V8 Man

the flyin`scotsman !

I`m not saying this is the solution to your problem, but...

What about a power bleeder ?

My experience with changing brakelines and valves is that it`s HARD to bleed ALL the air out of the system. It`s easy to just move around the air pocket as you walk around the car without getting it all out.

Put pressurized brake fluid into all of the bleeder valves, and watch it rise in the filler container in the engine compartment, and you will aventually have lost all air pockets.

worf928

+1

Remove the suspect rear caliper and see if you can move both pads freely in the bore. I've found that about half of the rear calipers I touch on 928s have pads that won't move. Dirt, pad material, etc. gets between the pad and guide plate and between the guide plate and caliper body. Sometimes the buildup is bad enough that you have to replace the guide plates.

Garth S

Also an excellent point: when confronted with guide plates that have suffered 'frost heave' ... and have ugly looking retaining screws ... some have touched up the backing plates of the pads with a bench grinder so as to custom fit them to the caliper .... not that I would do that to a Porsche .. ... but I have hear rumours to that effect that it works exceptionally well .. and saves a ****e load of time ....

One other quickie thing to verify is the smooth retraction of all 4 pistons in each caliper: this will remove doubt re. seized pistons. To do so, carefully work a thin screwdriver blade between each piston and the pad backing plate. With very modest effort, the piston should retract. This is a touchy-feelie thing, but try, and you will see what I mean.

Oh, yes ... re deglazing! For normal consumption, I am a fan of Bordeaux appelations - St. Estephe in particular; however, for this application - as more heat is required, my taste runs to the hot, firery black pepper nuances of the Rhone Valley; may I recommend a light marinade of Cote de Lirac over a medium grit garnet paper .... and this will effectively deglaze both pads and rotors.

Gary Knox

I will second the comment on pressure bleeding vs vacuum bleeding. I don't know which you used Malcom, but I definitely prefer pressure bleeding on my cars. Hope you get it traced down during the "cool season" in Alberta.

Cheers,

Gary Knox
West Chester, PA

the flyin' scotsman

Thx Gary............I've given the system much Motive to the point she bleeds blue under pressure

Its not cool yet; barely below freezing; lots of time for brakes and test runs.

worf928

Yup. You can make'em work. It only saves time if you have a bench grinder. Try it with a Dremel and you'll end up deciding that heating the caliper to get the button screw out to replace the plates the next time you need pads is quicker. Note to self: buy bench grinder.

the flyin' scotsman

Dave/Garth............I'll have the wheel off after lunch check piston movement, guide plates and backing plates.

Garnet Paper I may have to go get..............as the hardware store is beyond the Winery I'll kill 2 birds and many cells with one run.

cheers (hic)

the flyin' scotsman

Bench grinder and 'Dremel' are available shop tools out in the cool quonset........that operation may have to wait until the mid afternoon sun.

the flyin' scotsman

ok.............its apart; again.

Pads were not fixed in the caliper in anyway, have lots of meat on them but they're rather shiney/glazed.

The caliper pistons did move after they were introduced to Miss C Clamp but nothing that would indicate they were frozen/rusted. Rotors measured 22.8mm.

I can't see any bent or pinch brake line.

So, with the above, the pads are old and shall be replaced and considering the rotor thickness I believe they have to go also.

Appreciate all the input and humor (I'm sipping some deglazing form the Rhone Valley as I type).

Garth S

I would be very tempted to clean up the glazing that I had suspected and reassemble for many more miles of happy motoring: rears carry such a small percentage of normal braking, leaving them susceptible to this .... especially as they outlast fronts 2-3x.
This will be every bit as effective as new parts .... and in turn, finance another trip to David's 'Wine Cottage' in Calgary SW.

the flyin' scotsman

Your a man after my own heart Garth and appreciate the direction................cheers.