88 Superfly

iTrader: (1)

Ok here's the situation. I drive to the laundro-mat to do some stuff. I park the car using the hand brake. I get back into the car release the ebrake, then try to move and the car wouldn't go anywhere . I can't figure it out.

I already replaced the calipers/hoses/brake pads/etc...

Any help would be appreciated. I know it isn't the rear end which is the problem because I drove it around without brakes for a minute and drove fine minus the brakes.

Let me know.

AGreen

iTrader: (11)

So you already replaced the calipers/hoses/brake pads/etc... before or after this happened? Did you try unhooking the parking brake cables from the calipers? Is it only one wheel that's grabbing or is it both?

misterstyx69

iTrader: (142)

the Emergency brakes are operated by Cables.
the Cable attaches to the rear beakes by little "pivot arms" sort of thing(see a manual or take the wheel off,you will see what I mean0If I remember them correctly..
Now,the reason I mention those little arms is that they can STICK.they should be able to move freely.Also the cables should be lubricated as much as you can,if you can get at them.
That is the brakes,If that is your Problem.
If the Brakes are fine and the car just wouldn't go anywhere IN gear,momentarily,then that is another Problem.

88 Superfly

iTrader: (1)

I replaced the listed above after the problem. I haven't tried taking the ebrake off. I will try lubricating it though, that sounds like a good idea. I do know the part you are talking about. It has a spring on it and a little hook kinda thing and at the end of the ebrake cable is a T kind of fitting. I will try taking the ebrake completely off and see if that works.

Thanks for the help.

88 Superfly

iTrader: (1)

I took the ebrake cable off today and the problem is still there. It's like the brakes are getting pressure but not releasing it. Any help would be appreciated.

I just can't figure it out.

AGreen

iTrader: (11)

If you can crack the bleeder open and the brakes release, then you know it's something hydraulic. If that's the case, make sure you check brake pedal freeplay. You should be able to stick a ruler next to the brake pedal and see about .5" of freeplay. Too much won't cause that, but too little definitely will. This also may be one of those RARE cases where a combination valve goes bad.

If it still won't release when you loosen the bleeder screw, then it's mechanical. You did clean (and I do mean CLEAN... like wire brush and parts cleaner) the caliper slides, then lubricate them with silicone lube, right? That may be the whole problem if the slides are a little corroded.

88 Superfly

iTrader: (1)

It only did the problem after I used the ebrake. Would the master cylinder or combination valve go bad upon ebrake usage?

AGreen

iTrader: (11)

No, not really, but normally you would use the brake pedal before setting the emergency brake, and after releasing it, so it may not have anything to do with the emergency brake at all.

But, that's why it could be either mechanical or hydraulic. Make sure all slides are lubricated if it's not hydraulic lock.

88 Superfly

iTrader: (1)

I am thinking that it might be the master cylinder. Because I replaced the rear calipers I think that the master cyl is stuck in the brake position. Because when I released the bleeder the caliper got loose, and the brake pedal returned to be squishy again. It's like it will give pressure but it won't release it automatically.

So would you guys suggest getting a master cylinder?

Thanks in advance for any further help.

gxl87turbo

iTrader: (15)

Replace your master, and i bet it will go away. I dont want to get into detail, but sounds like a very common master cylinder valve that goes to the rear brakes.

AGreen

iTrader: (11)

Did you check pedal freeplay? Other things than the master cylinder can cause hydraulic lock. Is it just the one side, or both?

BTW, no, I don't think you should get a MC just yet. Not until you've verified that's the actual problem. You've already tossed a bunch of unnecessary parts at it, so let's use some reasoning before opening that wallet again.

gxl87turbo

iTrader: (15)

This is why I go to school for this. Now listen up.

Split Hydraulic System Operation

Primary piston applies front brakes and secondary piston when the vent ports are covered. Hydraulic pressure is built up and transmitted to the front and rear brakes.
Once the secondary piston bottoms this creates high pressure, same goes for the primary piston. Secondary piston applies rear brakes.

If there is a hydraulic failure in the brake lines served by the secondary piston, both pistons will move forward when the brakes are applied, as under normal conditions, but there is nothing to resist piston travel except the secondary piston spring. This lets the primary piston build up only a small amount of pressure until the secondary piston bottoms in the cylinder. So this could cause the rear brakes to get more pressure then the fronts.

But what would I know about cars, Im just some kid

88 Superfly

iTrader: (1)

Alright man that makes a lot of sence. How much do masters usually cost? I could be doing this by the weekend.

Here's the thing, I know brake lines / hoses are good based on the fact that when I'm bleeding them fluid comes out like it normally should. That's when I first thought it had to be the rear calipers. But then I replaced them and it's still there. Which leads me to think it's something under the hood.

But at anytime I can figure out what it is... I would be super happy to be driving the beast again. It's been 3 weeks without a car and I hate it.

When the brakes are bled and I push them until the rears are completely locked there is only like maybe an inch of pedal play at that time. But when I release the pressure manually via the bleeder screw there is a lot of pressure at first and it spurts out, not flow out. So that means it's not letting pressure back into the system. when the bleeders are loosened the pedal goes free with it's pedal movement.

So 87gxl you are sure it's the master? Would you be over 90% sure?

Thanks again!

AGreen

iTrader: (11)

Aahh... so you're still in school eh?

All I'm saying is there's an acutal diagnostic procedure you can go through to determine what's going on.

Now listen to this:
There's this thing called a compensating port. If the brake pedal freeplay is not in spec, i.e. not enough, the pushrod could be keeping the secondary piston past compensating port, not allowing it to do its job. What it does is allow fluid pressure to return to the reservoir for expansion/contraction.

Also, if the proportioning valve is stuck, it will leave residual pressure on the rear brakes. To determine if this is the cause, build up pressure in the system and lock your brakes to insert the problem. Crack open the INLET line to the combination valve on the side that controls the rear brakes. Just follow the line from the MC to the combo valve. If bleeding that pressure off frees up the rear brakes, then it's definitely NOT the combo valve. If it won't release the pressure, then it is.

If the freeplay's in spec, and the comination valve is good, then there's only one more thing it could be. That's when you can replace the master cylinder. It's all about testing before paying.

But what do I know, I'm just an ASE certified tech...

gxl87turbo

iTrader: (15)

Do you understand that all of that **** you just said is in the m/c which I just simply told him to replace in my previous post

BTW im doing my bachelors so I can become a Teacher at UNOH

AGreen

iTrader: (11)

Now it's official, you're just plain wrong. Look at this picture:



Does it look like the combination valve is IN the master cylinder to you? Anyone? How about the brake pedal freeplay. Is that inside the master cylinder? Hell no. Those are all peripherals. If you replace the MC and the freeplay is not in spec, YOU WILL STILL HAVE THE SAME PROBLEM! If the combination valve is the problem, YOU WILL STILL HAVE THE SAME PROBLEM!

Hmm....

Superfly, just check those things. It's really easy to do, and you'll know 100% what is wrong.

I'm not saying it COULDN'T be the master cylinder. Just do some diagnostics first.

88 Superfly

iTrader: (1)

Ok A Green can you post a step by step on this please. I don't know **** about brakes at all. If you could include pictures that would be awesome thanks alot.

I figured out the rear calipers easily but I just don't know what the heck I am doing under the hood braking wise.

AGreen

iTrader: (11)

Freeplay is checked with a ruler. One end goes on the floor, holding it perpendicular to the brake pedal. Move the pedal up and down with your hand, just enough until you feel pressure. .5" is typically what the spec is. If you look at where the pedal connects to the pushrod (goes through the firewall), you can see that the pushrod has a nut on it. Loosen the nut, turn the pushrod, and it should lengthen or shorten the pushrod. When the freeplay is right, tighten it back down.

To check the combination valve:

Take a look at the 2nd picture in my previous post. On the right of the pic is the master cylinder. To the left of that is the combination valve. To isolate the hydraulic lock, pump your brakes a few times, then loosen the line on the bottom of the master cylinder. If the rear wheels now spin freely, you know it's not the combination valve. If they don't there's still a hydraulic lock between there and the wheels. The only thing along the way is the combo valve. Looking at the combination valve, the top left line should then be removed. If the wheels can turn, it's the combo valve. If not, take the lines off the rear calipers and blow compressed air through the lines. Maybe use brake cleaner if you don't have any compressed air. Flush thoroughly with brake fluid after flushing the lines. This verifies that there are no obstructions.

Start with this for now. I'm sure you can figure it out by doing that.