My brakes are scaring me.....

[Kuntryboy865]

under heavy braking my brakes suck. i can feel like it almost shudders but normal day to day driving its fine but a good run or two on the dragon and it makes me want to upgrade .

Sent from my KFTT using Tapatalk

 

[Scot]

^^^
Um...
Upgrade your brakes.

 

[ChicksHateMe]

Hey, Anyone want to try an experiment. You'll need a SAFE environment where you can do over 60 and have no cars in front of you

OK, I got my car back, and I was kinda pissed off, but decided to wait and cool down and see if it was just me. I don't think it is...

My brakes now seem like they are all over the place. Spongy at lower speeds and they still mess up while accelerating.


I might go to the dealer and ask if I can take out another car, to see if that one will do what mine does. Maybe it IS just me. Here's what happens.

1. If I am driving normal, around town, the brakes seem between OK and not very good. Kind of squishy and they go lower to the floor than I remember them going. Seems to me like they need a better bleeding.

2. If I am on the highway, and have cruise control on AND the car is accelerating, the brakes are hard as a rock to press down. Once it stops accelerating, I get them to function. Al lower speeds, they are hard, but the cruise releases. At higher speeds, like 60+, if it's accelerating, they are hard as a rock, and won't release until it reaches speed, or if it does release, it is delayed. I REALLY don't want a delay in my brakes, especially longer ones the faster I am going.

3. IF I press the gas to accelerate, with cruise control off, AND try to press the brakes, The brakes are hard. I would think the brakes should work at ALL TIMES, and have priority over the gas pedal.

They say they changed the booster and master cylinder, and maybe they did. I was as pissed at the mess of oil left around my engine and the scratches on my hood from someone wiping it down with a dirty cloth as I was the brakes not working and losing the car for 5 days. But apparently they did something to it. But I don't THINK it's right still.

Anyone up to see if you get the same results, by trying a few of these things on a safe, empty road?

Press the gas, and while accelerating, see if the brakes work immediately, or there's a delay. And if the delay gets longer the faster you were going? That's if you can even press the brakes at all. At least this way, if you let off the gas, you regain control.

I wouldn't recommend trying the cruise control problem though, it's too dangerous. Here's what I did though, and it's scarey. I got up to about 70 and set the cruise speed for 70, then hit the brakes to take it out of cruise and let it slow down to about 55. Then I used the resume function. As it accelerated I tried to press the brakes. At times there was a delay, and cruise stopped and I had control. At other times the brakes we so hard they didn't move, and I accelerated to the 70 with rock hard brakes.

This, after they said it was fixed. I am now in the HATE stage of my Sonic's Love/Hate relationship.

I have to go back to the dealer now, and see if they can look at it again. If they treated my car so crappy the first time, I wonder what condition they will leave it in this time after my complaints. I even told them I talk on here, so they know who I am if they read this....

This sucks.... I trust my brakes even less now....

 

[94383Z71]

Take it back. There's no situation for your brakes to be hard as a rock. Any grandma should be able to drive this car and - at any point- stop it without over exerting herself.

If yours is not that way under all driving conditions, take it back and make them fix it, along with the scratches and mess.

 

[Stew]

Take it back. There's no situation for your brakes to be hard as a rock. Any grandma should be able to drive this car and - at any point- stop it without over exerting herself.

If yours is not that way under all driving conditions, take it back and make them fix it, along with the scratches and mess.

Agreed. At the very least insist that the tech ride with you in your car and then ride with him in a Sonic on the dealer lot and compare. As you said, brakes are about the most important feature in your car and they should work as expected.

 

[ChicksHateMe]

Yeah, I will go tomorrow. I worry about my anger level though, I don't want to lose it and make things worse down the road. I only have 4000 miles on it so I have another 4 1/2 years of warranty where I may have to deal with these guys. That's if I keep it.

I'd really like to know if it's just me or if anyone else can reproduce it too. I hope it's just me and not another Chevy design flaw.

 

[mitdr774]

Sounds like a bad one way check valve at the booster that they didnt replace last time.

 

[ChicksHateMe]

Sounds like a bad one way check valve at the booster that they didnt replace last time.

Thanks for your replies. Sounds like you know the brakes well. Think that check valve is something easy to get to and replace myself. I'm not afraid to do some work.

I am hoping someone will test there's an at least let me know the brakes kick in first when it's accelerating either with, or without cruise control on. I've had things get stuck under my brakes before, like a baby bottle, that scared me like this. But this is too consistent and repeatable. Just wondered if it was repeatable in others cars as well. If so, people should be made aware of the possibility ASAP. So they can get it fixed, or at least plan an escape route.....

1. Immediately shut off cruise (will try that today)

2. Not sure there are any faster and safer moves to remove the issue. Turning off the car probably removed brake boost.

3. Maybe going to neutral will automatically disable cruise too. (will try that today too).

I emailed this link to a Service rep at the dealer so they can see what's gone on. Out of site, out of mind.

The owners seem pro-active in giving 100% satisfaction, so may email it to them too. Or call them, This will show it's still an issue. Not sure I should forward it to anyone else in the organization or at Chevy. I'm surprised the Chevy reps that lurk here never chimed in on what could potentially be a serious problem.

 

[ahtoxa]

I am hoping someone will test there's an at least let me know the brakes kick in first when it's accelerating either with, or without cruise control on. I've had things get stuck under my brakes before, like a baby bottle, that scared me like this. But this is too consistent and repeatable. Just wondered if it was repeatable in others cars as well. If so, people should be made aware of the possibility ASAP. So they can get it fixed, or at least plan an escape route.....

Guarantee you, my friend, that no one will be able to replicate it, because it's not normal.

Just a week and a half ago, I drove 2000 highway miles in 4-5 days, and I was using cruise control a lot. I've accelerated with it, kept it steady, etc., and I've done plenty of pedal braking while cruise was on.

The brakes engaged immediately and with the same feel in the pedal as always. There wouldn't be any variables here in pedal engagement if everything is working as it should.

 

[Larrymer]

Yep, they're still not fixed. Go to a different dealer.

 

[ChicksHateMe]

This dealer has a great reputation, But I think they took it for a short drive and thought it was fixed. The brakes work, but not correctly.

I have emailed them that the problem still exists, and we're setting something up Monday. Neither of us could do it sooner. I'll just avoid cruise control til then.

I sent them a link to this thread. I'll give them another chance.

But I do wonder. I bought the car at one dealer. I am using a more local dealer for service. And I have been recommended to another dealer for service, not too far away.

I wonder how the Lemon Law works with multiple dealers involved. It appears this problem has been there since I bought it but was so intermittent I couldn't figure out what was going on. At least now I know how to reproduce it.

 

[jgrote]

I also agree that it is the check valve, but let me explain to you why. You seem to be someone who is capable of understanding this stuff, and works well when armed with the knowledge to get your problem solved.

So your engine creates vacuum when at idle or light acceleration. At full (or close to) throttle, it does not. (Anyone who has driven an old car with vacuum powered wipers knows they stop when accelerating.) The purpose of the booster is to store some of this vacuum so it is available when needed. When the engine is creating vacuum, it sucks the air out of the booster (leaving a vacuum). When you "give it the beans" the check valve in the hose between the booster and the engine closes, keeping the stored vacuum in the booster. When it fails, and you give it the beans, the vacuum (negative pressure) in the booster equalizes with the pressure the motor is making, and thus no brake help.

I hope this is helpful. Your problem is not a big one, but one that the tech missed. Usually, the check valve is buried in the hose somewhere, so the entire hose has to be replaced. It is a repair that should take no more than a few minutes. If you weren't under warranty I'd tell you how to fix yours, but since you are (and this is brakes we're talking about) I'll stop here.

 

[ChicksHateMe]

jgrote, Thanks for that explanation. It helped and made sense.

I was pretty frustrated when I got an email from the service rep. Saying they would look for a car that had the same features to test against. I took it as if I wasn't believed. Plus, that wasn't going to solve MY cars problem.

My frustration got the better of me. Lots of other stressors in my life right now. I didn't care much if the brakes went on me, but the thought of having to drive my grand kids around as it was, and having already had them in the car when it could have happened pushed me over the top. I went into the dealer ticked off it hadn't been resolved. I blew up, only to see the service rep had all my stuff in front of him. including this forum. Man, I felt dumb.

After the apologies, We went for a test drive and he was able to re-create the problem. Another intermittent problem came up that I wasn't even going to mention because it was so random, and the brakes are my priority.

I chose not to leave the car just yet as he looks further into it. Hopefully they do find it to be the check valve mentioned, take it in, replace it, and this problem will be over. As it is, I'm paying $360.00 a month for a car I am afraid to put others in. Hey, maybe they'll get rich if I keep driving it? J/K...

The other issue is a high pitched sound that comes from gawd knows where. Too random to associate with anything either. But the rep heard that twice. Maybe it's related and will hopefully go away when this issue is solved.

 

[ChicksHateMe]

They got back to me quick. They test drove another car and could see a significant difference. So I'm not crazy (wish I could get that in writing).

They ordered me a new Check Valve and another part that could have been affected by the leak to the booster, so I should be all set by Wednesday. It will be nice to see it resolved and have at least one thing go right this month We'll see....

 

[ChicksHateMe]

They ended up replacing the check valve and the vacuum pump (or auxiliary vacuum pump). Apparently both showed signs of contamination from the brake fluid.

Ahhhh, it feels great to have nice, consistent brakes again. I can hit the gas AND the brakes, and the brakes work. No more Hard pedal.

First attempt they changed the booster and Master Cylinder. I'm hoping the bad check valve didn't let much brake fluid through to do damage to those parts between the time they were changed and the check valve and vacuum pump was. I only put on a few hundred miles, so I hope not. I never saw a schematic of how it all works together.

Another issue I had was a high pitched noise, as if someone was letting air out of a balloon slowly. That was probably from the check valve leaking back. That should be gone too. Yay. We'll see.

 

[wbjones]

I come late to this discussion … and didn't know about the check valve per se.

but from my a-x and TT experience I would have said that you were losing vacuum in in the braking system … has happened to me many times, when I've been left foot braking and using both throttle and brake at the same time …

glad yours seems to be fixed

you and everyone else keep mentioning the loose of coolant … I've just bought a '14 Sonic 1.4T 6MT … is this coolant loss still a problem through out the model line ? is something being done about it at the corp. level ?

 

[ChicksHateMe]

Welcome and congrats on the new car. I love my car. How it feels, how it handles and the gas mileage. I just wish I didn't have so many issues with something so new. Brakes, water coming in right-front when raining, key-fob issues. and a few others. I'll be glad when they are all solved so I can just drive her.

Yes, my brakes are FINALLY fixed. That was wicked scarey. I wonder how many accidents have happened because of that, and have gone undetected. I know it's not just the Sonic that has the possibility, but I just wasn't ready for it.

As far as the coolant, I'd do a search for the threads on "losing coolant" specifically.

I've lost very little, but I started to watch it after reading other threads. One comment in the other threads really helped me. When it does go down below the line, I can hear the water gurgling through the heater. In the other thread they mention how to fill it slightly above the line to remove that. I'd do the search because there are a few different threads on it, and I don't remember which addressed the issue best.

Good luck.

 

[ahtoxa]

I come late to this discussion … and didn't know about the check valve per se.

but from my a-x and TT experience I would have said that you were losing vacuum in in the braking system … has happened to me many times, when I've been left foot braking and using both throttle and brake at the same time …

glad yours seems to be fixed

you and everyone else keep mentioning the loose of coolant … I've just bought a '14 Sonic 1.4T 6MT … is this coolant loss still a problem through out the model line ? is something being done about it at the corp. level ?

This begs a question - that's not normal behavior, right?

I heel-toe (HT) occasionally or double-clutch-heel-toe (DCHT) and I've never had a vacuum issue when using the brake and throttle at the same time. For giggles and practice, sometimes I'll run through 2-3 gears during DCHT, which means using the throttle however many times I decide to shift during braking, but never had an issue.

Since HT and DCHT work best with moderate to heavy brake application (due to common pedal set up, which levels the throttle and brake pedals during moderate to heavy brake application, making it easier to blip throttle), it would be scary to start loosing braking feel when coming in hot HTing before the corner.

 

[wbjones]

This begs a question - that's not normal behavior, right?

I heel-toe (HT) occasionally or double-clutch-heel-toe (DCHT) and I've never had a vacuum issue when using the brake and throttle at the same time. For giggles and practice, sometimes I'll run through 2-3 gears during DCHT, which means using the throttle however many times I decide to shift during braking, but never had an issue.

Since HT and DCHT work best with moderate to heavy brake application (due to common pedal set up, which levels the throttle and brake pedals during moderate to heavy brake application, making it easier to blip throttle), it would be scary to start loosing braking feel when coming in hot HTing before the corner.

you're correct … it's not normal behavior … but it's symptoms sounded the same as the OP …

this has usually happened during a-x … no need to HT .. since nearly the entire course is driven in second gear (very seldom have to shift to 3rd)…

there are times where both throttle and brake are used to help the car negotiate certain parts of the course …usually not a problem on the race track

and you are correct …it is scary (especially the first few times it happens) to have that "brake pedal won't move" feeling … once I figured what was causing the problem, if didn't bother so much … especially as I figured out that I could still use the two together AND have a normal pedal later, if I'd lift for a fraction of a second before hitting the brakes after I'd done the two together thing

 

[mja]

This is currently happening to my car, will try to replace the check valve and see if the cheaper part helps for the time being.

Anyone know the part number for the check valve? All I see in diagrams are hoses, no check valves. Is it possibly part of the #17 hose in the following picture:

(17 = PN# 95391441, 75$)

Master cylinder & seal
PN# 95390404, 95977364 - 120$

Brake booster
PN# 95491189 - 160$

Vacuum pump
PN# 96597326 - 215$

Brake fluid - Dot 4, 1 liter

...anything else I need? I've worked on brakes in the past. Seems like this is going to cost around 600$ :/