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.

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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.

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 .

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

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.

Re: Leaf spring suspension
 

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

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

Re: Leaf spring suspension
 

Hi Bill,

Does he have the split mono's with his caltracs?

I'll be putting 1000-1500 miles on mine a year, plus local bracket and 7.0 racing, True Street no/lo-prep, and possibly some drag week or similar.

It's a truck platform, full frame rail. Body issues shouldn't exist...hopefully.

Not sureif this will show, it's what Dziorny posted when he got to Joliet this weekend.

https://scontent-dfw5-1.xx.fbcdn.net...9f&oe=5BDC9CD7

Re: Leaf spring suspension
 

Wow, never seen or heard of one doing that, can't say that anymore.

Yes my son does run the split mono. For years he ran the Calvert/Rancho shocks but he recently switched to the dual adjustable Vikings and likes them.

While we trailer his car there. the route he drives on Drag Week is always over 1,000 miles.

He also drives it to the track, occasionally to work on nice days and to car shows. Probably another 1,500 miles or so.

I forget some vehicles have real frames!

Bill

Re: Leaf spring suspension
 

Daily Driver Sst. I run a 3700 lb 67 Camaro with a 496 pump gas John Lingenfelter engine. It runs 10.50's @ 127 mph. It's still a street driven car with full interior and working lights and such. It has Caltrac bars, Afco shocks, (which are a must with the bars). I installed Caltrac split mono leaf springs and did see a big difference. But, the biggest gain in 60 ft. times was when I installed a set of Mickey Thompson Pro Drag Radials. 60 ft times went from high 1.40s - low 1.50s, all the way down to mid to high 1.30s. The Calvert springs and bars put a HUGE down force on the tires this is why the Afco shocks are so important. I used to run Competition Engineering shocks, but there is no way they can overcome the body separation of the down force caused by the Caltrac bars. Coming of the trans-brake @ 3,000 RPM, the car used to flatten the tire to the point that it was wearing off the side wall writing of the tires, then obviously it would spin, then hook hard again, folding the tire, spin, then hook and take off. the only way I found this out, was by video taping the launch, and playing it back frame by frame in slow motion. The tires completely stopped all that from happening. Best thing I've ever done to the car. Now the cars carries the front wheels about 2 feet high till just passed the tree. I am very satisfied with John Calverts products. I did notice in the picture that you tie the car down using the frame. In theory, this is the correct way the not wear out the suspension during transport. But, keep in mind that you have a very heavy 4500 lb car. you may want to try tying it down at the rear axle instead, and stiffen the shocks during transport mode. It may be putting too much pressure on the springs during transport tying it down from the frame. Just my 2 cents. Hope this helps.
Lugnut

Re: Leaf spring suspension
 

Hi Lugnut,

Thanks for the info! That's not my photo, that's from Steve Dziony (same platform I have). Definitely going with double adjustables on each end, the front are stock mount so my only limitation is dimensionally correct shocks for the front. I'm adding a crossmember for the ARB and rear shocks, so I'll have regular mounts and a decent set of options for the back.

So you are finding that in your application, there is enough vertical separation available in the spring to give full droop to fully plant the tires? This was my main concern when talking to the tech at Calvert - they have a split mono profile for my application, but since they use spring arch to set ride height independent of spring rate, this is where my knowledge runs out. I'm use to using spring rate as a component of ride height in coil applications, and thought that it would at least factor in for my application given the obesity of the truck.

The problem I'm running into is that most of the setups on the platform I'm using are N/A, regular cab, and completely stripped out of all HVAC and anything else not required by stock/Sstk interior rules. I'm working with a power adder, extended cab, and fully functional interior. I'm 5-600 pounds heavier than most, and about 400 pounds over the next closest combination I can leach notes form.

This is exactly what I needed to know - I was planning to run the MT 3062S (29.5 x true 10.5 x 15) but given my weight, I wasn't sure even a stiff wall and 12 PSI would be enough to hold up. I've read some people have issues with the PBR tires on lackluster prep tracks, but every situation is different.