I scored an 8 3/4 at Monster Mopar so I'm finally ready to tackle the rear suspension on my 68 dart.

Just a mild 340 - hoping for a 12 second street / strip car that I can drive to work whenever.

The current rear springs are shot and flat as a board.

I was thinking about the caltrac setup but not sure how they work on the street also dont want it to sit like a monster truck.

I've never played with leaf springs before so if anyone could share a setup so I know what parts to look for at the Nats next weekend.

Cal Tracs seem to be what all the cool kids are using in the leaf spring world.
I had S/S leafs and it rode like a buck board and hiked the tail up pretty good.
I went with Cal tracs , but haven't had them rolling quite yet.
They do not raise the back of the car , and can be ordered - 1 " ride height.
Not cheap , but they sure seem to work for others , so I am optimistic.

To be honest I'd start with the stock springs, the correct pinion angle and a good pair of adjustable shocks for a 12 second a body

Cal tracs and mono's are the best thing since sliced bread......They are light, they are efficient, and they are effective and consistent. With a big block car, they are a must. A small block can get away without, but it will also benefit from them....I have them on my Cuda with a 605 Hemi, and they are awesome...

What you want is the best axle control with the lightest possible spring rate.
An SS spring set will put your head into the roof if you drive over a gum wrapper.

The Calvert setup seems to be on every leaf-spring car in Stock and obviously works.
For the 12s, there are hundreds of guys running stock or SS springs, in fact into the 10s.
You can put a SB A-body drag car on its rear bumper with an SS setup & roundabout 640 HP, done it.
The Calvert setup is more consistent and adjustable, though, and apparently bulletproof.
As for the ride, I haven't experienced any issues with the 002/003, was fine in my BB street/strip Duster.
They don't really have that much spring rate. But if you add leaves, they definitely stiffen up.

If you are doing much street driving the Competiton Engineering Slid-A-Links are a far better bar. In fact I'd take them over the CalTracks any time.

If you want the best bar, the Asassin bars have the most adjustability. Not sure how they ride though.

Whats the real world difference between the two springs below? Ride height, firmness?

Mopar Performance Competition Leaf Springs P3412002 3200 lbs
Mopar Performance Competition Leaf Springs P4120863 2800 ibs

My Cal tracs ride on the street isn't bad I'm using their rancho shocks turned to about 5 on the settings and it's comfortable

I've had good luck running super stock springs running anywhere from low 11's to mid to high 11's on my dedicated street/sportsman car. I've had a 360 and a 440 in the car at one time and it worked well with each. Comp Eng 90/10 shocks up front and just generic shock in the back. Car does have a 11.5 wide slick on it though with only a 1.52 60 ft. For a 12 sec street/strip car I would just use leaf springs and get a decent shock. I don't think you need to go with all the extra expense of Cal Tracs unless you really plan on to put alot more power to the car down the road..

On your deal I would buy and use the Mopar 3400 Lbs. automatic springs, they will work good for you along with a good set of 50/50 rear shocks

Ran 9’s forever with 002/003 leafs( and was ultra consistent) and the car drove like a Cadillac on the street. Zero issues with a “ rough” ride.
For a 12 sec car i would get some adjustable shocks and go have fun. No need to reinvent the wheel at that power level, and use the springs you already have

Sounds like I'll order some new springs so it doesnt drag the ground anymore, new bushings and maybe adjustable shocks and go play.

Thanks!

I’d just get some replacement 340 springs.

Yep. Good plan.

Unless you plan upgrading the engine later on. Then go with Cal-Tracs. 5 setting for street and 9 for strip if you use their shocks.

A good set of 90/10 shocks up front does wonders for traction!

That's what I would do. All I use on my 63 Sport Fury is the MP 3400 lb rated Super Stock springs. And the car rides great and does not bounce all over as its a nice ride and I drive it everywhere on them. I know some say their car rides rough on SS springs and I don't know which ones they use but my 63 rides great on the 3400 lb SS springs and does not bounce at all as it rides like a normal car. I don't even have adjustable shocks on the rear as I just use the longer ext MP shocks. It drives great and works fine at the track for a mild street/strip car as it hooks good and has run 10.70's with a best 60 of 1.50. Nothing out of this world but they work good for what I do. You put a good set of stock springs or even the SS springs and that will work fine for what you want. You can put a good adjustable shock on it or if not use the longer ext shocks. But for a 12 second street car you don't have to spend a ton of money on suspension. Just a good basic leaf springs and shocks that work will be fine for what you are doing. Good luck what ever you decide. Ron

What's the name of those rear shackles that slides back and froth which make the SS spring sit lower can't think of the name right now, but I think those would be an option as far as ride height.

I have SS springs on my dart, it does sit up a little in the back. I have seen guys swap the front spring hangers around and get it to sit a little lower, I am going to try that.

Sliders.

https://www.speedwaymotors.com/Speedway-Heavy-Duty-Chrysler-Type-Leaf-Spring-Slider,5817.html

yeah, i would do the same.
I don't know what shipping would cost, but there are THESE on sale at mancini, supposedly made for Mancini by ESPO.

the other option is buy the Mopar XHD 340 springs from Summit and get free shipping.