tuna55
tuna55 MegaDork
2/25/22 3:00 p.m.

The dealer says the case they opened with GM tells them to replace the caliper and line on that side for $415. I can buy a new ACDELCO caliper and Centric line from Rockauto for $47, and I'll just replace the other line while I am there. I am a little suspecious of needing a caliper though. Thoughts?

TurnerX19
TurnerX19 UltraDork
2/25/22 4:23 p.m.

In reply to tuna55 :

I would do the line alone without the caliper first. If it is the caliper you should be able to see a problem while you are working on it.

tuna55
tuna55 MegaDork
3/1/22 9:42 p.m.

My perpetual helper bled the brakes with me afterward, but I did get the line installed today. It took very little time, but the old one looked very good. I cut it open a few times along its length to inspect and it looked pretty new. I have very little confidence that I found it in this part. I was in a pretty big time crunch so I didn't check the other side for draggyness, nor did I pull the caliper to check it individually. Stay tuned.

TurnerX19
TurnerX19 UltraDork
3/1/22 10:25 p.m.

In reply to tuna55 :

Usually the failure point on a new hose is within the crimped end. The inner liner begins delaminating from the fabric and becomes a flap valve. Old hoses can collapse anywhere. Make two careful slices on the crimp with a mini whiz wheel (Dremel cut off disc) parallel to the hose. Just through the metal, and peel the crimp back, then pull the remaining hose off of the crimp. I bet you find it.

tuna55
tuna55 MegaDork
3/2/22 8:55 a.m.
TurnerX19 said:

In reply to tuna55 :

Usually the failure point on a new hose is within the crimped end. The inner liner begins delaminating from the fabric and becomes a flap valve. Old hoses can collapse anywhere. Make two careful slices on the crimp with a mini whiz wheel (Dremel cut off disc) parallel to the hose. Just through the metal, and peel the crimp back, then pull the remaining hose off of the crimp. I bet you find it.

Maybe I'll take the time to do that. We'll see.

 

For this morning's drive, I touched the caliper when I got to work. Both were ice cold.

tuna55
tuna55 MegaDork
3/2/22 5:06 p.m.

It's just me sitting here waiting for my brake to cool. The caliper arrived today, that's next.

Keith Tanner
Keith Tanner MegaDork
3/2/22 6:47 p.m.

In reply to tuna55 :

Argh, that's frustrating. 

tuna55
tuna55 MegaDork
3/2/22 8:48 p.m.
Keith Tanner said:

In reply to tuna55 :

Argh, that's frustrating. 

It sure is. I'm sure I can get it figured out and I'm also fine with the money because I'm still saving so much. The irritating thing is that this was exactly the type of failure mode I was hoping to avoid by staying with a known brand. I'm sure you understand that as we've had these talks before. I'm happy to eat a little crow here as my safeguard didn't work out it seems. Still saving about $18 a day over a gas car, but brakes were one of those things I expected to not have to spend money on.

Keith Tanner
Keith Tanner MegaDork
3/2/22 10:46 p.m.

Stuff like this happens to every manufacturer. 

tuna55
tuna55 MegaDork
3/3/22 6:17 a.m.

You're not wrong!

 

Almost 50k miles, and it's my first piece of maintenance other than tires, so it's not bad. I still think it's super weird having ice cold calipers on the hour long drive to work, and hot enough to grab the rotor on the way home. Granted the latter hada bit higher speeds and the ambient temp was higher. I am worried that even the caliper won't fix it. 

 

tuna55
tuna55 MegaDork
3/3/22 10:48 p.m.

Taking the non highway route home, still with speeds up in the 60 range, no trouble noted, though the passenger caliper was a tiny bit warmer than the driver. I expect ambient temperature on each after a normal drive. This was maybe 5 degrees warmer. Just barely enough to notice. I might start carrying an infrared thermometer with me. 

tuna55
tuna55 MegaDork
3/5/22 1:56 p.m.

 

This caliper has basically never been used, nothing appears to be wrong with it and I'm pretty irritated.

Jesse Ransom
Jesse Ransom UltimaDork
3/5/22 2:07 p.m.

In reply to tuna55 :

What's that band of crustiness on the piston near the groove?

You're in a better position to say whether it's anything at all, but it jumped out at me.

Keith Tanner
Keith Tanner MegaDork
3/5/22 2:24 p.m.

Any chance it's corroded/sticking slider pins? I could see that causing this sort of problem, and the picture of the pads does show the outboard pad in greater contact than the inboard.

tuna55
tuna55 MegaDork
3/5/22 3:20 p.m.

The pins are in pretty good shape but then I saw this and I think this might be the issue

Is this what you meant Jessie?

 

Keith Tanner
Keith Tanner MegaDork
3/5/22 4:09 p.m.

I was wondering about that as well but since you said nothing was wrong with the caliper I assumed you'd dismissed it. The corrosion is inside the boot but outside the bore of the caliper, right? 

tuna55
tuna55 MegaDork
3/5/22 5:01 p.m.
Keith Tanner said:

I was wondering about that as well but since you said nothing was wrong with the caliper I assumed you'd dismissed it. The corrosion is inside the boot but outside the bore of the caliper, right? 

Probably. Like this?

 

Jesse Ransom
Jesse Ransom UltimaDork
3/5/22 6:18 p.m.

In reply to tuna55 :

Yep, that's what caught my eye. Even if it's under part of the seal I wonder whether it might swell it and cause a little binding?

EDT (Forum Supporter)
EDT (Forum Supporter) Reader
3/5/22 6:20 p.m.

Those sure look like phenolic pistons to me and I've have terrible luck with them. I have Mustang calipers on my Factory Five Daytona and when I don't drive it regularly about half the time the brakes stick and drag something terrible. I've been through 3 calipers now (thank you parts store lifetime warranty) and they all work perfectly fine until they sit and then they're never right again. 

I have measured a couple of the pistons that stuck and they were a good bit bigger than new ones (I forget exactly how much). I recently found metal pistons that were a direct swap and I haven't had the slightest issue since. It could be that the car not using the brakes enough to cook out any moisture is the issue. 

tuna55
tuna55 MegaDork
3/7/22 9:11 a.m.
EDT (Forum Supporter) said:

Those sure look like phenolic pistons to me and I've have terrible luck with them. I have Mustang calipers on my Factory Five Daytona and when I don't drive it regularly about half the time the brakes stick and drag something terrible. I've been through 3 calipers now (thank you parts store lifetime warranty) and they all work perfectly fine until they sit and then they're never right again. 

I have measured a couple of the pistons that stuck and they were a good bit bigger than new ones (I forget exactly how much). I recently found metal pistons that were a direct swap and I haven't had the slightest issue since. It could be that the car not using the brakes enough to cook out any moisture is the issue. 

I hit the piston with a file, and it sure doesn't seem like metal. If it is phenolic, what's the crud stuck on there?

Keith Tanner
Keith Tanner MegaDork
3/7/22 10:00 a.m.

Interesting, I'd never heard of this. One link suggests that acidic brake fluid could be a problem, and another stated that they're more likely to seize than metal ones. EDT's statement about them giving trouble when sitting would follow with a one-pedal EV.

tuna55
tuna55 MegaDork
3/7/22 10:19 a.m.
Keith Tanner said:

Interesting, I'd never heard of this. One link suggests that acidic brake fluid could be a problem, and another stated that they're more likely to seize than metal ones. EDT's statement about them giving trouble when sitting would follow with a one-pedal EV.

Well it is two year old brake fluid, so while it's not new, it's not exactly deferred maintenance either. It has 50K on it now, but maybe one brake usage per week doesn't get anything really hot.

Agent98
Agent98 Reader
3/7/22 6:47 p.m.

Brakes as hot as a supernova....I've been through guide pins and finally both front calipers on my 1998 Firebird Formula....super Nova a boiling hot star named for GM product....this is a rare case I fully support shotgunning. Went through a lot of brake fluid part by part....

Agent98
Agent98 Reader
3/7/22 6:56 p.m.

There's a method to bleed brakes by yourself, check out you tube A1 Auto or JRGo..they have videos.

tuna55
tuna55 MegaDork
3/8/22 9:03 a.m.

Mild update: The caliper indeed seemed to fix the issue. The brake hose was $11 and the caliper was $30 for new AC Delco OEM. The fluid was around $5. It takes nearly $17 to drive our modern minivan back and forth to work for one day, and roughly a tenth of that for the Bolt. 

 

The spring is coming, and the good news is that I can get a decent measurement of the efficiency of the new tires, now with around 5K on them. My one-day average so far is 4.1-4.2 mi/kwh, so pretty much exactly the same as it was before. The new battery indeed has more capacity, but I still only charge to 90%, so it's not easily to compare.

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