# Power brake booster **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** bravada, oldsmobile, brakes\ **Created:** [October 12, 2009, 3:17pm UTC](https://community.cartalk.com/t/power-brake-booster/37996 "2009-10-12T15:17:07Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![jeff\_lowell](https://avatars.discourse-cdn.com/v4/letter/j/74df32/32.png) [@jeff\_lowell](https://community.cartalk.com/u/jeff_lowell)\ **Post date:** [October 12, 2009, 3:17pm UTC](https://community.cartalk.com/t/power-brake-booster/37996/1 "2009-10-12T15:17:07Z")
i have a 2000 Bravada,and it seems that only one piston of the duel piston brake caliper is working.would a faulty brake booster cause this to happen,or should i be worried about somethjng else? ---
**Author:** ![cigroller](https://avatars.discourse-cdn.com/v4/letter/c/c68b51/32.png) [@cigroller](https://community.cartalk.com/u/cigroller)\ **Post date:** [October 12, 2009, 3:23pm UTC](https://community.cartalk.com/t/power-brake-booster/37996/2 "2009-10-12T15:23:00Z")
The brake booster will have nothing to do with it. This will be a problem in the caliper itself, or perhaps in the brake line leading to it. The brake booster just helps the pedal apply force. Other than that it has no direct effect, and couldn’t affect only one part of a caliper. ---
**Author:** ![jeff\_lowell](https://avatars.discourse-cdn.com/v4/letter/j/74df32/32.png) [@jeff\_lowell](https://community.cartalk.com/u/jeff_lowell)\ **Post date:** [October 12, 2009, 3:58pm UTC](https://community.cartalk.com/t/power-brake-booster/37996/3 "2009-10-12T15:58:38Z")
what if it sounds like air leaking whenever i step on the brake? ---
**Author:** ![cigroller](https://avatars.discourse-cdn.com/v4/letter/c/c68b51/32.png) [@cigroller](https://community.cartalk.com/u/cigroller)\ **Post date:** [October 12, 2009, 4:02pm UTC](https://community.cartalk.com/t/power-brake-booster/37996/4 "2009-10-12T16:02:45Z")
If your brake booster was leaking that badly then your engine would likely stall or at least nearly so whenever you stepped on the brake. However, a normally functioning brake booster does work by a leak - of sorts - a purposeful one. When you step on the brake it lets air rush into it - the difference in pressure between the air coming in and the vacuum on the other side of a diaphragm is what makes the brake booster work. Look at this: [http://auto.howstuffworks.com/auto-parts/brakes/brake-types/power-brake2.htm](http://auto.howstuffworks.com/auto-parts/brakes/brake-types/power-brake2.htm) ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [October 12, 2009, 4:07pm UTC](https://community.cartalk.com/t/power-brake-booster/37996/5 "2009-10-12T16:07:17Z")
Why do you say “it seems that only one piston of the duel piston brake caliper is working”? How do you know this? ---
**Author:** ![jeff\_lowell](https://avatars.discourse-cdn.com/v4/letter/j/74df32/32.png) [@jeff\_lowell](https://community.cartalk.com/u/jeff_lowell)\ **Post date:** [October 12, 2009, 5:03pm UTC](https://community.cartalk.com/t/power-brake-booster/37996/6 "2009-10-12T17:03:21Z")
when i pulled the tire off,the wear on the rotor only looked like it was only from the lower piston pushing on the brake shoe ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [October 12, 2009, 5:08pm UTC](https://community.cartalk.com/t/power-brake-booster/37996/7 "2009-10-12T17:08:36Z")
Well now you’ve confused me. The two pistons each should press on the entire width of the rotor, so I don’t see how the rotor’s wear pattern would indicate one or the other piston isn’t working. Is this what it looks like? [![](http://www.handymanlyness.com/archives/auto/repair/brakes/GM/Jimmy/mxbrfp02a_brake_pads_99_jimmy.jpg) ](http://www.handymanlyness.com/archives/auto/repair/brakes/GM/Jimmy/mxbrfp02a_brake_pads_99_jimmy.jpg) ---
**Author:** ![cigroller](https://avatars.discourse-cdn.com/v4/letter/c/c68b51/32.png) [@cigroller](https://community.cartalk.com/u/cigroller)\ **Post date:** [October 12, 2009, 5:52pm UTC](https://community.cartalk.com/t/power-brake-booster/37996/8 "2009-10-12T17:52:09Z")
I would also assume that it wouldn’t show on the rotor - though it would likely show in the pads - perhaps worn unevenly back to front or vice versa. ---
**Author:** ![jeff\_lowell](https://avatars.discourse-cdn.com/v4/letter/j/74df32/32.png) [@jeff\_lowell](https://community.cartalk.com/u/jeff_lowell)\ **Post date:** [October 12, 2009, 5:57pm UTC](https://community.cartalk.com/t/power-brake-booster/37996/9 "2009-10-12T17:57:38Z")
can’t really tell too good by that pict.,but yes. ---
**Author:** ![jeff\_lowell](https://avatars.discourse-cdn.com/v4/letter/j/74df32/32.png) [@jeff\_lowell](https://community.cartalk.com/u/jeff_lowell)\ **Post date:** [October 12, 2009, 5:59pm UTC](https://community.cartalk.com/t/power-brake-booster/37996/10 "2009-10-12T17:59:35Z")
duhh.i don’t know why i didn’t check the pads ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [October 12, 2009, 7:52pm UTC](https://community.cartalk.com/t/power-brake-booster/37996/11 "2009-10-12T19:52:16Z")
OK. Please describe as completely as you can what you saw when you looked at the rotor. Also, are the brakes making any odd noises (besides the air noise)? How well do they slow you down? Has it changed lately? ---
**Author:** ![jeff\_lowell](https://avatars.discourse-cdn.com/v4/letter/j/74df32/32.png) [@jeff\_lowell](https://community.cartalk.com/u/jeff_lowell)\ **Post date:** [October 12, 2009, 8:44pm UTC](https://community.cartalk.com/t/power-brake-booster/37996/12 "2009-10-12T20:44:14Z")
it looks to me that the rotor is only wearing on the bottom.there is no unusual noise.i just replaced all calipers last year.i wish it would slow down better ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [October 12, 2009, 8:56pm UTC](https://community.cartalk.com/t/power-brake-booster/37996/13 "2009-10-12T20:56:27Z")
OK…where is ‘the bottom’ of the rotor? ---
**Author:** ![jeff\_lowell](https://avatars.discourse-cdn.com/v4/letter/j/74df32/32.png) [@jeff\_lowell](https://community.cartalk.com/u/jeff_lowell)\ **Post date:** [October 12, 2009, 11:39pm UTC](https://community.cartalk.com/t/power-brake-booster/37996/14 "2009-10-12T23:39:19Z")
okok,imeant to say the half closest to where it mounts on the studs.as if only one piston is working. ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [October 13, 2009, 12:46am UTC](https://community.cartalk.com/t/power-brake-booster/37996/15 "2009-10-13T00:46:33Z")
OK, now I get it. Each piston pushes across the entire surface of the rotor, so it’s not that one isn’t working. The caliper itself may be jammed or cockeyed. It definitely needs something fixed, you may want to go to a brake shop. ps - it also could be that one piston is frozen/jammed, messing up the pad alignment. Either way, you’ve got to get the caliper off and check it out, along with turning or (preferably) replacing the rotor. ---
**Author:** ![pleasedodgevan2](https://avatars.discourse-cdn.com/v4/letter/p/ad7895/32.png) [@pleasedodgevan2](https://community.cartalk.com/u/pleasedodgevan2)\ **Post date:** [October 13, 2009, 4:40am UTC](https://community.cartalk.com/t/power-brake-booster/37996/16 "2009-10-13T04:40:48Z")
The rust crept outward from the inner edge of the pads. If it isn’t too deep or the rotors aren’t worn out, you can have them resurfaced. Changing the rotors is easy once you get the caliper mount off. Those bolts may be tight because they require over 100 FT LBS of torque. I recommend new rotors.