Drag Launches - Does one work better then another?

[440]

So I've been reading up a lot on traction devices and launches and you learn things that you've never given much thought to that make sense. Wasting engine power on suspension/weight transfer on the line before actually accelerating out.

I'm old school and my brain is all about weight transfer, getting weight over the rear tires for traction, so I never quite understood why cars that jacked the rear worked. The light clicked when I read that it pushes the rear tires into the track for bite. Same with leaf spring vs 4 link/ladderbar, with leaf springs when the hammer drops the axle rotates before accelerating the car out.

Aside from 4 link/ladder bar do pinion snubbers or caltracs tend to be the most effective? (Everyone will say pinion snubber for Mopar)

Edit: I guess my question is a bit mixed, more of an open ended discussion on all things to do with launching.

[HPP]

There are several different dynamics at work at a launch and there are also several different ways to adjust for those.

In a stock body car, the body separation/lift that a leaf spring mopar produces is just as effective as the squat a coil spring car produces. However, it is not necessarily a leaf spring trait, but is a mopar specific trait based on the asymetrical layout of the Chrysler designed leaf spring. Leaf sprung Fords and Chevys do not have the same geometry that requires the same action. They need to squat to increase the weight transfer onto the springs. In the case of a mopar, the short front spring segment is trying to lever the car up and the weight resistance of the body to this action is what increases the traction.

Caltracs were developed by a Ford leaf spring racer to mimick the action produced by the Mopar Super Stock spring pack. John Calvert was a stock class racer that was dealing with very restrictive rules in regards to suspension mounting points. His method of working around those limitations was to create the cal-trac, which retains the stock mounting points of the Ford spring,but has a dynamic launch control pivot that shortens the effective length of the spring. By shortening the front segment of the leaf, you turn it into a more rigid device that acts less like a spring and more like a location device. This is exactly the premise behind the SS spring pack and this device has allowed leaf sprung Fords and Chevys to launch like Mopars.

Can a Cal-trac be used on a mopar, sure, but they are not as effective on our cars as on the others.  However, they do allow a small range of tuning as to how fast the shortening effect comes into play.   

There are still some tuning tricks available for leaf spring mopars without Cal-tracs or Slide Links. Clamping the front segment, unclamping the rear segment, and changing pinion angle are all means to dial in the action and effectiveness of the launch. In all honesty, if your leaf spring mopar suspension is working correctly, a pinion snubber may actually become useless, unless you're driving a 4 spd. This is because once you achieve the proper body separation to plant the tires, the snubber is simply hanging out in the air and may only work during a gear change that temporarily unloads the springs, like a 4 spd gear change.

[DixieRestoParts]

Good question and good reply. I have a 4-spd Dana car and added a pinion snubber. It definitely helped, but was a pain with normal driving, so I removed it and added the factory one back.

I've heard for years about the clamping of the front and unclamping of the back. But, never tried it.

The biggest thing I've learned is to practice with your car and learn the best way to launch it. Practice makes perfect.

Looking forward to other takes on this. Maybe this weekend, I'll try some different things!

[c00nhunterjoe]

Every mopar stocker at the track, or at least 99% of them, have switched to caltracs over super stock springs. Caltracs are far superior.

9" tire, footbrake launches, 3800 lbs,

[440]

Quite a different launch to something like this.

[c00nhunterjoe]

Lmao, that needs a little more cage to it.... here is a buddy's wagon on bone stock suspension other then caltracs out back and a bigass 468 on spray. Still footbraking though. And he has the cage to keep it from twisting like the one you posted.

[HPP]

Every mopar stocker at the track, or at least 99% of them, have switched to caltracs over super stock springs. Caltracs are far superior.

I don't know that I'd say they are far superior, but they do add some additional tuning capability over the SS springs which, in a stock class where .01 can be the difference between winning and loosing, matters tremendously. Combined with their split mono-leaf system, they also are lighter weight, again a big benefit for a class racer and you can  better dial in specific spring rates with them much easier, again a  possible tuning advantage

For your occasional bracket car, it is another variable that you can miss the set up on and jack up consistantcy with, but car guys tend to be tinkerers anyway, so can be a neat tinker point.

[Lennard]

Quite a different launch to something like this.

That's a low rider doing a 3 wheel motion. 

[c00nhunterjoe]

Every mopar stocker at the track, or at least 99% of them, have switched to caltracs over super stock springs. Caltracs are far superior.

I don't know that I'd say they are far superior, but they do add some additional tuning capability over the SS springs which, in a stock class where .01 can be the difference between winning and loosing, matters tremendously. Combined with their split mono-leaf system, they also are lighter weight, again a big benefit for a class racer and you can  better dial in specific spring rates with them much easier, again a  possible tuning advantage

For your occasional bracket car, it is another variable that you can miss the set up on and jack up consistantcy with, but car guys tend to be tinkerers anyway, so can be a neat tinker point.

I cant really say ive ever witnessed a spring change on caltracs. The guys i know dont touch them. Shock adjustments depending on what track we are at and temperature but that is every car regardless of the springs used. There are local guys running them on the street with no issues. And that nitrous wagon is a daily driver. It will almost hook on the street. Im sold on caltracs. I watch them outperform 4 link cars on smaller tires every weekend during the summer regardless of ford chevy or dodge.