hobbie2k

I remember reading a thread a while back about the rear drum brakes locking up early due to a poor adjustment (searched, couldn't find it). I've noticed this winter that my car under heavy braking on ice will tend to lock up the rears long before the fronts which is problematic because it means that the car wants to swap ends.

I've got a set of ice tires on the way (it was a serious pain to find a set this late in the year), which will hopefully help.

What I'm wondering is whether I'm remembering right that this is a common problem. The next question is what is involved in fixing the problem, and whether this adjustment or repair would be covered under the warranty (the car has 33k on it, '07 LS coupe).

mike25

not sure if this helps...but at one time i had problems with my rear brakes locking up. turned out to be a stick break line going to the calipers that was caused by using the handbrake(ie pulling the handbrake caused it to work loose over time). warrantied and covered by the garage to e fixed

Maven

iTrader: (1)

Do you have ABS?

When was the last time your brakes were cleaned/lubed/adjusted?

Do your brakes pulsate at all?(out of round drums will cause excessive brake drag)

If you dont have ABS, your drums are true and your brakes maintaned rear lockup on ICE isnt really a problem that can be solved. Meaning if you had premature lockup all the time, even on dry or just wet pavement there would be a definitie problem, on ice, not so much. Have your rear brakes maintained if they havent been, get some tires better suited to your conditions, and drive cautiously.

There are no TSBs for Cobalt rear brake lockup

hobbie2k

The car does not have ABS, there is no pulsation, the tires are still original, though they haven't reached the wear markers yet (I figure they've got at least one more summer in them). I do my own maintenance and check the condition of the brakes with every oil change. They seemed to be in decent condition, I'm a fairly gentle driver (but my last check was about 9000 mi ago).

I do drive cautiously on ice, which I think is the only reason I haven't been in a ditch yet. If this is a "normal" condition, it is terrible brake tuning on the part of Chevy. If those rear brakes lock up on ice, even if you're only going 30mph, the car will spin in an instant, and it feels like it takes a moment too long for the brakes to release.

I personally don't think there's any excuse for a set of brakes under light use to need significant maintenance after only 33,000mi. Anyhow, I'm planning on taking it to the dealer to get the oil changed, ice tires put on, and the brakes checked. We'll see.

Maven

iTrader: (1)

Drums brakes do take (slightly) longer to "unlock" than discs. The drums on the Cobalt are actually very modern and tuned quite well, they are about as cutting edge as you get in drums. Perhaps you need a fluid flush and bleed.( I would recommend on an 07 with 33k miles, once a year, every 2 years MAX) air/old fluid in the front can make them "softer" than designed,keeping the proportioning valve from doing its job, allowing rear brake pressures to be abnormally high in relation to the fronts

Drums brakes do require maintenance to work "optimally" I would never think of letting friends or family drive around for 30k miles without cleaning/lubing/adjusting rear brakes at least 3 times.