Composite mono-leaf w/ watts VS 4-link (DSE or similar)
 

Something says to just go with a 4-link but I was wondering if a composite mono-leaf with Watts link would be a viable choice.

I can do Hypercoil composite springs, Delrin bushings, Watts link and the same Koni shocks that DSE sells in their kit for virtually the same price.

I know it's hard to beat a 4 link and I'm probably just thinking too much. I am not a suspension engineer by any means, so maybe someone else can tell me hell no, or it's a real good idea.

Vehicle is a 71 Nova. It would have a 275 tire in front and a 315 tire in rear. Mostly street driven, but it would see our local road race course more than a few times a year.
What do you think about the idea?

What is the intended purpose of the car?

Personally, I'm using composite mono's. Many road racers can't say enough about them. However, I'm not sure if Nova's have the same rear leaf geometry as Camaros. If they do, it's pretty tough to top a well thought out leaf setup.

But, any link style suspension will offer adjustability that would otherwise be difficult to obtain with leafs.

As far as the watts goes, there's several schools of thought on that one:
1. Hyperco recommends a lateral locator with their composite springs, while other manufacturers say it's not needed. Personal experience of most people seems to all say it isn't needed either.
2. Defining a roll center may or not be necessary...only you can determine that for your vehicle.

I'm going to try it without a panhard/watts first, and go from there. Good luck!

Do they make a composite leaf spring for the camaro?

Yep, both Hyperco and Flex-a-Form makes them. Roughly $400-500 for a pair. I've got a set of 200lb Hyperco springs.

The kicker: they're about 10lbs each!

The low weight - mostly unsprung weight - and lack of static friction between leaves make these look very attractive on paper.

Do you know the stiffness (modulus of elasticity) of composite vs. steel? Given that the spring width will be the same, if the modulus of elasticity was much lower than steel you would get more lateral deflection and maybe want a lateral location device. If stiffness is close to the same, then I don't see why they'd need lateral location aids any more than steel leaves ...

Out of curiosity, I just weighed my newly delivered QuadraLink setup. Complete weight in the packaging, with everything except axle brackets, was 89 lb. Subtract maybe 10lbs for packaging, you're at about 80, with about 40 lb of that partially sprung. That seems to me about the total weight of a pair of steel multi-leafs, shackles, and shocks, but less unsprung weight. And obviously, more than a pair of composite leafs with shackles and shocks.

Coils and shocks: 13 lb.
Control arm and panhard mounts: 16 lb.
Control arms and panhard bar: 31 lb.
Shock/coilover crossmember: 29 lb.

I've tried to get some E numbers with limited sucess.

What I have found out that these tend to have more torsional stiffness than a comparable leaf spring, so consider that when calculating anti-roll bar diameters. On the other hand, lateral control of the axle is less than steel...but there's more to it than that.

First, in my case, I'm going from a spring with a 6" arch to 4.5". Reducing the arch shortens the moment arm that acts against the spring...causing it to twist and therefore lateral axle movement. Second, first gen Camaros have pretty good leaf geometry (tapered in front) which again increases lateral stiffness. If the geometry weren't as it is, I'd probably have to add a panhard for sure.

Back to the modulus question. Steel is easy, we all know that one. But, for the composite, it's way more complicated and I couldn't just compare the two numbers. The E in one direction (bending) may not be the same in another (lateral), depeding on the layout of the matrix material. Sheesh, I wont even try to compare two different brands of composite springs if the binders and fibers are different. Ah, aren't composites fun?

In the end: I'll just have to run them to find out and add roll stiffness (or remove) to suit...then I can make a comparative analysis between steel and "other" leaf springs. If I need to had a lateral locator, no big deal. So far, others haven't needed to. Should be interesting.

This is interesting.

So that works to about 30lbs of unsprung weight, and add another:
38lbs (roughly) - Ford 9" axle housing
18lbs (roughly) - Axles
71lbs - Limited slip diff
45lbs - Aftermarket discs

Equals about 200lbs of unsprung weight, which isn't bad. Obviously I'm not including 100lbs for tires, wheels, hardware, roll bar, etc. But this should be good to compare.

For a composite leaf:
172lbs -Axle housing (same as before)
4lbs - Spring bads
3lbs - Shackles
10lbs - Springs (half of total spring weight, some controversy here)

Total of 189lbs. So, we save about 11lbs of unsprung weight. Not a whole lot, and personally, if cost weren't an issue, I'd trade this weight for the adjustablility of a link suspension (I think). We'll see when the car is pushed to the limits.

Is there a website for these? I would also like to know the lateral deflection as well, good point by PTAddict.

http://www.hypercoils.com/Products/H...f-Springs.aspx

You won't get a specific "lateral movement" number, but they usually say a locator usually isn't needed for the street, but may be needed for sticky tires on the track.

They don't make these for the first gen camaros. :(

Well, the Q-link out of the box is adjustable only for ride height, although it would appear to be very simple to drill the front UCA mounting pockets for some SVSA adjustability. But then, I suspect you'd use a different brand of multi-link rear anyway :)

Where are you going to track your car? I'm based in Portland, and plan to hit 2-3 HPDEs at PIR, plus at least one in Seattle, this summer.

I have a set. Check their catalog on the website, it's at the bottom of the page for composite springs.

Really? I just called them and they said they have them for the second gens, not the first gen.

I have a set of 200LB Vette Brakes and Products composites on one of my unfinished 69 projects. I ran a set on my 80 Z28 with a transveres fiberglass leaf up front, and composite 200s out back.

I did a story on the 69 install and had the facts then, but that was 10 years ago. I will look for the story and see what I can find. I never finished the car, so i do not have any real world testing on the 69s, but I did like the 80 rear a lot.

I will probably sell these and put a G bar or Air Bar in it if I ever finish it.

Oh my God how time flys. I just found the story, not quite 10 years ago. I wrote the story more like 16 years ago! So composite springs for 1st gen Camaros have been around a while. But I never heard much about them.

It is pretty funny to read that old stuff. We were building a killer Camaro. Using polyurethane bushing and everything! We were even changing the subframe bushings! Wow how times have changed.

souds like you a pioneer back then and you are a pioneer today I salute you Sir:cheers:

Mee too Frank :cheers:

Do you know the differences between the first gen and second gen springs? I never really cared to find out. BUT, I've noticed that many replacement leaf springs are sold for years '67-'81. As long as the wheelbase remains nearly correct, as well as the shackle angle, I'm happy!

I hope, I Hope, I really hope this summer if I get the bugs worked out of the car fast enough. Haven't been to PR in a while.

Dimension wise 67-69 and 70-81 Camaro leaf springs are identical. The only difference is the 2nd gen normally uses a little stiffer spring rate. I just called Global west to confirm.

According to Global West, 67-69 and 70-73 use the same spring and 74-81 uses a little stiffer rate.

Hotchkis has one rate for the 67-69 and another rate for 70-81.

Matt, hopefully you get yours done soon. You can be the guinnea pig. LOL.

That's OK with me. If I bust a spring I'm sure I'll let you know!

Seriously, I've heard such good things about them I'm pretty excited.

Let me know how they work. I’m interested in those as well.

Me too. Is your car together what is the ride height for these springs? Got a measurement?

The car us up on jackstands at the moment, but the free arch is the same as Hotchkis...but keep in mind the spring rate is higher. Hotchkis springs vary from 160 to 180 lbs/in.

Thanks Matt. What is the free arch? Please lemme know installed height when you know.

Free arch is 4.5". Stock is usually 6 to 6.5".

BTW, the springs weigh 10.6lbs each.

I've been using the FAF springs for a while now. However, the as-supplied bushings were replaced with spherical bushings.

I also looked at the Hyperco, and liked the spring, but was disappointed at the spring eye. It was stamped steel and split horizontally at the end. The FAF's are a beefy aluminum extrusion.

Overall I like them. On the track there is more lateral deflection. If the car is max turning and hits a really hard bump the inside of the loaded tire will occasionally touch the inner fenderwell.

I too have thought about a locating device, but am hesitant to add complexity. If there was something that was easy to install and try I'd do it. Putting in a delrin bushing and creating a fixed spring end would also help.

There's some info on my website. http://www.geocities.com/casanoc

Carl,
What is your rear ride height with the composite springs? Did ride quality improve?

Distance from the center of the wheel to the top of the wheelwell opening is 14-1/4. This is with the spring eyes in the higher ride height position. They can be flipped to allow for another 3/4" drop.

The ride on my friends and my car is much better than the previous setups (his Hotchkis, mine Guldstrand.) I would like to do more shock tuning to get it really sorted out.

Steve, the distance from the wheel center to wheel arch is about 13-3/8" to 13-1/2" on mine. This puts the tire (275/40-18) slightly tucked into the fender.

Matt-

Enough already. Post pictures of your ride; I demand pictures!!!!!

Tyler

Heh, alright alright, I'll post some. Keep in mind the car isn't anything special. It's a driver, so it's got chips and scratches. To me, brake dust and a couple dozen rock chips looks pretty cool on cars like these. The quality certainly is not like Art or Craig's masterpieces.

Maybe Friday I can get some up.

Friday is almost over Matt.....

Tyler

Sorry for being late...check out the Open Discussion forum for photos!