Hi there, I have an 08 5spd SS and I recently changed my brakes. Everything was just fine afterwards except that ever since they have been changed my brakes have been acting up when I cold start. When I depress the brake pedal it feels and sounds like ABS is kicking in while I'm completely stopped. My boost gauge also goes up a lot, I even got it to 5 psi once. This is only when I cold start, after I let idle for 5 or 10 minutes my brakes return to normal, but I can still get my boost gauge to move quite a bit. My car has been holding about 13-15 psi at wot on the stock tune. I'm thinking it may be a boost leak or maybe a messed up ABS sensor but that doesn't explain why its only on cold starts. Any help would be much appreciated.

 

There is a known problem with what you are discribing. Install a vacuum pump or wait till it gets vacuum. (I wait, less then a minute) Use the search bar to see other possibilities. But it is VERY common to our cars. There was a recall, but I believe it's over now.

 

The known low vacuum problem was mainly for 08 SS's with an automatic trans. The 5 speed owners weren't reporting any problems.

Based on the OP stating it only started being a problem AFTER he changed the brakes, then the brake work would be the probable cause.
What he did wrong, I'm not sure since he didn't give the details of the work that was done.

 

I had replaced my front rotors and pads. Nothing felt funky, the calipers weren't sticking or anything. I also sprayed my calipers red but I was very careful to cover everything. I also inspected my ABS sensor after a week of this happening and it didn't look dirty or messed up other than the top rubber housing for the wire was all broken down. I did not bleed my brakes when I serviced them because I did not remove the lines at all. I'm not too worried about this issue but its really bugging me, mostly because I want to know what I did wrong. Also my car does have almost 131000 miles on it so maybe things are just starting to go bad idk.

 

Just a thought here. I'm guessing you compressed the pistons on the calipers to make room for the new pads. Also guessing you did this without opening the bleeders?

There has been some debate about doing it this way and possibly causing damage to the ABS system by forcing fluid back into the ABS module.
Me, I have no experience regarding this. Just some posts I've read.

Hopefully someone with a little more insight can post up their opinion.

 

Would any of that cause boost while cold? Still sounds like he is not getting vacuum to the booster for what ever reason. You have to have vacuum to the booster, before you have power brakes.????

 

I had read a lot of posts discussing closing/not closing the bleeder valve and I decided to compress the piston with the bleeder valve closed. Maybe some fluid did get up into the ABS module and is only messing it up on cold starts until I get enough vacuum to the booster? Idk, I might try to see if I can get my ABS to kick in once shes warmed up.

 

Maybe one of the hubs just gave up coincidentally? No clue about the boost, but sounds like maybe the vac tubing to the brake booster got a hole in it?

I really don't think brake fluid going back through the ABS is a problem especially because you don't mention ABS/ESC lights on the dashboard.
However,... I seem to have almost solved my ABS/ESC problems by A) redoing all 4 sensor connectors with liberal application of dielectric grease and B) flushing the brake fluid.

 

Hi overweightcobalt,

I’m sorry to hear of the difficulties that you have been experiencing with your brakes. I will like to take a further look into this for you. We rely on our dealerships for their technical expertise and I will be glad to contact your dealership on your behalf in order to further discuss your concern. Feel free to send us a private message in reference to this thread if any extra help is needed. I look forward to hearing from you soon!

Kristen A.
Chevrolet Customer Care

 

My '09 SS Auto does it. When first started the brake pedal acts funny; goes almost to the floor but when I get backed out of the driveway it is fine. It only does this after sitting all night and lasts only a few moments.

I thought it was a common brake vacuum problem and easily fixable with a vacuum boost made for this car. I just don't worry about it.

Boydie