[happydappyman]

i have a 1999 300m, and im noticing you have to press really quite hard on the pedal to stop quickly. the only other cars i have much experience driving are smaller. (ford focus, saturn l300) and were light so stopped easy. or they were new cars (KIA optima) with way over-boosted brakes. Anyway, its winter now and i'm in Canada, so its not exactly a big deal if braking force is down, because if anything it helps on ice. but during the summer on a dry road, even if I'm standing on the brakes, I MIGHT be able to get the wheels to just chirp as i slow down. certainly not enough that my ABS has to engage though and its a little concerning because it makes quick stops extremely difficult. Now, I don't know what this car felt like new, but are the brakes always like this? i replaced the rotors and pads myself and it helped a little. but im thinking maybe worn out expanding brake lines or the brake booster? does anyone want to back me up on that? or do you think calipers? even with new pads and disks i still need to literally stand on the pedal to stop fast. Oh I saw some vented Disks for the 300m, I like the looks of those.

 

[ImperialCrown]

Welcome to Allpar. The 300m already has good large vented discs. Front (and to a lesser extent, rear) pad material is an important choice to make. Fronts do about 80% of your stopping.
Hard, metallic brake pads will last a long time but not 'grip' as well as cause longer braking distances. They tend to be harsh on rotors and often outlast the rotors.
Softer, semi-metallic or organic pads will grip better, have a shorter life, make more dust, but tend to be gentle on rotors.
A good compromise for me is the ceramic brake pads that seem to have the best attributes of all. A lot less black dust too.
The power brake booster has to have a good closed throttle vacuum supply and no internal leaks.
A good 2nd opinion can't hurt either. Many brake shops will offer a free road test/4 wheel brake inspection and check the caliper-apply balance at all 4 wheels.

 

[happydappyman]

hey thanks, mine doesn't have vented disks...weird. i guess some sub-par brake components might have been installed by the previous owner.

(*EDIT i read it over, yeah the brakes are vented but not slotted, i saw some slotted disks for this car, THATS what ill be upgrading to. sorry brain-fart)
thanks for the recommendations about pads though. i think i'm going to get the slotted/drilled disks, and my next pads will probably be ceramic. If not ceramic then semi metallic. actually i thought you could get the slotted/drilled rotors with the police brake package? do calipers wear out slowly and become less efficient? or do they just go from working great to getting stuck and being broken with no noticeable drop in performance between?

 

[valiant67]

How is the pedal feel? Does it seem normal, yet there is poor braking action?
Or does the pedal seem hard to press?

 

[happydappyman]

I would say the pedal is a little hard to press yes. but only for the second half of the travel. to get the car to stop with any sort of quickness, i definitely need to press pretty hard (stand on it). like i said, second hand owner, so im not sure of the original feel... there's no way i could get it close to the floor without standing on the pedal though, that's forsure. once the pedal is pressed down near the floor, the car stops very fast.

 

[valiant67]

A hard pedal could be from a problem with the power brake booster. They are vacuum operated and can develop a leak but I'm not entirely convinced that is your problem either. too bad you don't have a similar car with decent brakes to compare it to.

 

[happydappyman]

yeah, i wish. Anyway, a rebuilt brake booster isn't too expensive and i can replace it myself. So maybe in the spring ill just buy one and try it, the car is almost 14 so it cant hurt anyway. As for the dew disks, i might just wait a little till these wear out. like i said, i replaced the pads and disks recently cause the guy who had the car before me had terrible brakes on it. thanks for the help. if there are no other ideas, ill be sure to post the outcome of the new booster. Im gonna check if this car has steel brake lines.

 

[valiant67]

Sometimes the booster will fail because the rear of the master cylinder leaks brake fluid into it. Though the fluid that leaks through gets sucked into the engine and burnt due to the vacuum, it can damage the booster. It may be worth changing booster and master cylinder both.

 

[happydappyman]

thanks for the tip. i have a friend who is a mechanic, I just don't see him often. before i replace anything i might have him look over it and see if he agrees. when it comes to brakes though, i have no problem replacing worn parts.

 

[ImperialCrown]

A 2nd opinion or diagnosis is much better than just replacing possibly still-good parts.

 

[happydappyman]

you know what? I was driving today and because of all this talk on the forums, i decided to test my brakes a little more. some of the roads here have dried up and so i had a chance to test my pedal feel because that came up in discussion. I hate to do this to you guys, but i pressed the pedal today and i can actually get it all the way down to the floor, and at that point the braking performance is still bad. So i guess the problem might be a different one than we thought. It does require some effort to get down there, but not too much. At that point it brakes as i described before, pretty fast, but not fast enough to get my ABS involved or i think even come close... very concerning especially with the relatively new pads and disks. Master brake cylinder u think? Sorry for changing symptoms on you guys! Also im going to check my brake fluid.

 

[ImperialCrown]

If the brake pedal can actually touch the floor board, the problem is either hydraulic or mechanical. Sometimes a 2nd 'pump' will bring the pedal up.
If the new pads are 'hard' it may affect pedal feel and stopping distance, but wouldn't cause a physically low pedal.
Let a technician give you his opinion. Something is not right.
A master cylinder is just another guess. it could be a number of things.
You might try a 4-wheel brake fluid bleed first to check for air, fluid condition, caliper/pad movement and a good squirt out of the bleeders all around.

 

[happydappyman]

thanks for the help. if it doesn't get worse ill take it into a shop in the spring to get another opinion. Its been consistent for the entire time iv had it so im not too worried about it suddenly getting worse. Until then, i have more brake force than i can use on the snow anyway. if there's nothing else said here, ill be sure to look around the forums and try to learn some stuff about the car. Ill post anything new i do to the brakes!

 

[Dave Z]

You might try a 4-wheel brake fluid bleed first to check for air, fluid condition, caliper/pad movement and a good squirt out of the bleeders all around.

It sure does sound like whoever had it before you, did not bleed it properly. That will certainly cause the conditions you are feeling especially when coupled with rubbish pads.

The original Mopar pads were very good. The Mopar Value Line feel and perform poorly.

 

[78LilRed]

Great advice to start with a complete fluid flush and fill with DOT4 fluid.

 

[happydappyman]

thanks for the bleed tip, ill try that.

 

[raymondo112]

You mentioned you replaced the brakes yourself, did you lubricate the slides properly, clean the oil off the rotors, and I have seen certain situations where people have gotten the calipers on the car and bolted them but they are not right and making good contact with the rotor, this is usually from inexperience, I would jack up the car take off the wheels grab a long enough stick or bar place it against your driver seat, and get the seat as far forward as you can and have the stick or bar on the brake pedal to apply pressure so you can see how the calipers look with the pads on the rotor. You should never have to go all the way down to the floor to get the car to stop good, so I have reason to believe your calipers are not on right and the pads probably are not making good contact with the rotor, you can probably have one foot on the brake and one on the accelerator pedal and then not be able to keep the car from moving forward that means the calipers are not able to put the pads to the rotor enough to hold it solidly. If the brake pedal was squishy you have a leak or air in there, if it is rock hard the booster has failed or there is no vacuum going to the booster.

These cars are not superior in brake performance under hard driving I can tell you that, but they can and will stop in the state of emergency in normal driving and do it quite well and effectively, changing brake boosters and all that is foolish and time consuming and a headache for nothing as it probably is not even close to being the problem here.

All else fails you can go ceramic which is expensive on Chryslers and will shorten your stopping distance a lot worth it if you want to spend the money, I have always ran semi metallic and never had problems with these LH cars, and mine have never made noise during stopping either if you do a brake job the right way there should be no problems, its when you just swap old parts for new parts, there is more to a brake job than that which is why not everyone that works on cars knows cars and should be servicing them, theres a big difference between paying backyard bob and an ASE certified tech and believe me you are not getting the same quality by far. If you are 100% not sure bring it to a quality shop please and not some joker who tells you he is a mechanic cause nothing on cars is mechanical anymore so no need for a mechanic.