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I recently changed all pads all corners, turned all rotors, and bled out old fluid from RR, LR, RF, and Front Left. Now brake response is bad and it take more effort to stop...pedal feels heavy...I was careful to not intro air in system during bleed. I don't know what I am missing on this one????
Anyone encountered this before? Could it be that brake modulator in rear that is accessible thru cargo area? A bad power booster? Thanks in Advance
Sounds like a bad booster to me. A quick test is to step on the brake with the engine off and then start the engine. When the booster gets vacuum the brake pedal will sink an inch or so.
Could it be a master cylinder? Has anybody here changed a booster on a 96? I once did a booster on a 5.0 Stang and it was very difficult. The booster was fine before I started brake work. Is it possible that all the pumping of brake pedal during fluid exchange damaged the booster?
i hate to be "that guy" but if the only thing different is the feel of the pedal AFTER you bled the brakes, i'd say you didnt get the brakes bled good enough. i JUST did all 4 corners on my car (1995 with the same J55 code your car has)...i replaced rotors, installed Hawk pads, painted my calipers, added SST lines and then "tried" to bleed the brakes...i spent 2 hours. i had clear fluid, what seemed like a solid flow but the "feel" of the pedal was wrong. i called a local tire shop and they said "bring it down, we only charge $44 to bleed brakes"...and that was possibly the best $44 i've ever spent. the brakes are perfect now. i told them i thought i did everything right...that i used about 1.5 qt's of fluid to get it clear and they said they went through 2 more quarts and that a normal bleed takes 2-3 quarts so basically i just fail at bleeding brakes
my point is, i would not ASSUME its other failed brake components if you never noticed any mechanical failure BEFORE you bled the brakes. i mean dont open a can of worms or fix something thats not broke...get a $50 bleed from a shop and go from there (dont let pride get in the way...maybe this is a good opportunity to learn something about your car??). maybe the C4's systems are difficult to bleed, who knows...my logic ( ) says that if your brakes felt and worked just fine before (other then needing new rotors and pads) i wouldnt even consider tearing the brake system apart to find a gremlin...i'd inspect the work that was just performed. good luck
A couple questions. Not to insult you, but to poke some ideas into your head. When I worked and wrote software and one of the team had an issue, we would sit and ask each other questions to get the thought process going and sometimes we answered our own questions.
1. did you use new hardware kits for the calipers ?
2. what condition are the rubber flex lines ? if they are going bad they can cause issues
3. what grade of fluid did you use ?
4. you say you turned the rotors. did you yourself turn the rotors or did you have a shop turn them for you. if they are cut too thin, then the piston(s) could be at (or almost at) the limit of travel and not working correctly
Do you have access to a micrometer to measure the thickness and compare that to what is allowable as the minimum thickness ?
typically today's rotors are pretty thin to save on unsprung weight and don't have all that much meat on them even when new
then:
Before you start changing parts, you could bleed them again. brake fluid is cheap as opposed to the other options. get yourself a piece of clear hose from Lowe's that will tightly fit over the bleeder nipple orifice and put some fluid in a clear jar. stick the tube down in the fluid and have your helper depress the pedal while you are watching for bubbles.
I always use rubber mallet to whack the calipers and get any residual air bubbles out.
also...now i'm just speaking for myself but for my entire adult life, i've never had rotors turned...i have always bought new. i mean these J55 13" rotors are under $70 each from napa and they will last forever at 5k miles a year driving. as the gentleman said above...who knows about the shop that turned the rotors...maybe he kept yours and gave you more worn out ones...maybe he has a J55 car at home and ripped you off or is a hack or whatever...(can you tell i really trust mechanics??)
i'd start with getting the bleed done and go from there.
(J55 is standard on 95-96 and is 13" fronts...the rears are all the same at 12" for all LT1 cars)
No insult taken... I had O'Reilly's cut and they took multiple measurements before hand for run out and checked against specs. Hoses looked good. Brake pads and pins good and piston seemed to travel okay but did not rebuild calipers. Fluid grade met specs. I am going to start with mark970's advice and get a pro bleed.
Thx for the thought process when I get home I am going to check everything again.
it would be awesome if you came back in here and kept us updated on the progress of this topic...i'm actually just learning these brake systems myself and i'd really like to soak up as much knowledge as possible.
you can do a "pro-bleed" yourself. they won't do anything that you can't do yourself except take your money (the caveat to this is that you didn't get air into the abs unit, which I doubt since all you did was bleed, not replace lines).
before laying down your money, try it again yourself. I just bled out my fronts and am going to do the back and a complete system flush when I swap out the rotors and pads in a week or so.
my buddy with a '90 had your symptoms, in fact he was p*ssing around and didn't notice that the cars in front were stopping and was millimeters away from the bumper on the car ahead of him before he got it stopped. a bleeding cured it and it is stopping great now.
please try it again using the tube and glass/clear plastic container method. plus you can see if there is crud coming out as it will discolor the fluid.
try it this way:
1. put a couple inches of fluid in the jar, put the neoprene tube (tight fit, might not be neoprene, Lowes, Ace hardware and other places have a rack of flexible clear tubing that is cheap by the foot) on the bleeder nipple. you might need to stick the end of the tube through a small box end wrench to hold it down in the fluid.
2. loosen the bleeder and the tighten just enough. have the person helping you pump up the brakes and then hold the pedal down. crack open the bleeder and the pedal should go to the floor. tell them to hold it there. tighten the bleeder.
3. repeat, whack the caliper and repeat. you will be able to see if there are air bubbles coming out and also if there is discolored brake fluid.
4. repeat at each wheel using your method above. the reason for the RR as the starting point is that it is the furthest and you push the most dirty fluid out of the system by going to it first.
BUT you do need to actually push enough fluid through to flush the system. This is one important aspect.
The other is to have the person helping you to hold that pedal down until you tighten the bleeder. Having a hose on it keeps it from sucking air (I even put some clamps on the hose if I am starting the process by myself) through the end, but if it is not tight and the pedal is released, it can suck air around the tapered seat down in the caliper itself.
You have to keep the pedal down and make sure that the master cylinder doesn't go dry or you will get an air bubble in the lines, which can migrate to the ABS unit.
The only time I have had to have someone bleed my brakes in the last 45 years is when I put completely new lines on my 2500HD diesel pickup. I put a complete set of stainless lines (front to back, including flex lines) and there was no way to keep air out of the ABS unit. On 2004 era GM/Chevy pickup trucks (that used the same ABS unit as the 2500HD) a GM Tech2 tool is needed to cause all 6 valves in the ABS to function and release the air. It took me 2 quarts of fluid to get it working partway and a Chevy dealership another 2 quarts, a Tech2 and time to finish the bleed.
Presuming you are certain it is not air in the system - Have you considered that the pads may still be bedding in? I've found on some cars that the pedal feels funny after a brake change but once the pads bed in it feels normal again. There is a bedding procedure in the FSM.
not everybody is as capable as the person next to them...i'm not a complete idiot but i'm also not a mechanic. i tried for 2hr to bleed my brakes (i tried both 1-man and 2-man method) and couldnt get it quite good enough. This was the first time in my life i tried to bleed brakes. I had just completed a full caliper removal (to paint all 4 of them) and i installed SST lines at all 4 corners so maybe i had a little bigger challenge than the Op had/has but i failed and for me, the $44 was WELL spent...in the process i learned something.
I had just completed a full caliper removal (to paint all 4 of them) and i installed SST lines at all 4 corners so maybe i had a little bigger challenge than the Op had/has but i failed and for me, the $44 was WELL spent...in the process i learned something.
if you didn't put plugs on the ends of the lines while you were painting the calipers and installing the flex lines, then you got air into the system. bleeding the brakes won't get air up into the lines unless a person lets the master cylinder go dry and sucks air down into the tubes, which then changes the entire procedure (on cars with ABS units, it is not like the old days when you just pumped a quart or 2 through to get the bubble out).
Originally Posted by 96LT1AUTO
Has anyone used the hand bleeder pump you can get at harbor freight/any parts store?
yes, me. spent the money, used it once, went back to the old fashioned way. it is still sitting on the shelf a couple years later. not that it is a bad tool, just I have always had better results bleeding them by hand.
it (bleeding tool) will suck fluid through, but when the other person holds the pedal down, there is pressure on the fluid.
one other thing I forgot, the last time of pumping it up and holding the pedal, simply crack it a little so it squirts some fluid but immediately tighten it back so that there is still pressure on the fluid. that way you can be 100% sure no air was sucked back in.
bleeding brakes is not a highly technical mechanical job. you just have to go through the steps.
I didn't want to drive my car until I got the timing gears and chain chainged out(168000).
I was starting the car every week to charge the battery. Went to pull it in for timing gear change and brake pedal stiff. inspected booster and a 4 inch crack somehow happened, mine was on top but inspect all around for exterior cracking.
If you have a compressor with a decent sized tank you can use a pneumatic vacuum bleeder. This winter I replaced all my brakes and installed stainless braided hoses. I bought the below pictured unit and it worked very well. It even comes with a reservoir replenisher that prevents the master from getting sucked dry. I did a complete system flush, including the abs unit. Worked well for the clutch as well. Food for thought if you think air may be the issue.
As an fyi I did use some of the adapters from a MightVac (hand op vac pump) that fit the bleed screws better. That may be a shortcoming of this unit.
06-23-2017, 09:05 PM
Brake pedal heavy and not as responsive...???
Thanks in Advance
) says that if your brakes felt and worked just fine before (other then needing new rotors and pads) i wouldnt even consider tearing the brake system apart to find a gremlin...i'd inspect the work that was just performed. good luck 
