Re-Braked

In a previous post, I noticed how the brake system was leaking fluid into the 'can' of the power booster.  This had been happening both with the original Midland 3400 booster, and also with the larger C490 booster.  I also wasn't very happy with the recent performance of the C490, so I pulled it from the car and disassembled the 'can' to see what was up.

The booster diaphragm had a nasty tear in it, which explains why the boost performance had deteriorated.  Combined with the fact that the seals were obviously leaking, I decided that it would be prudent to have the C490 professionally rebuilt.  Clearly the "rebuild" job (if there was one) that the original eBay seller advertised of this unit was worse than inadequate!

After some research, I contacted George at Harmon Classic Brakes.  He is very knowledgeable and provided some sage advice.  One thing he installs on power booster rebuilds is a stainless steel liner in the power cylinder to prevent rust.  Based on the amount of rust I found in my "rebuilt" 3400 unit, that seemed like a really good idea! I sent my C490 to him for a rebuild and after a minor glitch, George sent me a fully functional professionally rebuilt C490 unit.

It turns out that the C490 not only has a larger boost diaphragm than the 3400, the power piston is also a smaller diameter.  Taken together, this results in a much higher boost, and much more effective brakes.  Installing this Harmon rebuilt unit resulted in a much better brake feel, stopping the car with authority even at the end of long hills.  This is the kind of braking performance I had in mind when I installed the front disks in the first place, but really hadn't experienced until now.