bad brake booster?
Thread Starter
Racer
Joined: Oct 2008
Posts: 423
Likes: 48
From: winchester Virginia
bad brake booster?
Hi I have the typical C4 weak brake problem and I read that the booster should hold a vacuum if it is good. I can pump like mad with a small hand vac pump like mityvac and never generate any vacuum. However, when I push on the brakes (booster connected to engine vac normally) before starting engine then when engine starts I do get good pedal movement indicating that the booster at least works somewhat. Question is, could the booster have a slow-leak so my little vac pump can't pull enough vac but the engine can.
Brakes work well for gradual stops, but when attempting a panic stop its as if the pedal hits a wall and no matter how much additional force is applied stopping power doesn't increase.
Thanks in advance--E-fish
Brakes work well for gradual stops, but when attempting a panic stop its as if the pedal hits a wall and no matter how much additional force is applied stopping power doesn't increase.
Thanks in advance--E-fish
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
Hi I have the typical C4 weak brake problem and I read that the booster should hold a vacuum if it is good. I can pump like mad with a small hand vac pump like mityvac and never generate any vacuum. However, when I push on the brakes (booster connected to engine vac normally) before starting engine then when engine starts I do get good pedal movement indicating that the booster at least works somewhat. Question is, could the booster have a slow-leak so my little vac pump can't pull enough vac but the engine can.
Brakes work well for gradual stops, but when attempting a panic stop its as if the pedal hits a wall and no matter how much additional force is applied stopping power doesn't increase.
Thanks in advance--E-fish
Brakes work well for gradual stops, but when attempting a panic stop its as if the pedal hits a wall and no matter how much additional force is applied stopping power doesn't increase.
Thanks in advance--E-fish
Safety Car
Joined: Jan 2004
Posts: 3,759
Likes: 8
Burning Brakes
Joined: Jul 2006
Posts: 1,080
Likes: 2
From: Pittsburgh PA
put a gauge in line with the booster vacuum line. Start car and let run for a second to watch how much vacuum is made. Then shut car off. Watch the gauge to see if it bleeds down. A good booster is suppose to hold vacuum for many hours.
My car feels week and only holds vacuum for an hour or 2. I think its damaged inside and leaking.
My car feels week and only holds vacuum for an hour or 2. I think its damaged inside and leaking.
Racer
Joined: Mar 2010
Posts: 291
Likes: 1
From: Temecula Cali
put a gauge in line with the booster vacuum line. Start car and let run for a second to watch how much vacuum is made. Then shut car off. Watch the gauge to see if it bleeds down. A good booster is suppose to hold vacuum for many hours.
My car feels week and only holds vacuum for an hour or 2. I think its damaged inside and leaking.
My car feels week and only holds vacuum for an hour or 2. I think its damaged inside and leaking.
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Drifting
Joined: Jan 2005
Posts: 1,354
Likes: 325
From: San Antonio Tx
There is a 13 page thread on this forum about lousy brakes. I had the same problem, replaced pads, rotors, ss brake hoses, booster and master cylinder. Didn't help. did c5 upgrade and still lousy brakes under hard braking. Finall I removed the abs fuse and at 40mph I used both feet on the brake pedal and put all my weight on it. After the smoke cleared I had good brakes for the first time in five years. Reinstalled the abs fuse and everything is working great. My guess is something was stuck in the abs system and it took a lot of pressure to knock it loose.
