Some help with odd brake problem...

[SevenBizzos]

Hyundai
Wondering if someone has an idea for this.
Front calipers were old. This spring, I noticed that on the first few warm days my front driver's side caliper would stick shut and retract slowly over 5-10 seconds. When it got cold (40s-50s) again the problem went away. I finally got around to replacing the calipers.
This did not work. Even with the new set of calipers the problem only shows up with it's above 70 degrees or so and the warmer it gets, the longer it takes for that one to get back open. While it's nice having new parts, I'm confused as to what's going on and why.
Thoughts?

 

[KrisZ]

It is likely the flex brake hose that is partially blocked or collapsed. Change the brake hoses.
This would explain the correlation with the outside temperature. Rubber is stiffer when cold, so the hose stays open, once it gets warm, it closes internally.

 

[Trav]

+1 I would guess the brake hoses have some part in it but it would be nice if you could put it one a brake dyno but in the USA there is little or no chance of that. This is the next best thing if you wanted to invest in a tool instead of guessing and loading the parts cannon.

https://www.amazon.com/IPA-Tools-Innovative-Products-7884/dp/B000850MZK?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=AKDENCFW3A9SI

 

[eljefino]

Sometimes the master cylinder won't take fluid back. This can be if the pedal pushrod is too long, or if stuff just goes out of whack. There's a little port that allows fluid back through the MC into the reservoir which is supposed to be blocked as soon as the pedal moves 1/4". Does your pedal ever feel really wooden?

 

[SevenBizzos]

Thank you! The issue is certainly isolated to that brake, so that makes sense. I will give it a go. It looks like something I can easily do.

 

[tnt_motorsports]

Thank you! The issue is certainly isolated to that brake, so that makes sense. I will give it a go. It looks like something I can easily do.

I'd change the brake hose and then bleed the caliper. Suck out the fluid reservoir and fill with new fluid prior to bleeding.

Just my $0.02

 

[Donald]

Many people replace the flex brake hose when they replace a caliper.

 

[GMBoy]

My vote also for brake hose replacement - also check that the caliper was not rotated when reinstalled causing a kink in the hose - seen that happen too.

 

[Number_35]

My vote also for brake hose replacement - also check that the caliper was not rotated when reinstalled causing a kink in the hose - seen that happen too.

Blush - I did that once. Quite embarrassed, but at least I discovered it myself.

 

[GMBoy]

Blush - I did that once. Quite embarrassed, but at least I discovered it myself.

I did as well and it was instantly declaring! Soon as I backed up the front wheel was locked lol.

 

[D60]

Blush - I did that once. Quite embarrassed, but at least I discovered it myself.

While not the OP's problem, the other big one is mounting mirrored calipers on the wrong side (upside down) and then wondering why you can never get a good bleed I've never done it but come close!

 

[SevenBizzos]

I made an attempt. I need to stay in my lane and away from YouTube. Gave up after three hours (I'm not going to catalog everything that went wrong). Car is at my preferred shop now.