excess_lumens

Thanks... Drag feels quite more than expected both directions, in the reverse direction the caliper rotates slightly in the bracket (by design). Square o-rings should retract the caliper piston a minimal amount when pressure is released, in this cae they appear not to. I believe the master cylinder is fully at rest with no brakes applied, as fluid flows freely from the reservoir - the fill ports are closed as soon as the master piston is moved, and I also too off 0.005" from the booster piston that actuates the master. I've bled a few gallons through this using mainly a vacuum bleeder. No ABS module. My two thoughts at this point are: the combined remote reservoir and master cylinder height of 4' provides enough hydraulic pressure to create drag somehow caliper rebuilds and rebuild kit square O-rings are oversized and so tight as prevent the piston from retracting naturally Re: pedal to hydroboost: on this unit the pivot shaft has a zerk (greased it) and it appears to return the whole way - there is some play at the hydroboost actuator rod.

First indicator of brake drag was TPMS sensors increasing to 120°F from radiated rotor heat - open road not using brakes. After all the repairs (multiple iterations) no change - they still heat up on the open road, rotor temp is about 330-350° on a moderate (70°) day at 60mph. Yes, checked temps by pulling off without using brakes. Hand-turn drag seems more significant than I would expect, but haven't measured. The reservoir is filled about 1" below top and the cap vents are good. Two things I can think of: Somehow all the rebuilt and Delco kits have O-rings that are too thick - so the piston doesn't naturally return. The static brake line pressure from the elevated mater cylinder and reservoir is enough to prevent the caliper from releasing - but then pretty much any of these coaches would have that issue. There is nothing in the docs about only partially filling the reservoir - and if static pressure was the issue I would expect the caliper to release when I opened the bleeder - it doesn't.

For air actuated parking brakes the warning light switch is an air pressure switch sometimes mounted directly to the dashboard brake valve. Part could be FSC 2749-2108 or FSC 1749-2134 equivalent.

I've been chasing brake caliper drag on this RV for a few years - hoping someone has an actual answer... TLDR: 1996 Dayton dual 2.88" calipers drag, replaced everything, still drag, what an I missing? 1996 Beaver 36' Diesel Pusher: Mgnum 4-bag chassis, 22,000lbs, Cat 3126, Allison 6-speed automatic, Reyco Granning airbag suspension. Brake system: Bosch HydroMax (#2239045 2" master, power steering servo brake booster, electric pump backup) remote reservoir mounted about 4’ above the master cyl Front and rear disk brakes, calipers are Dayton 600-908 dual 2.88” piston, cast-iron, sliding caliper (1996 Ford F700 truck). Purchased in 2016, used only a few times a year. In 2019 I added a EEZTPMS with pressure/temp sensors. Was driving on a long highway (cruise, no brakes) and the front TPMS temp warnings tripped at 120°F - pulled off and checked with IR temp gun - both front and rear rotors were about 330°F. Checked brake pedal play, ok, Opened bleeder valves, flow but no excess pressure. Continued the journey (more slowly) no seeming issue other than temp (and likely wasted fuel). With wheels free can feel the brake drag, pushed the pads back with a big wrench and now free, step on brake and release it's dragging. Did these things - they still drag: Brake fluid flush and bleed - DOT4 Replace master cylinder (2x) Bosch new (not rebuilt) Replaced all 5 brake hoses (in-frame bulkhead fitting - nightmare) Tested brake pressure (electronic sensor) run up to redline - no change in pressure Grind off 0.005" of booster interface to master cylinder Change power steering fluid (Dexron III) Replaced front calipers: Nugeon rebuild (one was phenolic pistons, one aluminum), then again with Delco rebuild - sliding surfaces sliding surfaces greased (copper disk brake grease) Replaced pads Rear rotors turned and look perfect, fronts minimal runout There is about 2psi static pressure in the brake lines: 1/2 gallon remote reservoir is mounted 2' above the master cylinder, master cylinder is 2' above the calipers After all that: Step on the brakes and release, brake drag Open bleeder, flows but not squirt like there was pressure, still drag (so don't think it's hydraulic issue) Press pads back in with big pliers, no drag I have disk brakes on lots of other vehicles, and releasing the brake releases the calipers. This is my first experience with medium truck parts - what am I missing? Thanks!

Got replacement cable, exact match custom made from Bunker Hill Cables, 1 day turnaround 2 day shipping, $98 total. P/N B188-II0309-23.5/12.63

Need to locate a replacement cable for the driveshaft parking brake (1996 Beaver on Magnum 4-bag chassis), CAT 3126, Allison MD3060, Eaton diff, parking brake ???. The parking brake has become much less solid, crawled under it and found the cable actually kinked on release, which likely caused it not full release and wear. I found several suppliers who custom make these, does anyone know the OEM? Or who actually makes the parking brake - I can't find a matching image from Meritor, maybe Eaton or Delco? Thanks! Possible cable suppliers: https://bunkerhillcables.com/parking-brake-levers-cables/parking-brake-cables/ https://push-pull.com/ https://www.cablecraft.com/cables/ https://bruinbrakecables.com/

Flare nut wrenches are your friends. In my case, loosen the crimp nut and work out the line. Depending, you may be able to pull the bags with the line attached for easier access (just don't pull to hard on the lines). Move the fittings to the new airbags, use air/gas pipe dope or teflon tape. I added straps on my suspension (1996 Magnum 4-bag) to prevent the suspension pulling on the bags when fully lifted by the levelers.