JamesBB

Active Member

• May 18, 2014

• #1

I purchased some replacement bolts for my rocker covers (GEMS 4.6 P38) and decided to avoid future rust issues to go for stainless steel. I think I got A2.

I have not fitted them yet but I have recently read up on galvanic corrosion caused by the stainless steel being of a different nobility to aluminium.

Some posts I have read say use copper grease between the two to stop it, other people have said it is a simple no.

Should I forget it and go for the zinc passivated 12.9 bolts instead which apparently do not cause galvanic corrosion?

What are you thoughts and experiences?

Thanks in advance.
James

 

Last edited: May 18, 2014

Dr_evil

Banned

• May 18, 2014

• #2

why do you need 12.9 grade bolts for a rocker cover ?

 

the_wolf

Well-Known Member

• May 18, 2014

• #3

Just in case, y'know

 

JamesBB

Active Member

• May 18, 2014

• #4

What bolts are in there when it is built?

Regular steel?

The bolts go down into the head, which is aluminium, I just wanted something that looks better than regular steel that will go rusty.

Cheers

 

Dr_evil

Banned

• May 18, 2014

• #5

wont be anything above 8.8 thats a standard strength bolt which does more or less everything!


You use 10.9 for brake components from memory and 12.9 is just complete overkill for rocker covers! They're only done and nipped up to seal against the gasket

 

JamesBB

Active Member

• May 18, 2014

• #6

OK, makes sense. But whatever is chosen besides regular steel, go for the zinc plated ones I guess and not use stainless?

 

Dr_evil

Banned

• May 18, 2014

• #7

just throw some oil into the hole or moly grease not gonna harm it, I've used a thin smear of RTV before on things I don't want to rust, works well enough

 

the_wolf

Well-Known Member

• May 18, 2014

• #8

A bolt going into the rocker cover will not go rusty easily so I wouldn't worry about it

 

zen

Well-Known Member

Events Planner

• May 18, 2014

• #9

why you talking about what tensile the bolt is???

its stainless steel..they are crap..well not strong!!much less than 8.8...ie dont use in critical positions, ie suspension...

BUT for rocker cover etc, they will be FINE...espically if cap heads as they will always undo..

common practise to use stainless bolts on motorcycle engines, they do not corrode, its not like its going under the sea..

yes you can use copper slip.I DO.espicaaly on spark plugs!..though you can buy alli slip (if you really look)

 

JamesBB

Active Member

• May 18, 2014

• #10

I have been doing a lot of reading up on nuts and bolts and never realised the subject was so complex. I am gradually getting there but from now on I will be a bit more careful what bolt is used where.

I was using the higher tensile zinc bolts on another project (non-LR) and I thought I may as well use the same kind of bolts as they look good and are pretty cheap.

Cheers

 

zen

Well-Known Member

Events Planner

• May 19, 2014

• #11

oh yes..bolts are quite specific in where to use...have to be quite careful at work..wouldnt want a 2 ton breaker dropping on someones head cos i put wrong bolt in!!ie life critical in some cases...stainless should only be used in non critical uses..ie engine cases..panels etc...
but they are brillent at those jobs..ie in 5 yrs time they will undo, rather than be rotted away !!

 

Dr_evil

Banned

• May 19, 2014

• #12

you can get high tensile stainless but still no where near as good as normal ones or chromoly