2021 - removal of mud flaps and airflow redirectors

4039 Views 15 Replies 9 Participants Last post by Cryogenix1, Dec 17, 2021

Cryogenix1

Discussion Starter · May 6, 2021 (Edited)

9

I've never liked a straight-on view of the rear of the 3rd Gen Muranos, for many reasons. The mud flaps, especially, seemed to jet outward like a dress, and I felt made everything look too dainty and squared off, along with making the already-narrow tires look even thinner. I also never liked what I presume are airflow deflectors that possibly direct more air across the wheels to help get rid of brake dust, or maybe to even help cool the brakes or rotors a bit. In any case, just like with my 2003 when I got it back from the dealership and discovered they had installed a set of bulky, plastic, low-hanging fuel tank stone guards beneath the car, I have to remove them due to their ugliness.

Tools required for the mud flaps (without having to remove the wheel)... Philips bit with ratchet wrench, plus a regular philips screwdriver. Four coarse-thread screws to remove.

Tools for the airflow redirectors.... 10mm socket, 6" extension, ratchet. Three fine-thread screw to remove.

I replaced all the screws back into their holes in case I need them later, and so crud doesn't build up within the holes. Took less than 15 minutes to remove all four flaps.

I think MO's looking a whole lot better now. Better shape, sits higher... The first "before" picture reminds me of the spaceship in the movie Explorers, The Thunder Road. I left the front mud flaps on because the tires can kick up a lot of debris while turning, plus they look fine. Given the plastic wheel well trim on the rear-quarters, I don't see the need for the mud flaps anyway.

See less See more

1 - 16 of 16 Posts

I need coffee

· #2 · May 7, 2021

Cryogenix1 said:
I've never liked a straight-on view of the rear of the 3rd Gen Muranos, for many reasons. The mud flaps, especially, seemed to jet outward like a woman's dress, and I felt made everything look too dainty, along with making the already-narrow tires look even thinner. I also never liked what I presume are airflow deflectors that possibly direct more air across the wheels to help get rid of brake dust, or maybe to even help cool the brakes or rotors a bit. In any case, just like with my 2003 when I got it back from the dealership and discovered they had installed a set of bulky, plastic, low-hanging fuel tank stone guards beneath the car, I have to remove them due to their ugliness.

Tools required for the mud flaps (without having to remove the wheel) philips bit with ratchet wrench, plus a regular philips screwdriver. Four screws to remove.

Tools for the airflow redirectors.... 10mm socket, 6" extension, ratchet. Three bolts to remove.

In all cases, I replaced all the screws/bolts in case I need them later, and so dust and crud don't build up in the holes. Took less than 15 minutes to remove all four flaps.

I think MO's looking a whole lot better now. Better shape, sits higher... The first "before" picture reminds me of the spaceship in the movie Explorers, The Thunder Row. I left the front mud flaps on, mainly because the tires can kick up a lot of debris while turning, plus they look fine. Given the inner plastic wheel well trim on the rear-quarter, I really don't see the need for the mud flaps anyway.

I think it actually does look better without the flaps. Mo is crying for wider tires.

DaBudMan

· #3 · May 7, 2021

I always wondered what those "air deflectors" were, and why they were there. Removing ours soon.

byeager21

· #4 · May 7, 2021

2

Great write-up and pics! I agree with the above, taking those off really highlights our stock "pizza cutter" width tires.
Personally, I went with the widest tires I could on our stock 20's and also added aluminum wheel spacers. It gave the Murano and MUCH needed and improved look. Another added benefit is my Murano handles so much better now. When it was stock, taking broad turns at highway speeds felt squirrelly. This has added much more driving confidence at all speeds while turning and reduced body roll.

Thanks again for sharing!

See less See more

Cryogenix1

Discussion Starter · #5 · May 7, 2021 (Edited)

DaBudMan said:
I always wondered what those "air deflectors" were, and why they were there. Removing ours soon.

I could be wrong. They may be for safety reasons, such as to decrease the likelihood of a hard object being kicked forward of the rear tire, ricocheting off the pavement and possibly hitting something like a fuel line or the gas tank, which could create a fuel leak, fire or explosion (probably unlikely, though). Might even be to protect brake lines. I didn't check to see how they're run. If Nissan would've made them more conical with depressions that mimic MO's side panels, I probably would've left them on. But, if for some fuel safety thing, couldn't they have just used a plastic cover on the exposed/fragile part they're trying to protect that's not such an eyesore? It's possible they exist to reduce drag on the rear tires and create a drafting/strafing effect to improve fuel economy. I don't recall where on my 2003 they had installed them. I thought they were more forward by a couple of feet, and I know that was a safety thing that had to do with either the fuel tank or the fuel line. It also got me thinking that they may be able to create/direct more focused air turbulence/flow over/around/past the tailpipes to help push or draw emissions away from the car. I don't know. Maybe one of the Murano designers heard they were getting canned, and decided to get even by requiring these ugly things be placed on MO.

See less See more

DaBudMan

· #6 · May 7, 2021

Cryogenix1 said:
I could be wrong. They may be for safety reasons, such as to decrease the likelihood of a hard object being kicked forward of the rear tire, bouncing off the pavement and possibly hitting something like a fuel line or the gas tank, which could create a fuel leak, fire or explosion (probably unlikely, though). Might even be to protect brake lines. I didn't check to see how they're run. If Nissan would've made them more conical with depressions that mimic MO's side panels, I probably would've left them on. But, if for some fuel safety thing, couldn't they have just used a plastic cover on the exposed/fragile part they're trying to protect that's not such an eyesore? It's possible they exist to reduce drag on the rear tires and create a drafting/strafing effect to improve fuel econonmy.

Not doubting you. Nissan put them there for a reason, unknown to me. I do know that I own 2 Mo's. Mine is a 2016, the wife has a 2018. And both of them have said flaps hanging on by just the bolt. The outer hole has either lost its screw or push pin. They're an eye sore to me, and they rattle with that outside push pin missing.

Sent from my SM-G996U using Tapatalk

PaulDay

· #7 · May 7, 2021

The reality is that the main function of both the rear and front air dams is for fuel mileage, tire kick up is second.. They perform the function of increasing the size of the air flow around the tire, which in turn creates a smoother air flow down the side of the car.

The more you can encase a rotating object, the less turbulence is created by that object as it moves thru the air. Removing both front and rear flaps reduces the size of this "dam" containing the rotating air, decreasing the area of the turbulence free sized zone down the side of the car. This reduces the drag ecoefficiency of the Murano, decreasing MPG.

Search YouTube, several videos showing visual air tunnel testing showing how the turbulence is effected by rotational air flow.

Have a good day.

Reactions: 5

DaBudMan

· #8 · May 7, 2021

PaulDay said:
The reality is that the main function of both the rear and front air dams is for fuel mileage, tire kick up is second.. They perform the function of increasing the size of the air flow around the tire, which in turn creates a smoother air flow down the side of the car.

The more you can encase a rotating object, the less turbulence is created by that object as it moves thru the air. Removing both front and rear flaps reduces the size of this "dam" containing the rotating air, decreasing the area of the turbulence free sized zone down the side of the car. This reduces the drag ecoefficiency of the Murano, decreasing MPG.

Search YouTube, several videos showing visual air tunnel testing showing how the turbulence is effected by rotational air flow.

Have a good day.

Great explanation! Thanks.

Reactions: 1

YoGeorge

· #9 · May 8, 2021

One other reason could be protecting the rear brake calipers from mud and gravel, and salt paste in the winter thrown up by the front wheels. I have replaced rear calipers on a few cars, most commonly because the parking brake mechanism gets screwed up. GM had a chronic problem with the rear calipers rotting out and our experience was with a '91 Grand Prix that we bought new; 2nd was with my '98 Acura TL. In both cases, the parking brake assemblies were messed up beyond repair from being driven thru salty winters.

I agree with Paul about the aerodynamic advantages also, and there was a thread on the possible fragility of the rear wheel well liners, so if the flaps deflect junk from getting blown up and around the whole inner fender that can only help.

As for the mud flaps, they look dorky, but I've had many cars with the paint sandblasted off the rockers and I don't like visual dirt and mud on the side of a "fancy" car like the Murano. Driving around in a muddy Subaru or Jeep is good fashion sense but the Murano presents best when it's clean.

See less See more

Reactions: 2

mmg

· #10 · May 11, 2021

Removed the mud flaps on both my 2018 and now my new 2021. The air deflectors on the 2018 came off on their own. Will research them to see if I want to remove these and will post updates.

gmadigyal

· #11 · May 11, 2021

PaulDay said:
The reality is that the main function of both the rear and front air dams is for fuel mileage, tire kick up is second.. They perform the function of increasing the size of the air flow around the tire, which in turn creates a smoother air flow down the side of the car.

The more you can encase a rotating object, the less turbulence is created by that object as it moves thru the air. Removing both front and rear flaps reduces the size of this "dam" containing the rotating air, decreasing the area of the turbulence free sized zone down the side of the car. This reduces the drag ecoefficiency of the Murano, decreasing MPG.

Search YouTube, several videos showing visual air tunnel testing showing how the turbulence is effected by rotational air flow.

Have a good day.

This makes total sense to me. Flaps are there on all cars for good reasons based on manufacturers tunnel tests and also proven fixes for user feedbacks and issues. Notable aerodynamic factors like drag coefficient and related MPG, these flaps are continuously protecting dirt and road debris from kicking up and hitting sensitive parts of your vehicle. They also protect the paint and finish of body side panels. One will notice these issues after driving for a period of time without the flaps. This is like discarding something without learning/knowing the actual purpose and protections offered by these. I trust all car companies do their research and continuously improve and make better cars. Undoing something just to make it look better would likely cause bigger functional and cosmetic damages eventually...

Pilgrim

· #12 · May 11, 2021

There are small details all over cars today that make a difference in air flow. Some are surprising.

Cryogenix1

Discussion Starter · #13 · May 11, 2021 (Edited)

gmadigyal said:
...these flaps are continuously protecting dirt and road debris from kicking up and hitting sensitive parts of your vehicle. They also protect the paint and finish of body side panels. One will notice these issues after driving for a period of time without the flaps. This is like discarding something without learning/knowing the actual purpose and protections offered by these. I trust all car companies do their research and continuously improve and make better cars. Undoing something just to make it look better would likely cause bigger functional and cosmetic damages eventually...

Since the rear wheels are fixed and the OEM tires are well within the wheel well, there shouldn't be any added hazard to removing the rear mud flaps for fear that sand will blast off or abrade the paint over time. I've had older vehicles with extra wide tires that extended far outside the wheel well cavity, and their paint never got damaged. But even the tires pictured above that extend beyond the wheel well... Unless that vehicle is being driven rapidly across The Sahara for months or blazing over pea-stone roadways in Greece, the lower rear-quarters still shouldn't be affected. If anything, the inner well and side flares/trim might get dinged up, but that would happen even with mud flaps on. If my view, mud flaps are snow and ice retainers during the winter. I was constantly having to clean off MO '03's tires before entering my garage because of that buildup against the mud flaps

And, to keep things real, what are the chances of debris from a forward-spinning rear wheel actually being able to propel itself forward of that tire, let alone at a velocity fast enough that it might actually have enough momentum to damage anything given the speed of the vehicle in motion away from that object (i.e. is the road object really going to be able to catch up to your vehicle that's speeding 55MPH away from it, and with enough force to do any harm? Always possible, but probably very unlikely.) At slower speeds, I think those draggers might offter a little protection, but probably moreso when going in reverse on loose gravel. Now, if you're talking stone guards rearward of the front wheels, that would make more sense and offer a lot more protection, and I'd be inclined not to remove those

While anything unexpected can happen when driving, in my view the key is staying alert to the road and things that may be in your way ahead. By not driving blindly, you greatly increase the likelihood of not running over something that has a remote chance of kicking up and another remote chance of hitting some critical aspect of your vehicle. I accelerate quickly past big rigs because if one has a blowout, tire shrapnel will go flying everywhere. I try to get out of the way of potential hazards as soon as possible, provided it's safe to do so. If not, I'll hang way back to allow more time to react to whatever might happen. Last year while doing 50MPH in high winds on a straight road, there was a large truck loaded with bales of hay headed towards me (it was about 1/4 mile away) and I could see that one of the bales on top was lifting and getting ready to fly off. I immediately veered into the breakdown lane and gunned it to close the distance, and I made it past just as the bale came off and landed in front of the car behind me who probably thought I was drunk or something. They hit it, I didn't.

In any case, if in five years I still have this car, I'll return to post pictures of the back-lower rear-quarters. I have a hunch they'll be fine.

EDIT: However, perhaps a good argument that can be made for both sets of flappers being left in place has to do with aerodynamics, where the flow of air at higher speeds when acting upon those flaps might have greater ability to stream away sand particles from the body a bit, reducing their potential abrasion on the paint. In other words, those flappers (combined with the well-designed contours of the body panels) might create a shield of air over the rearward metal, preventing sand from contacting the paint. I still feel such damage is pretty slim, especially if driving mostly on paved roads.

See less See more

Reactions: 1

DaBudMan

· #14 · May 12, 2021

Well I have removed my air deflectors. I will watch for any changes in exterior damage or mileage. I put around 30-32k a year on my car, so it gets driven. Average mileage is 27mpg right now. We'll see if that changes.

Sent from my SAMSUNG-SM-T817A using Tapatalk

mmg

· #15 · May 16, 2021

The mud flaps are an accessory only and are not a part of the equipment used control airflow. The air deflectors, according to my sources at Nissan, are part of several air deflectors on the car that improve fuel economy. They state that .5 mpg may not mean anything to the consumer, but It does have significant meaning for fuel eco ratings that the manufacturer wants to meet.

You can remove them and probably would not notice any significant mpg decrease, from the consumer perspective.

Reactions: 2

Cryogenix1

Discussion Starter · #16 · Dec 17, 2021 (Edited)

8

Since my stock tires were still okay at 28,000 miles but wouldn't work for me for winter driving, I had to break down and buy new tires. I really liked the Firestone LE2 Destinations on my 2003, so I went with LE3s on the 2021. It's the widest I could go and still be inspectable (and that were available now) and the driving experience is night and day. Sticking with the stock wheels through the snow months and will buy new wheels next year. I feel the car is grabbing into the asphalt much better and producing less roll and wandering. A far better ride. Depending on varios things, I might do what you did and put wheel spacers on after the car passes the state inspection next year. The tread on the LE3s is much cooler-looking than the stock Bridgestone Duellers.

See less See more

1 - 16 of 16 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.