13 replies to this topic

[MikeRotherham]

I'm looking for suggestions to prevent nuts and bolts and screws from rusting and preventing their removal at a later date.

 

As an example when replacing the front headlamp bowls or when rebuilding things like subframes what do people coat the threads of fixings with to prevent rust and make removing them easier?

 

Plain old grease, copper grease or would something like Loctite be any good?

 

What do you people use?

[cal844]

Grease or a small amount of engine oil

[rally1380]

Copper grease for me. Or for things like self tappers into sheet metal i use stainless screws.

 

Don't use stainless nuts and bolts for suspension components though as they're not as strong as high tensile...so in this case copper grease them.

 

But if the nut, bolt, screw can be shook loose and it is an important component (i.e. holding brakes on!!) then don't over grease and use a spring washer if spec'd or even better use loctite.  I've had greased bolts come undone before!!!

[Icey]

Nothing.

 

Any lubricants you put on threads that aren't specified by the manufacturer/service manual will alter the torque values.

 

 

With that out of the way, I use ACF50 on most things that are likely to corrode and don't have a specific torque setting (e.g body fixings).

[Spider]

For most mechanical type stuff, I use plain chassis grease. I hate Stainless with a passion, it's a crap metal and when fitted in to or on to ordinary steels, it makes the steel rust like crazy.

[Tamworthbay]

Copper slip grease for me,

[TMW.Racing]

Do not lubricate threads at all - In lubricating the threads, you will vastly reduce the friction between the bolt / nut and threaded material which can cause a number of problems! Firstly the lower thread friction can cause the joint to loosen due to the nut / bolt slipping especially in high vibration areas, especially if the lubricant has got onto the mating face of the nut / bolt and the component it is joining as this will also reduce the under head frictional force as well.

 

Also if the threads have been lubricated prior to assembly, the reduced friction from the thread (and possible from under head frictional loss) can also cause you to over tighten the joint, which can at least damage the components you are joining, but can more seriously potentially cause you to yeild the bolt (i.e. stretch the the bolt beyond its elastic limit) which will reduce the strength of the bolt leading to either a failure of the bolt whilst you are doing it up, or worse still cause the bolt to fail under load while you are moving, which could be very dangerous!

 

The best way to avoid corrosion within the bolt is to buy good quality fixings which have been given a corrosion preventative coating - this is what the major car manufacturers are doing. I speak from experience as I work in a major manufacturer's threaded joints cae analysis department!

Edited by TMW.Racing, 12 February 2015 - 10:09 PM.

[Fast Ivan]

Do not lubricate threads at all - In lubricating the threads, you will vastly reduce the friction between the bolt / nut and threaded material which can cause a number of problems! Firstly the lower thread friction can cause the joint to loosen due to the nut / bolt slipping especially in high vibration areas, especially if the lubricant has got onto the mating face of the nut / bolt and the component it is joining as this will also reduce the under head frictional force as well.

 

Also if the threads have been lubricated prior to assembly, the reduced friction from the thread (and possible from under head frictional loss) can also cause you to over tighten the joint, which can at least damage the components you are joining, but can more seriously potentially cause you to yeild the bolt (i.e. stretch the the bolt beyond its elastic limit) which will reduce the strength of the bolt leading to either a failure of the bolt whilst you are doing it up, or worse still cause the bolt to fail under load while you are moving, which could be very dangerous!

 

The best way to avoid corrosion within the bolt is to buy good quality fixings which have been given a corrosion preventative coating - this is what the major car manufacturers are doing. I speak from experience as I work in a major manufacturer's threaded joints cae analysis department!

 

correct

[nicklouse]

Do not lubricate threads at all - In lubricating the threads, you will vastly reduce the friction between the bolt / nut and threaded material which can cause a number of problems! Firstly the lower thread friction can cause the joint to loosen due to the nut / bolt slipping especially in high vibration areas, especially if the lubricant has got onto the mating face of the nut / bolt and the component it is joining as this will also reduce the under head frictional force as well.
 
Also if the threads have been lubricated prior to assembly, the reduced friction from the thread (and possible from under head frictional loss) can also cause you to over tighten the joint, which can at least damage the components you are joining, but can more seriously potentially cause you to yeild the bolt (i.e. stretch the the bolt beyond its elastic limit) which will reduce the strength of the bolt leading to either a failure of the bolt whilst you are doing it up, or worse still cause the bolt to fail under load while you are moving, which could be very dangerous!
 
The best way to avoid corrosion within the bolt is to buy good quality fixings which have been given a corrosion preventative coating - this is what the major car manufacturers are doing. I speak from experience as I work in a major manufacturer's threaded joints cae analysis department!

Shame that the car makers still can't get it right though.

To change a side light bulb on my car I had to undo a number of bolts and cross head machine cut screws. 75% of them failed.

And this was the first time they had been undone.

[nicklouse]

Ps, I use an anti seize compound.

[jakejakejake1]

Depending on where the nut/ bolt is, I often apply grease on any protruding threads that stick out of the nut, that prevents the protruded section rusting, as well as preventing water getting into the threads. 

It also doesn't have any effect on torque values as its only applied after the thing has been tightened. 

Also the grease should stay put, but won't penetrate the threads and loosen them or anything. 

And example where I do this is the thermostat studs that protrude up through the nuts, after having one shear off previously I don't want to risk it again! 

[Icey]

after having one shear off previously I don't want to risk it again! 

 

Just the one, you lucky, lucky person

[spiguy]

I have recently taken to putting a wee squirt of bilthamber dynax wax on to protruding threads to prevent corrosion. Seems to work, 6 months on and no surface rust on those that have been done.

[MikeRotherham]

Thanks for all the input.

 

I was aware not to grease wheel nut threads.

 

I'll look into anti seize compound.

 

The suggestion about coating exposed threads is a good one too

 

I'm only thinking about rebuilding lights to bodywork at present.

 

I always try and use zinc coated nuts and bolts.