HELP calipers holding on

TrevD · Post by **TrevD** » Sun Aug 10, 08 3:27 pm

ive just converted the camper (dodge B300) to disc brake front (it was drums) ive used calipers and rotors from a later van , also used the master cylinder from the same van. all plombed in ok but they seem to be holding on as if it still has fluid presure to them, ive checked the usual , the calipers are free to move etc, its got all new flexy hozes so cant be that. any ideas ????

Pete · Post by **Pete** » Sun Aug 10, 08 3:45 pm

Just had this on a car - it was the M/C that was US. Change time, I think.

You can prove it by letting some fludi out of the caliper bleed nipple, backing the pads off, locking the nipple up and then applying the brake. If it "locks" again, then its the M/C. Sorry.

Jon · Post by **Jon** » Sun Aug 10, 08 3:48 pm

does it have an external residual pressure valve somewhere in the lines?

Pete · Post by **Pete** » Sun Aug 10, 08 3:49 pm

I think you are lucky if you have fluid in an old moppar line

TrevD · Post by **TrevD** » Sun Aug 10, 08 3:59 pm

cheers guys jon it dosnt have any other valves, only the one for the brake warning light, looks like i need a new master cylinder

Jon · Post by **Jon** » Sun Aug 10, 08 6:38 pm

before splashing out on a new master I'd pull the brass seat that the brake line sits against and check there isn't a valve in there...stranger things have happened, and it costs nowt to have a look

Matt · Post by **Matt** » Sun Aug 10, 08 8:13 pm

is there a brake servo ? check there is sufficient clearance between the servo pushrod and the m/c piston when assembled. THe pushrod is probably adjustable, and if it's too long the m/c piston won't return fully.

Dave999 · Post by **Dave999** » Tue Aug 12, 08 9:11 am

did they do this on the other van???could this be why the brakes were up for sale????

if so your master cylinder is a drum brake one.

it will have a valve in it (to keep residual pressure in the lines that keep the shoes near the drums) to stop you filling your pants when the peddle hits the floor (which is what you get with drum brakes on a disk master cylinder)

sounds like matt hit the nail

Dave

TrevD · Post by **TrevD** » Tue Aug 12, 08 8:53 pm

all sorted, i striped the callipers and found the pistons to be out of round and tapered by 6 thou, would work fine with worn pads but as ive fitted all new they are/were too tight a lottle bir of machining work and hey presto all sorted, i might start manufacturing stainless pistons as a replacement for the phonolic (read plastic) originals used on many mopars. ther camper now stops

Anonymous · Post by **Anonymous** » Tue Aug 12, 08 8:56 pm

Good find Trev.