Are composite leaf springs worth it on a street ride?

[ashford]

the early g-body(lumina, cutlass supreme,etc) gms had a single composite spring in the rear

 

[66bluepony]

Springs

I fitted a set of Flex-a-Form composite leaf springs to my 66 Fastback last January. At the same time, I also fitted a new 3.55 ring and pinion, a new Currie Limited Slip Diff and a new Currie Aluminum Third Member, and a new aluminum driveshaft, a new set of Koni shocks, and a new set of heavy duty rear shackles with delalum bushings... Obviously a lot of stuff changed in one fell swoop, but I can honestly say that the difference in handling in the rear end is breathtaking. The leafs are so light that the rear axle assembly lost almost 120 pounds in unsprung weight. The handling improved out of sight. Pliable, and ultra smooth yet wonderfully predictable and stiff when needed.

My best investment yet, suspension wise. I also own a Lexus ES300 with a nice IRS and the Mustang is probably 90% as stable (in the rear) I would venture to say. I have a few local undulations and bumps around my local streets that I use to do these sort of comparisons - and those composite leafs really are that good.

What specs did you ask for in spring weight as far as supporting the rear of car.

 

[Edbert]

I'd say 200-225 depending on your preference for stiffness and the type of rear end you have, maybe even 250 for a road racer with a 9. At least that is for conventional steel springs...I assume they would work the same way in that regard.

 

[66bluepony]

Weight

I have been told that 225 lbs have a lot of bounce. That is why I was asking what Boo Boo Foo used. But I think that Edbert is in the ballpark.

 

[brianj5600]

What is the ride height like for them? Are the eyes bonded, or just bolted? I am wondering if eyes can be easily changed or flipped for ride height adjustments.

 

[70vert]

wait, do you mean slider mounts?

You like those springs, wait until you find out what raoller perches are.

roller perches are for front suspension, are you thinking about slider mounts for the rear a la what is sold by Cobra Automotive?

 

[70vert]

thread on corner-carvers

Hey all,
Check out this thread on corner-carvers.com:

http://www.corner-carvers.com/

and just type in "composite leaf springs" in the search and you'll find it. Boo Boo is there, and it's good reading - too much to summarize. I am now seriously thinking about these and a Maier panhard down the road.

 

[10secgoal]

roller perches are for front suspension, are you thinking about slider mounts for the rear a la what is sold by Cobra Automotive?

I know the roller perches are for the front. That's what I mean. Those change the ride of the car some much it's unreal. I don't know how much a composite can change the ride, but it seems hard to beat freeing up the ENTIRE front end.

 

[Taranis]

Does anybody know what happened to flex a form?
I tried www.flex-a-form.com and the domain name expired...

 

[atomicpunk]

I guess they goofed and lost the domain. They're still around, I just received a set of leafs from them a couple of weeks ago.

I have their number as 864-261-7006

 

[Taranis]

Sweet. Thanks for the info.

 

[Tubo(2-bo)]

I understand, though only from articles I've read, that the composite springs have no wrap up, and traction bars are not needed. So there's a little more weight saved. I had the impression about 80lb. was saved using composits, and wondered if the loss of weight in the rear of the car would have a negative effect on handling & traction.
If your building from scratch, the money saved on traction bars could be rolled into the cost of the composite springs.

 

[SNAKEPILOT]

Boo Boo Foo,
Did you use Global West Delalum bushings in your Flex-a-forms? Is the bushing diameter the same as the original leafs?

 

[atomicpunk]

Someone posted elsewhere that GW recommended against using their bushings in composite springs.

I went with Mustang Depot's Prothane HD shackle kit instead. The Flex-A-Forms had bushings that were the same as the original diameter. In my case, they reversed them front and rear, and the instructions said "do not remove the bushings". However, they finally got back to me and in his usual cryptic 3 word emails, George indicated swapping them wasn't an issue, but couldn't clarify why they said not to remove them.

 

[rbohm]

http://flex-a-form.com/Default.asp