Installed the Teraflex big bore master brake cylinder in my mostly stock 2011 COD Unlimited. What an incredible difference! I was lazy and didnít want to bleed the brakes more than once, so I changed the brake lines at the same time. Future plans for my Jeep include the Metalcloak Gamechanger lift, so I installed the extended brake lines from them. I expect that these new lines contributed to the reduction in stopping distance seen, but I doubt if it is significant.
Changing the master brake cylinder is pretty straight forward. One suggestion, if you have an old turkey baster laying around use it to remove some of the brake fluid before cracking open the lines, cuts down on the mess. Brake the torque on the two brake lines, easier to do while the mounting hardware is still holding the cylinder tight. Do not pop them out of the housing yet. Remove the two mounting nuts. Remove the lines. Pull the cylinder out. There is a vacuum behind it so it takes a little effort to pull it out. (We remembered after getting it out that there is a vacuum line we were supposed to disconnect to release this pressure, oh well.)
The diameter of the Teraflex big bore master brake cylinder is 1/8Ē larger than the stock diameter. This may not seem like much but if you consider the increase in area you find that the stock bore has an area of 0.785 sq in, and the Teraflex bore has an area of 0.994 sq in, this is a 27% increase in area.
Changed all of the brake lines, and bled the brakes. My buddies were the ones pumping the brake pedal while I was cracking open the bleed ports, so they had an idea of how much better the brakes felt. We got everything buttoned up and we hopped in the Jeep for more testing. The instant I put my foot on the brake pedal to shift into reverse I felt a significant increase in braking power. Back to the arena parking lot we went.
We set up in the parking lot of a sports arena for testing. We didnít have a cone so we placed the bright yellow bottle of brake fluid on the ground for the point I would apply the brakes. I could only safely accelerate to 30mph in the space we had, so I would accelerate to 30mph maintain that briefly and when I reached the yellow bottle I slammed on the brakes like I would for a panic stop. This was repeated multiple times until we had a good sampling of data for comparison. We threw away outliers and compared consistent data from the stopping distances acquired with the stock cylinder and brake lines, and the Teraflex big bore cylinder and Metalcloak brake lines. Here are the numbers we came up with:
Stopping distance in feet from 30mph
29% reduction in stopping distance