One hundred and seventy pounds Where's the gold plating then?
I think the problem is water getting in between the alloy and steel parts, acting as an electrolyte and accelerating corrosion. I guess you need to stop that happening but I'm not sure how effective powder coating would be as I suspect they'll get fairly hot & expand at different rates, which will crack any sort of coating.
I would just give them another coat of something durable, maybe even lacquer or something?
I thought these backplates were discontinued? or was it that the cost was scary? as seen here I think you've done the right thing buying new ones like this but the dealers have you over a barrel because where else can you get them?
Cars in my care:
2021 Kia Spottage 1.6 Pez Turbo Dual Clutch Gearbox Trickery
2013 Renner Twingo - donkey work
Its a pure rip off, but the ones on at the moment are crumbling and it needs a handbrake for the next mot.
Your right MJB about the rubber parts, they can dry out and become useless very easy. I use some silicone spray on all the accessible parts that are made of rubber like the door seals, hoses, mounts etc which seems to keep them from drying out.
got my backplates back from the zinc-plating company.
Here are the pics.
IMAG0531.jpg
The chaps did say that the plastic coating that was still surprisingly good but couldn't tell at first, was a bastard to get off - even after shot blasting. Maybe FP's new ones will last a while without further treatment?
IMAG0534.jpg
Sadly the shot blasting put a hole in the backplate, will patch this up before fitting.
May still spray them to protect them further??
2003 2.2hdi estate - mine 1998 Volvo 940 auto estate - also mine 2019 Citroen C3 something - the wife's PP2000 user, can help with faults / diagnostics in the Bournemouth area.
It's a shame they didn't give you a chance to patch it before it was plated I suspect you'll need a specific primer, one for galvanised metal ('cos that's what zinc plating is).
The zinc plating looks like it did a good job especially on the mounts where the shoes mount to, it doenst look like they had any problems with warpage.
I fitted the plates today, but while i was there decided to change the rear shoes and pads, then decied to change the rear disks as they had plenty of grooves.
All was going back smoothly, but the rear passenger side callier seized, to unseize it i tried to put it in place with the pads on and press the pedal, but i forgot to put the drivers side rear calliper on with rather disasterous results, brake fluid everwhehere, and said calliper is wrecked, currenlty off the car and i have no way of stopping the leak other than a tray to collect the fluid.
To stop the leak put mole grips or ideally a brake hose clamp on the rubber brake hose to clamp it off.
The caliper should not be wrecked, all that has happened is the piston has come out.
When the hose is clamped off pump the pedal to force the other piston out, clamp off the hose here as well.
Get yourself a caliper repair kit which contains 2 inner seals and 2 outer seals (they may come as individuals).
Remove the seals and clean off the rust on the inner caliper surface (the outer bit usually) using a sharp blade and some fine wet and dry (120 or similar).
Clean out the grooves where the outer seal sits and clean out the caliper insides with brake cleaner (you have a compressor so blow out the dirt).
Using some rubber lubricant or condom lube (not vaseline) fit the new inner seal and outer seal.
After cleaning up the pistons coat them in rubber lube and slide them inside the outer seal...a bit fiddly....then carefully enter them inside the caliper and push them all the way home, they should slide in very easy.
Remove clamp, top up fluid and bleed.
Whilst the calipers are off clean up where the pads fit and grease them, along with the slides.
Put the fixed callipers back on, it was off the car overnight.
But on the issue of bleeding i replaced what fluid was lost and loosened the bleed screws got my dad to push the pedal and even though fluid is coming out free of air the pedal is spongy it doesnt have much resistance at all
When i tried to compress the pistons on the old calipers i remembered to remove the cap on the reservoir, but after wrecking the caliper it was left off overnight with just a plastic bag over the connection held in place with cable ties, about a cupful of fluid was in the bag this morning.
As for bleeding i reconnected the new calliper, released both rear bleeder screws, poured in the new fluid and pressed the pedal until it came out the bleed screws, then closed them off and got my dad to press the pedal in while i loosen the screws, there is fluid at the rear calipers but the pedal isnt giving much resistance
Going off that description you've bled it wrong mate,
You only open the bleeders one at a time.
Pump the pedal first.
Get the assistant then to push the pedal to the floor and not let the pedal up
You then undue the bleed nipple..
Instruct the helper not to let the pedal up until you shout them... thus closing the bleed nipple..
If you don't all that will happen is ..air getting drawn in .
When I used to play with old clunkers there were two things I noticed: bleed nipples don't exactly make a tight seal, so all the time they're open air can be drawn into the system just by the brake fluid dribbling out (even worse if the pedal is raised) and slow movement of the fluid doesn't take air bubbles with it. So the technique used to be: After loosening the nipple (and nipping it up again) the assistant puts pressure on the pedal, then open the nipple to allow the fluid to be pushed through while the assistant pushes the pedal swiftly to the floor. The nipple should be shut just before the end of the travel, then once it's shut the assistant can allow the pedal to slowly rise to the top. Down! Open-shut. Up... Down! Open-shut. Up... Oh yes, hours of fun, especially if the master cylinder's goosed and all it does is blow bubbles...
I think you've done the right thing buying new ones like this but the dealers have you over a barrel because where else can you get them? 
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