Help! I brake at stop sign /light and then i feel brake pedal go down .

[marce]

I come to a stop at light but then I feel the pedal go down so I push down hard. Feels spongy.Had them checked cause of squeal but dealer said just dust in them.Now yesterday had to brake on left turn lane cause lady pulled out in frt of me from Frys (And me pulling in)head on you can bet I stood on the brake pedal! and it stopped fast.So what can it be causing this ? Now mind its not every stop. Thanks

 

[IllogicTC]

When I get down to idle speed or so where the vacuum from the motor would be a bit less, my brake pedal sinks a little but it's literally maybe another 1/4 inch. I myself am not sure if this is an actual issue or normal operation. But it sounds like yours is going down considerably, like way over 1-2"?

 

[marce]

I would say about well feels like 1"

 

[marce]

I have had mi TB for going on9 yrs daily driver so I know it well . This is a new feel.

 

[The_Roadie]

How many miles?

A spongy feel is part of the vehicle, but if you say yours is deteriorating, I'd guess leaky seals in the master cylinder. Or a bad vacuum boost unit. Or spongy brake lines that are bulging out and could burst. (not likely)

Are you going to be doing the repair yourself?

 

[marce]

Hello Roadie. TB has 109193 miles.Thinking yes if its on the forums on how to do.would you say aftermarket parts or GM and does my hubby do both or one or other?

 

[The_Roadie]

We don't have how-to's for things like the brake booster, but there are manuals available for download. Just locate the Pinned post with the link. Aftermarket in most cases is totally trustworthy. If you have time for an Internet order, many of us use Rockauto.com with a discount code that's easy to find.

Only your hubby knows how stocked he is with skills and tools to do various jobs. Every DIY'er has a different threshold of experience/time/frugality/etc.