how to prevent bolts to rust?

[spock]

Hello guys and gals

Today I took care a little of the wonderful fz6 - installing new rear tire, washing, cleaning, lubricating some parts and when removed my front break calipers I noticed those bolts had a little rust on them, nothing big so I can get them off and on without problems, but anyway the rust is getting there.

What can apply to them to prevent more to appear, some lubricant, maybe a thin layer of white lithium grase (I have a can of 3 in 1 one), wd-40 ?

I really appreciate your help.

Cheers :thumbup:

 

[RJ2112]

Hello guys and gals

Today I took care a little of the wonderful fz6 - installing new rear tire, washing, cleaning, lubricating some parts and when removed my front break calipers I noticed those bolts had a little rust on them, nothing big so I can get them off and on without problems, but anyway the rust is getting there.

What can apply to them to prevent more to appear, some lubricant, maybe a thin layer of white lithium grase (I have a can of 3 in 1 one), wd-40 ?

I really appreciate your help.

Cheers :thumbup:

A picture would help. Depending on where the rust is forming, the answer changes. Applying anything to bolts that are closely associated with brake calipers is potentially dangerous. If you grease the bolts, can the lubricant fall onto the rotor or pads?

Is the rust forming at the edges of the bolt head, where you apply the tool to remove and replace? On the threads themselves?

 

[Goop]

I had bad rust problems on my front rotor bolts. I removed them (required an impact driver to get them off to avoid stripping the hex head), sanded them down and painted the heads with black Rustoleum paint.

 

[spock]

Thanks for your answers mates

Now here we go with the photos, please take a loot at them

 

[youngy]

you want a smear of copper grease on the threads to stop them corroding and seizing in.

 

[RJ2112]

The corrosion on the threads is due to the presence of moisture, and the two dissimilar metals. The steel bolt, and the aluminum of the brake caliper body. The steel attracts the lighter metal, because it is the cathode in the circuit.

The only way to prevent this sort of corrosion is to prevent the water from entering the threads. You can see the damage is worst near the bolt head, and is almost not present at all at the far end of the bolt.

I would use a wire brush and remove all of the deposits from the bolt, or use a new bolt in it's place. The real issue is that there are now less threads available to hold the bolt in place. All of the aluminum that has migrated to the steel has been removed from the threads on the block. It's safe to say you only have about 1/3 of the thread area remaining to hold the bolt in the caliper.

New bolt will not repair the lost threads in the caliper. Less threads increases the risk of stripping out what remains, if you over torque the bolts when you put them back in.

I would consider re-threading the damaged holes one size larger, and replacing the bolts one size larger as well.

If not, I would clean the bolts, add some teflon tape to fill the voids to prevent further water intrusion, and look for a compression washer to seal between the bolt and the caliper body.

 

[youngy]

That's not an aluminium deposit on the bolt, it's oxide - the threads have not been removed from the caliper. The bolts will work just fine. The holes do not need to be rethreaded. Coppaslip will stop this re-occurring.

 

[RJ2112]

That's not an aluminium deposit on the bolt, it's oxide - the threads have not been removed from the caliper. The bolts will work just fine. The holes do not need to be rethreaded. Coppaslip will stop this re-occurring.

Just curious how you make that assumption. Where do you think the oxide came from?

 

[youngy]

Just curious how you make that assumption. Where do you think the oxide came from?

25 years of dealing with corroded Japanese brake caliper bolts. Obviously the oxide came from the parent metal, not outer space, however the amount of oxide is negligible and will not have detracted from the mechanical strength of the thread. The white stuff is from the fork leg where the bolt passes straight through. The bolt has a plain shoulder and a lead in to make it easier to locate in the hole.

So............. how did you make your assumption?

 

[RJ2112]

25 years of dealing with corroded Japanese brake caliper bolts. Obviously the oxide came from the parent metal, not outer space, however the amount of oxide is negligible and will not have detracted from the mechanical strength of the thread. The white stuff is from the fork leg where the bolt passes straight through. The bolt has a plain shoulder and a lead in to make it easier to locate in the hole.

So............. how did you make your assumption?

30+ years of dealing with dissimilar metallic corrosion.:thumbup: USN for 20 years, living on farms roughly 20 other years.... lots of weather exposed bits and pieces and years and years of wrenching on stuff.

If, as you say, the area that is corroded is not actually used for threaded contact, brush it off, and weather proof it. Why didn't they use shouldered bolts, rather than leave all those threads to corrode?

 

[TownsendsFJR1300]

I'd clean the threads with a wire brush and put some anti sieze on the threads. It'll keep the bolt from rusting and seizing to the aluminum... (Make sure the hole is clean, run the bolt in and out once or twice and blow out with an air compressor if available).

Same for spark plugs, front brake master cylinder phillips head screws. They tend to corrode/stick with age, time, weather.



BTW, DO NOT drill and tap the hole for a larger bolt, there's nothing wrong with what you have unless you pulled some threads out. It'll be fine...

 

[youngy]

30+ years of dealing with dissimilar metallic corrosion.:thumbup: USN for 20 years, living on farms roughly 20 other years.... lots of weather exposed bits and pieces and years and years of wrenching on stuff.

If, as you say, the area that is corroded is not actually used for threaded contact, brush it off, and weather proof it. Why didn't they use shouldered bolts, rather than leave all those threads to corrode?

ah another old relic :thumbup: ..................... I'd say those bolts are the same ones Yamaha have used for that application since they started fitting hydraulic disc brakes.......... and they never thought to change the design.

 

[TownsendsFJR1300]

25 years of dealing with corroded Japanese brake caliper bolts. Obviously the oxide came from the parent metal, not outer space, however the amount of oxide is negligible and will not have detracted from the mechanical strength of the thread. The white stuff is from the fork leg where the bolt passes straight through. The bolt has a plain shoulder and a lead in to make it easier to locate in the hole.

So............. how did you make your assumption?

+1 on the above.....

 

[spock]

Thanks all for the replies and for the nice technical discussion

I will proceed to get and applying copper grease.

Cheers and ride safe!