S14 Brake Problem

[TheBleeding]

Hey. First post on the forums here. I just bought a 95 240sx about 3 months ago. Took me a year to find one in decent condition. First thing before the fun upgrades is to get her running properly. I'm currently facing some brake issues. Any advise would be extremely appreciated. Heres the story.

When I got the car the brakes were kind of spongy but worked without thinking too much into it. After about 2 months the brakes started acting funny. Whenever i get into the car the brakes work fine. After driving for a while (maybe 15 to 20 minutes)... more so with stop and go traffic and constant brake use... the pedal will start to become harder and harder until it only goes down about half an inch and takes longer to stop the car than normal. It feels pretty unreliable. After the car is shut off for at least 15 minuets or so the brakes go back to normal and the whole process repeats. Also, when driving and hitting the brakes it feels like the car is pulling hard to the right. When the pedal gets hard, sometimes I wont be able to accelerate properly. Like somethings stuck. Finally, When i accelerate to about 60-70 mph and hit the brakes the steering wheel shakes pretty bad. This might be a separate issue though.

First thing i thought was a bad brake piston. I pulled all the tires. All the brake pads were relatively new and everything was in good condition except the rear passenger side caliper. The brake pads were extremely worn and the piston wouldn't turn to go back in so I could put new pads on. Also, it wouldnt slide on the pins easily. It took me a few minutes of forcing it back and forth before it worked. Seemed liked a bad deal so I bought a new caliper yesterday and put it on. I replaced all the rear brake pads and bled the new caliper. The spongy feeling went away but the same issue is still occurring. (Not sure if the vibration of the wheel or the acceleration issue is still there. Haven't felt it.)

Next i checked the brake booster to see if that was an issue. When i pulled the connection off there was definitely pressure. I started the car with the booster connection off and their was vacuum suction.

The only thing I've done to the car is a Royal Purple oil change and a Seafoam treatment. 1 can in the gas tank. Half a can in the crank. Half a can thru the booster line (not in the booster itself of course). As a million other people have done the same way before without issues. This was about a month prior to any issues occurred.

I'm pretty stumped. I'm looking to put some 300zx calipers on the front and possibly swap the master cylinder with the 300zx one as well when money is available so I don't wanna dump a ton of cash into a new master cylinder or new front calipers if I don't need to.But that's life, so if it needs done I'll do it. Again, any help would be greatly appreciated. Thanks in advance.

[chituntang]

Did you bleed the back or all 4 corners?

[TheBleeding]

I just bled the back calipers. The front two caliper bleeder valves are jammed and will take some fighting to get them loose. I was about to bleed those yesterday but I figured if the pedal was hard and not hitting the floor there's probably not air in the lines. I might be wrong though.

[herbieS13]

no because you can build pressure in the system which would make the pedal feel stiff, but that doesnt mean it doesnt need to be bled, quit half assing it do all 4

[TheBleeding]

Good point. That's my next effort. I also checked the booster check valve and thats working good. I picked up two new bleeder valves this morning to replace the front corroded ones. I'll post my progress after I get it done. Thanks for the quick reply.

[dued]

I had the same problems, my brakes got so bad that they didn't disengage at all and made my car slower

The solution was to replace the brake master cylinder with a brand new unit (z32 BMC) and I also replaced all of the brake calipers with used z32 units. Have not had the same problem since.

[bboyyumm]

Thanks for posting this. I have the same prob in my zenki. All brakes were bled and all calipers & pads replaced. Still had the shaking prob at around 60mph. Have new brake booster and master cyl on deck. Going to throw these in with another bleed job and HOPEFULLY this fixes this AGGRAVATING problem!!

[tqstarburst]

^to both of you. Does the car shake at 60 when you guys brake? or shakes going at that speed?

[TheBleeding]

It just shakes at that speed. I originally had the shaking problem with braking too but after replacing the rear caliper with the blown piston it shakes when just going that speed. 60 to 70mph. Anything faster or slower it's fine. I replaced a bad tie rod in the front driver side but that didnt fix it.

As far as my brake issue... After I removed the Brake Check Valve and blew into it I haven't had any brake issues. It's really weird. Don't know if it was just sticking or what. I'm gonna get a new one just incase. Their only 20 bucks. I'm gonna bleed the front brakes this week anyway. It's just hard to believe that something so simple would cause such a massive issue.

[curbhuggerrps13]

Originally Posted by dued

I had the same problems, my brakes got so bad that they didn't disengage at all and made my car slower

The solution was to replace the brake master cylinder with a brand new unit (z32 BMC) and I also replaced all of the brake calipers with used z32 units. Have not had the same problem since.

Change the master cylinder and call it a day. I've dealt with almost every 240 I owned.

[One_love_silvia]

if u end up needing new front calipers, i have some s14 ones for cheap, along with the rotors. lmk