I havea 85 gsl-se and the brakes dont really start working till i am almost at the end of travel. is this normal? i have completely bleed the system, which made it better but still worries me its that close to the floor. is there a rod adjustment on the booster? Thanx for any help.

 

sounds like you have master cylinder problems

 

like how?

 

Does it make a differnce if you pump the brakes? If so, could be air in
the system. Have you check your brake pads and rotors? If there almost all the way done, then yeah the pedal will go further to the floor before it works.

The next time you do a brake job take a little pen and mark the level of your
brake fluid. Now compress all your brake cyl and watch how much fluid rises.

Is there any brake fluid leaks any where? Have you check around the master
cyl?

 

I just had the rotors turned, put on new pads in the front, and dont see any leaks. Where does the pedal get stiff normally?

 

I have not owned a first gen in a while. I don't know what normal is.

How was it before your brake job? New pads, fresh brake bleed, then
goes almost to the floor this that right??

Does it make much difference if you pump the brake pedal?? If it makes
a night and day difference on the second or third pump you still have air
the lines. All cars will go up a little bit when you pump the brakes.

You did not mention this, but I will ask any ways. Has the master cyl been
replaced recently? When you replace the master cyl it is very hard to get all
the air out with out bench bleeding it first.

 

Not normal.

With any disk brake system, whenever you change out pads (front or rear) you should also go through the effort of replacing the brake fluid to ensure that you have fresh fluid in there, no air bubbles which will prevent hydraulic compression, and no water absorbed into your brake fluid which will boil off under heat. Brake fluid, being hydroscopic, absorbs water from the air which leads to water being carried in the lines and eventually causing internal rust to MC components, lines, and calipers.

On a well-tuned braking system, the pedal should move about 1" before you start to feel the brakes taking hold, and they should NEVER approach the floor - as this indicates that brake line pressure is being lost somewhere. You are not getting maximum braking performance, and the car could be very risky to drive, particularly in the city.

From your description of replacing pads recently, I would think that you've introduced some air bubbles in the system, and this will likely be resolved through a thorough bleeding of the brake system. Start by getting a fresh bottle of brake fluid and add it to the reservoir until it's near the top. Start at the right rear corner (or left front corner), and bleed each caliper until you see clean, clear fluid being released from the bleeder valve - *** you will need to refill the MC reservoir often to ensure an uninterrupted supply ***.

Once you get this done, brake pedal travel should be greatly improved. Beyond that, you can start looking at other things like caliper rebuilds which can allow brake fluid to seep past the internal seals and into the dust boot - hard to detect until the boot cracks and you get a geyser of brake fluid.

STart there, and let us know how it goes,

 

Perhaps you are leaking brake fluid? if the master cylinder is old, or if it has run low on fluid it may be ruined. It has certain tolerances that must be met, if the pedal is pushed too far you can upset/ruin the seals and seats that can only happen if the brake linings are too worn and/or you have alot of air in the line/ not enough fluid. drain your sytem, if bleeding doesnt help, take the master cylinder off and replace it. Then bleed from the master cylinder and then do the closet wheel first and then work your way away from the master cylinder, all while adding DOT-3 to the master cylinder to keep it full.... or have it professionally done, hope this helps.

 

i imagine if you didn't have this problem before you changed the brakes, you probably introduced air in the top of the system. so IF you dropped the fluid level to zilch and sucked in some air in the top you gotta do alotta bleeding. If you ever do, do that, you can give your brake pedal one pump, hold, crack the lines to the MC, and you should hear a snap of air rush out. You wanna prevent pushing that air farther down the line, plus give it a bit of time and they should rise. Seen as how your past that point bleed like LongDuck posted.

 

Try bleeding your brakes again. Here is my experience:

I recently rebuilt my master cylinder and used the 7 dollar ONE MAN BLEEDER KIT. I was impressed how easy it was to bleed the system. I recommend this method over speed bleeders.

The 'Kit' is so simple you almost feel stupid spending a measly 7 dollars on it, but it is worth it. It contains a small plastic cone adapter that you push into the bleeder, and then a clear tube is attached. This tube then goes into a catch bottle. (Bottle top has a magnet to secure it upright on the fender or disc or drum).

To bleed, simply open the bleeder valve and begin pumping. I had to pump about 20-30x for each wheel and to get fresh fluid there. The neat thing was that you can SEE the very small air bubbles in the clear tubing. When the fluid looks clear eith no tiny bubbles, close the bleeder valve and move to the next wheel. I had a solid pedal when done.

I have read about the bench bleeding procedure, but it did not make sense in my mind. They certainly don't bench bleed at the factories... AND I did not want a messy cylinder leaking while I re-installed the brake lines. So that was not for me.

Bottom line, being able to SEE the FLUID CONDITION coming out of your caliper is a great advantage.

 

thanx guys. I have rebuilt brake systems before and never had one be so soft and non responcive before i guess i will try to re bleed it and then look into a mastercylinder. pumping the brakes doesnt change anything, I am still trying to get my oil system closed back up. oonce i got it back running again i will investigate further. thanks.

 

I'm almost positive that a way to check for proper master cylinder operation is to perform a "master cylinder bypass" test. Its basically used to check for internal leaks inside the master cylinder, ie fluid bypassing the seals.

Have someone depress the brake pedal as you observe the reservoir. If the fluid level rises and then when they release the pedal the level falls off, the fluid is moving around the primary seals and thats none to good.

Also sometimes you need to hold the pedal down for up to a minute, if it sinks any further and there are zero external leaks, its also probably the master cylinder.

This is just from my experience, but I've never introduced air to a system when changing pads and resurfacing rotors. Except like Gavin said if you ran the reservoir dry. Did you do the brake work because of the low pedal, or is this an after effect?

 

The MC has a bleeder on it, use it. If any air got in the top its now trapped in the MC and will never bleed out until you bleed the MC first. I had this exact problem after replacing some brake lines. I bled everything up front but couldn't get the rears to bleed very well, even after centering the brake bias valve. Then I noticed that the MC had a bleeder on it and I bled it. Fixed the whole problem and then I could bleed the rears to get the new fluid in them.

 

Someone just mentioned that their 84 FB doesn't have a bleeder on his MC, so maybe FB's MC don't have this bleeder, then a bench bleed of the MC would need to be done I would guess. I have an 80 SA so my MC can be bled and my ujoints are replacable :-) SA's rule!