Quick background: 2009 JKU-R, stock rear brakes other than longer brake lines that came with the JPP 4" lift, and the Mopar BBK up front that includes calipers, rotors, booster, m/c, and again the longer brake lines from the JPP 4" lift. I'm battling a long pedal throw before any brake action happens, and then the pedal is very soft. The brakes work OK, but the pedal feel is less than confidence inspiring. I've bled the brakes several times, both via the pedal pump method and a vacuum bleeder. However...
I can't wrap my head around what's going on here: when bleeding the rear brakes via the pedal pump method, the brake pedal stops roughly 1/2 way through the pedal arc when you crack the bleeder. Stops dead and will not go any further, period. I can push hard enough to bulge the firewall pretty severely, but simply no more travel. WTF???
In stark contrast, the front brakes bleed exactly as you'd expect, with the pedal travelling all the way to the floor when you crack the bleeder.
When you installed the BBK master/booster are you sure you got the booster pushrod seated properly in the M/C piston? some reports out there of it not seating properly. Otherwise I'd do a pressure bleed of the entire system using a Motive pressure bleeder, etc.
'09 JKRU. 4" Teraflex long arm, Teraflex R44 housing, Teraflex / Fox Resis, Poly Performance skids, Nemesis Billy Rockers, Nemesis flares, 37" ATZ P3s on 17" 5x5.5" Trailready HDs, Spyntec hubs, Teraflex BBK, Mopar BBK master/booster, Superior front & Alloy USA rear axle shafts, CTMs, Reids, Synergy drag link & tie rod, WTOR hydro-boosted steering, 5.38s, TF Dual Rate front bar, TF bumpers, Warn Powerplant, Tom Woods shafts, AA xfer case cable, Kilby canister relo, RH4x4 cage.