Rear subframe rust

[CTquattro21]

Just wanted to post an fyi for everyone that encounters salted roads in winter. I have a ‘15 SQ5 with ~65k miles. I saw some rust while putting on my summers. I know there’s usually some surface rust but felt this was a little worse than that.

IMG_1501.jpg

Had a frame guy take a look and he confirmed that it was more than surface rust. So I decided to just replace the whole thing. Just had the new one installed and this is what was under the plastic panels on the bottom of the subframe.

Image1651799857.971354.jpgImage1651799872.292313.jpg

Had the new one coated and the plastic panels removed.

[kt883]

cant hurt to replace it but I think you're years away from seeing any real issues form that sort of rust. Pretty standards for any car in the rust belt

[CTquattro21]

cant hurt to replace it but I think you're years away from seeing any real issues form that sort of rust. Pretty standards for any car in the rust belt

You do realize the large hole in the second picture is supposed to be solid metal right? This is more than surface rust. There is material missing. I agree a failure wasn’t imminent but my family rides in this vehicle so why wait. Again just an fyi.

[pdnation]

When I bought my ‘14 TDI, I had a DEF leak right after that. They repaired it under warranty. Right after that, I discovered that my rear left subframe was badly rusted. It was not as bad as yours, but bad nonetheless. I pulled the plastic rock guard, wire wheeled it, and sprayed it down with POR 15. That was two years ago. It has been stable since then, but it is definitely on my monitoring list. I live in Phoenix, but I bought the car from the Midwest, so I don’t know if the rust was there when I bought it or the DEF spraying the entire underside of my car caused it. I do know those rock guards hold an unnecessary amount of moisture in place up against the metal.


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[RPMtech147]

That's pretty minimal. I'll be cutting the control arms out of my A3...cuz rust.

= (

[CTquattro21]

When I bought my ‘14 TDI, I had a DEF leak right after that. They repaired it under warranty. Right after that, I discovered that my rear left subframe was badly rusted. It was not as bad as yours, but bad nonetheless. I pulled the plastic rock guard, wire wheeled it, and sprayed it down with POR 15. That was two years ago. It has been stable since then, but it is definitely on my monitoring list. I live in Phoenix, but I bought the car from the Midwest, so I don’t know if the rust was there when I bought it or the DEF spraying the entire underside of my car caused it. I do know those rock guards hold an unnecessary amount of moisture in place up against the metal.


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I was thinking wire wheel and coat with POR15 at first. But the frame guy confirmed I was beyond that and wanted to start cutting out and replacing sections. Thinking there was more under that plastic I just replaced the whole thing. Like you said that plastic is perfect for allowing salt and moisture in and keeping it there and hidden from sight.

[CTquattro21]

That's pretty minimal. I'll be cutting the control arms out of my A3...cuz rust.

= (

That sucks. Yeah mine wasn’t about to fail but the clock was ticking.

[Fast4esT]

wow, ive never seen an Audi frame look that bad and I am in the salt belt too

[pdnation]

Just out of curiosity, how much was it to have it replaced?


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[CTquattro21]

wow, ive never seen an Audi frame look that bad and I am in the salt belt too

That pic with the hole was under a plastic panel that Audi put on the lower half of the subframe. The plastic is a bad idea by Audi and the reason I made the post.

[CTquattro21]

Just out of curiosity, how much was it to have it replaced?


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My mechanic did the replacement in about 6.5 hours which came out to just over $800 plus tax. I got the new frame off eBay for $288 plus $125 shipping from California.Image1652137610.504952.jpgIMG_2894.JPG

[pdnation]

Yeah, I do a lot of work on mine, but from the looks of it, I would gladly pay someone $800 in labor to do that job.


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[CTquattro21]

Yeah, I do a lot of work on mine, but from the looks of it, I would gladly pay someone $800 in labor to do that job.


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My thoughts exactly

[arjun90]

I'm in the Northeast as well but my 2013 Q5 only has surface rust on the rear subframe and rarely goes outside anytime it snows. Por-15 / penetrating oils go a long way but only works well when used at the earliest. I always thought these SUV's were a little more immune to rust versus the wagons. Looking forward to tackling the pinch bolt soon

[Theiceman]

just so you guys dont feel all alone

your A4 cousins are feeling the same pain ..


2014 ..





25 year old tremclad and a dollar store brush to the rescue.

[lumberwood]

just so you guys dont feel all alone

your A4 cousins are feeling the same pain ..


2014 ..





25 year old tremclad and a dollar store brush to the rescue.

Ew! Nice work


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[SchreibCity]

Thanks to those who have posted here already. It's good to know I'm not alone. I have a '14 SQ5 at 120k miles and I need to replace my rear subframe crossmember due to rust.

I'm hoping to find a used replacement rather than buying a new part from Audi. Does anyone know whether there are other models in the Audi family (e.g., '14 Audi A8) or VAG family (e.g., '14 Porsche Macan) that use the same rear subframe and can be used as direct replacement? I guess i'm not even sure if Q5 (2.0T) or Q5 (3.0T) are direct replacements? Thanks in advance for any guidance.

[NikolaZ]

Mine is rusty as well. In the future I will have to change it.

[Fizzhole]

Quick question about this, but a little back story first. 2014 Q5 3.0 here and have been hearing weird pops and creaks for the past 6+ months. While i was under the car the other day I noticed pretty much the same situation you have here. I guess my question is, did you have and creaks or noises coming from the subframe areas at any point? I have noticed that if my approach is at any sort of an angle i sometimes get a pop and I usually have creaks when initially accelerating. Seems like its coming from the "mid to rear" area driver side. Thoughts?
Also, i am in very upstate NY with 118k on the clock. All the bushings "seem" to look good and I find myself exhausted from searching.

[CTquattro21]

Thanks to those who have posted here already. It's good to know I'm not alone. I have a '14 SQ5 at 120k miles and I need to replace my rear subframe crossmember due to rust.

I'm hoping to find a used replacement rather than buying a new part from Audi. Does anyone know whether there are other models in the Audi family (e.g., '14 Audi A8) or VAG family (e.g., '14 Porsche Macan) that use the same rear subframe and can be used as direct replacement? I guess i'm not even sure if Q5 (2.0T) or Q5 (3.0T) are direct replacements? Thanks in advance for any guidance.

Definitely find a used one. I found one on eBay for $440 shipped. A new one was something like $1300. I’m not sure about compatibility with other models but I believe all the SQ5/Q5’s of that generation have the same sub frame.

[CTquattro21]

Quick question about this, but a little back story first. 2014 Q5 3.0 here and have been hearing weird pops and creaks for the past 6+ months. While i was under the car the other day I noticed pretty much the same situation you have here. I guess my question is, did you have and creaks or noises coming from the subframe areas at any point? I have noticed that if my approach is at any sort of an angle i sometimes get a pop and I usually have creaks when initially accelerating. Seems like its coming from the "mid to rear" area driver side. Thoughts?
Also, i am in very upstate NY with 118k on the clock. All the bushings "seem" to look good and I find myself exhausted from searching.

I’ve had pops and occasional clunks since I installed diff and drivetrain inserts. I also have subframe inserts among other mods. I also have a pop just after I move the car and just before coming to a stop. The entire car has been inspected more than once and no one can find the reason for the pop. But, none of my sounds are from the rusty sub frame. I still have them all after the subframe was replaced.

[Fizzhole]

I’ve had pops and occasional clunks since I installed diff and drivetrain inserts. I also have subframe inserts among other mods. I also have a pop just after I move the car and just before coming to a stop. The entire car has been inspected more than once and no one can find the reason for the pop. But, none of my sounds are from the rusty sub frame. I still have them all after the subframe was replaced.

Good to know.... I guess, lol.
I did notice the sounds beginning around the same time I was installing inserts and RSB. It would stand to reason then that the inserts may be shifting around under load. Glad to hear that the sounds probably aren't from a failing sub frame though. Gonna slide under tomorrow and get a better look, brush some rust and see how bad it REALLY is. Hopefully its just superficial.
Thanks for the input!

[SchreibCity]

Definitely find a used one. I found one on eBay for $440 shipped. A new one was something like $1300. I’m not sure about compatibility with other models but I believe all the SQ5/Q5’s of that generation have the same sub frame.

Thanks! Managed to track down a cheap local replacement from a Q5 3.0T on car-part dot com. Haven't swapped it out yet.

[CTquattro21]

Good to know.... I guess, lol.
I did notice the sounds beginning around the same time I was installing inserts and RSB. It would stand to reason then that the inserts may be shifting around under load. Glad to hear that the sounds probably aren't from a failing sub frame though. Gonna slide under tomorrow and get a better look, brush some rust and see how bad it REALLY is. Hopefully its just superficial.
Thanks for the input!

If you still have the plastic covers over the bottom part of the subframe try to get a peak under them if you can. That’s where the worst of it was for me. They seem designed perfectly for catching salt and holding it there to achieve maximum rot. Not sure what Audi was thinking there. I had them removed from my replacement sub frame.