Master Cylinder storage

[Eleven]

I am changing my MC to a smaller bore on and will be storing the old one. I've had them rust shut before and need to avoid that. My plan is to disassemble it, clean all the brake fluid out and put it into a plastic bag. So my question is what to use to coat it before storage or it I have to. Petroleum will dry out the seals but prevent corrosion. Is there something else? I know that before reuse it would have to be rebuilt but I also don't want to introduce a contaminant into the system if I miss some grease. Thanks for any thoughts.

 

[Gordon Holsinger]

I am changing my MC to a smaller bore on and will be storing the old one. I've had them rust shut before and need to avoid that. My plan is to disassemble it, clean all the brake fluid out and put it into a plastic bag. So my question is what to use to coat it before storage or it I have to. Petroleum will dry out the seals but prevent corrosion. Is there something else? I know that before reuse it would have to be rebuilt but I also don't want to introduce a contaminant into the system if I miss some grease. Thanks for any thoughts.

Girling rubber grease!

 

[RootesRacer]

I'd seal it in 2 resealable plastic bags with a coat of oil and some dot4 fluid in the bores. Not sure what may happen to the bags though if the fluid escapes. Without brake fluid, the rubber seals will shrink.

 

[Eleven]

The Girling rubber grease makes sense.The brake fluid also except I am worried about any water absorbed and then doing damage.
Thank both of you for your help!

 

[65beam]

Grease is a lubricating oil with a thickener added to hold the oil in suspension. Stop by your local Autozone, Advance, O'reily's or any other parts store and you'll find they sell small packages of grease for various applications. Covering the bore of the cylinder with any Lithium based grease after removing the inner parts will be fine and when you plan to rebuild the cylinder clean it with non chlorinated brake cleaner. Store it in a zip lock bag.

 

[RootesRacer]

The Girling rubber grease makes sense.The brake fluid also except I am worried about any water absorbed and then doing damage.
Thank both of you for your help!

Thats why I mentioned double bagging the MC, to keep the humid air out.

 

[sunalp]

Why not clean and lube the bore and store it without seals? When you want to use it again,
just put the seals in.

 

[65beam]

Why not clean and lube the bore and store it without seals? When you want to use it again,
just put the seals in.

I have to agree leaving the seals out is a good idea. A good example of what can happen to aluminum bores was the brake booster for the RHD car. It appeared that Ian or someone else had installed a repair kit in the C/D booster. Don't know when it was done but it set unused for 8 years after I bought the car . I pulled it apart and the bore had corrosion and the rubber parts were bad. Whatever lube was used had caused the seals to soften and no longer held their shape. Some modification was required before being installed.

 

[mikephillips]

You could also buy some desiccant packs and throw one in with it to absorb any moisture than might get in.

 

[Bill Blue]

This a difficult problem. I bought a Willwood master cylinder that was frozen. Gave it a good wack to break it loose, but that evidently destroyed the seal. Moral: If manufacturers struggle with an issue, don't expect perfect results when you do it.

Bill

 

[Eleven]

I think I am going to pull it apart, clean it and wipe it with a thin coat of grease (on the inside of the bore). I'll probably leave the seals on the rod but store the whole unit with the rod pulled. If I need it again, I will get a rebuild kit. Thank you all for your help!