MINI friends,
I tore my rear BMW/ MIINI (R53 06) rear calipers apart to paint then as a Winter project.
I used Aircraft Stipper to get the original paint off. During the stripping process I submerged them in water (rubber gloves on) to help get the Aircraft Stripper and old paint off...so the stuff was diluted, but it def got inside the caliper (where the piston goes in, also shown by the Yellow arrow in the pic below). I blew it all out after each rinse with the air compressor.

My question is....is there a rubber seal(s) deeper inside the caliper that may have been damaged?
I do not mean the main piston seal or the rubber dust boot....those were pulled and I have new ones.

If there were other seals in there, does anyone have a diagram of that part of the caliper and a line on getting the seal(s) I would need?
Is there a way to test if they will hold prior to putting I all back together?

A bit more info:
- the piston it self was not effected
- I did not pull the handbrake mechanism apart...did not think you could, but now I am second guessing that.

Thanks for the help!

 

Yes there is, behind the parking brake actuator. I think in one of my post I have the info for the rebuild of the back calipers. I had mine powder coated and the heat damaged the seals behind there.
And yes, it was fun pulling the actuator. I bought a sacrificial caliper to test on before trying on the powder coated ones.


Thread with the seal:
https://www.northamericanmotoring.co...ng-a-part.html

 

lotter1,
thank you so much for the reply. I am even worse off than I thought...if the paint remover did not hurt the seal, the heat from the power coating did...either way, I think I am in need of two seals.

I followed your thread, but did not see how to pull the e-brake pulley or where you ended up finding the seal (hopefully you did).x
I'll search your posts again, but if you have it handy please share.

thank you!

 

I had to do some head scratching there for a minute as this was a while ago. I believe I got those seals from donor calipers. I think I bought one here from a member and got the other from a yard? I never did find a source to buy a replacement seal. If I where to do it again, I would disassemble the whole thing before cleaning or coating again, but that is hind sight for you.
That stop pin is pushed in. On the sacrificial unit, it just went ape s**t on it to see what I was dealing with. Then on the powder coated one's, stubbornness, punch and a hammer, I slowly worked them out. I will see if I have any more pictures.

 

Thanks again....yes pics or more detail would help. I am not certain which pin you are talking about pounding out...the stop pin (1) or the pin that the actuator rotates on (2).




Overall, I'm bummed....I had no idea that would happen to the seal. I even searched powder coating calipers and did come across any warnings.
I feel like I have two options at this point:

1. Put the powder coated ones on and keep an eye out for leaks. Basically pray the heat did not damage the seal.
2. Find a used set (I saw a genuine BMW set in decent shape for about $120 for both) and either just use them as is, spray paint them myself (take the loss on the powder coating) or take them apart and swap seals (which is what you did).

I would prefer to take them apart if I can get some good direction and feel confident I can do it. I'll keep searching for more info across the WWW.

 

I may have missed it, but what makes you believe the seal has gone bad?

I just rebuilt and painted my rear calipers. I ordered, the kit that provides new o ring and piston boot. Didn't disassemble parking break mechanism. Media blasted mine before die grinding to get a smooth surface for a better finish. Baked the paint per instructions for high temp paint.

​​​​​​The, soft goods on brake calipers are made for a high heat environment. Powder coating wouldn't harm them from Temps.

 

You must have been lucky or me unlucky, mine leaked as soon as it came back from the coaters. Also OP use chemicals to clean, that might have damaged the seals? Anyhow, here is more info:
Caliper break down - use google translate
https://ffclub.ru/topic/48022/jump_990/

Appears to be a FULL rebuilt kit
Frenkit 238041

 

Husky44,
Good info and I like the way you think...I will have to put them on and see what happens.
Hoping for the best. I am not certain what temp the Powder coater cured the paint at, but you may be right that it is in the range of normal to hot for a brake caliper.

I pick them up today and have to wait for a bit warmer day to rebuild and install rear and fronts (fronts were StopTech and had no "hidden" seals).

I will update when I get it all back together....hoping for the best.

 

Thank you for the link. I will check it out and be ready for which ever way I have to go.

 

I pm'd you on how I did it. But the link shows the caliper parts break down.
Good luck!