funny feel at the brakes pedal

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MMamdouh
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funny feel at the brakes pedal

Post by MMamdouh »

Hi guys

my brakes pedal feels a bit funny now... some times it is working perfictly normal, some times it travels a mile till it almost hits the fire wall and some other times it brakes right off the first inch i step on the brakes.

i replaced my brakes fluid - upgraded to DOT 4 - and bled the system 3 months ago so it is not air in the system and my pads are genuine GM and they are 1000 kms old... some people say it is a faulty master cylender but shouldn't this ber associated with a leak from the master cylender itself??

Need your advice guys.

MMamdouh
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Audacity Racing
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Post by Audacity Racing »

could be master but i was thinking you have an blowout on the line...


inspect all the rubber hoses to see if there is a "blow out." it would look like a bubble on the side of the line when the brakes are applied. this is when the pressure in the line blows through the rubber and makes a little sack on the outside that absorbs the brake pressure instead of the pad...

just look for a worn line somewhere or a funny looking spot
Daniel
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Post by Daniel »

Mamdouh,

Refer to the master cylinder drawings. There are two pistons. Primary piston (near brake pedal) pushes secondary piston. If on pedal release the secondary piston stays blocked I think that you can loose braking power. No leaks outside. I've had this pb on a very old Skoda when I've bled the brakes by flooring brake pedal. Master cylinder's seals were dead.

Take care,

Daniel
MMamdouh
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Post by MMamdouh »

i will give it a throughout inspection before i go crazy on replacing parts... will check all steel lines as well as rubber lines and will check every individual wheel's master and pads as well as the mechanism... will keep you all posted.

MMamdouh
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MMamdouh
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Post by MMamdouh »

just out of curiosity... what should i expect if i got a bigger master cylinder than the one i got? i am thinking of a Nubira 1.6 master which is some 1.5 mm 0.062 inch) bigger assuming it will fit the booster.

i an guessing the brakes will be more responsive, you won't have to push it a mile to start feel the braking power and maybe the pedal will be a bit harder but i am only guessing... got any feedback n that??

MMamdouh
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3oweida
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Post by 3oweida »

Had this problem before ......
the problem is the main brake master...try to replace it soon ... as u wont find brakes in matter of days !!
i replaced my master by a Daewoo racer master ... it works great .. and slightly bigger than the lanos stock ...it gives more pressure while u arent pressing that hard ... i just relax my feet over the brake pedal .. and it do the rest !! :badgrin:


as for ur old master ... it doesnt have to leak outside .,.. it could be leaking into the air server .. as the internal parts got weared off ....
try observing the oil tank placed over the master cylinder... try to catch a leak ... if it keep decreasing without observable leaking .. consider replacing it asap.
as it could damage the air server BTW ..
MMamdouh
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Post by MMamdouh »

why did you get a racer master instead of a nubira master? i know the nubira one is bigger than ours as well?

MMamdouh
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GsiTurbo
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Post by GsiTurbo »

I agree with the other members who answered this... I had this problem number of years back, and it was the master cylinder...
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2002 Lanos 1.5 SOHC... stock!!!
MMamdouh
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Post by MMamdouh »

i did replace the master cylinder and it cured the problem indeed... after through checkup i found out that the cylinder itself got coroded from the inside and it is leaking the pressure applied by the pistons and that caused the miss balance of brake power.

i am now considering swapping the master cylinder with a bigger one from a nubira - or a racer - to improve pedal responce... do you guys think it is a good mod to do??

MMamdouh
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3oweida
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Post by 3oweida »

The Nubira is larger and heavier than the Lanos .. so .. it's master cylinder is designed in a way that it gives more pressure to the rear wheels " check it's rear wheels tubes, u will find them thinner than the front ones ,also the Nubira is bigger than the lanos .. so the oil tubes is longer " as for that .. if it got installed in a lanos .. u will find it uncomfortable , you could see that ur speed is dropping on the odometer.. but u wont feel it .. front brakes will be kinda weak that u will have to press hard to feel safe . so after all u did nothin ..!!

I think the Racer master cylinder is a perfect match for the lanos .. as it is slightly bigger ,have a good pressure ratio , and literaly .." nails the car in the ground " as it is designed for a car that is nearly the same size ,weight and have the same length of the lanos oil pipes.. over that , it has bigger capacity = more powerful brakes.
MMamdouh
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Post by MMamdouh »

forget about tubing and that stuff.. all what matters is the inner diameter of the master and the OEM 1.5 lanos is 19mm and the nubira is 22mm... if the racer one is 22mm aswell then the nubira and racer master are the same part.

80% of the braking effort is handled by the front brakes so if you have a big and heavy car that you want to stop then the focus should be on the front... i dought that the nubira braking system is so much relying on the rear brakes... anyways i can just swap the master and keep my OEM regulators for the rear to keep the balance.

MMamdouh
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MMamdouh
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Re: funny feel at the brakes pedal

Post by MMamdouh »

correction:

1.5 SOHC lanos master cylinder is 20mm in dynamiter not 19mm

the master cylinder of a 1.6 lanos and 1.6 nubira sends LESS pressure to the rear wheels than the master on a 1.5 SOHC... this is due to the fact that the 1.6 lanos/nubira got bigger brake rotors at the front thus more front bias and accordingly rear braking power has to be reduced compared to the 1.5 SOHC lanos with the smaller front brakes and less front bias.

the less pressure management is done through the proportional valves not the tube diameters were the valves marked 3\40 will send more pressure to the rear brakes than the ones marked 3/30

MMamdouh
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Check out my ride: http://www.cardomain.com/ride/567267
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