Leaf spring suspension

DailyDriverSst · 07-14-2018, 05:44 PM

(Posting here because leafs are more common)

Looking for some tricks and tips for leaf spring setups. Calvert says to run a 200 pound split mono, but I've read that split mono's aren't great on the street AND i saw that Steve Dzoirny had one break in his trailer on the way to Joliet.I'm not fond on the design anyways.

My factory leaf spring rate is 130 pounds. Something that was brought to my attention is that some people run very soft coil-overs to add spring rate to the leafs, IE 130 leaf rate + 70 pound coil spring, or take a leaf out of the pack so it's 100+100.

I've already cut the bandings off the back side of the leaf and added the extra front clamps. Is there anything else I'm missing?

What is the "magic function" on rear leaf spring rates - I know how spring rates affect alot of things on a ladder bar and 4 link cars, but I'm new to this whole leaf spring deal.

With a coil, the rate and length is a function of available travel and weight jacking. But since leaf's do not have much for vertical travel and weight jacking is primarily achieved through the anti-roll, I'm not sure I 100% understand the physics of a 130# spring versus a 200# spring.

-----

Maybe something else to consider is that I'll be running super street, 7.0 index, and general bracket racing with a race weight of about 4400-4500 pounds. I'll be leaving on the stop (albeit only on stop for 1/2-3/4 sec) for SST and brackets, 7.0 doesn't allow stops so that's the only time I'll be leaving hard (and even then I can use the MSD timing table to soften the hit).

As a result, main focus would be to cut a decent mechanical reaction time and have downtrack stability. Even with the procharger, I'll be able to control how the boost loads the chassis and comes in through the throttle stop release speed adjustment and MSD and shock settings. I just need some guidance.

ss3011 · 07-14-2018, 10:06 PM

On a 4 link or ladder bar car , you want to run floaters on the spring perches . This allows the rear end to float on the springs , the springs only suspend the car and do not transfer any forward motion to the car . I weight jack by installing different thickness blocks between the spring and the rear end .

DailyDriverSst · 07-14-2018, 10:17 PM

I plan to just run a set of CalTrac's and that's it...have no intention of adding any longitundinal links or anything.

I'm just not sure if I want to use the factory triple leafs @ 130 pounds, go to a stiffer leaf spring, use coil-overs to add spring rate, remove a leaf and add in coil-overs....the only thing I know for sure is that I'll be putting an anti-roll on it using the same crossmember that I'll be welding in for the shock mounts.

Calculator I used - https://www.suspensionmaxx.com/tech-...ng-calculator/

On mine, I have
2.5" wide x 1 Leaf x 56" long x .25" thick = 19.38 lb/in
2.5" wide x 1 leaf x 45" long x .25" thick = 37.35 lb/in
2.5" wide x 1 leaf x 36" long x .25" thick = 72.96 lb/in

Total = 129.69 lb/in, or basically 130 lb/in

DailyDriverSst · 07-14-2018, 10:36 PM

I just don't understand exactly the physics that goes into picking a leaf spring rate...I know a couple people running mid-11's/mid-7's on the stock 130' leaf pack and caltracs and nothing else. But if there's room for improvement or extra adjustability, I'd rather be able to factor that into the chassis modification when i add the ARB and shock mounts instead of putting it together, trying to run 10.50's, and finding out that I need to add/change a bunch of things.

Larry Hill · 07-15-2018, 07:50 AM

Launcher Springs work and Gregg is always helpful. Or find someone with the same type car and copy it.

340Cuda · 07-15-2018, 10:42 AM

I my son has Caltracs on his car, he feels there are no issues on driving it the street. He has taken it on five drag weeks with no issues. I think he could always run a 10.90 even in the heat.

Other than your report I have never heard of a CalTracs failure although as many as are out there there must be more. I think most folks would say its a very robust product.

I would tell Calvert exactly what I planned for the car and follow their recommendations.

This is not to say some of the other combinations won't work.

In my opinion if you don't at least put frame connectors in it at sometime in the future you will have trouble closing the doors.

Good luck with your project.

Bill

07-14-2018, 05:44 PM	#1
DailyDriverSst Junior Member Join Date: Dec 2017 Posts: 53 Likes: 0 Liked 4 Times in 4 Posts	Leaf spring suspension (Posting here because leafs are more common) Looking for some tricks and tips for leaf spring setups. Calvert says to run a 200 pound split mono, but I've read that split mono's aren't great on the street AND i saw that Steve Dzoirny had one break in his trailer on the way to Joliet.I'm not fond on the design anyways. My factory leaf spring rate is 130 pounds. Something that was brought to my attention is that some people run very soft coil-overs to add spring rate to the leafs, IE 130 leaf rate + 70 pound coil spring, or take a leaf out of the pack so it's 100+100. I've already cut the bandings off the back side of the leaf and added the extra front clamps. Is there anything else I'm missing? What is the "magic function" on rear leaf spring rates - I know how spring rates affect alot of things on a ladder bar and 4 link cars, but I'm new to this whole leaf spring deal. With a coil, the rate and length is a function of available travel and weight jacking. But since leaf's do not have much for vertical travel and weight jacking is primarily achieved through the anti-roll, I'm not sure I 100% understand the physics of a 130# spring versus a 200# spring. ----- Maybe something else to consider is that I'll be running super street, 7.0 index, and general bracket racing with a race weight of about 4400-4500 pounds. I'll be leaving on the stop (albeit only on stop for 1/2-3/4 sec) for SST and brackets, 7.0 doesn't allow stops so that's the only time I'll be leaving hard (and even then I can use the MSD timing table to soften the hit). As a result, main focus would be to cut a decent mechanical reaction time and have downtrack stability. Even with the procharger, I'll be able to control how the boost loads the chassis and comes in through the throttle stop release speed adjustment and MSD and shock settings. I just need some guidance. Last edited by DailyDriverSst; 07-14-2018 at 06:12 PM.

07-14-2018, 10:06 PM	#2
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 892 Likes: 65 Liked 229 Times in 107 Posts	Re: Leaf spring suspension On a 4 link or ladder bar car , you want to run floaters on the spring perches . This allows the rear end to float on the springs , the springs only suspend the car and do not transfer any forward motion to the car . I weight jack by installing different thickness blocks between the spring and the rear end .

07-14-2018, 10:17 PM	#3
DailyDriverSst Junior Member Join Date: Dec 2017 Posts: 53 Likes: 0 Liked 4 Times in 4 Posts	Re: Leaf spring suspension I plan to just run a set of CalTrac's and that's it...have no intention of adding any longitundinal links or anything. I'm just not sure if I want to use the factory triple leafs @ 130 pounds, go to a stiffer leaf spring, use coil-overs to add spring rate, remove a leaf and add in coil-overs....the only thing I know for sure is that I'll be putting an anti-roll on it using the same crossmember that I'll be welding in for the shock mounts. Calculator I used - https://www.suspensionmaxx.com/tech-...ng-calculator/ On mine, I have 2.5" wide x 1 Leaf x 56" long x .25" thick = 19.38 lb/in 2.5" wide x 1 leaf x 45" long x .25" thick = 37.35 lb/in 2.5" wide x 1 leaf x 36" long x .25" thick = 72.96 lb/in Total = 129.69 lb/in, or basically 130 lb/in Last edited by DailyDriverSst; 07-14-2018 at 10:27 PM.

07-14-2018, 10:36 PM	#4
DailyDriverSst Junior Member Join Date: Dec 2017 Posts: 53 Likes: 0 Liked 4 Times in 4 Posts	Re: Leaf spring suspension I just don't understand exactly the physics that goes into picking a leaf spring rate...I know a couple people running mid-11's/mid-7's on the stock 130' leaf pack and caltracs and nothing else. But if there's room for improvement or extra adjustability, I'd rather be able to factor that into the chassis modification when i add the ARB and shock mounts instead of putting it together, trying to run 10.50's, and finding out that I need to add/change a bunch of things.

07-15-2018, 07:50 AM	#5
Larry Hill Live Reporter Join Date: Oct 2004 Location: Hickory, Ky Posts: 10,320 Likes: 1,675 Liked 9,582 Times in 1,990 Posts	Re: Leaf spring suspension Launcher Springs work and Gregg is always helpful. Or find someone with the same type car and copy it. __________________ IHM Used Parts https://ihmusedparts.com 888-821-1817

07-15-2018, 10:42 AM	#6
340Cuda VIP Member Join Date: Apr 2003 Location: Tulsa, Oklahoma Posts: 1,576 Likes: 3,297 Liked 685 Times in 293 Posts	Re: Leaf spring suspension I my son has Caltracs on his car, he feels there are no issues on driving it the street. He has taken it on five drag weeks with no issues. I think he could always run a 10.90 even in the heat. Other than your report I have never heard of a CalTracs failure although as many as are out there there must be more. I think most folks would say its a very robust product. I would tell Calvert exactly what I planned for the car and follow their recommendations. This is not to say some of the other combinations won't work. In my opinion if you don't at least put frame connectors in it at sometime in the future you will have trouble closing the doors. Good luck with your project. Bill