Truck and Tractor Pulling | Tech Talk | 4WD Trucks

[00:00:00]So, this week on Tech Talk with Marvin Epperson. Marvin, so the last few weeks we've kind of talked about universal things that apply to pulling as far as safety and checks like that, but now we're going to do specific vehicles.

[00:00:11]We'll start with the four-wheel drive this week, and we've got some safety items and then some super tech items that you would check. You know, some you don't do it, you do it sporadically.

[00:00:19]It's not one of those things where you tell the pullers we're going to do it, right?

[00:00:23]>> Yeah, so there's legal length or measurements on every vehicle and every division. And today we're going to do the four-wheel drive.

[00:00:30]We're going to show you how we measure a four-wheel drive for hitch length, for wheelbase, for overall length to keep them within the rulebook for all competition.

[00:00:38]And then there'll be a couple safety items we're going to look at on the front as well while we're doing this.

[00:00:42]But we don't do this every time.

[00:00:45]Once you know a guy's good for a while, he's good unless he builds a new chassis or whatever, or I'll just randomly pick a couple out and say, "Hey, meet me at the hitch pad. We're going to measure today." So, it it alarms them a little bit, but most of them's okay.

[00:01:00]>> It just kind of makes, you know, makes everybody aware that, "Hey, you guys are watching."

[00:01:03]>> We are watching, yep. And it's very important. You don't want to have one guy get another advantage over another, and they all got to be within the limits. So, we'll get started here and see what we get.

[00:01:12]>> All right.

[00:01:13]>> So, what we're doing here, there's a length limit from the center of the rear axle to the hook point. And we plumb bob every point.

[00:01:21]The best way of measuring a vehicle exactly or accurately is a plumb bob cuz it never lies.

[00:01:26]So, we drop the plumb bob down, wait till it stops moving. He puts the pointer right at the tip of the plumb bob, and then he's going to pull that up, and we're going to move around and start doing the wheels.

[00:01:37]We'll do the same thing for the center of the front axle, center of the back axle, and also the overall length in the front of the weight box.

[00:01:45]So, they can only be 39 and 1/2 in from the center of the rear axle to the hook point, not the end of the hitch, but the hook point from where the hook of the sled goes. And that's the longest a hitch can be. And then there's an angle limit of what the hitch can be.

[00:01:59]They can be 0° plumb to the ground up to 25. And that's the maximum. Nothing negative to the front. It could be level or up to 25°, and that's from the center of the pivot point of the hitch where it's anchored exactly back to the hook point as well.

[00:02:16]So, we'll move around here to the side.

[00:02:18]See what he's doing at the axle.

[00:02:21]We've got a tool made up that works very well here with two levels. It tells him the exact center of that wheel, which would be the exact center of the axle.

[00:02:29]And he's going to drop that plumb bob down the side. And as soon as he gets it still there, he's going to apply another pointer right at where the plumb bob is.

[00:02:43]And when we we get done here and get all the measurements, uh I can tell you we're usually within an eighth of an inch of being exact, and I'm good with that.

[00:02:55]So, the wheelbase limit is a minimum of 131 in, a maximum of 133.

[00:03:03]So, when we get done here with all the points, then we go to the overall length on it. Uh it used to be 60 in from the center of the rear axle to the farthest point forward, and that excludes does not count the tow hook on the front. But anything out front, whether it be the top of the weight box cover, whatever makes the plumb bob hang out the farthest, that's where the point of measurement is taken.

[00:03:28]So, we we have changed that in the last couple years. The new chassis, the way the axles are mounted, we now measure from the center of the rear axle to the front of the weight box. So, if you take your 133 in, add the 60, now that number is 193 overall, and they can't be over.

[00:03:45]And uh believe it or not, I have found some in the last couple years that were 1/2 in over. And if you don't think uh 1,000 lb a half inch forward makes a difference on a four-wheel drive, think again. We made them move it. They had to cut the frame off and and scoot it back.

[00:04:00]What some of the guys don't understand when you measure a vehicle, excuse me, sorry Tom.

[00:04:06]When the vehicle is measured, set up, ready for competition. So, they build them level in the shop or on a a chassis jig >> [music] >> and they set everything up exactly plumb level. Well, the vehicle is measured ready for competition. That means all the weights is in it, it's down on the stops, they got the tire pressure where they want it to be, just the same as they're getting ready to go to the sled.

[00:04:29]Cuz that's what I'm concerned about it, when it's ready for competition. So, some guys will get a little um confused and think it's good. Well, when they bring it out here, they put all the weight in the front, they let the front tires down flat, all of a sudden the chassis leans forward, the plumb bob swings out a little farther and then you get iffy, uh-oh, you're over on length.

[00:04:49]So, they got to factor that in that it's it's measured ready for competition. It doesn't matter if it's four-wheel drive, two-wheel drive, super stock mod, we do them all that way.

[00:04:58]>> Now, you had talked about Marvin about the overall length out to the end of the the box itself, but is there a a width limit on the box itself? You just got to work it in amongst yourself to make it fit.

[00:05:08]>> Whatever however they want to make it, it doesn't matter to me, uh but I just take whatever's the farthest thing out. In this case, we're going to hang the plumb bob over the edge and you can tell the edge of that uh lid is probably the farthest thing out because of the angle of the weight box and wherever the plumb bob hangs there, that's where we're going to take the measurement. And again, that's excluding the tow hook. That doesn't count. They're allowed to have that out there.

[00:05:38]So, then it's very important as well, uh we try to get the front wheels as straight as possible. That way uh you're getting the exact center.

[00:05:46]Some guys will argue, excuse me, it makes [clears throat] a difference. It It It kind of does, but if it's turned a little bit right, turned a little bit left, it's the same on both sides. So, it's going to come out fairly close, you know. Like I said, if we do our job right, we're going to be within an eighth of an inch, and I'm good with that.

[00:06:04]>> Okay. Well, now we've backed the vehicle up. You've strung both the front and the back from the width of the vehicle. So, let's talk about some of these safety items we look at.

[00:06:13]>> Okay. So, what we're going to do here we Like you said, we put the strings across the two points to represent where the center of the axles are, and you can see here in front of me this point represents the farthest point forward where we plumb bob the front of the weight box. So, what we're going to do now is we're going to string a tape under the truck and use them strings to reference every measurement to make this truck legal for competition. So, I'll send the tape under the truck. Tom's going to hold it on the string for the back axle, and I'm going to pull the tape forward. I'm going to measure the wheelbase limit, which that string will represent, then I'm going to bring it out here to this point and get the overall length limit. So, the truck's allowed to be 131 to 133 in for wheelbase.

[00:06:56]So, we'll see what we get.

[00:07:04]Right exactly on 133. Perfect. They got it to the limit. All right. Hold the tape, Tom.

[00:07:10]So, move over toward the center.

[00:07:16]There you go.

[00:07:19]Well, I don't have a long enough tape for that.

[00:07:25]>> Marvin, looks like you're about an inch short. So, >> it's 193 is the limit. I I'm pretty sure that tape is a 193.

[00:07:32]That's the >> I would say right on the money there.

[00:07:34]Yeah.

[00:07:34]>> on the money. And I can tell you this truck was legal when we measured it 2 years ago and right on the money, and it's still right there today. So, that represents the overall length of 193.

[00:07:45]They were right on 133 for the wheelbase. So, we're going to go around the back and see if the hitch is at the minimum and no longer than 39 and 1/2 in.

[00:07:55]>> Now, Marvin, like we were talking before, there really there is no width limit on the four-wheel drive. So, but like you say, the hauler pretty much limits as far as how wide you can go.

[00:08:04]>> The only thing that is limited on a four-wheel drive, it shows in the rule book, they do have a stagger. The front wheel to the back wheel, they have to have at least a 1-in minimum of overlap from the rear tire to the tread of the front tire, whether it's inside or outside. So, you can pretty much see that with the eye without putting a string on it. I have had a couple that's close and we've put a string or a straight edge on them, but most of the time you can look at that and make sure it's within the limits.

[00:08:31]>> My micrometer, like I says, it's just over an inch. So, it looks like a couple inches to me, Marvin.

[00:08:36]>> Yep. Yep. They're good there. The other thing here on the weight box is safety item that we look at is the safety wheels that they're required to have.

[00:08:43]Years ago, they didn't have that on a four-wheel drive and if this truck was to break an axle, break a rear end, the drivetrain locks up, it stops immediately, tips up in the back because all the weights in the front, this weight box would dig in the ground and then all of a sudden the sled would hit the back of this truck and just fold it up like an accordion. So, that become a huge safety problem and actually injuring the driver from the inertia and the crash going forward. So, they come up with this detail on the safety wheels. They have to have safety wheels on the front of the weight box, 6 in off the ground, 6-in diameter, 4 in wide, and no farther than 6 in back from the front edge of the box. The reason that is, if that if this truck was to tip in the back like they do because of the weight carried in the front, we want these wheels to hit the ground and start rolling before this weight box digs in the ground and causes a horrible crash. So, that's uh proven to be pretty good over the years.

[00:09:43]There's all different designs of them.

[00:09:45]>> So, Marvin, we've made all the measurements. We've made, you know, all the safety checks.

[00:09:50]What's there left to do? So, we got to sign off on our super tech. We got to sign off on our safety check.

[00:09:55]>> That is correct. So, I've got sheets made for every division that we have in NTPA, every divisional class. So, there's a sheet for four-wheel drive that represents every measurement that we took here today to make sure that this vehicle is legal for competition.

[00:10:09]So, I will write down our findings, our measurements, have them sign it. They know we measured today. It'll go in a file box in my trailer. That way, if there's a situation where they're get they get protested, I can pull that out, say we measured it a week ago or a month ago or 2 months ago. Or, if we measure it again and find something off, then they've done something. But, I've got that recorded in my trailer for everything that we have measured in the last 4 years. Then, we'll go ahead and go ahead and do the regular uh safety check that we do every week to make sure it's got all the safety items, kill switch works, driver's got his uniform, all the stuff that we do on every vehicle every week. They'll sign that.

[00:10:47]That goes in the paperwork for this event. So, we do that every week, just the regular uh tech check.

[00:10:53]>> Well, Marvin, that pretty much covers the teching out a four-wheel drive truck. We thank you this afternoon for uh showing us all that.

[00:10:59]>> Thanks for watching. Appreciate it.