New Master Cylinder

kachemakian · 11-18-2008, 10:02 PM

So guys, I am going to go through my brakes. I am going to stay stock on the calipers and rotors and am wondering what master cylinder would be the best all around for street driving, 17mm or 19mm?

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Lots of different opinions on this. Mine:

Unless you enjoy jumping on the pedal with both feet, stay with the 17mm one. The 19mm one feels "harder" because the pedal moves less, but you also have to push it harder to get the same braking force. Think of it as using a shorter lever between your foot and the brake pads.

--DD

kachemakian · 11-19-2008, 05:16 PM

Thanks Dave

I like to think of it as having less hydrallic mechanical advantage, but, what I didn't know was how the pedal would feel. Some people talk about changing out to a 19mm as an upgrade. Wouldn't you then have to then change to calipers with a larger diameter piston to have the same pedal pressure in braking?

kachemakian · 11-19-2008, 05:19 PM

Dave, after my last post I flipped over to master cylinders at Pelican and they list the 19mm as an upgrade!!!!? How soooooooooo???

kachemakian · 11-19-2008, 05:33 PM

Does anyone out there have stock calipers and a 19mm master cylinder? I figure the 19mm would take 24.9% more pedal pressure but require only 80% of the movement.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

That number sounds about right; it is proportional to the ratio of the squares of the diameters.

The catalog lists what the catalog lists, and as I said there are a range of opinions on the subject.

I have the 19mm MC on my car with stock calipers, and I think the pedal effort is higher than I would prefer. It does feel reasonably stiff though.

--DD

Rrrockhound · Rrrockhound's Garage

I have stock brakes with the 19mm MC and even though I've come to enjoy the hard pedal, I would definitely hesitate to let a small person drive--the effort is that high. You tend to think there's something wrong with the brakes until your leg learns what is an appropriate amount of effort.

kachemakian · 11-20-2008, 11:43 PM

OK, that does it! 17mm it will be. I want a lady to be able to make a panic stop in it too! Thank you both for your opinions.