40 replies to this topic

[JonnyAlpha]

Hi;

 

When I refit my Subframe I have read that it is good practice to use Copper Grease on the Mounting Bolts to prevent corrosion. 

I am also cleaning up my Radius Arms and Hubs and the Haynes Manual says to apply High Temp Grease to the moving parts of the Brake Shoes and Backplate, the picture in the manual is Copper Grease?

 

So assuming that there is only one type of Copper Grease (This Stuff) I'll be using it as follows:

 

1. Rear Sub Frame Mounting Bolts (Captive Nuts in the Heelboard)

 

2. Moving Brake Parts.

 

Question:

 

When refitting the Brake Pipes and Hoses can copper grease or any other long lasting lubricant be used in the brake union nuts, the ones that secure the Copper Pipes to Brass Unions and Flexible Hoses? Or is there a possibility of it contaminating the brake system? The reason I asked is because some of these where corroded when removed?

 

Should it also be used around the nuts and threads that hold the Brake Unions and Pipes to the Subframe / Radius Arm Brackets is should these just be greased with some other type (if so what)? 

 

Thanks

[henri1972]

i would only use copper grease on the brakes use normal LM grease for bolts

[r26megane]

I've pondered this is the past and this is what I decided...

 

Grease on the bolts effects the torque setting you're tightening them too. Therefore it wouldn't be wise to grease any bolts that are structural or safety critical which need a specific torque setting that aren't specified as needing greasing in the manufacturers documentation. 

 

For example, rear subframe bolts weren't greased by the factory and are designed to be tightened to a certain value. In this case I wouldn't grease them. How much the grease effects the torque and whether or not this would have any actual real world implications is another story but my stance would be to do something as designed rather than take a chance.

[henri1972]

it would only affect the torque if it was going into a blind hole where the grease would cause pressure at the end of the bolt seeing as the heel board is open then the bolt could be torqued up

[cal844]

We use copper grease on

heelboard bolts(only a smear)

On every other bolt on the subbies 

On the brake shoe and pad touch locations(on the calipers, and backplates)

[Coxie]

I've put it on all nuts and bolts.
I was advised to by the mechanic in the workshop next to mine.

[r26megane]

it would only affect the torque if it was going into a blind hole where the grease would cause pressure at the end of the bolt seeing as the heel board is open then the bolt could be torqued up

 

Can't say I agree with you on that one but each to their own. As stated... probably won't make a difference but I wouldn't.

[bikewiz]

Any lubricant affects the torque rating. You can find multiple charts online that give you the difference like this one http://www.mechanics...olt_torque.html

I use copper never seize on anything that needs to come apart again in a high corrosion area of the car, with the exception of lug nuts, and adjust the torque rating accordingly. The factory didn't do it because they never think so much about taking things apart and the time to lube threads would slow production.

[Gremlin]

Of course it would make a difference to the torque setting, it reduces the friction therefore the same turning force is doing the bolt up tighter because more of the force goes into clamping rather than overcoming friction

[bikewiz]

Of course it would make a difference to the torque setting, it reduces the friction therefore the same turning force is doing the bolt up tighter because more of the force goes into clamping rather than overcoming friction

Most people don't understand that the torque spec for most fasteners is dry unless otherwise noted, that's why I pointed it out. I've read too often when questions like this arise that the answer is "yeah use copper grease" with no recommendation to reduce the torque. On a 5/16 x 24 bolt found in the rear sub it would be a reduction of 30-45% depending on the composition of the copper grease.

[Fast Ivan]

up to 90% of the torque applied is used in overcoming friction leaving just the 10% that's used on the axial load of the fastener. If you add a lubricant to this the friction is reduced and the danger is that the fastener is over torqued and may fail in tension because of the increase in axial load.

[JonnyAlpha]

Geeze that started a whole load of comments, all good stuff though. Just throwing one in there I have just prised off the Rear Rubber Doughnuts from the Subframe Cups and also from the Ali Trumpets.

This is an area prone to corrosion, I had to cut the rubber off and separate the Dougnuts to remove from the Trumpets.

 

When I re-assemble should I use Copper Grease to help prevent a re-occurence? If not what else standard Lithium Grease?

 

Thanks 

[JonnyAlpha]

Geeze that started a whole load of comments, all good stuff though. Just throwing one in there I have just prised off the Rear Rubber Doughnuts from the Subframe Cups and also from the Ali Trumpets.

This is an area prone to corrosion, I had to cut the rubber off and separate the Dougnuts to remove from the Trumpets.

 

When I re-assemble should I use Copper Grease to help prevent a re-occurence? If not what else standard Lithium Grease?

 

Thanks 

Just found this thread, post 5 suggests Copper Grease - Happy Days

[Lincsminbin]

Just to add my tuppence to the debate.....

The term copper grease is a bit misleading, whilst it is a lubricant, it's main purpose is as an anti-seize compound. For moving parts - bearings etc.. you generally want to be using a suitable LM grease.

 

Now for the biggie - Brakes - There is an 'old mechanics' trick of smearing a bit of copper grease on the back of pads to reduce brake squeal (I do it, but I remain unconvinced it makes much difference ). For the brake pistons and seals, when assembling, use rubber or other silicone based grease, the reason being that petroleum-based lubricants (including copper grease) can degrade the rubber in the seals causing binding, or worse a leak. Under no circumstances put grease on any other brake components, the end result could be fatal!

[Ethel]

You could reduce the dry torque figure by about a 6th for greased threads, but if it's a used fastening the friction may be altered anyway.

 

Apart from clamping joins in components by increasing the friction between them, tensile load on a fastener can keep it from fatiguing by ensuring the preload is already higher than the applied loads that would continually make it stretch and relax until it fatigued. The nearer the preload + applied load is to yield, without ever reaching it, the better.