics of them if I get a chance tonight...

Nice!

curoius to hear how they work for you!

Posted By: brads70

Re: Fiberglass Springs any good? - 02/20/12 04:57 PM

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sorry it took so long:

Could you weight one before you put them on the car?

How did you decide what rate to choose?
When mounting them do they just slip in place of the steel springs or do they have to be mounted in rubber or something? Is there a maximum tourque spec when tightening up the u-bolts or anything like that?

Posted By: brads70

Re: Fiberglass Springs any good? - 02/20/12 07:42 PM

Found these instalation instructions on hypercoils website.... answering my own question! LOL

Here is the list of the most common tips we have given our customers concerning the use of Composite Leaf Springs:
U-bolts should never come in contact with the composite portion of the leaf spring. Hyperco recommends a heavy gauge rubber or plastic hose be fitted over the U-bolts to ensure that there is no metal to composite contact.
U-bolts should be tightened evenly to a torque value of 80 to 100 ft. lbs., or until the center mounting plate yields / deflects. The torque value should be checked on a regular basis to ensure adequate and consistent clamping force.
The mounting pad must extend a minimum of �" past the steel mounting plate.
Additional protection for the composite leaf can be obtained by wrapping all exposed surfaces with high quality duct tape.
When installing springs it is important to check the alignment. The inner sleeves must not bind inside the spring bushings on both the front and rear mounting brackets.

Posted By: dangina

Re: Fiberglass Springs any good? - 02/21/12 07:00 AM

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Could you weight one before you put them on the car?
How did you decide what rate to choose?

I weighed one on a car scale - 10 lbs! I'm gonna weigh them on a more accurate scale soon to see if thats correct

I choose the rate based on my previous experience with spring rates:

8kg (448lbs)on the front and 6kg(338lbs) on the rear - Max I'll ever go on the street again - not so great on the lower spine but awesome on the track - little to no body roll

6kg(338lbs) front and 4kg(224lbs) on the rear - tolerable on the street (barely bearable for the wife) - still great on the track - little body roll

now these were on a car 800-900 lbs less than my big old bbody

so I figure that with a 5kg (270lbs) front I figure a good match would be a 3.5kg (200lbs) rear in a heavier car should still have the firm feeling and roll I want but not so harsh of a ride that the wife would want to stay in the passenger seat!

This is all speculative right now - I'll see how well its put into action this summer - I also based this on the hotchkis setup for the ebodies which are running a 4kg(225lbs) front and a 3kg(160lbs) rear
and they are anywhere from 600-800lbs lighter than the bbodies...

Posted By: brads70

Re: Fiberglass Springs any good? - 02/21/12 02:46 PM

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Quote:

Could you weight one before you put them on the car?
How did you decide what rate to choose?

I weighed one on a car scale - 10 lbs! I'm gonna weigh them on a more accurate scale soon to see if thats correct

I choose the rate based on my previous experience with spring rates:

8kg (448lbs)on the front and 6kg(338lbs) on the rear - Max I'll ever go on the street again - not so great on the lower spine but awesome on the track - little to no body roll

6kg(338lbs) front and 4kg(224lbs) on the rear - tolerable on the street (barely bearable for the wife) - still great on the track - little body roll

now these were on a car 800-900 lbs less than my big old bbody

so I figure that with a 5kg (270lbs) front I figure a good match would be a 3.5kg (200lbs) rear in a heavier car should still have the firm feeling and roll I want but not so harsh of a ride that the wife would want to stay in the passenger seat!

This is all speculative right now - I'll see how well its put into action this summer - I also based this on the hotchkis setup for the ebodies which are running a 4kg(225lbs) front and a 3kg(160lbs) rear
and they are anywhere from 600-800lbs lighter than the bbodies...

Thanks for the reply! Wow 10 LBS!!!! that IS light!

When you ordered from Hypercoil did you or were you able to specify the lenght and segments. Like for my e-body I'd need 22 in the front and 35 in the rear to be able to bolt in?

Posted By: dangina

Re: Fiberglass Springs any good? - 02/21/12 08:50 PM

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Thanks for the reply! Wow 10 LBS!!!! that IS light! When you ordered from Hypercoil did you or were you able to specify the lenght and segments. Like for my e-body I'd need 22 in the front and 35 in the rear to be able to bolt in?

unfortunatly they one make the most common spring which is a 20" front segment - that fits most mopars - you need the 2" front hanger from firm feel to run these springs, just as you would use the same hanger to run the SS springs....I'll post a pic of the firm feel hanger tonight - they're pretty beefy - the beefiest ones i could find,,,

Posted By: brads70

Re: Fiberglass Springs any good? - 02/21/12 11:29 PM

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Quote:

Thanks for the reply! Wow 10 LBS!!!! that IS light! When you ordered from Hypercoil did you or were you able to specify the lenght and segments. Like for my e-body I'd need 22 in the front and 35 in the rear to be able to bolt in?

unfortunatly they one make the most common spring which is a 20" front segment - that fits most mopars - you need the 2" front hanger from firm feel to run these springs, just as you would use the same hanger to run the SS springs....I'll post a pic of the firm feel hanger tonight - they're pretty beefy - the beefiest ones i could find,,,

Sounds good! I'm almost ready to order a Dana 60 and Dr Diff's offset kit for B-Body width. I don't know if this will work for my application?

Posted By: brads70

Re: Fiberglass Springs any good? - 02/25/12 01:46 AM

Found this place that will custom make them for you? I have no idea of costs?
http://www.heathcotes.com/compositesprings.html

Posted By: brads70

Re: Fiberglass Springs any good? - 02/26/12 07:41 PM

Looking forward to the picture!

Posted By: dangina

Re: Fiberglass Springs any good? - 02/26/12 09:33 PM

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Looking forward to the picture!

sorry brad been up till 4am the last 2 nights prepping my car for the bodyshop - ill get a pic of the bracket for u today

Posted By: TC@HP2

Re: Fiberglass Springs any good? - 02/27/12 04:05 PM

he is a link to the Firm Feel units. I don't think they offer them with the inboard offset; http://www.firmfeel.com/leafhang_e.htm

This is the Mancini Mopar set up that is .8" per side, that is also set up for SS length front spring segments. http://chucker54.stores.yahoo.net/manofshacand2.html

There is also the Dr Diff offering for 1" offset for use with SS style spring segments. http://www.doctordiff.com/?page_id=41

If you planning on a Body rear with the inboard spring set, either Dr Diff or Mancini can supply the kit you need, even if you do use fiberglass springs. I believe Firm Feel can also, but you need to ask them as it may be an unadvertised unit that is not listed on their website.

Also, just so you know, most oval track spring suppliers who are offering the composite springs have lifted their design directly off the Direct Connection oval track spings developed in the mid 70s. The same typically holds true to any steel spring offerings they have as well. These springs have a 20.5" front segment at installed height and are not a true 20" set up like an SS springs. SS hangers will work with these, but will move the housing back half an inch. Not a huge amount, but to some, a noticeable distance.

Posted By: brads70

Re: Fiberglass Springs any good? - 02/28/12 04:17 AM

Thanks for the reply! Ya I knew DrDiff had them . I am going to go with a B-Body width rear end also.
What do you think about either spray on bedliner or rattle can rubberized undercoating to protect the composite springs from rocks etc...?
For my set up I was thinking the 175Lb rate? Hotchkis sway bars 1" t-bars, bilstein shocks....

Just thinking about the extra 1/2" .... if it was a issue ( which I doubt) one could fill in the holes and drill them 1/2" forward no?

Posted By: TC@HP2

Re: Fiberglass Springs any good? - 02/28/12 04:40 AM

I wouldn't worry about a half inch. You figure a longer, wider wheelbase contributes to more lateral holding power, albeit it minor, but what the heck.

I never thought about undercoating as a means to protect the spring. That is a good idea. It is semi-flexible, so that might be a good way to avoid the nicks that could lead to splintering without it cracking and flaking off. Sure would look better than wrapping them in duct tape.

The rate may be pretty decent. I don't recall if you have a rear sway bar or not, but if you don't you may not need to add one. If you do, you may want to experiment with disconnecting it. Not sure. I've never used fiberglass springs myself, but some of the oval track guys I've talked say you actually need to rate them higher than steel springs. I wouldn't know why, rate is rate, so maybe it is a old witch doctor's tale to confuse the competitors.

Posted By: dangina

Re: Fiberglass Springs any good? - 02/28/12 08:56 AM

Quote:

I wouldn't worry about a half inch. You figure a longer, wider wheelbase contributes to more lateral holding power, albeit it minor, but what the heck.

I never thought about undercoating as a means to protect the spring. That is a good idea. It is semi-flexible, so that might be a good way to avoid the nicks that could lead to splintering without it cracking and flaking off. Sure would look better than wrapping them in duct tape.

The rate may be pretty decent. I don't recall if you have a rear sway bar or not, but if you don't you may not need to add one. If you do, you may want to experiment with disconnecting it. Not sure. I've never used fiberglass springs myself, but some of the oval track guys I've talked say you actually need to rate them higher than steel springs. I wouldn't know why, rate is rate, so maybe it is a old witch doctor's tale to confuse the competitors.

What he said is true - Here is is a few answers I got from Richie Cox of Hypercoils as I was asking a few of the same questions when I was looking to buy them(sorry I mashed them all into one answer but you get at what I was asking him):

"We do make a Chrysler leaf spring in 225#. You may wish to check the dimensions of your leafs against our dimensions, since the 1971 B body�s differed slightly from model to model. The overall length from center of each eye is 53 7/8�, the center of front eye straight across to the center pin is 20.5�. Our leafs are all made to a 4.5� arch as well.They handle pretty well, as long as they are used in conjuction with a good shock. We have had several people use them and they all seem to like them for street use.Our leafs could be used, but you would have to slightly modify the mounting location on the front side, the rear mount should be close enough to work, but the front mounts would be about 1.5� too far forward. The bilstein shocks would work great with these leaf springs. Our Chrysler leafs were designed to work on the 64-70 b-bodys.The rear shackles should work ok, and the longer front shackles may help with the extra length of the springs. As for the bushings, they are 2 pc urethane, and the duct tape idea is for helping to keep damage to the leafs from rocks, etc hitting them, and any duct tape should work if you choose to use it.The leaf spring rate will as a rule of thumb be much lighter than the rate you would use for a coilover, mainly due to the fact that the leaf spring works over a much larger area. On most street stock dirt track cars, they use a 225-250# rate on the leaf springs, and they hold up really well. The ride will probably be softer with the leafs, than on coils, since the leaf has much more area to absorb the weight put on it. There may be slightly more �bounce� in the ride than a coilover, but the performance mixed with comfort is a pretty good balance."

I just fired off Richie about using the rubberized coating so I'll post his answer when he gets back to me - And here is the brackets as promised(couple days late) they are a full 1/4" thick from firm feel but not advertised on their site yet:

Posted By: brads70

Re: Fiberglass Springs any good? - 02/28/12 02:13 PM

They look nice! I wonder why they don't box them in at the top? That sure would take any flex out of them.

Posted By: brads70

Re: Fiberglass Springs any good? - 02/28/12 02:27 PM

Quote:

I wouldn't worry about a half inch. You figure a longer, wider wheelbase contributes to more lateral holding power, albeit it minor, but what the heck.

I never thought about undercoating as a means to protect the spring. That is a good idea. It is semi-flexible, so that might be a good way to avoid the nicks that could lead to splintering without it cracking and flaking off. Sure would look better than wrapping them in duct tape.

The rate may be pretty decent. I don't recall if you have a rear sway bar or not, but if you don't you may not need to add one. If you do, you may want to experiment with disconnecting it. Not sure. I've never used fiberglass springs myself, but some of the oval track guys I've talked say you actually need to rate them higher than steel springs. I wouldn't know why, rate is rate, so maybe it is a old witch doctor's tale to confuse the competitors.

Yep I have both front and rear Hotchkis sway bars. As mentioned B-Body's are slightly heavier so I figured the rear should be less too, that and Hotchkis advertises a 160Lb rate for e-bodies?

Posted By: dangina

Re: Fiberglass Springs any good? - 02/28/12 03:31 PM

Quote:

They look nice! I wonder why they don't box them in at the top? That sure would take any flex out of them.

I thought of that too - I may or may not still do this - I'll have to wait and drive with them first to see

Posted By: Rick_Ehrenberg

Re: Fiberglass Springs any good? - 02/28/12 03:53 PM

I've wanted to run these for years for the huge unsprung weight reduction, but durability testing at Chrysler (Chelsea PG) had ALL fiberglass / composite springs failing, and this was on an undriven rear axle (minivan).

If I could be convinced that something has changed / improved...

Rick

Posted By: patrick

Re: Fiberglass Springs any good? - 02/28/12 06:32 PM

Quote:

I've wanted to run these for years for the huge unsprung weight reduction, but durability testing at Chrysler (Chelsea PG) had ALL fiberglass / composite springs failing, and this was on an undriven rear axle (minivan).

If I could be convinced that something has changed / improved...

Rick

at what level of cycling did the failure occur? steel leaf springs are most likely designed to be infinite life items, if in the minivan testing, it failed at 500k or 700k cycles, well...it's not infinite, but it doesn't mean it wouldn't last a very long time in an application that gets driven 6 months and maybe 4k miles out of the year...

I'd definitely inspect regularly, but they have been proven in a street application over at GM in the vette (albeit loaded completely different fashion), and IIRC in the astro van (in a very similar fashion to our rear suspension configuration)...couple them with something like a cal-trac to take the wrap out of them, and maybe a panhard bar the lateral load out of them, and that would go a long way in their long term durability.

Posted By: autoxcuda

Re: Fiberglass Springs any good? - 02/28/12 06:55 PM

Quote:

I've wanted to run these for years for the huge unsprung weight reduction, but durability testing at Chrysler (Chelsea PG) had ALL fiberglass / composite springs failing, and this was on an undriven rear axle (minivan).

If I could be convinced that something has changed / improved...

Rick

wrack71 just found cracks in his Flex A Forms he bought a year ago. Don't know the milage on them. But Mitch Lelito has had them for years. So have others.

So...

Posted By: jcc

Re: Fiberglass Springs any good? - 02/28/12 07:09 PM

Quote:

They look nice! I wonder why they don't box them in at the top? That sure would take any flex out of them.

Like this?

Attached picture 7094715-IMG_2440hanger.jpg

Posted By: jcc

Re: Fiberglass Springs any good? - 02/28/12 07:21 PM

Quote:

I've wanted to run these for years for the huge unsprung weight reduction, but durability testing at Chrysler (Chelsea PG) had ALL fiberglass / composite springs failing, and this was on an undriven rear axle (minivan).

If I could be convinced that something has changed / improved...

Rick

So a vette application has zero axle wrap issues. This set pictured below is my second set from Flex a form about 7? years ago. They "looked" rather shoddy. My first set from Flex nearly 20 years ago looked pretty sweet. This second set failed after a few miles on a street driven 3300lb b body 273 4 speed with street tires and zero abuse. Flex replaced with no questions asked, but I posted earlier a pic of the "Chevy"? replacement spring. That spring on my own accord I radius-ed the edges, and painted a heavy coat of grey epoxy for protection. My third set of composite springs are hyperco's?, dark blue and looked well made, and will be likely my next supplier for any more sets.

Attached picture 7094730-DSCN1109-Cracked-Fiberglass.jpg

Posted By: brads70

Re: Fiberglass Springs any good? - 02/28/12 09:49 PM

So far the only one I would consider are from Hyperco.... I haven't seen a better design....yet?

Posted By: brads70

Re: Fiberglass Springs any good? - 02/28/12 09:52 PM

Quote:

Quote:

They look nice! I wonder why they don't box them in at the top? That sure would take any flex out of them.

Like this?

Looks good!

Posted By: dangina

Re: Fiberglass Springs any good? - 02/29/12 01:00 AM

here is the reply I got from richie today - the first answer I was asking him if my weight of 10 lbs was correct.

"The weight is correct, and yes, you can most definitely use undercoating on the springs. Anything will work as long as it doesn�t have any harsh acids."

Posted By: dangina

Re: Fiberglass Springs any good? - 02/29/12 01:03 AM

Quote:

Quote:

They look nice! I wonder why they don't box them in at the top? That sure would take any flex out of them.

Like this?

curious as to the hole in the middle - weight savings?

Posted By: jcc

Re: Fiberglass Springs any good? - 02/29/12 01:07 AM

yup

Posted By: brads70

Re: Fiberglass Springs any good? - 02/29/12 02:46 AM

I'm thinking I'll get mine coated with this to protect them from road debris? They have a location close to my house.
http://www.linex.com/pages/2010/bedliners/index.php

Posted By: dangina

Re: Fiberglass Springs any good? - 02/29/12 03:45 AM

i don't know if the high heat is good for leaf springs:

"here are two separate materials that are precisely dispensed through a high pressure, plural component internal mixing polyurethane spray machine. They are each heated to 120-140 degrees with the temperature maintained through a heated hose. Using high pressure, the materials are mixed internally at a 1:1 ratio at the tip of the spray gun. As the material is applied it takes less than 5 seconds for it to harden. As soon as LINE-X lands on the surface, it's dry!"

I was thinking cheaper more like this:

http://shop.advanceautoparts.com/webapp/..._T%7cGRP2050___

Posted By: brads70

Re: Fiberglass Springs any good? - 02/29/12 04:11 AM

Ya that was my second choice. 120 isen't that hot? On another forum a member suggested maybe that bedliner might not be such a great idea because you couldn't inspect for cracks? Good point.

Posted By: brads70

Re: Fiberglass Springs any good? - 03/03/12 10:22 PM

Quote:

Quote:

They look nice! I wonder why they don't box them in at the top? That sure would take any flex out of them.

Like this?

I was thinking of drilling another set of holes so I could also run the stock lenght e-body springs if I so choose down the road. Just in case the composite springs give me grief? I was thinking of boxing in the top to stiffen things up.

Posted By: jcc

Re: Fiberglass Springs any good? - 10/03/12 03:48 PM

In a reply above I mentioned fiberglass springs used in Semi truck applications. I recently came across the Peterbuilt flyer I referred to and thought I would share it for reference sake.

Posted By: jcc

Re: Fiberglass Springs any good? - 10/03/12 03:51 PM

In a reply above I referred to fiberglass springs in Semi truck applications. Below is the Peterbuilt flyer I referred to and thought to share it.

Attached picture 7405391-500img-B206-Fiberglass-spri.jpg

Attached picture 7405391-500img-B206-Fiberglass-spri.jpg

Posted By: Mopar Mitch

Re: Fiberglass Springs any good? - 10/03/12 06:49 PM

Those front/rear attachments look pretty strong! I recommend that after you know your rear corner weights of the car, you then determine the poundage so to further determine the free arch and compressed arch. You should consider about a 1" remaining arch after weight of the rear is compressing for best performance handling (near flat).

I've used FLEX-A-FORM mono-fibergalss leafs since the late 1980s and never experienced any fatigue problems (cracking, etc). The fglass springs do, however, take about 2-weeks to settle to the permanent arch (as per my experience)... so, you could add some extra weight to the car during its initial resting time after you install them.

Posted By: Dan@Hotchkis

Re: Fiberglass Springs any good? - 10/03/12 09:24 PM

While I've often considered fiberglass leafs on a race car for the obvious advantages, I'd hate to have them in a street car 1000 miles from home if they went bad.

Posted By: Skeptic

Re: Fiberglass Springs any good? - 10/04/12 12:03 AM

A lot of OE's use glass springs, they are not shattering and snapping all over the road. That being said, if you are pushing your car hard, you need to do more inspections to catch stuff before it fails. Common sense, but too rare.

Posted By: mopardamo

Re: Fiberglass Springs any good? - 10/04/12 04:19 AM

From my understanding of reading this thread. Those who had non-defective parts have experienced zero problems in the performance, OE passenger car and apparently heavy transport industries. To me it seems hard to not seriously consider fiberglass leafs. So what is there to give consideration to except getting a properly made product?

Damon

Posted By: dangina

Re: Fiberglass Springs any good? - 10/04/12 07:29 AM

seeing how alot of us never drive our cars in the fall or winter conditions, even less chance of failure i would assume - those semi truck ones are some impressive springs!

Posted By: brads70

Re: Fiberglass Springs any good? - 10/04/12 12:44 PM

I got mine installed about a month ago. I find they do react noticably quicker than the stock steel springs.
I used spring hangers from DrDiff, had to weld up the hole and move it forward 1/2" as the Hyperco front segment is 20 1/2" and added a gusset plate to the top. I got the 175lb rate , wish I had got the 200lb rate .

I had to machine up some spacers so it fit in the hanger .

Also machined a spacer for the location pin

Posted By: Mopar Mitch

Re: Fiberglass Springs any good? - 10/04/12 03:45 PM

The main reason I elected to give the fiberglass leafs a try, back in the lat 1980s, was primarily for reduced weight -- remember, I was in serious SCCA Solo II/autocross competition. Reducing the weight here, there, everywhere "legal", was a main goal for continuos performance improvement. Flex-a-Form was helpful in my discussion with them to determine the puonds/inch and the arch, but they needed to know the rear corner weights of the car (left-rear, right rear), with my driving intentions (95% solo II/autocross, 5% street... back then) to make a best conclusion. So, although I've only tried the one size (5" arch with 225 pounds/inch), I'd be curious if a little stiffer would be better. I know that below 200# and less would have resulted in increasing the free arch to achiveiheve a near flat compressed arch, but I took what they suggested and eventually played with the adjustable red KONI shocks to find an acceptable performance ride in the autocrossing. Overall, I'd say that I've been satisfied with the results, even for increased street driving that I've been doing in the recent years. I do remember that they supplied rubber front bushings, and it was a hassle getting that material out, and that I had to slightly decrease the OD of the urethane bushings to make those fit into the front eye of the new leafs... the rear was no problem for urethane. Also, I know that some other SCCA national solo/autocross racers were running the fglass leafs on their Camaros, FBirds and Mustangs... all with about the same 225 pounds, a couple were a little stiffer... then, some of the C/Prepared pony cars (all-out race) were stiffer up to ~300.. little free arch and still flat.

Posted By: brads70

Re: Fiberglass Springs any good? - 01/25/13 05:33 AM

Ok so I just bought another set of Hyperco composite leafs but this time at 225# rate. I get them home and compare them to the 175# that's still on the car. I measured with a vernier and they measure exactly the same as the 175# rate? Great!

So now I'm thinking they have screwed up and put the wrong decal on them so I phone Hyperco and explain what I found. They quickly replied yes all the spring rates will measure the same, the rate comes from the different composite material? And that they are marked in case the decal comes off with a coloured square that's molded in. So I double checked that and yes the 175# has a green square and the 225# has a blue square.
Anyone else run into this? I'm not quite sure I belive Hyperco yet?

When I get one off the car I'll turn it over arc up and stand on them, measure and compare? Anyone have any other idea's/experiances?

Posted By: Mopar Mitch

Re: Fiberglass Springs any good? - 01/25/13 06:24 AM

Brad... maybe the eventual settling of them will make the difference.. I recall that my flex-a-form leafs needed about 1-2 full weeks to settle to the flatness they still remain at today (and i installed mine ~1987). Did you tell them how much compressed arch you wanted? did you tell them thje weight of the rear? did they ask those questions? Flex-a-form had specifically asked me those questions.

Attached picture 7560571-Mitch'sChallenger-30.jpg

Attached picture 7560571-Mitch'sChallenger-30.jpg

Posted By: dangina

Re: Fiberglass Springs any good? - 01/25/13 08:25 AM

Quote:

Ok so I just bought another set of Hyperco composite leafs but this time at 225# rate. I get them home and compare them to the 175# that's still on the car. I measured with a vernier and they measure exactly the same as the 175# rate? Great! So now I'm thinking they have screwed up and put the wrong decal on them so I phone Hyperco and explain what I found. They quickly replied yes all the spring rates will measure the same, the rate comes from the different composite material? And that they are marked in case the decal comes off with a coloured square that's molded in. So I double checked that and yes the 175# has a green square and the 225# has a blue square.
Anyone else run into this? I'm not quite sure I belive Hyperco yet? When I get one off the car I'll turn it over arc up and stand on them, measure and compare? Anyone have any other idea's/experiances?

is the square under the decal? I have the 200# rate and am curious now and would like to find out

Posted By: brads70

Re: Fiberglass Springs any good? - 01/25/13 01:10 PM

Quote:

Brad... maybe the eventual settling of them will make the difference.. I recall that my flex-a-form leafs needed about 1-2 full weeks to settle to the flatness they still remain at today (and i installed mine ~1987). Did you tell them how much compressed arch you wanted? did you tell them thje weight of the rear? did they ask those questions? Flex-a-form had specifically asked me those questions.

No Mitch , I just picked the part number from the cataloge and ordered them.

Posted By: brads70

Re: Fiberglass Springs any good? - 01/25/13 01:14 PM

Quote:

Quote:

Ok so I just bought another set of Hyperco composite leafs but this time at 225# rate. I get them home and compare them to the 175# that's still on the car. I measured with a vernier and they measure exactly the same as the 175# rate? Great! So now I'm thinking they have screwed up and put the wrong decal on them so I phone Hyperco and explain what I found. They quickly replied yes all the spring rates will measure the same, the rate comes from the different composite material? And that they are marked in case the decal comes off with a coloured square that's molded in. So I double checked that and yes the 175# has a green square and the 225# has a blue square.
Anyone else run into this? I'm not quite sure I belive Hyperco yet? When I get one off the car I'll turn it over arc up and stand on them, measure and compare? Anyone have any other idea's/experiances?

is the square under the decal? I have the 200# rate and am curious now and would like to find out

It's on the front segment, facing down about 9" back from the eye

Posted By: prrc

Re: Fiberglass Springs any good? - 01/27/13 06:21 PM

I just bought that second set from Eric. Hmm hope I didn't make a mistake. After reading all the input on this subject I wonder why they work for some and pretty much not at all for others. Also why would the car get loose on a road course setting with this type of spring?

Quote:

Quote:

I've wanted to run these for years for the huge unsprung weight reduction, but durability testing at Chrysler (Chelsea PG) had ALL fiberglass / composite springs failing, and this was on an undriven rear axle (minivan).

If I could be convinced that something has changed / improved...

Rick

wrack71 just found cracks in his Flex A Forms he bought a year ago. Don't know the milage on them. But Mitch Lelito has had them for years. So have others.

So...

Posted By: Mopar Mitch

Re: Fiberglass Springs any good? - 01/29/13 10:06 PM

Just so you know, I have always inspected my flex-a-form leafs for any possible fatigue/cracks, etc. The ONLY thing I've ever had to do is re-tighten the front spring-eye bolt, having installed urethane bushings (front and rear). When I originally had discussion with Flex-a-form about the durability of the fiberglass mono-leafs, they did tell me, then (late 1980s) that off-road dirt track cars were running their leafs w/o any problems. I've trailered the car for many years (~late 80s thru early 2000s), but raced it hard when on a track (mostly med-speed pylon autocross, and some hi-speed road course events)... and in the past ~3 years I've been driving it (easy/enjoyment!) on the roads/hwys and still no problems. IF you want weight reduction... consider the fiberglass mono-leafs, but i encourage the right choice/selection/design for your car's weight and your primary driving intentions.

Fiberglass Springs any good?