Underbody Suspension Rust

[champignon]

My 1M lived its first 3.5 years in Toronto, including 3 winters during which it was driven. When I received the car I noticed that there was quite a bit of visible rust on various suspension parts, with chipping of whatever coating used to be on them and significant rust in those areas. There was also road salt, caked on, on the underside of the car to noticeable thickness.

Most of the underbody and the body itself is pretty well protected from rust, but some of the suspension parts are not and hence were rusted. My mechanic at the local BMW dealer commented when the car was up on the lift, that the car had way more rust than he is used to seeing in this part of the country (Idaho).

None of the rust is deep enough to have any impact on performance or to be likely to rust through anytime soon, and the body panels are fine, it's just parts of the undercarriage that are involved.

I posted about this several months ago on this or another BMW forum (I forget where) and ultimately was convinced to use a "rust converter," called Corroseal, which is applied after the undercarriage is cleaned and thicker rust is brushed off. Corroseal is apparently used by the US Navy, who thinks highly of the stuff. It turns rust black and converts it (supposedly) to an inert form of iron that forms a protective coat, and that doesn't progress further. It is recommended however to put a paint or sealant or undercoating on top of it, however.

I've power washed the car several times, including intense attention to the undercarriage, and all the salt and whatever else down there were removed. I put the car up on a lift yesterday and wire-brushed off any rust that looked at all thick (there wasn't much but a little bit of the original coating came off in some places), then test-applied the Corroseal to about 1/4 of the affected undercarriage and in fact it does seem to work as advertised. The Corroseal goes on like a thick milky suspension, turns the superficial rust black, and leaves a slightly shiny clear coat over everything else. I then, today, did the rest of the undercarriage and suspension that had evidence of rust, as much as humanly possible although there are places you obviously just can't get to with your arm, hand, and a paint brush. The underside now has no visible rust and seems to be well coated with this stuff.

I am at this point trying to decide whether or not to do anything else. My intention is to use this vehicle as a "garage queen," sunday driver type car, only in good weather and never in snow or in the winter. The climate where I live is quite dry and we are far from the ocean and salt breezes. Metal does not corrode much where I live.

I did buy some cans of 3M "Professional" Rubberized Undercoating in the spray can. My original intention was to apply two coats of this stuff on top of the dried Corroseal to "lock in" or protect the effects of the Corroseal. It's probably going to be a bit difficult to spray this undercoating very accurately and even with masking it may make a big mess. But, I have no experience with this product so perhaps I'm worrying too much.

My question is whether there is any point in doing anything else to the underside of this car, given what I have already done, and how the car is going to be used, going forward. All comments appreciated.

[IEDEI]

that's not really rust, right?...just oxidation and corrosion probably. you aren't going to see actual rust in 3.5 years of even heavy snow use. The subframes are aluminum on the 1M (E9X M3 subframes) so those won't have rust but will corrode to create an outer protective layer.

I have driven my 1M hard through snow and don't see any rust....just standard corrosion you'd see in any car after being driven through wet weather. Doesn't cause any actual harm...as it's an inherently limited process if cleaned somewhat regularly.

[champignon]

Originally Posted by IEDEI

that's not really rust, right?...just oxidation and corrosion probably. you aren't going to see actual rust in 3.5 years of even heavy snow use. The subframes are aluminum on the 1M (E9X M3 subframes) so those won't have rust but will corrode to create an outer protective layer.

I have driven my 1M hard through snow and don't see any rust....just standard corrosion you'd see in any car after being driven through wet weather. Doesn't cause any actual harm...as it's an inherently limited process if cleaned somewhat regularly.

The aluminum parts looked fine, but there's a lot of steel on the underside of these cars, either that, or I've seen aluminum turn into red rust for the 1st time :-)

The iron/steel has some sort of protective coating on it which clearly comes off if any sort of debris hits the underside, which I'd imagine happens every day in normal driving. Once the protective coating comes off, then the steel underneath RUSTS.

I've spent a fair amount of time under this car already, up on the lift 3 or 4 times with mechanics, plus in my garage because I now have lifts.

I would imagine that if the former owner had bothered to clean the underside of the car very regularly in Toronto, the problem would have been way less obvious, but the fact that I found caked road salt 1/8 or 1/16" thick on the underside at delivery tells me that he didn't put out any effort to keep the underside clean.

[IEDEI]

Originally Posted by champignon

The aluminum parts looked fine, but there's a lot of steel on the underside of these cars, either that, or I've seen aluminum turn into red rust for the 1st time :-)

The iron/steel has some sort of protective coating on it which clearly comes off if any sort of debris hits the underside, which I'd imagine happens every day in normal driving. Once the protective coating comes off, then the steel underneath RUSTS.

I've spent a fair amount of time under this car already, up on the lift 3 or 4 times with mechanics, plus in my garage because I now have lifts.

I would imagine that if the former owner had bothered to clean the underside of the car very regularly in Toronto, the problem would have been way less obvious, but the fact that I found caked road salt 1/8 or 1/16" thick on the underside at delivery tells me that he didn't put out any effort to keep the underside clean.

yeah the caked salt is weird......i almost always get an undercarriage wash done after big storms or somewhat regularly in the winter.

considering that you will not be driving it in snow.....you should be fine either way. 3+ years isn't a long time...now that you've cleaned it, etc....it should be ok for a while!

[swagon]

Eh, they're made in Germany, and they've got snow and salt there, too.

One of the first things done to the car was this: got the underbody coated in some sticky shit that prevents rusting.

[Iron Man]

Originally Posted by IEDEI

that's not really rust, right?...just oxidation and corrosion probably. you aren't going to see actual rust in 3.5 years of even heavy snow use. The subframes are aluminum on the 1M (E9X M3 subframes) so those won't have rust but will corrode to create an outer protective layer.

I have driven my 1M hard through snow and don't see any rust....just standard corrosion you'd see in any car after being driven through wet weather. Doesn't cause any actual harm...as it's an inherently limited process if cleaned somewhat regularly.

Rust is oxidation (iron oxide) and both are forms of corrosion.

[champignon]

Is anyone here knowledgeable about what I posted about, above, rust "converters" like Corroseal, and whether it would be worthwhile for me to do anything else to the car beyond what I have already done, given the circumstances, above?

I am not the original owner of the car, I bought it when it had 3.5 years of age, from an owner living in the epicenter of winter road salting, who appears not to have put any effort into keeping the undercarriage clean during the 3 winters it lived in Toronto?

Thanks.

[MightyMouseTech]

Originally Posted by swagon

Eh, they're made in Germany, and they've got snow and salt there, too.

One of the first things done to the car was this: got the underbody coated in some sticky shit that prevents rusting.

Nothing like what we use here in Ontario. In fact, Ottawa has the highest salt use of any municipality in the world.

[IEDEI]

Originally Posted by Iron Man

Rust is oxidation (iron oxide) and both are forms of corrosion.

I agree...but generally when we refer to 'rust' in cars it is a more infiltrative process as opposed to oxidation which is more of a superficial process. at least that's how I always thought of it....although as you alluded to rust starts with oxidation.

[Iron Man]

Originally Posted by IEDEI

I agree...but generally when we refer to 'rust' in cars it is a more infiltrative process as opposed to oxidation which is more of a superficial process. at least that's how I always thought of it....although as you alluded to rust starts with oxidation.

It makes no difference how it is formed. Iron oxide is commonly known as "rust", which is a form of corrosion. Without oxidation of iron, you do not have rust.

[IEDEI]

Originally Posted by Iron Man

It makes no difference how it is formed. Iron oxide is commonly known as "rust", which is a form of corrosion. Without oxidation of iron, you do not have rust.

sure but for example brake discs get oxidation on them---we don't consider that 'rust'. it's not destructive. it may look like rust but it doesn't infiltrate the disc just sits on top. know what I mean!

[tock172]

Corrosion of any kind would bother me, but it's never a concern because every vehicle I've owned has spent it's entire life in California, where it is essentially a non issue, unless you live within a few hundred yards of the beach.

My questions to the OP are as follows:

1. Did you buy the vehicle knowing about the corrosion?
2. Do you plan to enter the vehicle into a concourse?
3. Are you keeping it forever or do you have plans for an eventual upgrade?

If you knew about the corrosion, have no plans to enter a concourse and aren't keeping the car for the rest of your life, I say drive it and enjoy it. From what you've told us, it already sounds like you've gone above and beyond to treat and prevent further corrosion. I say relax and enjoy the car for what it is. How old are your dampers and control arms/bushings anyway? They don't last forever as it is.

[Iron Man]

Originally Posted by IEDEI

sure but for example brake discs get oxidation on them---we don't consider that 'rust'. it's not destructive. it may look like rust but it doesn't infiltrate the disc just sits on top. know what I mean!

Rust doesn't have to be destructive. Oxidation on cast iron brakes is rust, no matter what you call it.

Not sure how much more simple I can make it, iron oxide is rust.

[IEDEI]

Originally Posted by Iron Man

Rust doesn't have to be destructive. Oxidation on cast iron brakes is rust, no matter what you call it.

Not sure how much more simple I can make it, iron oxide is rust.

i don't disagree with you. I agree with your definitions...

but in common terms, when we shop for cars...especially OLD cars we refer to 'rust' as a destructive process. Nobody refuses to buy a car because it has a film of oxidation on it.....

that being said

[champignon]

Originally Posted by tock172

Corrosion of any kind would bother me, but it's never a concern because every vehicle I've owned has spent it's entire life in California, where it is essentially a non issue, unless you live within a few hundred yards of the beach.

My questions to the OP are as follows:

1. Did you buy the vehicle knowing about the corrosion?
2. Do you plan to enter the vehicle into a concourse?
3. Are you keeping it forever or do you have plans for an eventual upgrade?

If you knew about the corrosion, have no plans to enter a concourse and aren't keeping the car for the rest of your life, I say drive it and enjoy it. From what you've told us, it already sounds like you've gone above and beyond to treat and prevent further corrosion. I say relax and enjoy the car for what it is. How old are your dampers and control arms/bushings anyway? They don't last forever as it is.

#1: I did not know about the corrosion, however since the car came out of Toronto it is, in retrospect, not surprising;

#2: No

#3: At my age, "forever" might not be quite as long as you imagine :-) If the question is, will I keep the vehicle for as long as I would be capable of enjoying to drive it, let's say (on the upside) 20 years, the answer would be "Yes"

[Iron Man]

Originally Posted by champignon

#1: I did not know about the corrosion, however since the car came out of Toronto it is, in retrospect, not surprising;

#2: No

#3: At my age, "forever" might not be quite as long as you imagine :-) If the question is, will I keep the vehicle for as long as I would be capable of enjoying to drive it, let's say (on the upside) 20 years, the answer would be "Yes"

I think you are good at this point. Cleaning everything off and coating to protect it should be more than adequate. I would just inspect everything once/year or so, but I don't think you need to worry about it.

[MightyMouseTech]

Originally Posted by IEDEI

sure but for example brake discs get oxidation on them---we don't consider that 'rust'. it's not destructive. it may look like rust but it doesn't infiltrate the disc just sits on top. know what I mean!

Rust is rust. Period. The rust on brake rotors is just very thin.

[NorthernDancer]

champignon: I think you're fine as is. Drive the car and enjoy it. As someone else has mentioned, once a year get it up on a hoist and touch up any necessary areas.

[Mr Rooty Von Tooty]

If you have a car you wish to keep for a number of years, then you must keep it off the roads during the winter season. Moisture and salt will do a number on any car. At the very least, you should do a chassis wash in the spring.

I have a small fixed sprinkler head that I place under the car at five spots, at each wheel and the middle, for an hour each. A power chassis wash is good too, but to often most shops don't do a thorough or long enough job to be worth much.

[champignon]

Originally Posted by Mr Rooty Von Tooty

If you have a car you wish to keep for a number of years, then you must keep it off the roads during the winter season. Moisture and salt will do a number on any car. At the very least, you should do a chassis wash in the spring.

I have a small fixed sprinkler head that I place under the car at five spots, at each wheel and the middle, for an hour each. A power chassis wash is good too, but to often most shops don't do a thorough or long enough job to be worth much.

This is also (obviously) dependent on where you live. Salt is used sparingly or not at all in most of the Western US, and hence one doesn't see the sort of rust damage in Western cars that one sees in the East and in the Midwest.

I intend to drive my 135i during the winter; in fact I recently bought a set of Blizzaks and an extra set of wheels for it. I will, however, keep the underside clean, as much as possible, and I've never heard of, no less seen, significant rust in cars used year round in my area (Idaho Rocky Mountains) as I see on this 1M purchased out of Toronto.

Thanks for your comments, please keep them coming!

[IEDEI]

Originally Posted by MightyMouseTech

Rust is rust. Period. The rust on brake rotors is just very thin.

true! but nobody avoids buying a car for a bit of film!

[autosense]

Can you share a pic of the underbody?

I'm actually going through a similar situation. Based on my situation, we could replace the bolts with new ones? on the control arms, exhaust, and other areas.

Where could we get replacement bolts/fasteners? I'm sure on ECS but what are their names?

after cleaning did you apply protectants? Like AMMONYC's wheel protection? or other "wax" type products?

Can you share a pic?