Painting brake calipers. Yes or no.

[Rigger178]

Hi, my other vehicles all have 4 wheel drum brakes so this is a first time on vintage disc brakes,and I’m in the process of cleaning up some spider brake calipers that have sat for some time in what I’ll call moist conditions. I’m not worried about the function of them as the rebuild is pretty straight forward, but I notice that the aluminum has this whitish crust in some areas that I’ve already cleaned off, and was wondering if painting the outside of the calipers with high heat paint to prevent this is worth it.
I’ve noticed higher end calipers come painted, but was wondering if that would not allow them to cool enough under long or heavy braking.

[SteinOnkel]

A DIY paint job will be fine with VHT paint.

[Nut124]

The cool factor of painted calipers certainly would offset any loss of brake cooling from the paint, if any, right? If you have the wheel to show the color. Nothing wrong with it.

How do you get them clean enough for paint to stick?

The brakes are barely adequate for street. On a track, I find that they last a few quick laps at most. That is if you bleed and replace fluid before.

Not sure if the paint would have any effect on that.

[SteinOnkel]

The cool factor of painted calipers certainly would offset any loss of brake cooling from the paint, if any, right? If you have the wheel to show the color. Nothing wrong with it.

How do you get them clean enough for paint to stick?

The brakes are barely adequate for street On a track, I find that they last a few quick laps at most.. That is if you bleed and replace fluid before.

Not sure if the paint would have any effect on that.

This doesn't sound normal. What fluid are you running?

[Nut124]

Steiny, when you say "not normal" are you referring to my street or track statement?

I have been using Pentosin Super DOT 4 fluid.

When I used to go to the road track some 40 miles away, I would lose the breaking after 2-3 laps , for the rest of the nite. This was strange. So, on the way home, I had to drive carefully as the pedal was soft. This was with non-stock rotors but with stock calipers.

Even now, with fresh fluid, when I drive in stop-n-go highway traffic, I expect that new cars with ABS will stop better than I can in case of an emergency stop. I maintain extra distance accordingly.

What is your experience?

[SteinOnkel]

What I mean is that it is not normal for you to experience brake fade after 3-4 laps. On any reasonable car with a reasonable brake system.

For comparison, I could do almost an entire session (25 minutes) on my Derby even when it still had rear drum brakes!

The spider's stock brakes should be very much capable of stopping your car with minimal (if any) brake fade or change in pedal feel.

Looking at the spec sheet of your fluid, it's simply not up to the job. It's dry/wet boiling points* are a joke - 265C/165C respectively. We run RBF660 in all of our cars (914, Derby, Fiesta ST, Spider) and it boasts 328C/204C. If you want better, go with Castrol SRF - 310C/270C. For us, it's a bit cost prohibitive and the only advantage is its wet boiling point so you can go longer between changing it. I like bleeding my brakes before every track day - it's super easy and you need to check out the rest of the car anyway.

*Dry means fresh fluid, wet means fluid contaminated with water due to use.

Long story short, your brake system is most likely fine, but your fluid sucks.

Cheers
Steiny

P.S: My 124 has a firmer pedal than the Fiesta ST.

P.P.S: The second and third most important variable are disc shape and brake pad material. Autozone "premium brake select" or whatever? Stay away from me when on track, thank you. We run Stop-Tech components. Great on track and not too noisy on the street.

[Rigger178]

Ok, thanks. Rattle can VHT it is then. This car wont see a track, but my wife will be driving it so same thing.

[Nut124]

Steiny, thanks for the info. I have not been to the track in a few years but back when I used to go there I was trying to find better brake fluids. For some reason, the Pentosin was the what I was able to find. Perhaps was not looking hard enough.

Access to the track is no longer as easy as it was back then.

[SteinOnkel]

Access to the track is no longer as easy as it was back then.

Hmmm. Nowadays you go to www.motorsportreg.com find an event and sign up. Sure, there's a couple of rules to follow, but they make sense.

How was it "back then"?

[Nut124]

This is a track near South Haven, MI. It used to be open to public Thursdays from 6pm to dark. $50. Sign a waiver and go, open track. No racing. This was several years ago.

Now you pretty much have to participate in organized events only.

[Nut124]

Steiny, what would you say is the fluid volume needed to be drawn from each caliper to completely replace the brake fluid?

Assuming the tank is empty before being filled with the new fluid.

[SteinOnkel]

Steiny, what would you say is the fluid volume needed to be drawn from each caliper to completely replace the brake fluid?

Assuming the tank is empty before being filled with the new fluid.

Don't drain the system completely, you will get a ton of air into it that way. Bleed it like you normally would, just make sure you cycle the entire bottle of new fluid through the system. The system holds less than is in the bottle.

That's a fluid swap, which is a bit more work obviously. Once that is done, you can just replace the fluid at the calipers by doing a normal bleed. It's not an exact science, but if you get one of those one man bleeder bottles from autozone or wherever (the little ones) let them fill up about 3/4 of the way on each caliper. That way the fluid is fresh right at the caliper, where it is exposed to the majority of the heat.

By the way, ATE made Super Blue which makes this whole process MUCH easier. But it was banned by the DOT >:(

[manoa matt]

Just be sure to mask off the sliding surfaces that interface with the wedges. If you paint those surfaces, you might as well glue the entire system together, because it will not slide and re-center like it's designed to do.

Light white powdery corrosion on the caliper exterior surfaces is normal and will not affect the breaking or degradation of the base metal. Corrosion on the interior where the caliper piston slides and in the square O-ring land is what's important.

I have a pair of Ferodo pads I'm looking to sell, if you want to improve your breaking distance.

[Rigger178]

Thanks to all for the advice.

[RRoller123]

Painting the calipers doesn't get us anywhere near the CTI, or Critical Thickness of Insulation, so there is no adverse heat buildup.