JLPurcell Posted March 9, 2019 Share #1 Posted March 9, 2019 I need some help on my brake system. I will start our with the history. The brakes were working fine. I sourced and installed a vented MK63 front brake upgrade. Upon completion I had a hard pedal and poor braking situation. I took off the brake booster and sent it out, it tested good. I put the original stock front brake /rotors and calipers. Still hard pedal. I have bleed the brakes repeatedly, today I started the car and felt for vacuum has vacuum in houses to the brake booster and holds vacuum after engine is turned off. Any suggestions? I am my end on this problem. Thanks for any help! Link to comment Share on other sites More sharing options...
Patcon Posted March 9, 2019 Share #2 Posted March 9, 2019 How old are the flexible lines? Link to comment Share on other sites More sharing options...
JLPurcell Posted March 9, 2019 Author Share #3 Posted March 9, 2019 32 minutes ago, Patcon said: How old are the flexible lines? Fronts for the MK63 calipers recently sourced, Stock and rear NOS. Link to comment Share on other sites More sharing options...
Diseazd Posted March 9, 2019 Share #4 Posted March 9, 2019 Sounds exactly like the symptoms of a missing reaction disc in the master vac. Did you replace the brake master cylinder when you did the front upgrade? 1 Link to comment Share on other sites More sharing options...
Patcon Posted March 9, 2019 Share #5 Posted March 9, 2019 Hard pedal or excessive pressure to stop the car? Link to comment Share on other sites More sharing options...
Terrapin Z Posted March 9, 2019 Share #6 Posted March 9, 2019 You mentioned you pulled the booster off to have it tested. Like Diseazd says that reaction disc can fall off the plunger and end up inside the booster shell. Plagued me for a while, Once I fixed that everything worked fine. It is worth a second look to eliminate that as the problem. Link to comment Share on other sites More sharing options...
JLPurcell Posted March 9, 2019 Author Share #7 Posted March 9, 2019 18 minutes ago, Patcon said: Hard pedal or excessive pressure to stop the car? Hard pedal with very little stopping power. The booster checks out ok. I started after the MK63 upgrade and remained when I changed back to the stock brake system. I sent out the booster and it checked out ok. Link to comment Share on other sites More sharing options...
JLPurcell Posted March 9, 2019 Author Share #8 Posted March 9, 2019 2 hours ago, Diseazd said: Sounds exactly like the symptoms of a missing reaction disc in the master vac. Did you replace the brake master cylinder when you did the front upgrade? No, I did not do anything with the booster or the brake master until the change of the front calipers at which time the problem emerged. I then sent out the brake booster for inspection. Link to comment Share on other sites More sharing options...
Patcon Posted March 9, 2019 Share #9 Posted March 9, 2019 I would also suspect reaction disc or bad/hard pads on the brakes. If you need a reaction disc and can't find one. I have one sitting on the bench right now. 1 Link to comment Share on other sites More sharing options...
JLPurcell Posted March 10, 2019 Author Share #10 Posted March 10, 2019 2 hours ago, Patcon said: I would also suspect reaction disc or bad/hard pads on the brakes. If you need a reaction disc and can't find one. I have one sitting on the bench right now. How much for the disc? I need to get it coming just in case, I have an event for the car in early April. Thanks Charles. Link to comment Share on other sites More sharing options...
Patcon Posted March 10, 2019 Share #11 Posted March 10, 2019 4 minutes ago, JLPurcell said: How much for the disc? I need to get it coming just in case, I have an event for the car in early April. Thanks Charles. PM me an address. I will send it to you for free. 2 Link to comment Share on other sites More sharing options...
Diseazd Posted March 10, 2019 Share #12 Posted March 10, 2019 You don’t have to disconnect the steel lines from the master cylinder to install the disc. Just take off the two nuts holding the m/c to the master vac and carefully pull it away from the master vac. Pull out the plunger/adjuster shaft. Super glue the disc to the back of the plunger/adjuster shaft and reinstall in reverse order. 1 Link to comment Share on other sites More sharing options...
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