yeahkkyle

Just something for others to look out for. I'm not usually this picky about a car but being this is my first brand new car I'm trying to keep it like new as long as possible. I pulled the wheels off today to clean the brake dust off good and noticed the front knuckles are already starting to get surface rust on them. My car only has 560 miles, never driven in the rain and stays in a garage but must just be from the moisture. I'm going to wire brush the knuckles to get all the surface rust off and put a coat or two of paint on them to stop any future rust.




Also figured I'd share, if anyone is looking for a good brake dust removing product. I used CarPro Iron-x on the wheels, let them sit for 3-5 minutes and scrubbed them with soap. Brake dust came off like nothing. I then coated the wheels with some CarPro Reload to help keep some of the dirt and dust off them. Also amazed at the amount of wheel weights to balance the tire.

ednigma

Thanks for the pix,

Regarding the number of wheel weights, this can happen when the imbalance of the wheel and the imbalance of the tire lines up on the same side. I usually request the the tires be mounted on a Hunter Road Force Balancer. The Hunter machine spins the tire and presses it against a heavy drum to simulate the road force the tire would experience on the car. When the machine senses a large imbalance, it tells the installer where the heavy spot is and tells the installer to remount the tire 180 degrees and then does a rebalance. Usually the number of weights used is much less. I had a problem with vibration and tried getting it balanced twice and the best I could get was no vibration until about 65mph. One guy I worked with said to get an on-car balancing. Another guy whose father was head mechanic at a BMW dealership told me NOT to get on-car balancing (you can't rotate the tires and if you remove the wheels, they have to be put back on in the same orientation), he said that the BMW dealership uses the Hunter machine. The cost was the same as the balancing jobs I got before, but I noticed that one wheel/tire had zero weights and the car was smooth as glass at close to 100mph (shhhh!, no cars were around on a four lane section of the interstate). I know the Discount Tire near me has one of these Hunter machines and the local Costco also has one, but make sure to ask if the tire technician is properly trained on the Hunter.

Wander

The knuckle appears to be cast iron and the surface rust is normal and harmless. If you didn't have your nose stuck into your RDX's tender parts, you would never know. If you paint it, the rust will return.

Sometimes cast iron parts have a thin coating, but if you have ever cooked with cast iron you know that doesn't last very long.

If you can't resist messing with it, be careful. You don't want to damage the hydraulic brake lines or the sensors in that vicinity, and you don't want to contaminate the braking surfaces.

MI-RDX

Some iron alloys are designed to develop surface rust that acts as a protective barrier (I don't know if that's the case here) that will only go a few 1/1000ths of an inch deep and then stabilize.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5459218/

More likely in this case though the rate of rust penetration will be so slow on that particular component due to it's mass that the part will last much longer than the rest of the car.

yeahkkyle

I understand structurally the knuckle is going to be sound even with surface rust. I'm just saying the fact that everything else behind the wheel is painted and then the knuckle is just completely bare. Eventually that just leads to rust drops on the wheels and in the future changing the front strut out will be even more of a hassle. A coat or two of paint will keep it looking good and help in the future for maintenance.

ednigma

I've never used this stuff before, but I remember someone on another forum a while back talked about a brush on coating from Germany that turned surface rust into a hard black coating, I don't remember the name but this stuff sounds a bit like it.

https://www.kbs-coatings.com/RustSeal.html

Googling "rust coating" brings up several maybe related type of coatings

If you try it out, be sure to post back.

97ws6

POR-15 is a nice product.

ednigma

Reading a little more, RustSeal seems like an epoxy type coating, the other type of rust treatment was a product that claimed to convert rust into an inert black substance, again I forget the name since it was from Germany and was mentioned on a BMW forum. Have a look at this link for a description of a rust converter, again no personal experience.

https://www.theruststore.com/Rust-Co...-FAQs-W48.aspx

yeahkkyle

I use Fluid Film on the underneath of all my cars being in the NE. I bought my 03 Jetta tdi with 156k miles from a guy in Vermont who swore by the stuff and after looking underneath I was pleasantly surprised by how clean it was. At around $35 a gallon and can be applied either with a brush or spray gun its worth it. Goes on like a jelly and hardens to a wax almost in the colder weather. I coated both my wife Jetta and mine last year and used roughly 1/8 gallon so it goes a long way. I plan on just painting the knuckles with some black paint and then this fall I'll coat the whole underneath with the Fluid Film.

https://www.fluid-film.com

Rocket_man

I don't think it is that some parts are painted and some aren't, but rather they are a different material. The cast iron knuckle was made out of cast iron for a reason. Maybe it is slightly more flexible than the steel parts and is part of the design of the suspension? Not really sure but I'm sure there is a reason it is made out of a different material.

Stew4HD

I vaguely recall a very similar picture of the front suspension parts on the TL and TLX. I don't think this is something new

quantum7

^^^ yeah....I recall some TLX pics showing the same early rust.
This Fluid Film is something that I would consider for any new car, esp if you plan on keeping for a long time.
The suspension on my 07 TL has rust but the big problem is not long term failure of parts as much as seized nut/bolts. I have had multiple occasions where removing a bolt is virtually impossible because of rust. I like to do my own work so having non-rusted parts is very appealing. Fluid Film seems to have very good reviews and seems like a perfect solution.

yeahkkyle

I also do all my own maintenance as well and do plan to keep the car for 10-15 years so any protection helps. Nothing worse than doing maintenance that should only take 30 minutes and it turns into a 2-3 hr job because of a stubborn bolt or rusted part. I usually also use a little bit of anti-seize on bolts or molykote p-37. A little bit goes a long way for removing the bolts in the future.

Wander

Cost comes to mind. The complex shape is amenable to casting. Forged steel is supposed to be superior, but it requires specialized machinery to fabricate. Apparently cast aluminum is another option. Don't neglect tradition and decades of data on the properties of a part made of a certain material, including fatigue life. Sucks when the front of the car falls apart on the Interstate.

Amongst our current and past fleet of Honda/Acura products, some had a coating on the cast iron steering knuckle when they were new, and some didn't. But the surface rust is most obvious when it just starts and it is bright orange. It mellows with age.

Rocket_man

That makes sense. Complex shape, only a few mating surfaces to machine. And by not coating it they could afford to make the front turn signals LEDs lol

37tzee

Wow!

And I thought I was OCD!

That part will outlive all of us.