So, what is that soft, cardboard like material on the under body?

I have only owned my car for two weeks or so. The other day I went crawling under the car to check things out. I was very surprised at the amount of rust in some areas but the dealership mechanic assured me it is normal.

I noticed a product on the bottom of my CX-5 that I have never seen on a car before. It is like a fiber board made from plastic and maybe wood etc. and then formed into pieces that are bolted all over the under body of the car and even in the wheel arches. It is obvious what it is for. Is there a name for this product? How does it hold up long term? Has anyone seen the product hold moisture between itself and the steel under body causing rust?

Photo of the rust I was talking about:
Rust.jpg
 
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Ottawa, Ontario
:
17 Mazda 6 GT
That's a rusty rear brake caliper.
If you bought your car brand new, then there's no way it should look like that after two weeks.
If you bought it used, then that's another matter.
My 3 year old car with only 12,000 miles on it has rusty calipers and rotors that look like that.
I'm really disappointed in Mazda and the poor quality of their components.
Things start to rust on these things the day after it's made apparently.
I'm going to see my selling dealer next week to argue with them about my brakes.
I also sent a note to Mazda Canada, and their response so far....crickets.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
That's a rusty rear brake caliper.
If you bought your car brand new, then there's no way it should look like that after two weeks.
If you bought it used, then that's another matter.

My 3 year old car with only 12,000 miles on it has rusty calipers and rotors that look like that.
I'm really disappointed in Mazda and the poor quality of their components.
Things start to rust on these things the day after it's made apparently.
I'm going to see my selling dealer next week to argue with them about my brakes.
I also sent a note to Mazda Canada, and their response so far....crickets.
“If you bought your car brand new, then there's no way it should look like that after two weeks.
If you bought it used, then that's another matter.“


Agreed!
 
I bought the car two weeks ago, it is a 2017 with 14,150 miles on it.

I was kind of surprised when I saw the rust because the three year old Subaru I traded didn't have any rust even close to that.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
I have only owned my car for two weeks or so. The other day I went crawling under the car to check things out. I was very surprised at the amount of rust in some areas but the dealership mechanic assured me it is normal.

I noticed a product on the bottom of my CX-5 that I have never seen on a car before. It is like a fiber board made from plastic and maybe wood etc. and then formed into pieces that are bolted all over the under body of the car and even in the wheel arches. It is obvious what it is for. Is there a name for this product? How does it hold up long term? Has anyone seen the product hold moisture between itself and the steel under body causing rust?

Photo of the rust I was talking about:
View attachment 227093
Not sure what material of fiber like paper board is called. But there’re plenty of rust complaints either underbody or interior, especially from snow-belt area. I believe some sort of rust-proofing at least for underbody is needed for a new CX-5 in snow-belt area, and those living in Northeast and Midwest should know better, so as those Canadian CX-5 owners. I’m glad I’m in Texas and road salt is not giving us too much problem.

Just joined the club and question on rust

Rustproofing & Undercoating...is it necessary?

This CX-5 should be from Illinois:
Just spent 3 hours under my 3 year old CX-5. Did AT, Engine and 2x TC oil changes.

Rust level in various spots on 36 month car was tad too much. Mark this post, but in 4 season weather I don't see this version last 10 years.

If this is CA/FL type of no salt climate - all should be fine, but winter states beware.

This CX-5 is from Toronto area in Canada:

Here is comparison pictures between his CX-5 and Toyota Matrix from Southern New Hampshire:
Rust like that after a few years even with heavy use of salt I believe is unacceptable with today's coatings and materials to look worse than a car that is 13 years old is not acceptable. How can Mazda get away with this? I love how this car drives and looks but also want one that will last. Also very happy with fuel economy so far getting around 30.5MPG on my 100 mile round trip commute.

2005 toyota matrix/pontiac vibe - 225K miles driving 100 miles a day

View attachment 216618

2014 CX-5 (seen 2 winters) -28K miles


View attachment 216616
View attachment 216617
 

HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
I noticed a product on the bottom of my CX-5 that I have never seen on a car before. It is like a fiber board made from plastic and maybe wood etc. and then formed into pieces that are bolted all over the under body of the car and even in the wheel arches. It is obvious what it is for. Is there a name for this product? How does it hold up long term? Has anyone seen the product hold moisture between itself and the steel under body causing rust?
You piqued my interest. They're splash shields, keeping water and road whatnot away from the underparts. On my 2020, the shields under the engine compartment are plastic as are the front wheel well liners. The shields behind the engine compartment and in the rear wheel wells are of the material you describe.

I wouldn't worry about it. I've had that fibrous material in my Sienna wheel wells for 6 years, 90,000 miles with no evidence of deterioration. As for the shields trapping water and causing rust, after feeling around at the side without getting underneath I found one hole maybe the size of silver dollar, presumably a weep hole. I imagine there are others. I also noticed a gap between the engine shield and the fibrous one which looks to allow any liquid to drain out of the engine compartment.

As for the rust problem, it seems excessive for a new vehicle if that's what it is. My 2020 has a manufacture date of October 2019 with 5,000 miles and the only rust I see in that area is the washers, which may be by design. It would have seen some salt as an Ohio dealer loaner dating from February through June.

If this is an older vehicle, I'll say this much: I've had cars with this kind of surface rust caked on the non-operating surfaces of calipers for years and years without incident.
 
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2018 CX-5 Sport
If you are okay with crawling under your car and getting a little dirty, I would recommend you get a can of this and spray the rusty metal without getting any on the rotors.
Fluid Film
 
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2018 CX-5 Sport
I see that my muffler is starting to get rust. I hit that too with FF even though it gets hot. I think that rust prevention should not be a maintenance item for a modern car with the advancement in coatings.

Rust.JPG
 
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2019 CX-5 White Pearl Sig
I was also curious about the fabric material used in the wheel wells when I brought the car home from the dealer. It looked like something that would catch and hold bits of road tar or whatever and not look good after a short amount of time. As an experiment, I removed the rear wheels and sprayed the wheel wells with Scotchgard Heavy Duty Fabric Protector. After a year and 6k miles, the material still looks like new. I don't know about untreated material , but I've noticed that when I wash the car the fabric liners don't even get wet, the moisture just falls away. I was impressed enough to give our Allroad the same treatment as well when we brought it home.
 
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