Brakes / Master Cyl. / Booster concerns

zerowkul98

zerowkul98

New member
Our 03 V8 Sport Edition has already had the front calipers replaced and its got all new OEM brakes pads n' rotors on it. Im aware that once a braking system is apart and components are replaced its rarely ever the same, and others in here have more "pedal travel" after having calipers replaced (esepecially non-oem calipers like myself), but im becoming a little concerned and i'd like some experienced people's opinions on this:

I hear & feel the booster kick in pretty often when i step on the brakes, and if im driving a while w/o touching the brakes, when i finally DO touch them, the pedal has a good deal of travel b4 braking, and then after that first initial "pump", the pressure increases nicely.

Im just trying to avoid having to replace anything under the hood for the braking system.

Thanks
 
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Sounds like you have air in your master cylinder

Do you notice that more often once your driving that the pump comes on and vibrates the brake pedal?
 
I'll tell you exactly how it goes:

Driving along, initial 1st pedal-travel is deep, but the brakes def. kick in, but after i let off the pedal or i keep it depressed a few seconds, the booster kicks in. I feel the "hum" and feel the pedal pressure push against my foot. When i take my foot off the pedal, continue driving, the next time i need to slow, the process repeats.

Ive had this rig for a long time. The 2 front calipers are replacement A1 Cardone calipers. ALL the rotors are new, as are the pads. I had the 90k service done a while back, the brakes were bled and calipers cleaned and pins greased.
 
When your vehicle is off, press the pedal. It should go down fairly easy. Pump it a few times and it should get hard. That lets you know that your booster is working. As you pump it with the engine off the pressure bleeds out of booster and you are feeling unassisted brake pressure. Wait about 30 mins with the engine still off having not started it from the last test and try again. If your pedal is soft and firms up as you pump it, you have air in the system. If the pedal is still firm then it sounds like your problem could be booster related.
 
bleed the brakes, then after that, with no key, pump the brakes 40+ times then add fluid, the fluid resevoir says u must pump atleast 40+ times with no key in, and it should tell u how much fluid is left and needs topping off. make sure ur cap is on while doing this.
just like the other thread where the guy did ebc brakes
 
riceandpho said:
bleed the brakes, then after that, with no key, pump the brakes 40+ times then add fluid, the fluid resevoir says u must pump atleast 40+ times with no key in, and it should tell u how much fluid is left and needs topping off. make sure ur cap is on while doing this.
just like the other thread where the guy did ebc brakes
Click to expand...

worked perfectly for me. brake pedal is back just like it did before the brakes were changed.
 
Im aware that once a braking system is apart and components are replaced its rarely ever the same,
Click to expand...

I 100% DISAGREE with that. This is NOT rocket science. The parts are NOT super complicated. You should be able to replace every single brake component on your vehicle and it should act and feel EXACTLY the same way it did when it was new. If it's NOT then the mechanic screwed up. I've replaced the front calipers and pads twice..and the front rotors once...The rear brake pads once. I've also flushed out the brake fluid twice. My brakes are as good as they were when new.
 
MikeInNH said:
I 100% DISAGREE with that. This is NOT rocket science. The parts are NOT super complicated. You should be able to replace every single brake component on your vehicle and it should act and feel EXACTLY the same way it did when it was new. If it's NOT then the mechanic screwed up. I've replaced the front calipers and pads twice..and the front rotors once...The rear brake pads once. I've also flushed out the brake fluid twice. My brakes are as good as they were when new.
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i can say (not trying to start an argument) but i will disagree with you. i have been a mechanic for over 25 years done 100's of brake jobs and never had the problem i had with the 4 runner. i did a complete all wheel brake job on my gmc sierra and no problems, the 4runner was different and obviously some people on here are having the same problem. i even did a reverse pressure bleed with the Phoenix systems brake bleeder i have and no luck. maybe with the electronic system on the 4runner(do not know when they started it). i did the suggested repair and it worked. it even said what to do in the master cyl res.
 
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