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Dissimilar metal corrosion


E30TECH

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Let me start off by saying it has been about 20 degrees with 40 MPH gusts along with ice on the road.....

 

I took the front fender off the RT to install the Fenda Extenda - while doing so, I found the top 2 bolts seized in place. I didn't realize they had seized until I was holding the head on the bolt while the threads where still in place.

 

I ended up breaking the 2nd bolt so I could get the fender off and soaking the area in some Boeshield T-9 hoping it would penetrate the threads and allow me to remove the threads from underneath with a pair of vise grips.

 

I was able to get the one side out with a little trouble. The other side didn't have the same amount of threads protruding. The vice grips kept slipping off. So I decided to take my dremel and put a slot in the bottom of the threads. I couldn't get a good bite with a screwdriver, so I had to remove the front tire. I was able to move the threads a little, so I threw some heat on the situation. After a few minutes of fighting it, the bastard broke free.

 

The bracket seems to be powder coated aluminum. I noticed some bubbling under the paint, so I took the dremel and removed the loose paint, cleaned it, masked it, and painted it with POR15.

 

Is this a common thing with BMW bikes? There seems to be some corrosion in strange places on my RT.

 

I have 2 new bolts on order and plan on coating them with never seize to avoid this in the future.

 

BTW - Now I can really get in there and polish those pipes!

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Region dictates corrosion issues on most anything. Ask the brits. Their bikes are subject to some big time corrosion and it all starts with a little rock ding or chip.

 

As you stated dissimilar metals do have reaction issues and a anti seize is a good idea.

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Region dictates corrosion issues on most anything. Ask the brits. Their bikes are subject to some big time corrosion and it all starts with a little rock ding or chip.

 

As you stated dissimilar metals do have reaction issues and a anti seize is a good idea.

 

Brits here thumbsup.gif Over here we do have quite a bit of corrosion, only due to a road department, that throws rock salt down at the slightest whiff of a cold morning.

 

I use AS8 from Snap On, copper/graphite blend with a high temp threshold.

 

I also use Starbrite Liquid Electrical Tape,Forms a protective, waterproof, UV resistant, dielectric coating Prevents corrosion on wires and terminals, it seems to keep the corrosion at bay.

 

When ever I get a new BMW, normally 4-5 years apart, I strip the fairing totally and go around and clean up any bad welds that have already started to rust, and cover them with BMW wax-oil, just again to keep the rust at bay thumbsup.gifthumbsup.gif

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I was just reading Boffin's report on his battery search/replacement, he's a UK guy here, I see a picture on his posting on his new RED battery and in front of that is a alloy part with just the start of corrosion. His bike is a 2004 according to his profile.

 

That just seems to be a awfully young age for a BMW to start corroriding away.

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The top fender bolts on my LT are Blue Loc-Tited on!!

 

Pat

 

Blue locktite should break away fairly easy as it is a low to medium strength. The side bolts of the fender had slugs built into them. I suppose it is possible that the bolts were loctited. The thought it corrosion since there was evidence of it around the bolt sticking thru the bracket, as well as some bubbling coming thru the paint.

 

only due to a road department, that throws rock salt down at the slightest whiff of a cold morning.

 

They do the same thing here in the North East. We had a slight dusting of snow which has since melted. The roads have a nice coating of a glistening white crust.

 

When ever I get a new BMW, normally 4-5 years apart, I strip the fairing totally and go around and clean up any bad welds that have already started to rust, and cover them with BMW wax-oil

 

This is a shame that you would even have to do that! Rust on a brand new bike? I'll have to do a search for BMW wax-oil. I've never heard of it. The cars used to be sent over to the states with a cosmoline coating - I guess they dont do that with the bikes (as they are crated).

 

I have some corrosion on the transmission - it is that white coating that bare aluminum gets. I'm assuming this is normal, but I was thinking about dousing it with some WD40 and wiping it down.

 

Do any of you spray the bike down with WD40 if the bike is going to sit for several months?

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Do any of you spray the bike down with WD40 if the bike is going to sit for several months?

 

Probably THE most over rated product in automotive history, WD-40.

 

And no I would wash the bike thoroughly, dry it well, polish it, and as long as it is in a garage that is not exposed to too much temp. variables, kiss it good-night.

 

For products that really work check this out.

 

http://www.lpslabs.com/products.asp

 

I have worked as an A&P in the northwest on float equiped AC and in the Peruvian jungle.

Corrosion, corrosion, corrosion, did I mention corrosion?

These are some of the products we relied on to prevent and stop corrosion and free up corroded threads.

I am sure we have lots of folks here who have experience with these and others but now these products are more available to the general public and I would suggest checking them out.

WD-40 is basically varsol. Long term protection just isn't its long suit.

 

I would concur you are looking at dissimilar metal corrosion, the dreaded galvanic reaction.

ANY time you have two different metals in contact with each other you have the potential for it, generally you want something between them that is neutral, salt water ain't it.

 

Want to join the club?

 

http://www.corrosion-club.com/galvanic.htm

 

 

No affiliation BTW.

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This is a shame that you would even have to do that! Rust on a brand new bike? I'll have to do a search for BMW wax-oil. I've never heard of it. The cars used to be sent over to the states with a cosmoline coating - I guess they dont do that with the bikes (as they are crated).

 

I have some corrosion on the transmission - it is that white coating that bare aluminum gets. I'm assuming this is normal, but I was thinking about dousing it with some WD40 and wiping it down.

 

Do any of you spray the bike down with WD40 if the bike is going to sit for several months?

 

The BMW wax I have, is an old tin from when I used to Work at BMW. It is called Cavity Protection (HOHLRAUMSHUTZ) Part No: 81-22-9-407-479

 

waxoyl

 

 

The only reason I coat the subframe, is there are loads of nooks and crannies where water will sit for ages, and eventually corrode, as these are also the areas, where there is usually the least amount of paint, and some blobs of weld spit and flux.

As for using WD40, well I apply that to the bike after it has had a good wash and is totally dry, spray it liberally, and keep away from the discs.

 

The WD40 seems to keep the white corrosion on the alloy, at bay.

 

Another trick is, if you get home late and there is salt on the road, spray the WD40 all over the motor, it will protect it until you get around to cleaning it, and cleverly, when it hits the hot motor, it evaporates, up under the fairing and coats everything up there too thumbsup.gifthumbsup.gif

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[http://www.lpslabs.com/products.asp

 

I have worked as an A&P in the northwest on float equiped AC and in the Peruvian jungle.

Corrosion, corrosion, corrosion, did I mention corrosion?

These are some of the products we relied on to prevent and stop corrosion and free up corroded threads.

 

Thanks for that info. I do have a can of that LPS in my cabinet - I think it is the penetrating oil spray.

 

I mentioned WD40 since someone at work suggested it.

 

The only reason I coat the subframe, is there are loads of nooks and crannies where water will sit for ages, and eventually corrode, as these are also the areas, where there is usually the least amount of paint, and some blobs of weld spit and flux.

 

 

That makes sense, however I would have assumed a better paint job from BMW.

 

Another trick is, if you get home late and there is salt on the road, spray the WD40 all over the motor, it will protect it until you get around to cleaning it, and cleverly, when it hits the hot motor, it evaporates, up under the fairing and coats everything up there too.

Good tip - thanks.

 

Will it discolor hot exhaust headers?

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When I was buying my 02 RT last August one on the service bullitins called for replacing the front fender bolts and greasing with copper based grease

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Will it discolor hot exhaust headers?

 

Not in my experience, but I have never sprayed it directly onto a hot exhaust. Have sprayed it all over a hot engine, and had some residue go onto the exhaust, never noticed any marking though thumbsup.gif

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ShovelStrokeEd

Are we sure we are seeing dissimilar metal corrosion here?

 

Usually this requires an electrolyte of some sort. Yeah, salt water is a good one but it would have to penetrate the threads to work its evil magic. Unlikely with the bolt torqued in place.

 

I tend to suspect the thread locking compound as the culprit. I have seen Loctite 242 (the blue stuff) and 271 (the red) do nasty things to unprotected aluminum. Loctite 222 (low strength) is recommended for aluminum and that is what I would use in this application.

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Are we sure we are seeing dissimilar metal corrosion here?

 

Usually this requires an electrolyte of some sort. Yeah, salt water is a good one but it would have to penetrate the threads to work its evil magic. Unlikely with the bolt torqued in place.

 

I tend to suspect the thread locking compound as the culprit. I have seen Loctite 242 (the blue stuff) and 271 (the red) do nasty things to unprotected aluminum. Loctite 222 (low strength) is recommended for aluminum and that is what I would use in this application.

 

No, I am not 100% sure, however "salt water" could get up into those threads since this bike was in the North East (we use calcium chloride on the roads in the Winter). Since those threads are directly above a tire that could be slinging the salt water right into the wicking threads.

 

I work with all of the loctite flavors you mentioned on a daily basis, and I have them at home as well. I dont think there was any loctite on those threads. I was able to get the 'stump' that was left behind out, and there is not even a trace on the threads.

 

I'm thinking a coat of never seize should do the trick as I dont see a need for loctite there if the bolts are tightened to the proper torque.

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ShovelStrokeEd

If I remember right, the fender mounts are through holes tapped into bosses on the fork legs. In that case, you are right and there is plenty of opportunity for the slush to work its way in there. Some form of gasket, like a small nylon washer might help although you would still need to plug the back side of the hole.

 

We haven't seen snow down here in about 40 years so salt is not a problem, but, I'm no more than a mile from the ocean so salt air is a problem. More for the exterior stuff than the threads on bolts.

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My R1200RT is 14 months old, and already I am seeing slight corrosion to various plated fasteners.

 

Mostly I'm a weekend rider, and in winter, I religiously hose the bike clean after riding on wet pavement, so it is not neglect on my part.

 

Latest fun was removing a damaged luggage rack from the grab handles to fit a replacement. Plated fastenesr screw into brass bushes set within the luggage rack's plastic. Corrosion had grabbed hold so tight that when I tried to undo them, the bushes turned within the plastic luggage rack. Only way to get them apart was to take a hacksaw to the luggage rack and rip it apart.

 

My feeling is that if BMW used more stainless steel fasteners, the bikes would stay looking better, live longer.

 

Most of the corroding fasteners are the lower ones, and I think I'll probably go round and replace them with stainless. Only minor irritation being that these will have hex heads rather than the torx originals.

 

Beyond this, I have completely removed the tupperwear and dowsed the bike in ACF50. Now that IS a product that I believe in, and I'll repeat the process annually.

 

Seems to me that BMW's design engineers do a great job of creating the bike, then their bean counters go round and see where they can slice a cent or two from the production cost in all kind of trivial areas. To the detriment of quality. Completely unneccesary.

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Seems to me that BMW's design engineers do a great job of creating the bike, then their bean counters go round and see where they can slice a cent or two from the production cost in all kind of trivial areas. To the detriment of quality. Completely unneccesary.

 

Well said.

 

Andy

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Seems to me that BMW's design engineers do a great job of creating the bike, then their bean counters go round and see where they can slice a cent or two from the production cost in all kind of trivial areas. To the detriment of quality. Completely unneccesary.

 

Well said.

 

Andy

 

I have to agree as this really was my underlying point to this thread. I didn't want to be the negative one though.

 

Someone else mentioned ACF50 - but I dont think it is available on this side of the pond.

 

I sure would be interested in trying some wink.gif

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Someone else mentioned ACF50 - but I dont think it is available on this side of the pond.

 

I sure would be interested in trying some

 

TRY HERE

 

http://www.aircraftspruce.com/catalog/appages/acf50.php

 

I find these hobby aviation shops fascinating for all kinds of neat stuff.

 

Remember folks that aluminum by nature is composed of different metals and can corrode all by itself if not properly treated at manufacture. Especially if you see it under a good coat of paint it is probably because of some contamination that was there at manufacture.

 

Stainless steel is a great metal but will not eliminate corrosion from the aluminum you are threading it into. I found on my RT that some of the fasteners had been over torqued thus deforming the base aluminum castings. Stainless steel is also very unforgiving in this area and because it is really a pretty brittle metal you want to be VERY careful about substituting SS for the manufacturers original.

Shear strength, tensile strength, the ability to deform as opposed to snapping off are all taken into account when designing the bike and its fasteners. In some cases the fastener may indeed be sacrificial in nature meaning it is better that the fastener corrode, wear, deform, stretch etc to protect the integrity of the whole.

 

I wouldn't be too quick to assume the BMW engineers would permit a bean counter to screw around with their values.

 

I also would hesitate to go throwing anti-seize on everything particularly if it has a torque value. Many values are established as dry torques or wet torques. Few in my experience are 'torque with anti-seize'.

 

eek.gif

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Many values are established as dry torques or wet torques. Few in my experience are 'torque with anti-seize'.

 

eek.gif

 

Thanks for the link.

 

You are correct about the dry torque. But I would not put never seize on something critical.

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ACF50 is an American product, made by Learjet. See http://www.learchem.com

 

Very expensive and, and if you are using it to protect the frame, keep it well away from the brakes and other parts that don't appreciated extra lubrication.

 

As far as torque values go, if I replace any carbon steel fasteners with stainless ones, it won't be in any critical areas.

 

I'm unrepentant about my comment on those penny-pinching bean counters. Most of the corroding fasteners I'm looking at are not under stress.

 

Not just fasteners: why for instance have they underspecified the windshield supports on the RT, which are liable to break if you use an overized screen? I could go on...

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Remember folks that aluminum by nature is composed of different metals and can corrode all by itself if not properly treated at manufacture.
eek.gif
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I got my new fender bolts today from A&S. Since I had some items on backorder (Fernando's full sticker kit), I decided to see if they could get the bolts in the order. Turns out, they shipped the bolts seperate, and didn't even charge me shipping.

 

Anyhow - the new bolts have a slug in them so there is no need for loctite. However, I am still going to use never seize on them.

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