Wheel Cylinder Sleeving and Piston Material

[Joao46]

Hi folks.

Ive see discussions on galvanic corrosion on wheel cylinders resleeved with stainless and pistons made of aluminum.

 

I just had mine sleeved with brass and the pistons made from stainless.

 

They are all assembled and ready to go but they used brake fluid as assembly lube. 
 

Would it be advisable to disassemble, wipe off the brake fluid and coat the sleeves with brake assembly grease before reassembly? 
 

If so, wouldn’t the assembly grease, which has silicone, cause problems with the Dot 3 fluid in the same way that Dot3 is not compatible with Dot 5,  which is silicone based?

 

So if it turns out it’s recommended to use assembly grease, any recommendations of brand?

 

Thanks!

 

 

[Bloo]

Worth taking back apart? I don't know.

 

You can and should use silicone-based brake grease when assembling that stuff. For what it's worth, I don't believe that is the same thing as silicone dielectric grease, but maybe someone with more chemistry knowledge than I can comment.

 

I have not personally had these troubles with sticking pistons, nor with re-using aluminum pistons that have lost some of their anodization. Maybe I just live a charmed life, but I attribute it to the fact that I always slime these parts up real good with Sil-Glyde just like I was taught in technical school longer ago than I would like to admit.

 

1 hour ago, Joao46 said:

If so, wouldn’t the assembly grease, which has silicone, cause problems with the Dot 3 fluid in the same way that Dot3 is not compatible with Dot 5,  which is silicone based?

I don't think so. I have never heard of nor had any trouble. Brake cylinder rebuild kits used to come with a little capsule of brake lubricant. It was a little runnier than Sil-Glyde, but I think it was silicone. It is usually not included today, and I think most people default to using brake fluid and have more trouble than they did back then. Most of the lubricant won't be getting in the brake fluid anyway because it is on the piston and the brake fluid shouldn't be getting out there. A little will be on the bore of course, and on the cup, because you should lubricate it all. There is still not very much in with the fluid. No one ever cautioned me against using silicone brake grease in school. Quite the opposite. I was told that sticking was likely if I didn't use it.

 

The incompatibility of DOT3/DOT4/DOT5.1 fluid with DOT5 Silicone is a separate issue in my opinion. Some people have reported a reaction between the two, but I have never personally seen it. In fact, the bottles I have seen of DOT 5 Silicone have all said you could mix it. You should not though. They don't really mix, the silicone floats to the top and you get all of the annoyances of silicone with none of the advantages. You would have to tear all the cylinders apart, thoroughly clean everything and flush the lines out with alcohol to get rid of a mess like that. Bleeding won't do it because the moisture contaminated DOT3 sinks to the bottom of every cylinder and low spot, and bleeders are at the top since they are designed to let air out.

 

 

 

Edited April 4 by Bloo (see edit history)

[joe_padavano]

I have only used brake fluid as an assembly lube when I've rebuilt brake hydraulics. I use DOT 5.1 fluid.

[Ben Bruce aka First Born]

I have been driving and working on my cars for 71 years.  Helping Dad earlier.  Always just used brake fluid . Even on my present 1950 BUICK , the brake cylinders were not "relined".  

 

  Ben

[Frank DuVal]

I have been using DOT 5 for 40 years. No problems. I also use it to lube the wheel cylinder parts.

 

I didn't go to tech school (school of hard knocks for auto is mine) so never heard of Syl-Glyde until a few years ago. But I buy my DOT 5 from the same people, AGS (American Grease Stick).😉

 

[Oz Dodge 4]

Like others have said, since the 1970s I have always just used brake fluid and have used it successfully on lots of re-sleeved cylinders done with both brass and stainless sleeves, none of which ever prematurely failed. 

[dodge28]

Just install the cylinders as they are given to you and use DOT 5 .