When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I took my 1996 Lt1 in for an oil change. I knew it needed brakes in the front. The shop mentioned it needed back brakes too.
When it went in the shop it actually stopped well. I had good pedal travel and feel and required little effort to stop the car.
Now I have new pads all around and it stops horrible and I have to mash the pedal down to stop at all. Has very little pedal travel too.
I've had it back to the shop twice and they say they can't figure it out. Next they are going to try a different brake pad. I really don't think that's it. They say they checked the booster and master but they are ok. They also bled them again and checked the lines for blockage. They mentioned some brake equalizer as well that was working.
Any ideas out there? Seems like it should stop better now than before but they can't figure it out.
My feeling is they blew out the booster pumping it too hard but I'm not a wrench guy. No faith left in this shop.
Any pointers?? Hard pedal, no stopping power.......
99% of the time a hard brake pedal is caused by a ruptured brake booster diaphragm. I guess the connection to the plenum could be open.
Are they fully metallic or semi-metallic pads? Those require a lot of heat to start working efficiently. That's why they're normally only used on race cars. They can also outgas and lift the pads off the rotor like an air hockey puck, which is the reason for slots and holes in rotors.
If the pedal effort is very hard then you have a power booster issue. If the car just takes longer to stop then it is cheap *** pads the shop put on to make more profit. I would put Hawk HPS pads on if for the street. They work great for the street.
Most shops put cheap pads on them. Turn your car off and pump the brakes about ten times. Press your foot hard on the brake pedal and simultaneously start the engine. If the pedal moves down further when the engine is started the booster should be okay.
To give a quick check of the booster, start the engine for 10 seconds and then turn it off.
Then press on the brake pedal. It should feel normal and go down to a normal point with a slight whoosh sound.
The second press on the pedal should get harder and have less travel than the first time (with a slight whoosh sound).
The third time travel should be quite shorter and feel real hard. Anything after that when you press should be a high pedal and feel real hard.
If this test does not fit you results, the booster can be bad.
All I can think of is when the brakes were bled, excess travel of the brake pedal could have ruined an older booster. Just a theory.
Also if they got the proportional valve out of position in the master, it can cause a similar effect and might even light up the brake light on the dash. (Another in depth opinion).
I'm sure they used cheap pads as the whole job cost $330.
I'm also sure they pumped the hell out of the brakes to bleed them.
I am going to try all those ideas you gave me.
In the end I'm going to let them put on the Wagner pads they offered.
I'll let you know when is fixed what fixed it.
Right now I'm looking for a C4 ZR1 to buy. I have the 14 but dig the C4.
Thanks members!!
Mike
Originally Posted by pcolt94
Pads can be a big factor.
To give a quick check of the booster, start the engine for 10 seconds and then turn it off.
Then press on the brake pedal. It should feel normal and go down to a normal point with a slight whoosh sound.
The second press on the pedal should get harder and have less travel than the first time (with a slight whoosh sound).
The third time travel should be quite shorter and feel real hard. Anything after that when you press should be a high pedal and feel real hard.
If this test does not fit you results, the booster can be bad.
All I can think of is when the brakes were bled, excess travel of the brake pedal could have ruined an older booster. Just a theory.
Also if they got the proportional valve out of position in the master, it can cause a similar effect and might even light up the brake light on the dash. (Another in depth opinion).
Last edited by msaporetti; 12-26-2014 at 12:29 AM.
I did not know my 1996 had a brake equalizer. Need to check my service manual for this.
There is no need for an equalizer as the master cylinder has that function designed in.
Originally Posted by l98tpi
If the pedal effort is very hard then you have a power booster issue.
that is easy to check and should be first. Often, I find a problem where someone had their hands/tools. The booster may be fine, but not getting proper vacuum, which may simply be poor connection of the vacuum connection to it or a problem in the line from the intake manifold.
Last edited by whalepirot; 12-31-2014 at 01:33 AM.
There is no need for an equalizer as the master cylinder has that function designed in.
that is easy to check and should be first. Often, Ii find a problem where someone had their hands/tools. The booster may be fine, but not getting proper vacuum, which may simply be poor connection of the vacuum connection to it or a problem in the line from the intake manifold.
It's called a proportioning valve. It adjusts the proportion of pressure that goes to the rear brakes. Most of your stopping power is in the front brakes (which is why they're much larger than the rears), so the proportioning valve reduces the pressure going to the rear brakes. Otherwise they would lock up very easily.
If you have a very hard pedal and it takes a while to stop: it is likely the booster is at fault - as pointed out by many before me.
Where to look: There is a black plastic diaphram attached to your fire wall immediately behind your master cylinder.
When my 93 had this condition, I replaced the booster. When I did my initial inspection, I saw a pretty massive crack at the top of the plastic diaphram, and when the car was running you could hear an air/vacuum leak.
When I replaced my booster, I did some investigation to see if I could replace it with a metal one: IIRC the ZR1 booster is metal, all others are plastic. The ZR1 booster was very expensive, and I decided that it was not worth the $/performance upgrade and got a replacement plastic one.
If you're looking in the area to see if the booster is damaged, you can also do a quick inspection of the hose that connects to the booster, that may be another culprit.
In my opinion, I would not bother waste my time taking the car back to the shop that replaced the pads (to put a different set in??), I would instead invest time in investigating the booster/ vacuum loop.
As a final comment on this topic, the replace job of the booster is pretty easy.
Inspect, as above, the booster, large-ish rubber vacuum line into it and for proper seating of the plastic fitting into the booster; the piece the hose attaches to entering the boost unit through a rubber seal. When running, you may (or not) hear hissing. Some search for vacuum leaks by spraying WD-40 or such, while listening or watching for RPM changes; messy, tho. I prefer a gauge.
Last edited by whalepirot; 12-31-2014 at 01:41 AM.
12-25-2014, 01:29 AM
Hard brake pedal?
