# Brakes Locked up?? wtf!!



## SERialThreatz (May 29, 2002)

i just replaced the MBC(Master Brake Cylinder) bled the brakes and i took it for a test run..a mile down the road i was turning the corner and i put it in neutral...i felt the brakes lock and the car started slowing down..i was lucky im two houses down or else id be fixing right there on the spot..i got to the driveway and it completly lock permanently.....Now what could cause this...it wont even roll down the driveway.. NEED HELP FAST ITS MY ONLY TRANSPORTATION.....BTW i have no ABS..... could this be the calipers??

get at me as soon as possible.....

thanks


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## Damodar (Sep 27, 2002)

Looks like the master cylinder you replaced may not be good. I guess it must be refurbished. The master cyclinder pistons may not be returning after you apply the brakes. So, the brakes at the wheels get harder and harder each time you apply the brakes. I hate to say you need to open-up the master cylinder to make sure the springs and pistons are moving freely or even replace it with a new one.

What you can do is put c-clamps at the calipers and push them in. This way the brake oil will be forced to go back to the master cyclinder and should push the master cylinder pistons back to their normal position. But no guarantees that this problem won't recur.

Damodar


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## nismo-vzr (Sep 14, 2003)

Did you bench test you M/C before using it?


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## SERialThreatz (May 29, 2002)

the car is back in the garage i didnt do any test on it..how would u know if it is good or not...how do u test it? right now were makin sure everything is all tight and were chekin all the calipers... it seems that the left passenger side is the one thats actually a bit tighter than the driver side....the rears are fine, tires are spinning freely...you think there is still pressure in the MBC?? i think the one thing that we didnt do after bleeding the brakes is bleed the MBC..... is there any other simptoms i missed... get back at me....

thanks


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## SERialThreatz (May 29, 2002)

alright it locked up on me again....need more suggestions....any other mechanics out there know what the problem could be...the last thing left is to just return it and get one from the DEALERSHIP.....


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## Damodar (Sep 27, 2002)

Since this problem never occured until you replaced the master cylinder, it is a good assumption that it's the source of the problem. Was the old one bad or you just decided to do a preventative maintenance? If I were you, I would just bite the bullet and get the dealer's master cyclinder instead of paying someone else to look into the problem just to do the same. 

I kicked myself many times when I bought after-market parts at a cheaper price and paid for it one way or another. Sometimes you can get away, but my time and frustration isn't worth it. I now usually purchase dealer parts unless it's not an important component such as accessories, bulbs, wiper blades, etc.

Damodar.


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## SERialThreatz (May 29, 2002)

the old one had a leak..had to replace it cause the pedal was sinking in while braking...hay thanks a lot for your solutions...imma go return it asap...


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## Damodar (Sep 27, 2002)

Make sure you bleed the master cylinder this time.

Damodar


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## SERialThreatz (May 29, 2002)

im back again.... i bought a new MBC returned the defected one... still having the SAME old problem.. took it for a run 10 minutes later it locked...im close to just trashing the car..and really frustrated....any other suggestions?? i bled everything i mean everything from the MBC and all four brakes...IS IT THE BOOSTER NOW THATS NOT WORKING?? QUESTION? WHILE I WAS BLEEDING THE BRAKES THERE WAS THIS SLIGHT TICK WHEN I PRESSED ON THE PEDAL I THINK IT WAS COMMING FROM THE BOOSTER . I ALSO ADJUSTED THE BOOSTER A LITTLE BIT... HOW DO I KNOW HOW MUCH I SHOULD ADJUST IT?? I NEED ALL THE HELP I CAN.....GET AT ME ASAP

THANKS AGAIN

PS I HAVE A BOOSTER FROM A SENTRA ARE THEY ALL THE SAME? CAN I USE THIS ONE ON MY SER??


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## Damodar (Sep 27, 2002)

That's a bummer! I don't understand one thing. When you had the old master cylinder, the brakes didn't lock-up. Now you put in the new one, the brakes do lock-up. Did you try freely spinning the wheels when on the jack? It should tell you if it's all four wheels or related to just one wheel or side.

Unfortunately, I haven't worked on the booster side. So I won't be able to give any input there. The only thing is that if it's the booster, then why didn't the brakes lock-up on your old master cylinder?

Damodar.


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## rx7racr (Jan 25, 2004)

I'm having the EXACT problem with my 1991 Sentra! Just installed the 2nd Tokico Master Brake Cylinder in 6 months! Car ran great for 10 miles - then the brakes locked!!!! 

I'm stuck about an hour from home and I don't know what the %#@& to do!

Is it probably the Master Cyl?? (I'm not looking forward to doing THAT job again...)


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## nastynissan (Jan 26, 2003)

Sound like a Locked up Caliper to me..... Yes I know it didnt lock untilo you put on a new Master... But the raised pressure from the new master might have caused something that was going to happen sooner or later to happen sooneer.... Before you replace the master AGAIN.... Pull your calipers, And pull the slide pins.... If the pins arent sliding freely your brake will heat and lock up... Also the caliper cylinder itself might be stuck... Crack the bleeder valve open and push the cylinder inward...(like when replacing pads)...If it doesnt move smoothly that may be the problem... Hope this helps....


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