Real Hard brke pedal

[LeDevil]

I just swapped out the old M/C on my 510 for a 280ZX unit and replaced my rear wheel cylinders with stock 510 ones. Well everything was good nice firm brakes. But now I have a real hard time pushing the pedal and when I do it will only go down about 1/4 to 1/2 of a inch. Then when I hold the brakes my dummy Brake light comes on. It's not low on fluid or anything. It feels almost like trying to stop a Sherman tank with a brake system for a bicycle.

 

Symptoms:

1. Hard as hell brake pedal

2. Feels like the brakes don't grab as hard as they should

3. When it stops it will stop straight, doesn't pull any direction

4. Dummy Brake light comes on

5. Real short brake pedal travel

 

Any help is appreciated thanks :D

[slodat]

Sounds like you have a major problem with your master cylinder. The light is an indication that one circuit (front or back) is not functioning.

 

Why are you running the ZX master cylinder with rear drums?

[DISLEXICDIME]

i was wondering the same thing slo mo fo

[slodat]

If you have ZX front and want good pedal with rear drums, the 7/8" master cylinder is what most recommend. That's what is going in my car.

[datzenmike]

Swap the stock m/c back in.

 

Either the shoes are wet or the m/c is no good. Seeing as how the brake warning light comes on (warning of an imbalance of front and rear line pressure) I'd say it's the m/c

[DISLEXICDIME]

i am still running stock mc steve gave me it works great with my zx brakes . when you drove my car thats what was in it

[LeDevil]

I 'm gradually gathering parts to do the rear disk swap and the 280 fronts. I figured seeing as I needed a new M/C might as well get the 280Zx so I didn't have to buy it later on. I was told that when I did the rear disks that I would need the 280Zx which is the only reason I bought it. Everything was fine until today they were stiff but not like this.

 

Dislexic: really? I thought you had to upgrade to the 280 because of the brake fluid or something getting to hott?

[slodat]

I recommend against rear disc. There's no performance gain unless it is a true race car. You lose the parking brake. They are expensive. The real reason most admit to doing the rear disc conversion is bling - they want the look.

[DISLEXICDIME]

i just putt bigger reservoir's on it. it didnt help much it turns out it is just because i am a late braker

[LeDevil]

Hmm...Ok cool thanks for the info guys, tomorrow while at work I'll order me a stock M/C. I guess I'll scrap the rear brake Idea as well seeing as I just wanted to say I actually did the rear disk brake swap lol. I know lame reason but once again won't learn how to do anything if you don't try it.

 

But is there anything I should check until the stock one comes in?

[slodat]

Yes, DO NOT BUY A BRAKE MASTER CYLINDER FROM SCHUCK's!!!! Unless it is NEW. NOT rebuilt. NEW!

 

Rebuilt are complete and utter shit. They aren't worth a nickel. You are better off with a used stock master cylinder out of another 510 than those rebuilt POS.

[datzenmike]

Are you saying you are using a four wheel disc brake master cylinder on a car with front disc and rear drums????

[LeDevil]

LMAO! Yea I know we don't sell the best products. Yea this one was New and the 510 will be New as well.

 

I guess back out to the garage to mess around and see if I can't get this to work for me until I get the 510 one here.

 

 

Thanks Slodat and Dislexic

 

EDIT: mike no the one I got was for disk front drum rear. I was told the 280Zx one was good enough to handle the rear disks because of the bigger bore size.

[DISLEXICDIME]

who knows maybe we are wrong and something els is the matter

[slodat]

who knows maybe we are wrong and something els is the matter

 

True

[LeDevil]

Nah! You guys are probably right, you've both been around 510's alot longer then me.

[LeDevil]

I checked for leaks and couldn't find any, checked for binding with the pedal linkage and nothing, so I figured hell might as well bleed the brakes again and BINGO! That brought the brake pedal to the way it was before it got all hard. My Dummy light for the brakes doesn't come on any more now. But now I noticed three more things.

 

1. My Front "rear tires" reservoir will drain of fluid and then fill back up. alot more then I am used to. Drain down to about the min line and once I lift my foot it will fill all the way back up to the max line.

2. I now have to pump the brakes like there was air in the line. After pumping the pedal if I hold it it's firm and doesn't sink to the floor but as soon as I go to push it again the pumping starts all over again. I already bleed them and had nice solid streams coming out of each bleeder valve.

3. I hear a squish noise from the M/C it looks like it maybe blowing by the push in reservoir cap for the rear tires.

 

Thanks again for any help

Edited December 16, 2008 by LeDevil

[slodat]

Put the stock master cylinder back on, bleed and report back. My bet is a junk master cylinder, even though it is new..

[jesusno2]

Did ya bleed the master?? My zx has bleeder valves right on it.

[slodat]

Good call jesusn02!

[LeDevil]

Update: So after trying a 510 M/C still no good, so I put the 280Zx one back on. While tightening down the reservoirs I noticed a hair line crack. I swapped out that one for a smaller one and it now seems to be holding pressure. The Squish noise is also gone and the brakes feel great. But we'll see in a hour when I go back out and check again.

 

Jesusn02: Yea I bleed the M/C both times, I'm thinking the issues was the cracked reservoir or at least that's what I'm hoping

 

 

Thanks for all the help guys if the problem comes back I'll report here :D

[]2eDeYe]

The real reason most admit to doing the rear disc conversion is bling - they want the look.

 

Maybe for dimes, but for the trucks...man nothing beats never adjusting your brakes again, and you get to keep the ebrake :D

[Burabuda]

1. the zx master works good if you have a brake booster. the 7/8 works good without a booster

 

2. go with the maxima rear calipers/disc swap, and you can use the parking brake cables

 

3. there's supposed to be a check valve in brake masters that use rear drums. remove it if you do rear discs. or put it in if you still have rear drums

[LeDevil]

:mad::mad::mad: So the brakes worked fine when I parked it. Now the rears are dragging. First thought was my E-Brake might be stuck so I disconnected it, crawled under the car made sure the levers were not stuck. After that zip tied the E-brake cables up out of the way and went for a spin and they still dragged. No Dummy light and nothing else wrong except the rear brakes. Is there something I am over looking?

 

Current issue:

1. rear brakes are dragging

[slodat]

What master cylinder is in your car - stock 510 or ZX?