NHRA officials have issued a temporary rule amendment allowing “mud flaps,” or air deflector plates, to be optional in the Top Fuel category for the next four races.
This change will begin at the NHRA Arizona Nationals in Phoenix (March 21-23) as the sanctioning body seeks to evaluate the rear wheel load when these body panels located in front of the headers and rear tires are in use.
The effectiveness and necessity of mud flaps have been a hot topic among Top Fuel drivers and crew chiefs. Additionally, the recent announcement has sparked debate among fans, some praising the use of mud flaps while others questioning their impact on downforce and speed.
We reached out to multiple Top Fuel drivers, such as Scott Palmer and Shawn Reed, and crew chiefs Mike Green (Justin Ashley), Neal Strausbaugh (Tony Stewart) and Brian Husen (Shawn Langdon) to gather their insights on this pivotal adjustment. Here’s what they had to say.
What was the origin of removing the mud flaps from Top Fuel dragsters – when did the idea start?
HUSEN: It started last fall, essentially in Las Vegas. We had a headwind there, and we weren’t super hard on the tires, but we were definitely having some tire issues as far as pulling the centers out of them, which is pretty common in Top Fuel. That’s where my original thought came from, and then, over the wintertime, Toyota did some Computer Fluid Dynamics (CFD) work for us. We sent our car to Charlotte, and they scanned it, and then they can do a bunch of tests on it. They had some data on different configurations of mudflaps as well as just no mudflaps. Slugger [Labbe, TRD engineering manager] from Toyota was working with the NHRA trying to change the shape, the angle, and the size of the mud flap, and NHRA shot it down.
That kind of frustrated them a little bit. So then I came along and said I didn’t want to change the shape of them, I just wanted to take them off. That was where it became a bit of back-and-forth with NHRA. There’s no rule that says we have to run them, but they do have a rule that if you do any body modifications, you have to get approved. We went through the approval process, and it took this long to do it which was a little frustrating.
Can you explain downforce on Top Fuel dragster versus a nitro Funny Car?
HUSEN: On a Funny Car – overall downforce front and rear – the most amount they can create to the least amount they can create throughout a season is somewhere around 2,800-2,900 pounds. They have 2,900 pounds of adjustment, so when the track is really good, they can remove downforce up to 2,900 pounds versus when the track is 140 degrees, and they would put it at max downforce.
On Top Fuel dragsters, we only have one tool to use to adjust downforce – the rear wing. We have eight flap positions, and then we are in a box as far as angle goes – the maximum positive angle of the rear wing is positive one degree from the racing surface, and the minimum is minus two degrees from the racing surface. With the CFD data that we have provided by Toyota, if we go from the maximum amount of downforce we can produce to the least amount of downforce we can produce, we only have 1,100 pounds of movement. Dragsters notoriously, when the track is cool and gets really good, we damage our tires. I would say easily over 70% of the cars will pull the centers out of the tires, or in the even worst case areas, it kind of pulls this football-shaped chunk off the corner of the tire, which is a little bit more scary.
Once I realized this when we started sifting through the CFD data and if we were allowed to remove the mud flaps and then also still adjust our wing, that would give us an arrangement that’s similar to a Funny Car, and so that we can have more adjustability so that when the track does get really good, we can at least attempt to not ruin our tires, and potentially not wreck the car. That was the whole goal behind it all.
Will you guys be using the mud flaps at the NHRA Arizona Nationals?
STRAUSBAUGH: We will be for sure starting off with mud flaps, and with the foreseeable forecast [in Phoenix], I don’t know that it’s going to be conducive to being able to take them off due to the amount of downforce that they do provide. Also, with Phoenix being a new surface on the top end, I just don’t know if any cars are going to be taking them off.
GREEN: The only reason we wouldn’t run them is if the conditions were so that we thought we were going damage the tires and those conditions are probably not going to present themselves in Arizona.
PALMER: I can say honestly that I will be using them this weekend but more for signage purposes. I have a sponsor that loves that particular spot because it shows up in every picture it seems like.
HUSEN: I think these next four races, it’s all going to be conditions-based because you’re not just going to take them off. When the track’s over 110, we typically don’t have any tire issues. So, nobody’s really going to remove their mud flaps at that point. In Phoenix, the tracks will be over 120 every run we make this weekend and up to close to 150. So you’re not going to see any Top Fuel cars with mud flaps off this weekend. The forecast for Pomona looks a little more conducive for quicker times, and it’s going to be a basis of the track prep, the conditions and the temperature. Sometimes, if they’re a little light on track prep, but the track’s cool, we don’t necessarily have tire issues. So it’s going to be a balance kind of thing.
REED: I did talk to [Rob] Wendland a little bit about it, whether we were going to use them or not, but he said it just depends how the track is prepped and how the power level is. We feel that they put a lot of added downforce on the car, which is kind of hurting the tires. We had, in the last year, and even in Bradenton, one run on the tires, and they’re done. We just happened to see a lot of that tire damage lately, and they came to me in the finals at Bradenton and said you and Josh Hart are not going to run mud flaps. I’m like, okay, you know, I can’t feel the difference in the car.
Do you have intentions of taking off the mud flaps at some point during the next four races the NHRA has allowed them to be optional?
STRAUSBAUGH: We have full intentions of taking them off and making some runs. We kind of have to. I believe there is some performance advantage to taking them off. I think that was what pushed the whole thing to take them off in the first place was a performance push and maybe it was trying to be sold as saving the tires. Now, if there is a chance that it’s going to help from chunking tires, I’m all about it.
GREEN: It’s a safety thing for us. We may not run them again until we get a night run somewhere. It’s all about conditions, and we probably wouldn’t run without them unless the conditions warranted it and for us to make it safer for our drivers and make the tires last.
HUSEN: What’ll be really interesting is if we go to, I want to say, Q4 in Pomona, personally, I’ve got a plan for when I intend to run them and not run them, and if the track is going to be in the high 80s and the sun’s going down, and the track has been prepped for four days, I’m going to take them off. There are probably going to be cars there that don’t take them off. That’s when we’ll get a real true comparison [on data]. Goodyear is going to monitor the tire temperatures coming around the corner [in the staging lanes]. Hopefully, we’ll see some reduction in temperature tires, and then, maybe the cars that do run mud flaps will be able to really say, hey, this is definitely improving.
[The NHRA] put this four-race moratorium on it, and then they’re going to evaluate it. They allow us to start doing this in the spring when the tracks are starting to get hot. I was really pushing for this to start in Gainesville, and they drug their feet long enough. Gainesville would have been a perfect place to try it. I’ve tested in Bradenton without them three or four times. I tested in Gainesville twice without them just to get comfortable with it. I just don’t know how much data they’re gonna compile over the next four races; it’s all gonna be Mother Nature-based.
Have you seen any improvement in the tires when the mud flaps are removed?
HUSEN: When we’ve ran without, we’ve never chunked the tires. I’m not necessarily saying we would have had we not removed them, but at this point, we haven’t had any tire damage. We’re very limited on the runs.
In the final round in Bradenton, we offered up the panels [to replace the mud flaps] to Shawn Reed and Josh Hart. They accepted them, and they put them on their car. The only problem was that the whole theory behind removing the mud flaps is you take them off, and then you still put your rear wing where you would normally put it in those conditions, because where you would normally put it, it hasn’t seemed to be enough removal of downforce. So when those guys took the mud flaps off in the final, they actually raised the wing up, and so they kind of counteracted what they were trying to do. They both damaged their tires in the final round, but they didn’t utilize the tool to its full capacity.
Do you think there is a performance advantage when the mud flaps are removed from the car?
STRAUSBAUGH: I’m an advocate for taking them off if it’s going to come with some performance advantage, and from a couple of the runs that we’ve got to see happen already, there were some runs in Bradenton that were pretty good, and then, obviously, the Brittany Force run without them, where she ran 302 miles an hour to half-track. Not that that car isn’t capable of doing that anyways, but it definitely could have been a contributing factor.
GREEN: I don’t think we ran them enough to know that exactly. So, I couldn’t say one way or another at this point. We did it mainly for safety because we race on some tracks where the conditions get with the track prep and the air, quality of the air conditions, the coolness of the track, whether it’s cloudy or sunny is pretty hard on the tires sometimes, so we wanted another option. We were at our lowest amount of downforce we could run legally by NHRA rules, so we decided to take the mud flaps off and make some runs and see if it made a difference. It seemed to work in really good conditions.
REED: I don’t think so. In Gainesville, where Brittany ran 302 mph to the eighth, I don’t think that had anything to do with mud flaps or no mud flaps. That has to do with Grubby [David Grubnic] putting his finger in the air and praying it got that far. That’s what it had to do with. Whenever you change one thing, there are about seven or eight others that are going to follow. That’s why they’re going to allow us to test, and people that want to run them can, and people that don’t want to run them don’t have to. Aesthetically, I like the mud flaps on the car. I think they look cool.
HUSEN: I don’t think so. The big buzz was Brittany didn’t have them on when she went 302 to the eighth, but that was in testing, so who knows what else they were testing. Typically, what I’ve learned over the years is when cars run fast, the speed is fast, that’s all relatable to just horsepower. So, like when Austin Prock went 341 in Pomona, he didn’t change his Funny Car body – he did his normal thing, but they’re just making more power.
The mud flap numbers that we were looking at for downforce and things like that were all based on 300 miles per hour. I didn’t see any improvement on it. Mike Green didn’t run them on Justin Ashley’s car in Bradenton, and they made a good run, but there were no absorbent speeds, and nothing was crazy and out of line. So we may see some small performance advantages, and that would be more so like, it’s just gonna run a little bit better through every increment, but I don’t think it’s gonna be something where all of a sudden the cars are going 345 miles an hour and we’re running 60 flat.
The mud flaps have been associated with tire chunking. Can you elaborate on this when the mud flaps are present vs. when they are not?
PALMER: As far as the effectiveness of them, I don’t know what to think about that. If they have any downforce or put any load on the tire, I would say that the rear wing will be put up a half a degree or degree to make up the difference, so I’m not sure what effect it will have as far as saving or preventing the tire issues that have been happening lately. I don’t think we ran them enough to know that exactly. I couldn’t say one way or another at this point. It seems like every cool race track where everybody goes super fast. There’s always a tire chunking problem where it pulls chunks out of the tread down to the cord. I just think that comes from the tracks being so good and everybody getting aggressive with the tuneup when the tracks are so tight.
The tire chunking problem has been around for years, so it was just a matter of time, in my opinion, before we started seeing tire failures. When the tracks are not super sticky and glued down, nitro cars generally don’t have this problem.
What is the end goal here once the four-race trial period is over?
GREEN: We hope it’ll become a more permanent thing than just the next four races because, like I said, we might not run in the next four races; you just don’t know, but we think it’s an option that we would really like going forward to have when we get to late night conditions, and the conditions are such that we would be worried about tire damage, that we’d have that as an option for sure.
STRAUSBAUGH: I think NHRA was very smart about this move and how they’re going to roll it out, just giving us kind of a trial period. A lot of times, they make decisions from the tech department, and they make decisions, they’ll attempt to stand on them, and then they’ll have to retract them at some point. Maybe they don’t make the right move, or maybe there was some underlying stuff that wasn’t thought about, but this is, in my opinion, I think they’re doing this a really smart way if it’s going to be sold for saving the tires. We need to see the data that says look, it’s saving the tires, as opposed to just opening the door and saying okay, we don’t have to run mud flaps. Hopefully, it saves some tires, and hopefully, it doesn’t become a parody issue or anything like that. So, time will tell.
HUSEN: We just want a rule to be written that mud flaps are optional, and it’s up to the teams to run them or not run them whenever they so choose to. They’re not mandated to be ran, but if you showed up as a brand new team, and you built a brand new Top Fuel car, and you showed up and you did not have mud flaps on your car, there’s nothing they could say to make you put mudflaps on because you’re not making a body change. You showed up with your body that way. That’s how ignorant the rule is. It’s just the way they wrote the rules.
If you make a body change, then you have to ask for permission. There’s no rule anywhere about the mud flaps other than the size. If you want to modify anything, you have to basically beg them to change things. It’s just very frustrating.
We’re just trying to get some more downforce adjustability because we really have nothing to work with, like a Funny Car does. A Funny Car can change the wick around the front wheel opening. They can change the spoiler, and they have a lot of tools to use. They don’t run super fast. I mean, yeah, Austin went 341, but typically, the top speeds in Funny Car have increased substantially in the last five or six years, and definitely in dragster, they haven’t. 100% of the time, Top Fuel dragsters are the only ones that have tire issues, and it’s very obvious when you start looking at all the data. It’s like, oh, you only have about a third of the adjustability with your downforce compared to a Funny Car, and it’s like, okay, it makes sense.
This story was originally published on March 21, 2025.
The post DI Roundtable: NHRA Top Fuel Drivers, Crew Chiefs Weigh-In on Optional ‘Mud Flap’ Usage first appeared on Drag Illustrated.