Technical Rusty brake disc on one side?

[AnthonyH]

It's not difficult. You can also put new breaking fluid in, whilst you're on it. If you want to keep the fluid, you can put a sort of cork on the pipe after you disconnect it from the caliper then after reconnecting it you do the bleeding.
New does sound better, most of the times. But you can decide if the ones you have are worth keeping and if you can improve their state, after taking a closer look at them.

I might take the rubber on the slider pins off and see if i can live with the noise! I don't have much to lose as I would have to buy new ones to fix this anyway.

I was a bit nervous about pressing the brake to extend the piston, i have bad memories around killing rear wheel brake cylinders lol. So i didn't extend the piston much, but i think i'll have to do that and get a wire brush/scrubber on them.

I bled one of the front brakes to see what the fluid looked like and it was dark and grimey, not the worst, but i'll have to change all of the brake fluid as soon as practical.

 

[Mike1alike]

Better than wire brush, you can use scuff pads and brake cleaner.
I don't think you'll get much noise from removing the rubber. It's role there is to prevent dust going inside and to contain the grease on the slider.

 

[AnthonyH]

Better than wire brush, you can use scuff pads and brake cleaner.

Thats a good idea. I was possibly going to scratch them into failure.

I don't think you'll get much noise from removing the rubber. It's role there is to prevent dust going inside and to contain the grease on the slider.

OK, thanks, thats now the first port of call.

 

[AnthonyH]

I returned to this today.

I took off the sliders, removed their rubbers completely and left them off the car. I greased the sliders and put them back on. The calipers were moving freely. I then bled the brakes.

But it didn't make a difference.

I suppose I'm trying to avoid cleaning the piston or replacing the calipers.

Would cleaning the clips make a difference?

 

[the green vanper]

Clean everything

 

[AnthonyH]

I cleaned the hole into which the sliders go, and the sliders themselves, but that was it.

The pads looked flush but maybe they were at a slight tilt I couldn't see. It won't be difficult to clean the clips.

I presume I can't clean the piston properly without taking it off the car?

 

[AnthonyH]

I cleaned the clips and bracket, I had a lot of trouble getting the pads back in, previously they might not have been flush to the disc. I then drove the car and the discs seem to have been scratched flatter. These are some before and after pictures of the disc.

 

[GrandePunto PL]

This is what you get with lack of preventive maintenance (just reactive, "fire fighting").

To identify a problem, you need to clean the parts, a lot of rust everywhere. Sanding/grinding, sand blasting etc. Inspection of the parts: critical features, if the flat surfaces are still flat, right angles 90 deg., sizes, shapes, you know. Outside/external features. Then internals (yes, pop the pistons out of the cylinders/calipers) if dealing with external stuff will not help. Or actually, there is simple test: you pump the brake a bit, then push back the piston bare hands (if it's healthy it must go in - like in a video mentioned below).
Example video, addressing what's outside only (non-english), LINK. But the pistons were retracted bare hand (so they're probably good for now). For example areas where you put the brake pads are 18 mm wide (without those stainless steel sheet sliding inserts or whatever you call it). Sliding pins are "10 mm" (sliding fit, so 9,9x mm). Things like that. If there is too much wear somewhere, the mechanism like that will seize (too little and too much clearance/play is equally bad for moving parts).

 

[the green vanper]

Looking at the second photo I'd say some serious derusting is required. I'd sand blast it...

And for the disc, it needs at least some work on a lathe, or any other improvised treatment to make the surface totally rust free, clean and FLAT!

 

[AnthonyH]

This is what you get with lack of preventive maintenance (just reactive, "fire fighting").

To identify a problem, you need to clean the parts, a lot of rust everywhere. Sanding/grinding, sand blasting etc. Inspection of the parts: critical features, if the flat surfaces are still flat, right angles 90 deg., sizes, shapes, you know. Outside/external features. Then internals (yes, pop the pistons out of the cylinders/calipers) if dealing with external stuff will not help.
Example video, addressing what's outside only (non-english), LINK. For example areas where you put the brake pads are 18 mm wide (without those stainless steel sheet sliding inserts or whatever you call it). Sliding pins are "10 mm" (sliding fit, so 9,9x mm). Things like that. If there is too much wear somewhere, the mechanism like that will seize (too little and too much clearance/play is equally bad for moving parts).

Thats a very thorough brake job. It was interesting to see the measurements. I might get some micrometers and do the same myself. I used a sanding machine on the clips and brackets, but could do more.

Looking at the second photo I'd say some serious derusting is required. I'd sand blast it...

And for the disc, it needs at least some work on a lathe, or any other improvised treatment to make the surface totally rust free, clean and FLAT!

I might take it off and sand it. I realise its not optimal...at least i've found the problem and don't need to buy new calipers.