Corroded caliper - what to do?

[tomolmsted]

Any suggestions? Is bead blasting acceptable? Isn't that what the caliper rebuild companies do? I think the PO installed rebuilt calipers, then the car sat for over 10 years.

[proffighter]

Throw it away and buy a new or reman part. Corrosion is way too much

[Porboynz]

Well, counter viewpoint from a man who is careful with his money. First off clean off the surface rust and reinspect, a 3M type pot scrub will probably do it. Cast iron rusts up easily and usually looks worse than it really is. The pistons are the items that needs to be perfectly smooth and shiny, not so much the caliper bores. As long as the seal grooves are undamaged and there is no major pitting I would be comfortable. When in doubt replace though, agreed.

[chris_seven]

I would blast them and use them again but...

I don't think bead blasting is aggressive enough to do the job.

The standard process used by caliper reconditioners is to use a 'wheelabrator' type shot blast machine and a very aggressive chilled iron shot. The cycle time to blast a batch of caliper bodies would typically be around 20 minutes.

We stripped the calipers and thermally processed them in controlled pyrolysis oven to remove all grease and oils prior to blasting.

The calipers are then normally zinc plated and passivated within 4 hours of being blast cleaned. It is a real pain to find a blast cleaning contrator close to a plater so that you can plate them before they discolour.

Once they are plated the fluid pathways will need to be 'rodded' through with some very stiff brushes and thoroughly washed out.

I would re-assemble with ATE Plastilube because if you use brake fluid the seal friction will be high and you may experience pad knock off.

Here are some SWB Calipers we refurbed last week with Stainless Pistons.




We looked at acid pickling as an alternative to blast cleaning but even after neutralising and hot washing the plating discoloured badly.

Our plater also works for one of the UK's largest caliper rebuilders and he confirms that acid pickling is never successful.

We didn't try painting after pickling as we wanted a stock finish.

[proffighter]

Nothing you can do at home...

[tomolmsted]

Being cost effective is important, but I want to do what is right for safety and reliability.

[CCM911]

Plus One on the scotchbrite/bead blast approach. As previously mentined, the piston will ride on the rubber seal, not on the metal area.

At the minimum, why not clean it up and then re-post a photo. Then we can see what you are looking at.

[gtc]

I used Evaporust on a set of calipers I rebuilt recently. It works great... eats the rust away and leaves the base metal intact. Unfortunately it might attack your cad plating also. I bought a gallon at harbor freight, and I keep it in a small plastic bucket so I can soak parts for a day or so.

Here is one of mine: (credit to Eric @ PMB for instructions and seal kits)

(yes, the bolts should be black)