Found this cool page that describes how slapper bars (Jay Lincoln's Truck Traks) work:

How Slapper Bars Work

Daniel

 

Daniel, this is some of the best info I have ever read on this subject. I have Jay's Truck Tracks and I thought the smaller the gap the better the hook up. That is not what this says. I have 1.5" gap on both sides and the one on the drivers side just touches...the one on the passenger side hits hard. I can tell by the marks left on the springs, the left side just had a little mark on it but the right side you could tell where the snubber was hitting.

Jerry

 

Jay's directions are a great general reconmendation...but like any performance piece, individual tuning can improve their function...thats why I tracked this down. Jay does recommend 1" as the gap, which is what this article states too... you need to tune left/right a little because of weight differences in the truck...


Daniel

 

i am curious, what is meant by "Eye" of the spring, is that the little bolt at the front of the spring?

i got mine hitting right behind that

 

Very interesting article. Thanks!

 

We don't actually have an "eye" on the front of our springs, thats the part on the old springs where it was coiled up with the bolt through it.

You want it to hit the part where the spring is attached (but not on the rivet!), so its not bending the spring at all...thats my understanding of it...the directions say 7" measured back from the axel rod for the rear brace, which worked out good on my truck.

Daniel

 

i'll have to look at mine again, my memory is fading, mine hits directly on the spring about 1" or so behind the rivet

 

I think as long as its at a point where the spring is still in contact with the frame and not in the open-air yet (aka, can bend) its okay.

Daniel

 

Daniel, thanks for posting the article. I (and my customers) have found that theory doesn't always work in reality. The large gap really hits the F-1's too hard for to get acceptable traction. They hook, then unload and spin. This is due to the stiff sidewalls. The trucks make too much torque. F-1's need to be finessed to get all the available traction from them.

With slicks, the additional clearance can plant the tires harder, and this theory should work.

I think one thing we have to keep in perspective, is the lack of weight over the rear tires, and the relative stiffness of the rear spring for load carrying capacity. These do not allow the rear to squat (or the front to lift), enough to use large clearances between snubber and spring.

Pawn and beef, the exhaust doesn't allow us to reach the spring eye on the Lightning trucks. I had to trade this off and shorten the length of the bar.

Jerry, did the spacers help? You will all see a heavier mark on the right side spring, where the snubber contacts it. This is the natrual torque reaction, due to the direction of engine/drivetrain roatation.

If you have ever watched drag racing, you will see the high powered vehicles pull the left front first. This is caused by the twisting of the chassis due to engine torque. If you find that the truck is not going straight under hard acceleration, you can run less clearance on one side than the other. If it goes right, then you need to reduce the clearance on the left. If it goes left, then clearance is reduced on the right.

The bottom line, is everyone does things a little differently. It won't hurt to experiment to find the best combination. Shocks, gearing (both trans and rear end) and weight (especially weight distribution), all effect how a traction bar works.

LightninRod asked me about reducing the clearance to 1/4" to reduce reaction times. It's an old drag racer's trick. Yes, it will reduce your reaction time. When I went from large space to small space, I redlighted twice. It does definitely improve reaction time. I proved that one myself.

 

There ya go, spoken from the man himself. Thanks Jay!

Daniel