87MJROB Posted February 5 Share Posted February 5 Ok so I did a full 94 xj swap into my mj shell. Every hardline and soft line are brand new, brand new wheel cylinders, parts, shoes, parking cables, brand new pads and rotors, good calipers, new brake master cylinder. Rear shoes are adjusted to slight drag with no pedal applied. There is no mj load leveling valve in the system. The prop valve is from the donor xj. Pedal feels good and firm engine off. Pedal goes about 3/4 way to the floor with the engine running before stopping. ideas? I’m stumped besides somehow air is still trapped somewhere? Link to comment Share on other sites More sharing options...
89 MJ Posted February 5 Share Posted February 5 Did you bench bleed the master before installing it? Good flow out of it? Link to comment Share on other sites More sharing options...
87MJROB Posted February 5 Author Share Posted February 5 17 minutes ago, 89 MJ said: Did you bench bleed the master before installing it? Good flow out of it? Yes Link to comment Share on other sites More sharing options...
89 MJ Posted February 5 Share Posted February 5 23 minutes ago, 87MJROB said: Yes Ok, that’s what I figured, but wanted to cover the easy stuff first. We know how modern quality control is haha. Does the brake pedal have any adjustment? I can’t remember. Link to comment Share on other sites More sharing options...
Pete M Posted February 5 Share Posted February 5 engine off = firm pedal + engine on = pedal goes to the floor was a bad booster on my 88. Link to comment Share on other sites More sharing options...
fiatslug87 Posted February 5 Share Posted February 5 ^^^same with mine. Link to comment Share on other sites More sharing options...
AZJeff Posted February 5 Share Posted February 5 30 minutes ago, Pete M said: engine off = firm pedal + engine on = pedal goes to the floor was a bad booster on my 88. The definitive test for a bad booster is this: 1. Engine OFF. Pump brake pedal until it is rock hard. 2. While keeping brake pedal DEPRESSED FIRMLY, start the engine. 3. If the pedal “sinks” somewhat as engine vacuum is established, booster is working normally. Link to comment Share on other sites More sharing options...
87MJROB Posted February 5 Author Share Posted February 5 9 hours ago, Pete M said: engine off = firm pedal + engine on = pedal goes to the floor was a bad booster on my 88. 9 hours ago, fiatslug87 said: ^^^same with mine. Damn. I guess I’ll have to try replacing that then 🙃 Link to comment Share on other sites More sharing options...
87MJROB Posted February 5 Author Share Posted February 5 9 hours ago, AZJeff said: The definitive test for a bad booster is this: 1. Engine OFF. Pump brake pedal until it is rock hard. 2. While keeping brake pedal DEPRESSED FIRMLY, start the engine. 3. If the pedal “sinks” somewhat as engine vacuum is established, booster is working normally. I will try that when I can before I start replacing it Link to comment Share on other sites More sharing options...
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