Master cylinder cover screws

[JimSTer]

Has anybody else had this happen?

While doing my brake fluid replacement I wasn't able to get one of the screws out in order to remove the front master cylinder cover.
I stripped the grooves from the screw head. So I had to drill a hole into the screw and use an easy out to remove it. Thats not the first time I've had to use quite a little force to get these screws loose.
It dawned on me that the master cylinder is made of aluminum and the screws are most likely steel.
I don't have the proper term but I know from my bike riding days that's not a good combination. We always used an anti seise compound to prevent the two metals from welding themselves together.
So I went to the local Ace hardware and bought some stainless steel screws (hopefully much harder than the original) and some Permatex anti seise compound to prevent this from re-occurring.

 

[STammtisch]

Think that process is called bi-metallic corrosion but that stands to be corrected.

Jerry STOC 7945

 

[dduelin]

Galvanic corrosion. I haven't had this problem yet but my reservoir cap screws have been out one to two times a year with the mileage I put on my ST. Anti seize isn't a bad idea either.

 

[Byron]

Over torquing is another cause as some feel vibrations might back the screws out. Find your best driver that fits the screw head and apply a lot of downward pressure while trying to turn the screw. If it doesn't want to budge then tap the screw driver with a few hammer blows and try again. Jarring the screw with the taps from the hammer will sometimes break the bond. Because of the rubber gasket these screws really don't need a lot of torque to keep them in place. Without a specific torque a good general rule is once the screw had good contact, nothing more than another 1/4 turn should be enough.

 

[Igofar]

JIS Screwdrivers, only snug, they are only compressing a rubber gasket, cranking them down too much will only damage the seal and cause leaks.

 

[Mellow]

Over torquing is another cause as some feel vibrations might back the screws out. Find your best driver that fits the screw head and apply a lot of downward pressure while trying to turn the screw. If it doesn't want to budge then tap the screw driver with a few hammer blows and try again. Jarring the screw with the taps from the hammer will sometimes break the bond. Because of the rubber gasket these screws really don't need a lot of torque to keep them in place. Without a specific torque a good general rule is once the screw had good contact, nothing more than another 1/4 turn should be enough.

+1 I only snug them down. However, if you are in the more northern states and you get a lot of rain and other corrosive stuff going on the anti seize is probably a great idea.

 

[JimSTer]

Over torquing is another cause as some feel vibrations might back the screws out. Find your best driver that fits the screw head and apply a lot of downward pressure while trying to turn the screw. If it doesn't want to budge then tap the screw driver with a few hammer blows and try again. Jarring the screw with the taps from the hammer will sometimes break the bond. Because of the rubber gasket these screws really don't need a lot of torque to keep them in place. Without a specific torque a good general rule is once the screw had good contact, nothing more than another 1/4 turn should be enough.

Thanks Byron. And I tried all of these without getting the one screw out.

 

[Dinkie Diesel]

Even a little grease will curtail the dissimilar metal reaction. Stainless screws are another idea but don't bet the farm that they are "harder" than the regular steel screw you're replacing. My experience with stainless fasteners is that they are pretty soft. Certainly not on par with a grade 5 bolt. YMMV

 

[st1300r]

+1 the cover screws don't need to be cranked down it's just compressing the seal.
SS screws won't be as strong but plenty for that application.

Being in the neighborhood of brake fluid those seals won't be compatible with grease. Unlikely to be an issue but dielectric grease would be a better choice.

 

[SupraSabre]

I always make sure I have a couple of screws on hand so when I do mess one up, I have a replacement and don't have to wait for one to be bought.

 

[bursar]

I am great advocate of copper grease and use it on these reservoir screws. They always unscrew with minimum effort as a result.

 

[hoowasat]

I am great advocate of copper grease and use it on these reservoir screws. They always unscrew with minimum effort as a result.

Copper grease induces a third metal into the galvanic reaction, and of the three, which one do you think will be consumed first?