# 84 300ZXT Brake Problems



## blakeZX (Apr 29, 2005)

Hello-

Hello-

I have a rather strange situation to ask about; I recently acquired my 1984 300ZX Turbo, and when I bought it (for only $850, got a sweet deal), the brakes were hardly responding at all (grinding noises made it seem like the pads needed replacement). So I picked up some new brake pads for front and rear (both disc), and some high-quality brake fluid, and proceeded to change out the old pads for the new. This being my first brake job, I enlisted the help of my roommate, who has done this many times, and jacked up the rear driver's side wheel first, changed the pads, cleaned/re-greased some of the moving parts, and then attempted to bleed the brake fluid by unscrewing the bleed valve. However, when I went to pump the brake pedal and let the fluid drain, only a few drops came out. We tried the pump, hold, release method, and several other variations of pedal pressure, but nothing seemed to get any fluid out. Puzzled, I checked the level of brake fluid under the hood and it was all the way to the fill line. So, it doesn't appear to be a leak in the brake fluid, or the level would be lower. I suspect there is a clog somewhere, or that I need a new part of some sort. Anyone have an idea of what might cause this, or what might solve it? New master or slave cylinder? I also haven't tried to bleed or replace the front brakes yet, should I give that a shot and see if it is clogged too? Any ideas greatly appreciated. Thanks,


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## Zen31ZR (Mar 24, 2004)

Could just be a badly clogged bleed fitting. Remove it completely and see if the effect is still the same. If it is, there might be blockage in the caliper itself or the line going to the caliper is clogged. Does the pedal feel solid or mushy.


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## blakeZX (Apr 29, 2005)

the pedal feels pretty solid-there is resistance to the pressure i apply with my foot, but the resistance remains constant even when the pedal is pumped over and over again. to clarify, because i am just starting to learn the mechanics of cars: where is the bleed fitting? is that the piece on the brake system that houses the bleed valve? if so, i know exactly what you are talking about. i can try to remove that today after work. also, could there be any benefit to trying the front ones as well? as of now, i haven't even looked at them. i know the front rotors are scratched from the old pads, this seems to indicate uneven wear between front and rear. i also don't know if the front and rear calipers are fed fluid from the same line or if they are seperate...i have a haynes manual, i suppose it would tell me in the brake troubleshooting section.

btw, thanks for your help zen, it is very much appreciated. :thumbup:


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## Zen31ZR (Mar 24, 2004)

Don't remove the fittings except to see if they are clogged, maybe I should clarify that. New bleed fittings can be had at a dealer or the auto parts store. 
Brake safety regulations require that there be seperate lines for each wheel, however they are all fed by the master cylinder. There are differences in front and rear pressure as well, 70% of the braking force is applied to the front brakes. The rear brakes receive so little pressure because they would lock up otherwise. 
I would suggest dowlnoading and reading the factory service manual with regards to the brake system. The Haynes is ok, but the factory manual information can be trusted to be correct. It is located amongst the stickies at the top of this page.


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