Hydraulic cylinder repair.

[catfood]

Is there a trick to repairing master cylinders, brake cylinders etc? Some method that ensures a long lasting, leak proof fix. Whenever I replace the seals in brake cylinders or the like the quite often need doing again within a few months.

 

[TR3driver]

Not sure they qualify as "tricks", but here are a few thoughts:
1) Use brake fluid that is compatible with your seals. Not sure what the situation is in the UK, but I proved to my satisfaction many years ago now that American brake fluid would damage British brake seals on my TR3. I've also heard reports of seals that are not compatible with DOT 5 silicone fluid (although I use DOT 5 and never had a problem).

2) Use new seals, not "new old stock". Seals get old, even laying on the shelf.

3) Make sure the bore is perfectly smooth, and not too badly oversize. A sleeve may be necessary to bring it back to size, especially if the bore has corroded.

 

[JPSmit]

I second the bore issues - no pitting, though they should be reamed slightly to get a bit of a "bite" for the fluid