944t rear brakes sticking

[danielzink]

After doing the 944t conversion I'm having a bit of an issue......

I went for a quick spin the other night (still sorting the FI) and when I got home I noticed as I costed into the garage that the car wouldn't "roll" very well.

I tracked it down to the rear brakes....seems they had been dragging so badly that the rotor was starting to turn a "gold" color from the heat...and the rim was even hot to the touch....

So......do I pull off the calipers and rebuild 'em ?

I got these calipers off eBay..they bled out just fine but I'm worried that there may be some rust or gunk inside keeping the caliper pistons from retracting.

With the car on jackstands - if I press the brake pedal the rears stay pretty tight....I can move 'em - a bit - then after a while they seem to loosen up.

-OR- is it a master cylinder problem.....I'm using a late Ghia m/c....my pedal pressure has been fine up to this point - with no locking up etc...

Thanks !

Dan

[boygenius]

Are your rubber rear brake lines new or in good condition. If they are old they might be collapsed inside. The high pressure fluid will go one way to the caliper but will have a hard time flowing back to the master cylinder. When you look at the pistons in th ecaliper do they look shiny or are they a dull grey color. They should be smooth and shiny and free from any pitting. If they are very dirty or pitted the pistons won't return and the pads will drag. You could also still have some air in the system and as you drive the car the air expands in the caliper and pushes the pads out.

[Steve C]

Hi

Got to ask a silly question. Do you have enough freeplay on the MC? You could test the boygenius theory by getting the system hot again and then release the line at the caliper and see if there is any pressure in the system.

Steve C

[danielzink]

Raybestos BAF-12 Hydraulic Brake Cylinder Assembly Fluid.

Worked like a charm !

I had checked everything.

Hoses, Freeplay everything.......

Then I called one of my mechanic buddies he suggested the BAF-12.


I took the calipers off, took the smallest jewellers screwdriver I could find.

Then worked my way around the seal, pulling it away from the piston a bit..put a squirt of BAF-12....working all the way around all 4 pistons on each caliper.....time consuming..

but!

Then worked the pistons in and out a bit - reassembled the whole thing and voila!

Works great.

Just took the car out for a run...did a few hard stops..a few extended stops..

It all works as it should.

Thanks everyone for their help !!

Dan