Installed Splash Guards after found OEM piece in front of rear wheel failed

[Mach Len E]

I installed some 3rd Party Splash Guards or mud flaps after looking into what the splash guards in front of the rear wheel were for since they were breaking up. From what I can tell, they’ll prevent material from the front wheels impinging on the back tire ... but further research says they are 'Wheel Strakes' or 'Wheel Spats' and are mostly for aerodynamics. Given the wheel Center line to the bottom of the car I’m not sure of their utility for diverting material but it was highly recommended accessory for a 2007 truck I had. I do not see serious issues anywhere else except maybe these pieces were concentrating road schmutz on a piece of tubing that was polished a bit and it sits in front of an attachment point (can see in front of tire in one photo).

I have just over 20,000 km on the car and have had it since October and drove it regularly on 3 km of gravel and then 150 km of pavement one way, mostly divided highway in Central Alberta, Canada. This includes -30C and snow, ice and all the cheesy highway treatment that goes with it.

It looks like it is simply poor material selection for this piece and with just the 3rd party splash guards there is an improvement over no splash guards originally. Should I put new ones back on at about $30 a piece? For fun they are checking if they are warranty.

I should note, this same piece on my wife’s Buick Envision is softer material and more tightly installed and after 5 years looks like it could have been driven only in town.

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[Mach Len E]

Looks like I'm alone in my Deep Freeze frost heave road world given the response. Anyway, calling the dealership to tell them not to bother with getting these pieces even if it is warranty. Looks good without them and ruined the aerodynamic tweaking putting on splash guards anyway, so I'll see them soon enough to get my summer tires on with pretty non-aerodynamic wheels.

 

[21st Century Pony]

Yeah these things break off easily on Winter road ice ridges. I busted two off my car already. They seem to break right in their center where the bend is... the forward mount point there is the breaking point.

AFAIK they are indeed to smooth / deflect airflow away from the rolling tread of the tire for a slight gain in EV "fuel" efficiency.

 

[Mach Len E]

Got the typical ‘how much gravel do you drive on’ response at dealer. Highway driving here is brutal and it is typical for manufacturers to refuse to repair rock damage. I take these responses as permission to fix it myself, so I made my own from decent mudflap material and put some protective material on front louver area for good measure. Weird thing was when I went to try my Tesla Adapter it looks like I gained 3 kWh/100km (10%) in efficiency compared to having nothing in that location. Then found an engineer on LinkedIn that said this was possible. ?‍

 

[kindofblue]

... so I made my own from decent mudflap material and put some protective material on front louver area for good measure. Weird thing was when I went to try my Tesla Adapter it looks like I gained 3 kWh/100km (10%) in efficiency compared to having nothing in that location. Then found an engineer on LinkedIn that said this was possible. ?‍

Would you please expound on that?

 

[Maquis]

Got the typical ‘how much gravel do you drive on’ response at dealer. Highway driving here is brutal and it is typical for manufacturers to refuse to repair rock damage. I take these responses as permission to fix it myself, so I made my own from decent mudflap material and put some protective material on front louver area for good measure. Weird thing was when I went to try my Tesla Adapter it looks like I gained 3 kWh/100km (10%) in efficiency compared to having nothing in that location. Then found an engineer on LinkedIn that said this was possible. ?‍

There are too many variables that cannot be controlled which affect efficiency to draw any conclusions, especially on a single trip.

 

[Mach Len E]

There are too many variables that cannot be controlled which affect efficiency to draw any conclusions, especially on a single trip.

Yes, I will expound on it. When I removed the broken wheel spats or strakes in front of the rear wheels because of rock/ice/cold damage I did notice the range I was getting was as if it was 10 or 15 degrees Celcius colder on a couple 300 km round trip commutes.

Anyway, I made my own from softer more durable mud flaps that I had imitating the general geometry and fitted at the same points taking advantage of the contours of the ones I purchased. Now, it looks like I'm back to normal. The number quoted is conservative and it was a round trip average. I don't really care about the details but seeing 34 kWh/100 km at -5C instead of -20C was kind of disturbing. Not interested in repeatability so take it at as it is.

All things being equal I like them and they probably are providing some protection.

 

[phil]

I installed some 3rd Party Splash Guards or mud flaps after looking into what the splash guards in front of the rear wheel were for since they were breaking up. From what I can tell, they’ll prevent material from the front wheels impinging on the back tire ... but further research says they are 'Wheel Strakes' or 'Wheel Spats' and are mostly for aerodynamics.

I have now had both rear "wheel strakes" break up and drag on the ground under the car. So, two of them have failed in less than four years with the car. My Mustang has never been within 100 miles of any snow or cold weather, and runs almost exclusively on smooth streets and highways. I wonder why there are so few reports regarding this part on the forum.

The first one I got replaced under warranty. Now that it appears that these parts fail frequently, and since they don't seem to serve any important function, I'm thinking I will not get the second one replaced. They seem to be more trouble than they are worth. I just pulled off the remaining portion of the broken part so it doesn't scrape along the ground.

My dealer wants $74 to replace one strake - and that's in American dollars!!! - so I figure that's more than 3x what OP was quoted in Canada.

 

[markboris]

I have now had both rear "wheel strakes" break up and drag on the ground under the car. So, two of them have failed in less than four years with the car. My Mustang has never been within 100 miles of any snow or cold weather, and runs almost exclusively on smooth streets and highways. I wonder why there are so few reports regarding this part on the forum.

The reason there are so few reports on the forum of these rear air deflectors coming loose and breaking off is because in 2021, they were attached with one bolt underneath and two push pins front and rear. Starting in 2022 on the front push pin was replaced with a bolt and they rarely, if ever come loose.

 

[geeklifer]

I had one hang off after some road debris missed my tire but hit this thing. The dealer threw a push pin in the open hole and that held....for about a week. I then just removed mine since it was scraping the ground everywhere. I'm sure there is something missing on the back of the push pin that made it fail so quickly again. I may have the dealer take a look at it when I send it back in for one of the current recalls or issues popping up.

 

[phil]

The reason there are so few reports on the forum of these rear air deflectors coming loose and breaking off is because in 2021, they were attached with one bolt underneath and two push pins front and rear. Starting in 2022 on the front push pin was replaced with a bolt and they rarely, if ever come loose.

Thanks Mark, good to know.

If they can use the new bolt rather than the old pin, I may go ahead with the replacement. Even though $74 each still seems excessive...

 

[devyces]

I had one hang off after some road debris missed my tire but hit this thing. The dealer threw a push pin in the open hole and that held....for about a week. I then just removed mine since it was scraping the ground everywhere. I'm sure there is something missing on the back of the push pin that made it fail so quickly again. I may have the dealer take a look at it when I send it back in for one of the current recalls or issues popping up.

Same issue with horrible scrapping noises, minus the dealer involvement. I found this part for less that $25USD with shipping, so am replacing it more out of perfectionism than anything else since I put on mudflaps similar to OP as well.

Stone Deflector: https://ford.oempartsonline.com/oem-parts/ford-deflector-lj8z5811398f

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