hi all. im rebuilding a set of seized 4 pots. the reason they seized is not because of the pistons (they are fine with no rot) but because the calliper itself has actually rusted where the pistons slide in and out (above the seals)
Ive cleaned this up and some pitting remains.
Is this normal for them to rot in this position? the seals were not split. How can I prevent the bare metal rotting again?

 

Any pictures bud?

Really i would have acid dipped before removing pistons, but if you clean them up with sand paper paint on some rust proof suff then paint over the calliper

 

Hi
Yes they usually do have rust at the top of the bore , when we strip and bead blast them the are done inside and outside so no rust is left anywhere , as long as the dust boots don't come off then the top of the bore should stay rust free for many years to come .
Apply some caliper grease when fitting the pistons back in , the grease will stay under the dust seal on the piston which helps combat rust building up again.
That's is one of the problems with a cast steel caliper , they rust very quick if not treated
Hope this helps
Cheers Ian

 

ok, thankyou both. ill apply some grease to the insides this time and hope that holds off the rust.

 

Are these safe to use as all damage is above the seals and smooth?
Yes I should have got them out on the car and yes I got carried away with the pliers on the three that were seized lol


[URL=http://smg.photobucket.com/user/dj219957/media/DSC04025.jpg.html][IMG]

 

As long as the polished surface is unmarked they will be fine to use

 

thanks ian

 

dj, when I refurbed my calipers I noted the same as you, the pistons cleaned up fine (replaced anyway with stainless ones) but the calipers had some minor rust in the bores. I had the calipers powder coated. They shot blasted them and then dipped them in a a grey coloured anti corrosion coating, then power coated. This means that the bores shouldn't rust anymore. This only cost me £30 so might be worth looking into. Bear in mind that normal paint comes straight off if you spill brake fluid on, powder coating is much more resistant to this as well.