Saturday, April 04, 2020

Back in Nov. 2018 we redid the brakes with another booster and master cylinder, but kept the silicon brake fluid. Brake pedal pressure was ok but with the size of the 4 wheel discs that we had we just thought that it should stop better. All the brake companies that we talked to said to get rid of the silicon DOT 5 fluid. In fact most companies are now not honoring warranties if it is used. Recommendations are DOT 3 or 4. So the decision was made to drain the brake system of the Dot 5 and replace it with DOT 4. Initially we removed the master cylinder, opened the bleeders and forced compressed air through the system. Thinking this was good enough, Dot 4 was put back into the system, not realizing that what little residual DOT 5 was left in the system contaminated the DOT 4. In fact it jelled. Needless to say we had a mess on our hands. Long story short all the calipers and master cylinder were dissembled, and cleaned thoroughly.  More DOT 4 was forced through the lines to remove the remaining DOT 5. To do that, a Brake Bleeder Kit was purchased from Harbor Freight. What a time saver that turned out to be. Connect it to the bleeder and just keep adding fluid to the master cylinder.
Also when the master was installed on the new booster, we had no accurate way of adjusting the power booster to master cylinder pin. Online checking found a handy tool to do just that. These can be purchased from most brake companies. After looking at the design of it I decided to make my own. Turned out to be a simple milling job and it works great. Adjusting the pin reduces brake pedal travel, and if the pin is longer than it should be would put continuous pressure on the master cylinder, activating the brakes. So it is crucial that this adjustment is correct. Now everything is back together, but since the Jeep is not drive able actual brake testing is not possible. But just hand pushing it to a roll on the shop floor and stepping on the pedal it stops abruptly where as before it did not. We anxiously await for the time that we can drive it to see for sure if any progress was made. I do know I have DOT 5 silicon brake fluid in my J10 for years now and felt the brakes could be better. You have to really stand on them.

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