1993 Chevrolet Lumina spungy brake pedal

GEORGE THRONE

MEMBER
1993 CHEVROLET LUMINA
3.1L
6 CYL
2WD
AUTOMATIC
111,500 MILES

Will a faulty vacuum booster cause a spongy brake pedal?I have completely went over the break system and everything seems to be working properly although I do not know about the vacuum booster.

Saturday, January 31st, 2015 AT 8:47 PM

6 Replies

WRENCHTECH

MECHANIC
20,757 POSTS

No, it will not. A faulty booster will cause a high, hard pedal.

What else has been done to the brakes and how did this problem start?

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Sunday, February 1st, 2015 AT 6:13 AM

GEORGE THRONE

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11 POSTS

I installed a new master cylinder and I put a new flex line on the left front wheel, also cleaned the sliders and lubricated same, replaced both rear calipers, had rotors turned. I first bench bled the master cylinder and then again after I installed it on the car by cracking the lines one by one.I then power bled the whole system one more time. By having disc brakes all the way around, would that cause a spongy pedal? I am not used to a spongy pedal. Any help you could give me on this matter would be greatly appreciated. Thank you!

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Sunday, February 1st, 2015 AT 11:43 AM

WRENCHTECH

MECHANIC
20,757 POSTS

Lets clear one thing up first. GM brakes ALWAYS feel spongy when you are sitting still and pumping them but if the vehicle is moving it will stop long before applying that much force.

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Sunday, February 1st, 2015 AT 11:53 AM

GEORGE THRONE

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11 POSTS

Thank you for the information. I have a friend with an s10 pickup and it has excellent breaks. I wish my car had the same break set up, but it evidently does not. I guess I'll just have to live with it.
Thank you very much for for the information. Also I'd like today that I think you guys are doing a great job.

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Sunday, February 1st, 2015 AT 9:11 PM

GEORGE THRONE